SERVICE MANUAL AHE-450-DE4 - Aqua
AHE-450-DE4
SERVICE MANUAL
© 2012 Aqua-Hot Heating Systems Inc.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 2 —
Table of Contents
Section 1: Introduction to the Aqua-Hot 450-DE4
Introduction ............................................................................................................... ..Page 6-7
Danger, Warning, Caution, and Note Box Definitions................................................... ...Page 6
Section 2: Aqua-Hot Hydronic Heating System Overview
Technical Information ................................................................................................... ...Page 8
I.D. Label Sample ......................................................................................................... ...Page 9
Component Overview .................................................................................................Page 9-11
Aqua-Hot Operational Flow-Chart .............................................................................. ..Page 12
Antifreeze & Water Heating solution...................................................................... ..Page 13-14
Section 3: Interior Switch Panel
Diesel-Burner Switch .................................................................................................. .Page 15
Electric Element Switch .............................................................................................. .Page 15
Engine Preheat Switch ............................................................................................... .Page 15
Pin Label ................................................................................................................ Page 16-17
Section 4: Exhaust System Requirements
Exhaust System Requirements .................................................................................... .Page 18
Section 5: Aqua-Hot 450-DE4 Components
Interlock Switch ..................................................................................................... ….Page 19
Fluid Level Sensor ................................................................................................ ..Page 20-21
Control Thermostat...................................................................................................Page 21-22
A.C. High Limit Thermostat .......................................................................................... Page 23
D.C. High Limit Thermostats ........................................................................................ Page 24
Low Temperature Cut-Off Thermostat ......................................................................Page 25-26
Check Valves ...........................................................................................................Page 26-27
Tempering Valve ......................................................................................................Page 28-29
Circulation Pumps 1 & 2 ...........................................................................................Page 29-31
Stir Pump .................................................................................................................Page 32-33
Engine Preheat Pump ..............................................................................................Page 34-36
Electric Heating Element ..........................................................................................Page 37-38
A.C. Relay .................................................................................................................... .Page 39
Section 6: Electronic Controller
General Facts ............................................................................................................... .Page 40
Secondary 12 Volt DC battery Connection ................................................................... .Page 41
Terminal Strips with Screw-Type Fasteners ................................................................. .Page 41
Low Voltage Reset Feature .......................................................................................... .Page 42
Replacement Procedure ............................................................................................... .Page 43
Proper Jumper Pin Formation ...................................................................................... .Page 43
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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Table of Contents
Section 7: Electronic Controller Indicator Lights
Electric Heating Element Status Indicator Light ........................................................... Page 44
Heating Zones Status Indicator Lights 1-5 ................................................................... Page 44
Low Battery Voltage Fault Indicator Light ..................................................................... Page 44
Low Temp Cutoff Status Indicator Light ....................................................................... Page 44
Low Tank-Level Cutoff Indicator Light .......................................................................... Page 44
Heating Status Indicator Light ...................................................................................... Page 44
Engine Preheat Pump Indicator Light ........................................................................... Page 44
[Circulation] Pump #1 Indicator Light............................................................................ Page 45
[Circulation] Pump #2 Indicator Light............................................................................ Page 45
[Stir] Pump #3 Indicator Light ....................................................................................... Page 45
Diesel-Burner Status Indicator Light ............................................................................. Page 45
Overload Fault Indicator Light ...................................................................................... Page 45
Section 8: Diesel-Burner
Overview ...................................................................................................................... Page 46
I.D. Plate ...................................................................................................................... Page 46
Diesel-Burner Overview ............................................................................................... Page 47
Diesel-Burner Operational Flow Chart .......................................................................... Page 48
Diesel-Burner Operational Overview ...................................................................... Page 49-51
Section 9: Detaching and Reattaching the Diesel-Burner
Detaching the Diesel-Burner .................................................................................. Page 52-54
Reattaching the Diesel-Burner ............................................................................... Page 55-57
Section 10: Diesel-Burner Components and Repair Information
Diesel-Burner Component Overview ............................................................................ Page 58
Motor ...................................................................................................................... Page 59-62
Flame Sensor ......................................................................................................... Page 63-64
Ignition Electrodes .................................................................................................. Page 65-66
Fuel Nozzle ............................................................................................................ Page 66-67
Fuel Solenoid ............................................................................................................... Page 68
Fuel Pump .............................................................................................................. Page 69-71
Bearings ................................................................................................................. Page 72-74
Ignition Coil ............................................................................................................ Page 75-76
Controller ................................................................................................................ Page 77-78
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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Table of Contents
Section 11: Troubleshooting
If the Aqua-Hot is Black Smoking ................................................................................. Page 79
If the Aqua-Hot is Blue/White Smoking ........................................................................ Page 80
If one of the Aqua-Hot’s Heating Zones will not get hot................................................ Page 81
If there is a lack of domestic continuous hot water ....................................................... Page 82
If there is antifreeze leaking ................................................................................... Page 83-84
Appendix A: Wiring Diagram .........................................................................................Page 85-87
Appendix B: Wire Gauge Chart ......................................................................................Page 88-89
Appendix C: Fuel Pressure check and Adjustment .....................................................Page 90-95
Appendix D: Extreme Cold Weather Operation ............................................................Page 96-97
Appendix E: Aqua-Hot Annual Maintenance ..............................................................Page 98-111
Appendix F: Winterization Process .................................................................................. Page 112
Appendix G: Filling/Draining the Aqua-Hot ..............................................................Page 113-116
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 1: INTRODUCTION
This service and parts manual is designed to aid
trained and qualified service technicians with
the process of troubleshooting and servicing the
Aqua-Hot 450-DE4 Hydronic heating system.
The Aqua-Hot 450-DE4 heating system features a 12 VoltDC powered diesel-burner and a 120 Volt-AC, 1650 Watt
electric heating element. These two heating sources are used
in conjunction with an FDA-approved “GRAS” (Generally
Recognized as Safe) propylene glycol based boiler antifreeze
and water heating solution in order to provide a continuous
supply of domestic hot water, interior/fresh water tank heating, independent interior zone heating, and engine preheating. Be sure to reference Figures 3 through 5 for a complete component overview.
Please note that all Danger, Warning, Caution, and Note boxes, appearing as needed throughout this manual, must be
reviewed and adhered to during any service procedure in
order to avoid potential hazards, which could result in injury,
product damage, or property damage.
Should additional assistance be needed, please contact the
technical support department at 1-800-685-4298, Monday
through Friday, between the hours of 7:00 AM and 4:00 PM
Mountain Standard Time.
Danger, Warning, Caution, and Note Boxes:
Danger, Warning, Caution, and Note boxes appear throughout this manual as a means of alerting the service technician
to important information.
INDICATES THAT PERSONAL INJURY IS LIKELY OR
IMMINENT.
Indicates that serious damage to the heater will occur
and personal injury is possible as well.
Indicates that damage to the heater is possible.
NOTE: Indicates information that requires special attention by the service technician
TO THE
AQUA-HOT 450-DE4
Understanding the Aqua-Hot 450-DE’s Major Systems:
The basis for the Aqua-Hot heating system’s functionality is
the antifreeze and water heating solution, which is comprised
of water that is distilled, de-ionized, or soft, as well as FDAapproved “GRAS” propylene glycol based boiler antifreeze.
Through this solution’s ability to maintain and transfer heat,
the Aqua-Hot’s three major systems: the domestic water
system, engine preheat system, and interior heating system,
are able to function effectively. This antifreeze and water
heating solution is contained within the Aqua-Hot’s boiler
tank and is heated by the diesel-burner when its operating
criteria are met and/or the electric heating element when its
operating criteria are met. In order for the diesel-burner to
be considered as a heating source by the Aqua-Hot, it must
have an adequate fuel supply, receive power from the electronic controller, and be selected as a heating source from the
interior switch panel. In order for the electric heating element to be considered as a heating source by the Aqua-Hot,
it must receive power from either a generator or from shore
power and be selected as a heating source from the interior
switch panel. Once the antifreeze and water heating solution
achieves operating temperature (as determined by the AquaHot’s control thermostat), the domestic water system, the
engine preheat system, and the interior heating system are
permitted to operate as needed.
Domestic Hot Water Priority System:
The Aqua-Hot 450 is a Hot Water Priority System. Meaning, that the Aqua-Hot 450 cannot heat the interior of the
motor home, and produce continuous hot water simultaneously. When Domestic Hot Water is being used, the interior
heating system will shut down, until no more Domestic Hot
Water is called for.
The domestic hot water priority system is responsible for
providing hot water whenever a hot water faucet is opened
such as with a shower or sink.
When hot water is requested, domestic water from the motor
home’s fresh water tank is transported through a copper coil
in the Aqua-Hot’s boiler tank where heat is transferred from
the heated antifreeze and water heating solution to the domestic water flowing through the copper coil. The heated
domestic water then flows through the tempering valve to be
mixed with cool water from the fresh water tank to achieve
an appropriate temperature before it flows to the faucet requesting hot water.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 1: INTRODUCTION
Engine Preheat System:
The engine preheat system is responsible for heating the motor home’s engine block in order to make it easier to start-up
when cool weather conditions exist.
When the engine preheat system is activated via the interior
switch panel, the motor home’s engine coolant is circulated
through a dedicated copper coil in the Aqua-Hot’s boiler
tank, where heat from the antifreeze and water heating solution is transferred to the motor home’s engine coolant. The
heated engine coolant is then transported back to the engine
where it transfers the heat to the engine to gradually warm it.
Additionally, the Aqua-Hot 450-DE includes a motoraide
feature, which uses the circulation of the motor home’s engine to transport the engine’s coolant from the Aqua-Hot’s
boiler tank to the motor home’s warm engine and back to the
boiler tank. Through this process, the boiler tank is kept
heated, which reduces the time required to bring the tank to
operating temperature for interior heat and continuous domestic hot water. This motoraide feature is part of the engine preheating feature and plumbing system, and requires
no action on the user’s behalf to function.
Interior Heating System:
TO THE
450-DE4
Aqua-Hot’s boiler tank to be re-heated before being sent
back through the loop again. This process continues until the
pre-set temperature of the interior is reached, and the interior
room thermostat signals the electronic controller that heat is
no longer required.
AC Circuit:
Although the diesel-burner is the primary heating source for
the Aqua-Hot and is necessary for providing continuous domestic hot water, an alternate heat source exists for moderate
temperatures, which functions with an AC circuit. Whenever
the motor home is connected to an AC power source plugged into shore power or using a generator, the AquaHot’s electric heating element has the ability to function in
order to provide heat for the boiler tank.
When the antifreeze and water heating solution falls below
operating temperature (as determined by the control thermostat), a signal is sent to the electronic controller requesting
heat. Because the electric element switch is activated on the
interior switch panel, the DC power from the electronic controller is permitted to flow to the AC relay, which activates
the relay in order to allow AC power to flow to the electric
heating element. When the electric heating element receives
power, it becomes active and supplies heat to the boiler tank
until operating temperature is reached.
The interior heating system is responsible for providing heat
to the motorhome’s interior in order to maintain the temperature at a comfortable level.
For interior heating, it is the room thermostats that trigger the
Aqua-Hot’s interior heating system. When a thermostat recognizes that heat is required in a particular area, it sends a
signal to the Aqua-Hot’s electronic controller calling for
heat. The Aqua-Hot responds by activating the circulation
pump for that zone, which sends the heated antifreeze and
water heating solution through the Heating Loop corresponding to the zone requesting heat. The fans on the heat exchangers in the zone calling for heat are also activated; therefore, as the heated solution flows over the heat exchanger’s
fins, the heat is transferred to those fins and dispersed into
the interior of the motor home by the fans. Until the thermostat signals that heat is no longer required, the Aqua-Hot will
continue to send the heated antifreeze and water solution
through the loop, which returns the cooled solution to the
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 2: AQUA-HOT 450-DE4 OVERVIEW
Figure 1
Aqua-Hot 450-DE Technical Specifications
Diesel-Burner, Heat Input (Firing Rate) ................................................................................................................................................ 56,000 BTU/hr
Diesel-Burner, Fuel Consumption (Continuous Operation) ......................................................................................................................0.40 gal/hr
Heater, Voltage/Maximum Power Consumption .................................................................................................................... 12 Volt-DC/60 watts
Electric Heating Element specifications ................................................................................................................................ 120 Volt-AC/1650 watts
Zone Heat Circulation Pump specifications ................................................................................................................ (2) 12 Volt-DC/21 watts each
Number of Heating Zones .................................................................................................................................. maximum of 5, plus Engine Preheat
Domestic Water Heating Capacity ...........................................................................................................................................continuous/on-demand
Antifreeze Type Used ............................................................................................. Generally Recognized as Safe by the FDA - Propylene Glycol
Dimensions .................................................................................................................................................................................... 12”H x 18.5”W x 30”L
Dry Weight ..................................................................................................................................................................................... approximately 127 lbs.
Wet Weight ..................................................................................................................................................................................... approximately 184 lbs.
NOTE: All vehicle installations must comply with the requirements listed in the Recreational Vehicle Industry Association’s
(RVIA) ANSI/NFPA 1192 Handbook for Recreational Vehicle Standards. To receive a copy of this handbook and other pertinent RVIA Standards, write to: Recreation Vehicle Industry Association, 1896 Preston White Drive, P.O. Box 2999, Reston,
VA 22090-0999, call them at (703) 620-6003, or visit them online at www.rvia.org.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 2: AQUA-HOT 450-DE OVERVIEW
Refer to Installation
Manual
Figure 2
Figure 3
AC
Wiring
Port
Heating Zone
1 Outlet Port
Heating Zone
2 Outlet Port
Wiring Harness
& Harness Port
Diesel Fuel
Lines
VAC
Terminal
Block
Diesel
Burner
VAC
Access
Panel
Interlock
Switch
Zone 1
Circulation
Pump
Zone 2
Circulation
Pump
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 2: AQUA-HOT 450-DE OVERVIEW
Figure 4
2
4
6
1
5
3
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 2: AQUA-HOT 450-DE OVERVIEW
3
Figure 5
2
1
4
5
6
7
1
AC Wiring Cable Clamp
2
Heating Zone Outlet Ports
3
Heating Zone Inlet Ports
4
I.D. Label Location
5
Diesel Fuel Inlet/Outlet Ports
6
Air-Release Valve
7
Expansion Tank Connection
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 2: AQUA-HOT 450-DE4 OVERVIEW
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 2: AQUA-HOT 450-DE4 OVERVIEW
Antifreeze and Water Heating Solution:
As the antifreeze type and mixture ratio is essential to the
Aqua-Hot’s performance and ability to comply with regulations, the following information is being supplied to
understand various types of antifreeze, the quality of water necessary, and the mixture ratio. Aqua-Hot Heating
Systems Inc. recommends CAMCO’s Boiler Antifreeze
-100°.
tivity characteristics. Although these types of antifreeze
products are considered less toxic and safer than ethylene
glycol for people, pets, and the environment, they are not
“Generally Recognized as Safe” (GRAS) rated by the FDA.
Therefore, they must be marked with a “harmful if swallowed” warning. This additional warning is required because these types of antifreeze products contain high levels
of chemical inhibitors. Due to their potentially hazardous
properties, they should never be used in the Aqua-Hot’s
Hydronic Heating System.
Antifreeze Types:
Antifreeze Mixture Water Quality:
The following information addresses the necessary usage of
a propylene glycol based “boiler “ type antifreeze in the Aqua-Hot. Propylene glycol is a safer alternative to the more
toxic ethylene glycol antifreeze; however, as mandated by
IAPMO (International Association of Plumbing and Mechanical Officials), only those propylene glycol based “boiler”
type antifreezes deemed “Generally Recognized as
Safe” (GRAS) by the FDA should be utilized.
Because of the significant impact various types of antifreeze
can have on a Hydronic heating system, including the level
of safety provided, it has been recognized that there is a need
to provide an explanation regarding two additional prominent types of antifreeze/coolant available. The following
information should be utilized as an educational means of
ensuring that the proper type of propylene glycol based antifreeze is selected:
RV & Marine Antifreeze:
These types of propylene glycol based antifreeze products
are formulated specifically for “winterizing” applications
only. Although RV & Marine antifreeze is often “Generally
Recognized as Safe” by the FDA, it should never be used in
the Aqua-Hot’s Hydronic Heating System. This type of antifreeze is not formulated to transfer heat, which is essential to
the heating system’s functionality and does not contain rust
inhibitors. Please note, however, that RV & Marine antifreeze can be utilized to winterize the Aqua-Hot’s domestic
water heating system.
Automotive Antifreeze/Coolant:
These types of propylene glycol based antifreeze products
are formulated specifically to protect automotive engines
against corrosion, freezing temperatures, and overheating.
They also have excellent heat transfer and thermal conduc-
In order to ensure maximum performance and longevity of
an Aqua-Hot heating system’s boiler tank and associated
components, it has been determined that there is a need to
use distilled, de-ionized, or soft water in combination with
concentrated propylene glycol for the Aqua-Hot’s antifreeze
and water heating solution,. Please note that this is only necessary when mixing concentrated propylene glycol antifreeze
with water; suppliers of pre-mixed antifreeze are responsible
for the use of high-quality (distilled, de-ionized, or soft) water when preparing their antifreeze for sale.
Hard water possesses a high-level of calcium and magnesium
ions, which deplete the propylene glycol antifreeze’s corrosion inhibitors. This, in turn, causes the antifreeze and water
heating solution to begin turning acidic, which can corrode
the Aqua-Hot’s boiler tank and associated components prematurely. Therefore, concentrated propylene glycol should be
diluted with distilled, de-ionized, or soft water that is 80
PPM or less in total hardness. The local water agency should
have up-to-date water quality reports that should indicate if
the local tap water is within this guideline.
Antifreeze Terms and Mixture Ratio:
The following information addresses the process of selecting
an antifreeze and water mixture ratio that provides adequate
freeze, boiling, and rust/anti-corrosive protection. A 50/50
mixture of propylene glycol / water ratio is recommended,
which will result in a freeze point of approximately -28°F
and a boil point of approximately 222°F.
The following information should be utilized for the purpose
of clarifying some terms commonly associated with antifreeze.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 2: AQUA-HOT 450-DE4 OVERVIEW
Freeze Point and Burst Point:
Antifreeze lowers the freezing point of any liquid, to which it
has been added, by preventing the formation of ice crystals;
however, as the ambient temperature continues to decline,
the water in the solution will attempt to attain a solid state.
The point in which the water begins to solidify is termed the
“Freeze Point.” Although the water in the solution has begun to freeze, producing a “slushy” consistency, the antifreeze in the solution will continue to combat the normal
expansion of the solution as it freezes. The point in which
the solution can begin to expand, due to colder temperatures,
is called the “burst point.” Once the solution reaches the
burst point, the potential is present for ruptured pipes to exist. The burst point of the antifreeze and water heating solution is dependent upon the brand of propylene glycol employed.
Antifreeze is also primarily responsible for heat transfer
characteristics. Therefore, as water is an excellent heat conductor, it is added to the mixture. A 50/50 solution of propylene glycol antifreeze and water is recommended to provide the best performance combination of the aforementioned functions. If excess propylene glycol exists within an
antifreeze and water heating solution, the water’s heat absorption properties are compromised, which could ultimately
inhibit the Aqua-Hot from providing adequate domestic hot
water and interior heating.
Additionally, if the antifreeze and water heating solution
contains over 70 percent antifreeze, the freezing point is actually raised, resulting in less freeze protection.
Boiling Point:
The Aqua-Hot utilizes the antifreeze and water heating solution as a transportation means for the heat produced from the
internal processes. The antifreeze absorbs the heat created
until its boiling point is reached; it is at this point that the
liquid turns to a gas and is expelled to prevent the heating
system from overheating. Each time the boiling point is
reached, a loss of efficiency occurs because the heat produced is expelled rather than used for the function of the
heating system. Therefore, a higher boiling point is desired
in order to combat the loss of efficiency, which allows the
antifreeze to transport the heat created from the internal process throughout the motor home where it can be used productively rather than dissipating due to its change from a
liquid to a gas.
Rust and Anti-Corrosive Inhibitors:
Another major function of antifreeze is to provide protection
to the internal metal components of the Aqua-Hot Hydronic
heating system from corrosion and rust. Antifreeze is able to
perform this function by the addition of rust- and anticorrosive inhibitors, which are designed specifically to activate in a water solution.
Summary:
Antifreeze has three basic functions: freeze protection, boilover protection, and anti-corrosion and rust protection.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 3: INTERIOR SWITCH PANEL
The interior switch panel is used to control the two potential
heating sources for the Aqua-Hot’s boiler tank, as well as to
control the engine preheat feature. When a switch is activated, the indicator light on the switch will illuminate.
Diesel-Burner Switch:
When the diesel-burner switch is in the on position, any time
the control thermostat tells the electronic controller that heat
is needed for the boiler tank, the diesel-burner will respond
by firing up and providing heat. A cold boiler tank can expect to be brought to operating temperature by the dieselburner in approximately 10 to 20 minutes. In order to obtain
continuous hot water, the diesel-burner switch must be activated.
NOTE: If the diesel-burner fails to ignite, the diesel burner
status light will go out, indicating to the customer the burner has gone into a default. To reset the default, the diesel
burner switch must be turned off for 5 seconds and then
turned back on.
Electric Element Switch:
When the motor home is plugged into an AC power source
(e.g., shore power, generator, etc.) and the electric element
switch is on, the electric heating element will be used to provide heat to the boiler tank if the need arises. A cold boiler
tank can expect to be brought to operating temperature by the
electric heating element in approximately 1 to 2 hours. The
electric element, alone, will not be able to provide continuous hot water.
Engine Preheat Switch:
The engine preheat switch activates the engine preheat
pump, which draws the motor home’s engine coolant
through the boiler tank to heat it before returning it to the
engine block to transfer the heat there. Either the dieselburner switch or the electric element switch must also be
activated in order for the engine preheat feature to function.
The engine preheat switch does not need to be activated for
the motor-aide feature to work and should be shut off when
traveling.
Additionally, the diesel-burner switch can be used to reset a
low-voltage condition. This is accomplished by turning off
the diesel-burner switch for 30 seconds, then turning it back
on.
Figure 6
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 3: INTERIOR SWITCH PANEL—MANUFACTURED UP TO AUGUST 2011
For Heaters Manufactured Before January 2011
Figure 7
For Heaters Manufactured Between January 2011 thru August 2011
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 3: INTERIOR SWITCH PANEL - MANUFACTURED AFTER 09/01/2011
Aqua-Hot 450D Interior Switch Panel Rear View
Engine Preheat
Switch
10
9
2
Jumper Wire
Jumper Wire
10
4
Switch
Diesel Burner
Switch
Electric Element
Switch
9
10
2
2
4
4
Electronic Controller
Switch
9
Electronic Controller
Pin# 2
To “Preheat-O”
Pin# 2
To “Diesel-I”
Pin# 4
To “Preheat-I”
Pin# 4
To “Diesel-O”
Pin# 9
To Chassis Ground
Pin# 10
To “IND-LT (+) B3
Pin# 9
To “IND-LT (-) B6
Engine Preheat Switch to
Electronic Controller connections
Diesel Burner Switch to
Electronic Controller connections
Switch
Electronic Controller
Pin# 2
To “Electric-O”
Pin# 4
To “Electric-I”
Pin# 9
To Chassis Ground
Electric Element Switch to
Electronic Controller connections
NOTE: The engine preheat and electric element switches possess jumper
wires, which advance from terminal 10 to terminal 4.
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© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 4: EXHAUST SYSTEM REQUIREMENTS
Because the Aqua-Hot’s exhaust is hot and must be kept
away from any heat-sensitive material, the exhaust system
should be checked to ensure that it continues to meet the
following requirements:

The exhaust must not be directed downward as a fire
could result when parked in dry, grassy areas.

The exhaust must not terminate underneath the vehicle,
underneath an open-able window or vent, in the awning
area of the motor home (if applicable), or near slide-out
areas.

The exhaust must be able to freely exit away from the
vehicle without any obstructions.

Two-inch standard automotive-type exhaust piping
should be used with a maximum of two 90-degree pipe
bends and should not exceed 20 feet.

The 3-inch and 4-inch black-pipe nipples and the exhaust elbow - originally supplied with the Aqua-Hot,
must be present.
Figure 8
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 5: AQUA-HOT COMPONENTS
If continuity is not present with the button pushed in,
follow the instructions in this section to replace the interlock switch.
This section details various components of the Aqua-Hot
that may require troubleshooting and/or replacement in
the event of a malfunction. The diesel-burner and its
components are detailed in Section 10 of this manual.
Replacement Procedure:
Replacement parts can be ordered through Aqua-Hot’s
Web site at www.aquahot.com or by calling 1-800-6854298.
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
If additional assistance is needed, the Technical Support
Team can also be reached, Monday through Friday, from
7:00 AM to 4:00 PM Mountain Standard Time at 1-800685-4298.
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
Disconnect the interlock switch’s wires by pulling the
quick connectors from the switch’s spade terminals.
2.
Release the interlock switch from the Aqua-Hot cabinet
by pushing in on the locking tabs and pulling the interlock switch.
3.
The interlock switch is a safety device designed to ensure
that the Aqua-Hot’s access cover is securely installed before
allowing the diesel-burner to operate.
Remove the defective interlock switch from the AquaHot.
4.
Install the replacement interlock switch onto the AquaHot ensuring that the locking tabs snap into place.
Troubleshoot the interlock switch if the following condition
has occurred:
5.
Connect the Aqua-Hot’s wires to the replacement interlock switch with yellow wire #24 connected to the terminal labeled “NO” and yellow wire #25 connected to
the terminal labeled “COM.”
Sensors/Switches
Interlock Switch:


The diesel-burner fails to operate.
The diesel-burner switch light does not illuminate.
Troubleshooting:
NOTE: The interlock switch will prevent the diesel-burner
from operating without the access cover intact;
therefore, the switch will need to be manually
pressed during testing for the switch’s functionality.
1.
Turn the diesel-burner switch on from the interior switch
panel and ensure that the boiler tank has sufficiently
cooled in order to require heat from the diesel-burner.
2.
Verify that the “Heating Status” and “Diesel-Burner
Status” indicator lights are illuminated on the electronic
controller.
3.
Disconnect the two yellow wires from the interlock
switch noting that wire #24 is connected to the terminal
labeled “NO” and wire #25 is connected to the terminal
labeled “COM.”
4.
Using an ohmmeter, check the interlock switch for continuity
while
the
button
is
pushed
in.
NOTE: If the interlock switch’s wires are reversed, the interlock switch will only allow the diesel-burner to
operate when the access cover is removed and the
button on the switch is released.
Figure 9
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 19 —
SECTION 5: AQUA-HOT COMPONENTS
the electronic controller extinguishes when the
jumper wire is installed, inspect the wire harness for
damaged or severed wires. If no wires are found to
be damaged or severed, follow the instructions in
this section to replace the fluid-level sensor.
Fluid-Level Sensor:
The fluid-level sensor monitors the level of antifreeze and
water heating solution within the Aqua-Hot’s boiler tank to
ensure that an adequate volume exists.
If, however, the “Low Tank-Level Cutoff” indicator
light continues to illuminate once the jumper wire is
installed, follow the instructions in this manual to
replace the electronic controller.
Troubleshoot the fluid-level sensor if one of the following
conditions has occurred:


The diesel-burner and/or electric heating element fails to
operate.
The Aqua-Hot fails to operate and the “Low Tank-Level
Cutoff” indicator light on the electronic controller is
illuminated.
Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
Troubleshooting:
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected. Also, because this replacement procedure will involve the boiler tank and the potential for hot coolant, be
sure the heater has adequately cooled.
2.
Drain the antifreeze and water heating solution from the
Aqua-Hot’s boiler tank using the drain valve.
3.
Disconnect the fluid-level sensor’s wires by releasing
the clip securing the plug to the sensor and pulling the
plug away from the sensor.
4.
Using a 7/8” wrench, unscrew the fluid-level sensor
from the Aqua-Hot’s boiler tank. It may be necessary to
use a 7/8” Crow’s Foot wrench.
5.
Add a liquid thread sealant (such as Loctite®) to the
threads of the replacement fluid-level sensor.
Verify the functionality of the fluid-level sensor by completing the following:
6.
Screw the replacement fluid-level sensor into the port on
the Aqua-Hot’s boiler tank and tighten with a wrench.
A. Remove the faceplate from the electronic controller.
7.
Plug the fluid-level sensor’s wires into the replacement
sensor and secure with the clip.
8.
Refill the Aqua-Hot’s boiler tank with the antifreeze and
water heating solution.
1.
Verify that the Aqua-Hot’s boiler tank is full of the antifreeze and water heating solution.
2.
Verify that the wire connector is securely plugged into
the fluid-level sensor and secured with the attached clip.
3.
Verify that the fluid-level sensor’s wires are securely
installed in the terminal strip on the wire harness, as well
as tightly fastened to the electronic controller.
The fluid-level sensor requires power to operate and
possesses a third wire for power (#17), which advances
from the sensor to join the red #1 wire on the “PUMP
3+” terminal on the electronic controller’s JP3 plug.
NOTE: If pump number 3 shorts out, i.e. indicator light is
red, it will cause the Low Tank-Level Cutoff light to illuminate red.
4.
B. Install a jumper wire on the JP3 plug, between pins
15 and 16 (between “LWCO-I” and “LWCO-O”) on
the electronic controller in order to bypass the fluilevel sensor.
If the “Low Tank-Level Cutoff” indicator light on
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 5: AQUA-HOT COMPONENTS
Figure 10
Fluid Level Sensor
Thermostats
Control Thermostat:
The control thermostat is installed into the Aqua-Hot’s boiler
tank and monitors the temperature of the antifreeze and water heating solution to determine when it is at operating temperature and when it requires heat. The Aqua-Hot is considered to be at operating temperature between 158°F and
190°F.
If the “Heating Status” indicator light is not illuminated,
check the following:
A. Verify that the temperature of the boiler tank has
fallen below the 158°F minimum operating temperature by checking with a digital thermometer.
B. Disconnect the control thermostat’s wires from their
connections, and, using an ohmmeter, check for
continuity.
Troubleshoot the control thermostat if one of the following
conditions has occurred:
If there is no continuity, follow the instructions in
this section for replacing the control thermostat.


If continuity exists, complete the following:

There is a lack of hot domestic water and interior heat.
The heating Status light does not illuminate on the electronic controller, when the Aqua-Hot is below 158° F.
Excessive Blue or white smoke is expelled from the exhaust.
Troubleshooting:
1.
2.
Turn the diesel-burner and electric element switches on
the interior switch panel on and check the electronic
controller to ensure that the “Electric Heating Element
Status” and “Diesel-Burner Status” indicator lights are
illuminated.
Verify that the “Heating Status” indicator light on the
electronic controller is illuminated as it should be whenever the Aqua-Hot is below the operating temperature
range of 158°F.
a.
Inspect the control thermostat’s wiring and
connections.
b.
Install a jumper wire on the JP3 plug, between
pins 13 and 14 (“TSTAT-I” and “TSTAT-O”)
on the electronic controller in order to bypass
the control thermostat.
NOTE: The diesel-burner and/or electric element
switch must be in the on position also for
the “Heating Status” indicator light on the
electronic controller to illuminate.
If the “Heating Status” indicator light on the electronic controller does not illuminate with the jumper
wire installed, follow the instructions in this manual
to replace the electronic controller.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 21 —
SECTION 5: AQUA-HOT COMPONENTS
If the “Heating Status” indicator light is illuminated, But
the diesel burner fails to come on: check the following:
1. Verify the diesel burner’s control thermostat wires
are properly connected, and that there are no loose
wires, both at the diesel burner and at the JP4 plug,
on the Electronic Controller.
2.
Using a DC Voltmeter Verify both the
C1 (Orange - #22)and the C7 (White - #23) Wires,
on the Electronic Controller’s JP4 Plug have
12VDC.
If the C7 (White - #23) Wire does not have 12VDC, and
both the Diesel Burner Status Light and the Heating Status lights are illuminated, the electronic controller will
need to be replaced.
If the C1 (Orange - #22) wire does not have 12VDC Refer to the Webasto Diesel Burner Controller Troubleshooting, in section 10.
Control Thermostat Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPLIES AND/OR TO
ALLOW THE HEATER TO COOL BEFORE SERVICING COULD
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected. Also, because this replacement procedure will involve the boiler tank and the potential for hot coolant, be
sure the heater has adequately cooled.
2.
Drain the antifreeze and water heating solution from the
Aqua-Hot’s boiler tank using the drain valve.
3.
Disconnect the defective control thermostat’s wires by
separating the quick-disconnect terminals.
4.
Using a 7/8 socket, unscrew the control thermostat from
the Aqua-Hot’s boiler tank.
5.
Wrap the threads of the replacement control thermostat
with Teflon tape.
6.
Screw the replacement control thermostat into the port
on the Aqua-Hot’s boiler tank and tighten securely with
a 7/8 socket.
7.
Connect the replacement control thermostat’s wires in
the same configuration as the removed control thermostat’s wires.
8.
Refill the Aqua-Hot’s boiler tank with the antifreeze and
water heating solution.
9.
Test the Aqua-Hot for normal operation.
CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
Figure 11
185 º Control Thermostat
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 22 —
SECTION 5: AQUA-HOT COMPONENTS
AC High-Limit Thermostat:
The AC high-limit thermostat serves as a safety measure in
the event that the electric heating element continues to operate after the maximum operating temperature is reached.
The high-limit thermostat allows the current for the heating
element to pass through it until the boiler tank reaches a temperature of 215°F. Should this temperature be reached, the
high-limit thermostat blocks the current to the element,
which prevents it from continuing to provide heat to the boiler tank.
Troubleshoot the AC high-limit thermostat if the following
condition has occurred:

The electric heating element fails to operate.
Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR TO
ALLOW THE HEATER TO COOL BEFORE SERVICING COULD
CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
Ensure that the Aqua-Hot has been completely shut down
and that all power supplies have been disconnected.
2.
Remove the AC access cover.
3.
If applicable, remove the heat shrink insulation covering the
wires and terminals on the defective high-limit thermostat.
4.
Disconnect the high-limit thermostat from the electric element and the A.C. relay by removing the screws with a
Philips screw drive..
5.
Using a 5/8 wrench or socket, remove the defective highlimit thermostat from the Aqua-Hot’s boiler tank.
6.
Install the replacement high-limit thermostat into the port on
the Aqua-Hot’s boiler tank and finger-tighten only (15 in/
lbs).
7.
Connect the wires on the replacement high-limit thermostat
in the same configuration as they were removed.
Troubleshooting:
NOTE: If the High-Limit Thermostat is tripped, it is recommended to test the control thermostat, for proper operation.
1.
Disconnect all power supplies.
2.
Remove the AC access cover.
3.
Verify that the boiler tank’s temperature is below 215°F.
4.
Locate the AC high-limit thermostat and remove its
wires.
5.
NOTE: One wire will attach to the electric heating
element and one wire will attach to the A.C. Relay.
Using an ohmmeter, check the thermostat for continuity.
If there is no continuity, press the white reset button on
the thermostat and re-check for continuity.
8.
Secure the AC access cover back into place.
9. Test for proper operation.
If continuity is still not present after the reset button has
been pressed, follow the instructions in this section to
replace the AC high-limit thermostat.
Figure 12
A.C. High Limit
Thermostat
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 23 —
SECTION 5: AQUA-HOT COMPONENTS
B. Disconnect the wires from each thermostat and recheck each thermostat for continuity, as well as
each of the thermostats’ individual wires.
DC High-Limit Thermostats:
The DC high-limit thermostats serve as a safety measure in
the event that the diesel-burner continues to operate after the
maximum operating temperature is reached. The high-limit
thermostats allow the current for the diesel-burner to pass
through them until the boiler tank reaches a temperature of
215°F. Should this temperature be reached, the high-limit
thermostat blocks the current to the diesel-burner’s fuel solenoid valve, which prevents the diesel-burner from operating.
Troubleshoot the DC high-limit thermostat if the following
condition has occurred:

The fuel solenoid on the diesel-burner fails to operate.
If an individual wire does not have continuity, that
wire must be replaced.
If a thermostat with the wires removed that has been
reset does not have continuity, follow the instructions in this section to replace the high-limit thermostat.
NOTE: If the high-limit thermostats continue to trip, troubleshoot the control thermostat, and verify the boiler tank is
full of the antifreeze-water solution.
Replacement Procedure:
Troubleshooting:
1.
Place a jumper wire between the blue and purple wires
on the diesel-burner’s wire harness to bypass the highlimit thermostats. Check the Aqua-Hot for normal operation.
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
NOTE: Bypassing the high-limit thermostats is for testing
only and must not be used for the Aqua-Hot’s normal functioning.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected.
Disconnect the DC high-limit thermostats’ wires, then,
using an ohmmeter, check each thermostat for continuity.
2.
Remove the two wires from the defective high-limit
thermostat by pulling firmly on the wires.
3.
Using a 5/8 wrench or socket, remove the defective high
-limit thermostat from the Aqua-Hot’s boiler tank.
4.
Install the replacement high-limit thermostat into the
port on the Aqua-Hot’s boiler tank and finger-tighten
only (15 in/lbs).
5.
Connect the wires removed from the defective high-limit
thermostat to the replacement high-limit thermostat.
2.
If there is no continuity, complete the following:
A. Press the white reset button on the high-limit thermostat, then re-check for continuity.
Figure 13
D.C. High Limit
Thermostats
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 5: AQUA-HOT COMPONENTS
C. Disconnect the low-temperature cutoff thermostat’s
wires from the Aqua-Hot’s wiring harness, then,
jump the wiring harness wires for the thermostat
together to bypass the thermostat.
Low-Temperature Cutoff Thermostat:
The low-temperature cutoff thermostat operates the domestic
hot water priority system by blocking the interior heating
feature when domestic hot water is being used. This ensures
that even heat is provided for domestic hot water, which
avoids the possibility of cold water pockets during showers,
etc.
If the “Low Temp Cutoff Status” indicator light
illuminates on the electronic controller with the
thermostat bypassed, follow the instructions in this
section to replace the low-temperature cutoff thermostat.
Troubleshoot the low-temperature cutoff thermostat if the
following conditions have occurred:
3.

There is a lack of interior heat.

There is a lack of hot water and the “Low Temp Cutoff
Status” indicator light on the electronic controller continuously remains illuminated, which does not allow the
stir pump to operate.
Troubleshooting:
1.
Determine if the conditions are right for the “Low
Temp. Cutoff Status” indicator light on the electronic
controller to be illuminated.
A. Verify that the Aqua-Hot is at operating temperature
- between 158°F and 190°F.
B. Verify that the domestic hot water is not being used.
2.
If the “Low Temp Cutoff Status” indicator light on the
electronic controller is not illuminated after it has been
determined that it should be, complete the following:
A. Install a jumper wire on the JP3 plug, between pins
9 and 10 (“LTCO-O” and “LTCO-I”) on the electronic controller.
If the indicator light does not illuminate once the
jumper wire is installed, follow the instructions in
this manual to replace the electronic controller.
B. Using a temperature sensor, verify that the lowtemperature cutoff thermostat is above 90°F.
If the thermostat is below 90°F, verify that the Aqua
-Hot is up to operating temperature and that a hot
water faucet is not leaking.
If the “Low Temp Cutoff Status” indicator light does not
extinguish when domestic hot water is being used or
when the Aqua-Hot falls below operating temperature,
complete the following:
A. Using a temperature sensor, verify that the lowtemperature cutoff thermostat is below 90°F, which
is necessary for the indicator light to extinguish.
B. Inspect the wiring to ensure that the Aqua-Hot is
wired properly and that the low-temperature cutoff
thermostat has not been bypassed via jumper wires.
C. Disconnect the low-temperature cutoff thermostat’s
wires from the Aqua-Hot’s wiring harness.
1. If the “Low Temp Cutoff Status” indicator light
on the electronic controller extinguishes, follow
the instructions in this section to replace the
low-temperature cutoff thermostat.
2. If the light remains illuminated with the lowtemperature cutoff thermostat’s wires disconnected, verify that the jumper pins on the electronic controller are properly positioned. Reference Section 7 for the proper pin jumper con
figuration.
3. If the jumper pins are properly positioned, follow
the instructions in this manual to replace the
electronic controller.
Low Temperature Cut-Off Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 25 —
SECTION 5: AQUA-HOT COMPONENTS
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected.
2.
Locate the low-temperature cutoff thermostat on the
cold domestic water inlet pipe at the back of the AquaHot.
3.
Disconnect the defective low-temperature cutoff thermostat’s wires by separating the quick-disconnect terminals.
4.
Using a 5/8 wrench or socket, remove the defective lowtemperature cutoff thermostat from the Aqua-Hot.
5.
Install the replacement low-temperature cutoff thermostat tightening only to 15 in/lbs. Do not overtighten.
6.
Connect the replacement low-temperature cutoff thermostat’s wires in the same configuration as the removed
thermostat’s wires.
Figure 14
Low Temperature
Cut-Off Thermostat
Valves
Check Valve:
Check valves are installed into the zone outlet ports for each
heating loop to ensure that the antifreeze and water heating
solution only flows in one direction. If the heating solution
attempts to backflow into the boiler tank, the check valve
closes to prevent that from happening.
B. Check the circulation pump for operation by visually inspecting it for rotation of the pump.
2.
If interior heat is present after tapping the check valve,
the check valve was stuck closed and no further action is
necessary.
Troubleshoot the check valves if the following condition has
occurred:

There is a lack of interior heat in a particular zone.
Troubleshooting:
1.
Verify that the heating zone is operating properly by
checking the following:
A. Check the electronic controller to insure that both
the “Heating Zone Status” and corresponding pump
status (“Pump #1” or “Pump #2”) indicator lights
are illuminated green.
With the circulation pump operating, tap on the check
valve and wait five minutes to evaluate if interior heat is
now present.
3.
Check the Aqua-Hot’s antifreeze and water heating solution’s ratio of water to propylene glycol. The mixture
ratio should be approximately 50/50. If the solution is
comprised fully of antifreeze (100%), the check valves
will continue to stick.
NOTE: Storing the motor home for an extended period of
time can cause the check valves to stick. If, after
the initial release of the stuck check valve, it continues to stick, follow the instructions in this section to
replace the check valve.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 26 —
SECTION 5: AQUA-HOT COMPONENTS
Replacement Procedure:
5.
Unscrew the defective check valve from the Aqua-Hot’s
boiler tank.
6.
Remove the hose barb and the 1/2 inch coupler from the
defective check valve.
7.
Clean the hose barb and coupler, then wrap the hose
barb and the 1/2 inch coupler pipe threads with Teflon
tape.
8.
Install the hose barb and 1/2 inch coupler on the replacement check valve, ensuring that they are installed
properly with the hose barb on the arrow side of the
check valve.
Install the replacement check valve onto the Aqua-Hot’s
boiler tank. The arrow on the check valve must point
away from the boiler tank.
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected. Also, because this replacement procedure will involve the boiler tank and the potential for hot coolant, be
sure the heater has adequately cooled.
2.
Drain the antifreeze and water heating solution from the
Aqua-Hot’s boiler tank using the drain valve.
3.
Using constant tension pliers, loosen and slide back the
constant tension clamp securing the hose to the defective
check valve.
9.
4.
Remove the hose from the defective check valve.
10. Slide the hose back onto the replacement pump and set
the constant tension clamp back into place.
11. Refill the Aqua-Hot’s boiler tank with the antifreeze and
water heating solution.
Figure 15
Zone Check Valve
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 27 —
SECTION 5: AQUA-HOT COMPONENTS
Tempering Valve:
5.
Remove the pressure relief valve assembly from the
tempering valve assembly as the tempering valve cannot
be removed from the Aqua-Hot with the pressure relief
valve still attached.
6.
Using a back-up wrench, unscrew the tempering valve
from the Aqua-Hot.
The tempering valve for the Aqua-Hot mixes the heated domestic water from the boiler tank with cold domestic water at
a preset ratio to reduce the risk of scalding.
Troubleshoot the tempering valve if the following condition
has occurred:

There is a lack of hot domestic water.
Troubleshooting:
NOTE: Prior to trouble shooting the tempering valve, it is
recommended to review the Lack of Hot Water Trouble
Shooting guide in section 11.
1.
2.
3.
Inspect the tempering valve to ensure that it is not
leaking.
Test the temperature of the hot water using a digital
thermometer at one of the hot water faucets. Water
Temperature should range between 115° F - 123° F. If
the proper range cannot be set follow the instructions in
this section to replace the tempering valve.
A back-up wrench must be used for loosening and removing
the tempering valve from the Aqua-Hot. Failure to use the
back-up wrench will cause the copper domestic water coil to
twist and kink, which will render the domestic water feature
unusable.
7.
Remove the brass fittings from the defective tempering
valve.
8.
Install the brass fittings onto the replacement tempering
valve.
NOTE: Be sure to wrap Teflon tape around the threads of
the brass fittings, to prevent domestic water from leaking.
Install the replacement tempering valve onto the AquaHot using a back-up wrench to tighten.
Test the tempering valve’s functionality by turning the
knob.
9.
If the tempering valve’s knob does not turn freely, follow the instructions in this section to replace the tempering valve.
10. Install the pressure relief valve onto the replacement
tempering valve.
Replacement Procedure:
11. Reconnect the pex pipe and fittings to the tempering
valve and Aqua-Hot. Be sure to inspect the rubber seals
and replace if necessary.
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
12. Reconnect the motor home’s water lines to the tempering valve assembly.
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
Turn the motor home’s water pump off.
2.
Drain the water pressure by opening the faucets and allowing the water to drain.
3.
Disconnect the motor home’s water lines from the tempering valve assembly.
4.
Disconnect the pex pipe and fittings from the tempering
valve assembly.
13. Turn the motor home’s water pump back on and check
for leaks and the presence of hot domestic water.
14. Verify that the replacement tempering valve has been set
to the proper setting by taking a digital thermometer to
a hot water faucet and set the water temperature between
115*F - 123*F.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 28 —
SECTION 5: AQUA-HOT COMPONENTS
Figure 16
Pressure Relief
Valve
Tempering
Valve Knob
Pumps
Circulation Pumps #1 and #2:
The circulation pumps first draw the heated antifreeze and
water heating solution from the Aqua-Hot’s boiler tank, then
propel it through the Hydronic heating system’s interior heat
plumbing.
Troubleshoot the circulation pumps if the following condition has occurred:


The circulation pump is not operating and the “Low
Temp Cutoff Status” indicator light is illuminated on the
electronic controller.
The Zone Pump indicator light illuminates red on the
electronic controller.
Troubleshooting:
1.
Verify that the “Low Temp Cutoff Status” indicator
light on the electronic controller is illuminated, as it will
be whenever the boiler tank is at operating temperature
and domestic hot water is not being used.
2.
Turn on the interior room thermostat corresponding to
the circulation pump not operating (heating zones 1 and
5 operate with circulation pump #1 and heating zones
2,3,and 4 operate with circulation pump #2). Check the
corresponding “Heating Zone Status” indicator lights on
the electronic controller for illumination.
If the “Heating Zone Status” indicator light does not
illuminate, complete the following:
A. Install a jumper wire on the JP1 plug between the
pins corresponding to the room thermostat operating
the circulation pump that is not operating. Reference the wiring diagram in Appendix A. This will
bypass the room thermostat.
When the “Heating Zone Status” indicator light
illuminates on the electronic controller, the corresponding “Pump #1” and/or “Pump #2” indicator
light should illuminate as well.
B. With the jumper wire installed, check the indicator
light corresponding to the pump not operating.
If the indicator light illuminates green, complete the
following:
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 29 —
SECTION 5: AQUA-HOT COMPONENTS
A. Using a voltmeter, check for 12 volts of DC power
on the JP3 plug pins corresponding to the pump not
operating.
If 12 volts of DC power are not present, follow the
instructions in this manual to replace the electronic
controller.
B. Disconnect the circulation pump’s wires from the
wiring harness, then, using a voltmeter, check the
wires on the wiring harness for 12 volts of DC power.
2.
Drain the antifreeze and water heating solution from the
Aqua-Hot’s boiler tank using the drain valve.
3.
Disconnect the defective circulation pump’s wires by
separating the quick-disconnect terminals.
4.
Using constant tension pliers, loosen and slide back the
constant tension clamps securing the hoses to the circulation pump.
5.
Remove the hoses from the defective circulation pump.
6.
For ease of replacement pump installation, the defective
circulation pump’s mounting bracket should remain fastened to the heater, and only the pump should be removed. Therefore, to detach the defective pump, remove the three screws on the back of the attached
mounting bracket.
7.
Slide the defective pump out of the bracket and set
aside.
8.
The replacement pump will arrive complete with a
mounting bracket; however, because the existing bracket
remains mounted to the heater, the new mounting bracket must be removed by detaching the three screws securing it to the replacement pump.
9.
Slide the replacement pump into the existing mounting
bracket and secure with the three screws previously removed from the replacement pump.
If 12 volts of DC power are present at the wiring
harness, follow the instructions in this section to
replace the circulation pump.
If the indicator light illuminates red, complete the following:
A. Disconnect the circulation pump’s wires.
If the indicator light turns green with the circulation
pump disconnected, follow the instructions in this
section to replace the circulation pump.
If the indicator light remains red with the circulation
pump disconnected, check the wiring for damage.
If no damage is found, follow the instructions in this
manual to replace the electronic controller.
NOTE: The circulation pump can be tested by connecting it to an external 12 Volt-DC source to verify
that the pump is defective.
10. Slide the hoses back onto the replacement pump and set
the constant tension clamps back into place.
Replacement Procedure: A450-100277 TO A450-110278
11. Reconnect the wires on the replacement pump to the
wire harness on the heater by uniting the red quickdisconnect terminals.
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
12. Refill the Aqua-Hot’s boiler tank with the antifreeze and
water heating solution.
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
13. Test the Aqua-Hot for normal operation.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected. Also, because this replacement procedure will involve the potential for hot coolant, be sure the heater is
adequately cooled.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 5: AQUA-HOT COMPONENTS
Replacement Procedure: A450-110279 -
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR TO
5.
Remove the hoses from the defective pump.
6.
Release the pump from the mounting bracket by inserting an Awl between the locking teeth and gently prying
the locking teeth apart. Then remove the defective
pump from the Aqua-Hot.
7.
Slide the hoses back onto the replacement pump and set
the constant tension clamps back into place.
8.
Install the replacement pump onto the mounting bracket,
and squeeze the pump bracket together with a pair of
channel lock pliers, to secure the pump.
9.
Reconnect the harness plug into the replacement pump.
Be sure to push in on the red locking tab to secure the
plug into place
ALLOW THE HEATER TO COOL BEFORE SERVICING COULD
CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
2.
3.
4.
Ensure that the Aqua-Hot has been completely shut down
and that all power sources have been disconnected. Also,
because this replacement procedure will involve the potential for hot coolant, be sure the heater has adequately
cooled.
Drain the antifreeze and water heating solution from the
Aqua-Hot’s boiler tank using the drain valve.
Disconnect the defective pump’s wires by Pulling out on
the “Red Locking” tab on the harness plug, and separating
the Harness Plug from the defective pump.
Using constant tension pliers, loosen and slide back the
constant tension clamps securing the hoses to the pump.
10. Refill the Aqua-Hot’s boiler tank with the antifreeze and
water heating solution.
Figure 17
A450-100277 TO A450-110278
A450-110279 -
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 31 —
SECTION 5: AQUA-HOT COMPONENTS
Stir Pump / Circulation Pump #3:
If the “Pump #3” indicator light turns green when
the stir pump is disconnected, follow the instructions in this section to replace the stir pump.
The stir pump circulates the antifreeze and water heating
solution within the Aqua-Hot’s boiler tank in order to ensure
even-heating of the solution. To accomplish this, the stir
pump draws the solution from the bottom of the tank and
immediately deposits it back into the top of the tank.
If the “Pump #3” indicator light remains red when
the stir pump is disconnected, check the wiring for
damage. If no damage is found, follow the instruction in this manual to replace the electronic controller.
Troubleshoot the stir pump if the following condition has
occurred:


If the indicator light is illuminated green, complete the
following:
There is a lack of hot domestic water.
Pump #3 indicator light illuminates red.
A. Using a voltmeter, check for 12 Volts of DC power
on the JP3 plug between pins 1 and 2 (“PUMP 3+”
and “PUMP 3-”) on the electronic controller.
Troubleshooting:
NOTE: In order for the stir pump to operate, the dieselburner switch must be on and the indicator light for
the “Low Temp Cutoff Status” on the electronic
controller must be extinguished.
NOTE: Verify the Electronic Controller Proper Jumper Pin
formation . Reference Section 6: Electronic Controller, for
the proper jumper pin formation.
1.
Verify that the “Pump #3” indicator light on the electronic controller is illuminated
If the indicator light is not illuminated, check the following:
A. Verify that the diesel-burner Status Light is Illuminated, indicating the switch is on.
B. Verify that the “Low Temp Cutoff Status” indicator
light on the electronic controller is not illuminated.
If the diesel-burner switch is on, the “Low Temp
Cutoff Status” indicator light is not illuminated, the
jumper pins on the electronic controller are properly
positioned and the stir pump is not operating, follow
the instructions in this manual to replace the electronic controller.
2.
Check the color of the illuminated “Pump #3” indicator
light on the electronic controller.
If 12 Volts of DC power are not present, follow the
instructions in this manual to replace the electronic
controller.
3.
Disconnect the stir pump’s wires from the wiring harness, then, using a voltmeter, check the wires on the
wiring harness for 12 Volts of DC power.
If 12 Volts of DC power are not present, inspect and
test the wires going from the electronic controller to
the pump.
If 12 Volts of DC power are present at the wiring harness, complete the following:
A. Verify that the pump is operating by placing a hand
on the pump to feel for vibrations.
If no vibrations are felt, follow the instructions in
this section to replace the stir pump.
B. Once it is determined that the pump is active, verify
that the pump is operating properly by checking
both connected hoses for heat.
If both hoses are hot, the pump is working properly.
If only one hose is hot, or neither hose is hot, check
the cold hose for a blockage. If no blockage exists,
follow the instructions in this section to replace the
stir pump.
If the indicator light is illuminated red, the stir pump is
experiencing a short; therefore, complete the following:
A. Disconnect the stir pump’s wires.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 5: AQUA-HOT COMPONENTS
Replacement Procedure:
5.
Remove the hoses from the defective stir pump.
6.
Release the pump from the mounting bracket by inserting an Awl between the locking teeth and gently prying
the locking teeth apart. Then remove the defective
pump from the Aqua-Hot.
7.
Slide the hoses back onto the replacement pump and set
the constant tension clamps back into place.
8.
Install the replacement stir pump onto the mounting
bracket, and squeeze the pump bracket together with a
pair of channel lock pliers, to secure the pump.
9.
Reconnect the harness plug into the replacement pump.
Be sure to push in on the red locking tab to secure the
plug into place
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected. Also, because this replacement procedure will involve the potential for hot coolant, be sure the heater has
adequately cooled.
2.
Drain the antifreeze and water heating solution from the
Aqua-Hot’s boiler tank using the drain valve.
3.
Disconnect the defective stir pump’s wires by Pulling
out on the “Red Locking” tab on the harness plug, and
separating the Harness Plug from the defective pump.
4.
10. Refill the Aqua-Hot’s boiler tank with the antifreeze and
water heating solution.
Using constant tension pliers, loosen and slide back the
constant tension clamps securing the hoses to the stir
pump.
Stir Pump W/ Bracket
Figure 18
Insert Awl Into
The Pump
Bracket
Wire Harness
Plug, with Red
Locking Tab
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 33 —
SECTION 5: AQUA-HOT COMPONENTS
A. Verify that the low temperature cutoff light and the
diesel burner/electric heating element status lights
are illuminated on the electronic controller.
Engine Preheat Pump:
B. Using a jumper wire, bypass the engine preheat
switch on the JP3 plug, by connecting pins
Preheat-O and Preheat-I together.
The Engine Preheat circulation pump draws the cold antifreeze and water heating solution from the motor home’s
engine and then propels it through the Engine Preheat Heat
exchanger, located inside the boiler tank.
If the engine preheat pump indicator light illuminates
with the jumper installed, inspect for loose wires. If no
loose wires are found, replace the engine preheat switch,
on the interior switch panel, inside the motor home.
Troubleshoot the Engine Preheat Pump if the following condition has occurred:

The Engine Preheat Pump is not operating, and the
Engine Preheat Switch on the Switch Panel inside the
motor Home is in the ON position and the “Low Temp
Cutoff Status” indicator light is illuminated on the
electronic controller.

The Engine Preheat Pump indicator light illuminates red
on the electronic controller.
Troubleshooting:
NOTE: Either the diesel-burner switch or the electric element switch must also be activated in order for the engine
preheat feature to function.

The Engine Preheat Pump is not operating, and the
Engine Preheat Switch on the Switch Panel inside
the motor Home is in the ON position and the “Low
Temp Cutoff Status” indicator light is illuminated
on the electronic controller.
1.
Verify that the “Low Temp Cutoff Status” indicator
light on the electronic controller is illuminated.
2.
Verify that the Engine Preheat Switch is in the ON position, on the interior switch panel inside the motor home.
Either the diesel burner switch or the electric element
switch must also be activated in order for the engine
preheat feature to function.
3.
If the engine preheat pump indicator light does not
illuminate, and the Low Temperature Cut-Off Light is
illuminated along with either the diesel or the electric
element status indicator light, follow the instructions in
this manual to replace the electronic controller.

The Engine Preheat Pump indicator light illuminates
green on the electronic controller but the pump is not
running.
A. Using a voltmeter, check for 12 volts of DC power
on the JP3 plug pins corresponding to the pump not
operating.
If 12 volts of DC power are not present, follow the
instructions in this manual to replace the electronic
controller.
B. Disconnect the engine preheat circulation pump’s
wires from the wiring harness, then, using a voltmeter, check the wires on the wiring harness for 12
volts of DC power.
If 12 volts of DC power are present at the wiring
harness, follow the instructions in this section to
replace the engine preheat circulation pump.
On the electronic controller, verify that the engine
preheat pump light is illuminated.
If the Engine preheat pump indicator light does not illuminate, complete the following:
NOTE: The engine preheat circulation pump can be tested
by connecting it to an external 12 Volt-DC source to verify
that the pump is defective.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 34 —
SECTION 5: AQUA-HOT COMPONENTS

The Engine Preheat Pump indicator light illuminates red
on the electronic controller.
3.
Disconnect the defective pump’s wires by Pulling out on
the “Red Locking” tab on the harness plug, and separating
the Harness Plug from the defective pump.
4.
Using constant tension pliers, loosen and slide back the
constant tension clamps securing the hoses to the engine
preheat pump.
5.
Remove the hoses from the defective engine preheat
pump.
6.
Release the pump from the mounting bracket by inserting
an Awl between the locking teeth and gently prying the
locking teeth apart. Then remove the defective pump from
the Aqua-Hot.
7.
Slide the hoses onto the replacement pump and set
the constant tension clamps back into place.
8.
Install the replacement pump onto the mounting bracket,
and squeeze the pump bracket together with a pair
of channel lock pliers, to secure the pump.
9.
Reconnect the harness plug into the replacement pump.
Be sure to push in on the red locking tab to secure the plug
into place.
A. Disconnect the engine preheat circulation pump’s wires.
If the indicator light turns green with the engine preheat
circulation pump disconnected, follow the instructions in
this section to replace the engine preheat circulation
pump.
If the indicator light remains red with the circulation
pump disconnected, check the wiring for damage. If no
damage is found, follow the instructions in this manual
to replace the electronic controller.
Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR TO
ALLOW THE HEATER TO COOL BEFORE SERVICING COULD
CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
2.
Ensure that the Aqua-Hot has been completely shut down
and that all power sources have been disconnected. Also,
because this replacement procedure will involve the potential
for hot coolant, be sure the heater is adequately cooled.
Using hose pinch off pliers, clamp both hoses attached to the
engine preheat pump, closed.
10. Remove the hose pinch off pliers previously installed on
both hoses.
11. Test the Aqua-Hot for normal operation.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 35 —
SECTION 5: AQUA-HOT COMPONENTS
Figure 19
Engine Preheat Pump W / Bracket
Insert Awl Into
The Pump
Bracket
Wire Harness
Plug, with Red
Locking Tab
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 36 —
SECTION 5: AQUA-HOT COMPONENTS
with the jumper wire installed, follow the instructions in this manual to replace the electronic controller.
Electrical - AC
Electric Heating Element:
If the “Heating Status” indicator light on the electronic
controller is not illuminated, complete the following:
The electric heating element uses AC power as an alternate
power source for heating the Aqua-Hot’s boiler tank.
A. Check the temperature of the Aqua-Hot’s boiler
tank.
Troubleshoot the electric heating element if the following
condition has occurred:

If the boiler tank temperature is below 158°F, troubleshoot the control thermostat.
There is a lack of hot domestic water and interior heat
when the electric element is selected as the heating
source.
If the boiler tank is above 158°F, the Aqua-Hot is at
operating temperature and requires no heat.
Troubleshooting:
NOTE: For continuous domestic hot water to be present, the
diesel-burner must be selected also as a heating
source.
1.
2.
3. Verify the Electronic Controller is sending 12 Volt DC to
the A.C. Relay.
A. Using a volt meter check pins 11 & 12 (“AC
REL -” and “AC REL +”) for 12-Volt D.C on
the JP3 plug.
Verify that the motor home is either plugged into shore
power or that the generator is running to provide AC
power.
If 12 Volts of DC power is not present while the
“Electric Heating Element Status” and “Heating Status”
indicator lights on the electronic controller are illuminated, follow the instructions in this manual to replace the
electronic controller.
Verify that both the “Electric Heating Element Status”
and the “Heating Status” indicator lights on the electronic controller are illuminated.
If the “Electric Heating Element Status” indicator light
on the electronic controller is not illuminated, complete
the following:
4. If 12 Volts of DC power are present at the relay, complete
the following:
A. Locate the AC wires connected to the AC relay
(pins 2 and 4), and remove the AC wires from the
relay.
A. Verify that the electric element switch on the interior switch panel is on.
B. Using an ohmmeter, check the relay AC pins (2 and
4) for continuity.
B. Install a jumper wire on the JP2 plug, between pins
52 and 53 (“ELECT-O” and “ELECT-I”) on the
electronic controller to bypass the electric element
switch.
If the “Electric Heating Element Status” indicator
light illuminates on the electronic controller with
the jumper wire installed, check the Electric Element Switch, on the interior switch panel for functionality.
If the “Electric Heating Element Status” indicator
light does not illuminate on the electronic controller
If no continuity exists, follow the instructions in this
section to replace the AC relay.
5.
Verify that the electric heating element is receiving
adequate AC power by completing the following:
A. Remove the AC access cover.
B. Plug the Coach into shore power/turn generator on.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 37 —
SECTION 5: AQUA-HOT COMPONENTS
C. Using an AC voltmeter, verify that 110 volts of AC
power are present at the terminal block reference
figure 20. If there is not 110 VAC present at the
terminal block for the electric element, there is a
problem inside the motor home.
4.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected. Also, because this replacement procedure will involve the boiler tank and the potential for hot coolant, be
sure the heater has adequately cooled.
D. Using a digital clamp-meter, verify the electric element’s amp draw is between 11.2 to 13 amps.
2.
Drain the antifreeze and water heating solution from the
Aqua-Hot’s boiler tank using the drain valve.
E. Check the electric element’s wires for continuity by
completing the following:
3.
Remove the AC access cover.
a.
Disconnect the motor home from shore power/
shut off generator.
4.
Remove the two wires secured to the defective electric
heating element by releasing the screw terminals.
b.
Disconnect the wires from the electric heating
element.
5.
Using a 1-1/2 inch socket, remove the defective electric
heating element from the Aqua-Hot’s boiler tank.
c.
Disconnect the wires from the AC terminal
block.
6.
Install the replacement 1650-watt electric heating element into the boiler tank ensuring that the “up” lettering
on the element is installed in the up position.
d.
Check the black and white wires at the terminal
block for continuity.
7.
Connect the wires removed from the defective electric
heating element to the replacement electric heating element and tighten the screw terminals.
8.
Reinstall the AC access cover.
9.
Refill the Aqua-Hot’s boiler tank with the antifreeze and
water heating solution.
Check the electric heating element for functionality by
completing the following:
A. Disconnect all power supplies.
B. Remove the AC access cover.
C. Remove all wires from the electric heating element.
D. Using an ohmmeter, check the electric heating element for the proper ohms. The Ohms reading
should be between 8.5 - 9.5 ohms.
Figure 19
If the ohms reading is not between 8.5 - 9.5 ohms
follow the instructions in this section to replace the
electric heating element.
Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 38 —
SECTION 5: AQUA-HOT COMPONENTS
AC Relay:
A. Locate the AC wires connected to the AC relay
(pins 6 and 8), and remove the AC wires from the
relay.
The AC relay is an electrical device where the DC circuit
from the electronic controller determines whether the AC
power is permitted to flow to the electric heating element.
This allows the electronic controller to switch the electric
heating element on and off in conjunction with the interior
switch panel and control thermostat even though the electric
heating element is on a separate circuit.
Troubleshoot the AC relay if the following condition has
occurred:

The electric heating element fails to operate.
B. Using an ohmmeter, check the relay AC pins (6 and
8) for continuity.
If no continuity exists, follow the instructions in this
section to replace the AC relay.
Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
Troubleshooting:
COULD CAUSE SERIUOS DAMAGE OR PERSONAL INJURY.
1.
Disconnect the AC power source to the motorhome
(unplugging from shore power or shutting off the generator).
2.
Turn the electric element switch on the interior switch
panel on and check the electronic controller to ensure
that the “Electric Heating Element Status” and the
“Heating Status” indicator lights are illuminated.
3.
Using a voltmeter, check pins 11 and 12 (“AC Relay +”
and “AC Relay-”) on the JP3 plug for 12 Volts-DC.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected.
2.
Also, ensure that the motor home is not connected to
shore power and that a generator is not connected during
this replacement procedure.
3.
Remove the AC access cover.
4.
If 12 Volts of DC power are not present while the
“Electric Heating Element Status” and “Heating Status”
indicator lights on the electronic controller are illuminated, follow the instructions in this manual to replace the
electronic controller.
Release the wires from the defective AC relay by re
moving the corresponding screw terminals.
5.
Remove the defective relay by drilling the rivets that
hold the defective relay in place.
6.
Rivet the replacement AC relay to the AC access cover.
If 12 Volts of DC power are present, complete the following:
7.
Using the wiring diagram in Appendix A, connect the
wires previously removed to the replacement AC relay.
8.
Reinstall the AC access cover.
Figure 20
A.C. Terminal
Block
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 39 —
SECTION 6: ELECTRONIC CONTROLLER
Electronic Controller Overview
The electronic controller is an electronic circuit board that
controls the electrical functions of the Aqua-Hot heating
system. All wiring for the switch panel is connected to the
electronic controller, as well as the wiring circuitry from the
Aqua-Hot unit. Indicator lights on the front panel will illuminate red if there is a short circuit, overload, or fault condition within the system. It also will indicate when circuits are
functioning properly with a green indicator light.
Figure 21
Electronic Controller General Facts
Nominal input voltage range ............................ 10.6V to 15V
Idle current ................................................... Approx. 15mA
Low voltage cutoff threshold .......................................10.0V
Low voltage lockout delay ....................... Approx. 5 minutes
Input Load Currents
Output Current Capacity
Zone thermostats (each) .................................. Approx. 4mA
Diesel-Burner switch ..................................... Approx. 12mA
Electric Element switch ................................... Approx. 4mA
Engine Preheat switch ..................................... Approx. 4mA
Low-level cutoff switch................................. Approx. 10mA
Control Thermostat ......................................... Approx. 8mA
Low-temperature cutoff switch ....................... Approx. 5mA
Zone fans (each) .................................................... 2.0A max.
Circulation pumps (each) ...................................... 2.0A max.
Engine preheat pump ............................................ 2.0A max.
AC relay ............................................................ 500mA max.
B4+ burner (Webasto) power ................................ 6.0A max.
B1+ burner master control .................................... 2.0A max.
C1/C7 burner thermostat control ........................... 1.0A max.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 40 —
SECTION 6: ELECTRONIC CONTROLLER
Electronic Controller Features
Secondary 12 Volt-DC Battery Connection:
The electronic controller is equipped with two 12 Volt-DC
power source connections, which allow for a secondary 12
Volt-DC battery connection. This 12 Volt-DC battery connection is a product-safety feature that should be utilized
whenever the Aqua-Hot’s main 12 Volt-DC power supply is
connected to a battery disconnect switch. This feature will
ensure that the Aqua-Hot will be protected in the event that
the primary power is interrupted while the diesel-burner is
operating (e.g., during a burn-cycle). This secondary 12 Volt
-DC battery connection will ensure completion of the required 3-minute “purge cycle” of the Aqua-Hot’s dieselburner.
Figure 22
Terminal Strips with Screw-Type Fasteners:
Figure 23
The electronic controller uses terminal strips/plugs that are
equipped with screw-type fasteners, which are molded directly into the terminal strip/plug, itself. This will ensure a
positive mechanical connection between the electronic controller and all wire harnesses attached to it.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 41 —
SECTION 6: ELECTRONIC CONTROLLER
Low-Voltage Reset Feature:
Whenever the Aqua-Hot’s DC power is interrupted, for longer than 5 minutes, the “low battery voltage fault” red indicator light on the electronic controller will illuminate. Reset
the electronic controller by pressing the “low voltage reset”
button on the electronic controller (use a thin, straight, nonmetallic object to access the button through the faceplate) or
by turning off the diesel-burner switch on the interior switch
panel for approximately 30 seconds, then turning the switch
back on.
Figure 24
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 42 —
SECTION 6: ELECTRONIC CONTROLLER
Replacement Procedure:
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
6.
Snap the replacement electronic controller into the
mounting bracket.
7.
Ensure that the pin jumpers are properly configured for
an Aqua-Hot 450-DE; reference information in this section for proper pin-jumper configuration.
Install each terminal strip/plug back onto the electronic
controller and tighten the screws on the terminal strips/
plugs to secure them to the board.
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
1.
Ensure that the Aqua-Hot has been completely shut
down and that all power sources have been disconnected.
8.
2.
Remove the faceplate from the electronic controller by
removing the four screws securing it to the mounting
bracket.
NOTE: Check the terminal strips/plugs for loose wires and
tighten if loose.
3.
Disconnect the positive, negative, and secondary power
(if applicable) wires from the electronic controller.
4.
Disconnect the four terminal strips/plugs from the electronic controller by loosening the screws on each strip/
plug and pulling each strip/plug away from the electronic controller.
5.
9.
Connect the ground wire followed by the main 12 VoltDC power wire, then the secondary power wire (if applicable) to the appropriate screw terminals on the replacement electronic controller board. Reference Appendix A
for additional wiring information.
10. Reinstall the faceplate onto the electronic controller and
secure with the four screws previously removed.
Remove the electronic controller from the mounting
bracket by unsnapping each corner.
Proper Pin Jumper Configuration:
1.
Verify that the pin jumpers are configured as in the illustration in this section. If the pin jumpers do not match
the illustration, the Aqua-Hot 450 will not function
properly.
2.
If the jumpers pins need to be reconfigured, simply tug
gently on the black cap covering the pins to pull the
black cap off.
3.
Reseat the cap on the pins appropriately as per the illustration.
Figure 25
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 43 —
SECTION 7: ELECTRONIC CONTROLLER INDICATOR LIGHTS
Electric Heating Element Status
This indicator light shows the status of the electric heating
element by illuminating green for on, red for fault, or by
turning off when the element switch is turned off.
If the light is off and the electric element switch on the interior switch panel is off, then the system is functioning correctly. If the indicator light is green and the electric element
switch on the interior switch panel is on, the system is also
functioning correctly.
If the light is red and the electric element switch on the interior switch panel is on, then there is a short in the electric
element circuit. This could be due to a bad connection, a bad
switch on the interior switch panel, or an issue with the AC
relay.
Heating Zone Status (1-5)
These lights indicate the status of each motor home room
thermostat and the respective heat exchanger fan(s). The
indicator light will illuminate green when the system is on
and functioning properly, red when on and not functioning,
and the light will be off when the system is off.
If a fault condition occurs, this could be due to a wiring issue, a faulty thermostat, or issues with the heat exchanger
fans.
is up to operating temperature and hot water is not being
used. It also indicates that the interior heating zones will operate.
When the indicator light is off, it indicates there is a demand
for domestic hot water, or the heater is not up to operating
temperature, and the interior heat will not operate.
Low Tank-Level Cutoff
The Low Tank-Level Cutoff senses the level of antifreeze in
the boiler tank, and will shut the Diesel-Burner and the Electric Heating element OFF, when the light illuminates red.
Under normal operating conditions, this light will not be
illuminated because an adequate level of antifreeze and water
heating solution within the Aqua-Hot’s boiler tank exists.
When illuminated (red only), three possible issues exist - the
antifreeze and water heating solution level is inadequate and
must be refilled, there is a short in the wiring to the fluid
level sensor, or the fluid level sensor is not operating properly.
Heating Status
This indicator light will illuminate (green only) when the
diesel-burner and/or the electric heating element switch on
the interior switch panel is on, and the control thermostat is
calling for heat.
Low Battery Voltage Fault
This indicator light illuminates red when the DC voltage is
below 10.5 Volts for Longer than 5 minutes, and it will be
off when the system has adequate voltage.
If the heater is functioning and the light is not illuminated, or
the heater is not functioning and the light is illuminated,
there is an issue with the wiring or one of the components.
Engine Preheat Pump
If the light becomes red, the switch may be reset (after restoring voltage) by pressing the Low Voltage Reset Button on
the electronic controller with a long, thin, nonmetallic object,
or by turning the diesel-burner switch on the interior switch
panel off for 30 seconds, then turning it back on.
Low-Temp Cutoff Status
The Low Temp Cutoff thermostat shuts the interior heat off
when domestic hot water is being used, and activates the stir
pump in conjunction with the diesel burner switch.
When the indicator light is green, it indicates that the heater
This indicator light shows the status of the engine preheat
pump by illuminating green for on, red for fault, or by turning off when the engine preheat pump is not operating.
The system is functioning correctly when the indicator light
is green while the engine preheat switch on the interior
switch panel is on, the electric element and/or diesel-burner
switch is on, and the engine preheat pump is operating.
The system is also functioning correctly when the engine
preheat switch is off and the engine preheat pump is not operating.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 7: ELECTRONIC CONTROLLER INDICATOR LIGHTS
If the red light illuminates when the pump should be functioning, then there is either an issue with the wiring or the
engine preheat pump.
NOTE: The Low-Temp Cut-Off light must be illuminated
for the Engine Preheat pump to be activated.
the Diesel-Burner Switch on, or the Diesel-Burner Switch is
turned off.
The system is functioning if the Stir Pump is operating when
the Diesel Burner Status light is illuminated and the Low
Temp Cut-Off light is extinguished (i.e. running hot water).
The system is also functioning properly if the stir pump and
indicator light are off when the Diesel-Burner Status light
and the Low Temp Cut-Off status lights are illuminated, or
the Diesel Burner Switch is turned off.
Pump #1
This indicator light shows the status of the circulation pump
that controls the fluid for Heating Zones #1 and #5 by illuminating green for on, red for fault, and by turning off when the
system is off.
If the light is red under any condition, then there is an issue
with either the wiring or the stir pump.
Diesel-Burner Status
The system is functioning properly if the coach thermostat is
calling for heat, the pump is operating, and the light is green.
The system is also functioning properly if the pump and light
are off and the thermostat is not calling for heat.
If the light is red under any condition, then there is either an
issue with the wiring or the circulation pump.
This indicator light shows the status of the diesel-burner by
illuminating green when the diesel-burner is on, red for fault,
and by turning off when the diesel-burner switch is turned
off.
If the diesel-burner switch on the interior switch panel is in
the on position , then the indicator light should be illuminated green.
Pump #2
This indicator light shows the status of the circulation pump
that controls the fluid for Heating Zones #2, #3, and #4 by
illuminating green for on, red for fault, and by turning off
when the system is off.
The system is functioning properly if the motor home interior thermostat is calling for heat, the circulation pump is active, and the indicator light is green.
The system is also functioning properly if the circulation
pump and indicator light are off and the thermostat is not
calling for heat.
If the light is red under any condition, there is either an issue
with the wiring or the circulation pump.
When the Diesel-Burner switch on the interior switch panel
is in the off position, the indicator light will not be illuminated.
If the indicator light turns red, there is either a short in the
wiring or the diesel-burner is in need of servicing. When
checking the wiring, be sure to verify that the diesel-burner
controller’s harness connectors are completely locked together. Also verify the Photo Eye Wires have not been pinched.
Reference section 9 of this manual for additional dieselburner information.
Overload Fault
This indicator light shows the status of the DC voltage applied to the electronic controller and the Aqua-Hot. Under
normal operating conditions, this indicator light is off.
Pump #3 - Stir Pump
This indicator light shows the status of the stir pump by illuminating green for on, red for fault, and by turning off when
either the Low Temp Cut-Off Status light is illuminated, with
This light illuminates red when the Aqua-Hot is shut down
due to excessive DC voltage (over 14.8 Volts) and/or the
electronic controller has overheated. Once the excessive
voltage issue is resolved, the electronic controller will reset
itself.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 8: DIESEL-BURNER
Diesel-Burner Overview
The Aqua-Hot’s diesel-burner is a device that ignites a mixture of diesel fuel and air within a controlled setting to serve
as a heat source. The flame is established in a combustion
chamber within the Aqua-Hot’s boiler tank, and the heat
from the flame is transferred to the antifreeze and water heating solution where it can be used for each system of the Aqua-Hot - domestic hot water, interior heat, and engine preheat.
Figure 26
Figure 27
Diesel-Fuel
Return Banjo
Fuel Nozzle
Webasto Diesel Burner
Diesel-Fuel
Supply Banjo
Air
Intake
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 8: DIESEL-BURNER
Figure 28
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 8: DIESEL-BURNER
Operational Flow-Chart
Operation sequence once the Aqua-Hot’s Diesel switch is turned
ON
NOTE:
The Diesel switch’s indicator
light will illuminate anytime the
Diesel Burner switch is in the ON
position
The Motor (#2), which turns the
Combustion Air Blower (#5)
and drives the Fuel Pump (#14),
will begin to operate.
NOTE:
If the Aqua-Hot’s coolant temperature is approximately 190°F (+/5°F) or higher, the Motor (#2)
will not operate. Only when the
coolant temperature has dropped
below 160(+/-5)°F, and the VDC/
VAC Control Thermostat is calling for heat, will the Motor (#2)
begin to operate.
After approximately 10-25 seconds, the Fuel Solenoid Valve
(#6) opens and fuel is sprayed
into the Combustion Chamber
(#11) through the Fuel Nozzle
(#9)
Once the ignited air-fuel mixture
(FLAME) is observed by the
Flame Sensor (#13) the Ignition
Coil (#3) will automatically
switch OFF. The combustion
process now continues to operate
unassisted.
Once the heater switches OFF,
thermostatically or manually, the
Fuel Solenoid Valve (#6) closes,
which interrupts the supply of diesel fuel to the Fuel Nozzle (#9)
The Motor (#2) will continue to run
for approximately three (3) additional minutes. This process is referred to as the Purge-Cycle, which
cools the heater’s internal components and purges the Combustion
Chamber (#11) of any residual
exhaust gases.
NOTE:
The combustion process will continue to operate in this manner
until one of the following occurs:
A.) The VDC/VAC Control
Thermostat, which senses coolant temperature, reaches the preset temperature of approximately
190 (+/-5)° F.
NOTE:
If process “A” occurs, the AquaHot Heating Status Light on the
Electronic Controller will go
OFF.
When the Aqua-Hot’s Diesel Burner is switched OFF by the VDC/
VAC Control Thermostat, the
following process will take place:
1.
The Motor (#2) will shut off
once the three (3) minute
Purge-Cycle has expired.
-THEN2. The Aqua-Hot’s Diesel Burner
will automatically turn back ON
once the coolant reaches the preset
temperature of approximately 160
(+/-5) °F
B.) the Aqua-Hot’s Diesel Burner Switch is turned OFF.
NOTE:
After approximately 10-25 seconds, the Fuel Solenoid Valve
(#6) opens and fuel is sprayed
into the Combustion Chamber
(#11) through the Fuel Nozzle
(#9)
If process “B” occurs, the Diesel
Burner switch’s Indicator
Light, on the Switch Panel will
go OFF along with the Heating
Status and Diesel Burner Status
lights on the Electronic Controller.
Summary:
The Aqua-Hot’s Diesel-Burner is
operational anytime the operator
moves the Diesel Burner Switch to
the ON position. The DieselBurner will then automatically
maintain the coolant temperature in
the Aqua-Hot’s Boiler Tank without additional involvement from the
operator.
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SECTION 8: DIESEL-BURNER
Diesel-Burner Operations:
The following sequence illustrates how the Diesel-Burner
operates once it is activated. Also, if diesel-burner malfunctions are experienced, use this sequence of operating events
as a diagnostic tool to determine at what point in the dieselburner’s operation the malfunction is occurring. Use the
“KEY” provided to understand each symbol shown.
Figure 29
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 8: DIESEL-BURNER
Figure 30
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 8: DIESEL-BURNER
Figure 31
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 51 —
SECTION 9: DETACHING
AND
REATTACHING
THE
DIESEL BURNER
Instructions for Detaching the Diesel Burner
WARNING!
Be sure to move the Diesel-Burner switch on the Interior Switch Panel to the OFF position and disconnect the
Diesel-Burner’s power supply before detaching the Diesel-Burner from the Aqua-Hot. Failure to turn off the
Diesel-Burner and disconnect power could result in serious bodily injury.
CAUTION!
Be sure to clamp off the Fuel Supply and Return lines at the ports on top of the Aqua-Hot prior to beginning this
replacement procedure.
Step 1: Turn Off the Diesel Switch
Figure 32
1. Move the Interior Switch Panel’s Diesel-Burner switch to the “OFF” position.
Step 2: Remove the Access Cover
Figure 33a
Figure 33b
1. Remove the Aqua-Hot’s access cover by locating
the bolts securing it in place.
2. Unscrew the bolt securing the front of the cover in
place.
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SECTION 9: DETACHING
AND
REATTACHING
THE
DIESEL BURNER
Step 3: Disconnect the Diesel Burner’s Controller
Figure 34
1. Locate the Diesel-Burner’s Controller and disconnect both plugs.
Step 4: Remove the fuel lines from the Aqua-Hot
Figure 35b
Figure 35a
1. Locate where the fuel lines on the diesel burner
connect to the Aqua-Hot Bulkhead fittings.
2. Using an 7/16 wrench, loosen the nuts securing
each fuel line to the Aqua-Hot.
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— Page 53 —
SECTION 9: DETACHING
AND
REATTACHING
THE
DIESEL BURNER
Step 5: Remove the Diesel Burner from the Aqua-Hot
Figure 36a
Figure 36b
1. The Diesel-Burner is secured to the Aqua-Hot with two nuts that can be loosened,
and swung out of the way by using a 10mm socket wrench with a 10 inch long extension.
Figure 36c
2. Carefully pull the Diesel-Burner away from the Aqua-Hot 4 to 5 inches before
rotating the burner, and then remove.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 54 —
SECTION 9: DETACHING
AND
REATTACHING
THE
DIESEL BURNER
Reattaching the Diesel Burner to the Aqua-Hot
CAUTION!
When reattaching the diesel-burner be sure to properly align the diesel-burner before tightening the eye-bolt
nuts. Also, visually inspect all of the rubber grommets on the top and bottom of the diesel-burner’s castaluminum blower casing to ensure they are in place. DO NOT over tighten the eye-bolt nuts. Torque specifications are: approx. 20-40 in. lbs. An improper alignment and/or over tightening of the eye-bolt nuts can
cause damage to the diesel-burner’s cast aluminum blower casing.
Step 1: Reattaching the Diesel Burner to the Aqua-Hot
Figure 37a
1. The Diesel-Burner is secured to the Aqua-Hot with two eye-bolt nuts that can be swung into place,
after the diesel burner has been properly aligned and set in place.
Figure 37b
Figure 37c
2. The eye-bolt nuts can then be tightened by using a 10mm socket wrench with a 10 inch long extension. Use extreme caution when tightening down the eye-bolt nuts, over tightening of the eye-bolt nuts
can cause the aluminum blower casing to crack. (Torque Specifications = Approximately 20-40 in. lbs.)
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 55 —
SECTION 9: DETACHING
AND
REATTACHING
THE
DIESEL BURNER
Step 2: Reattach the fuel lines to the Aqua-Hot.
Figure 38a
Figure 38b
1. Align the fuel lines on the diesel burner with the fittings on the Aqua-Hot, and
using a 7/16 inch wrench, tighten down both the supply and return fuel fittings.
CAUTION!
Be sure to remove the clamps, off of the Fuel Supply and Return lines at the ports on top of the Aqua-Hot prior to starting the diesel burner, or serious damage will occur to the diesel-burner’s fuel pump.
Step 3: Plug in the diesel-burner’s controller and mount
3. Locate the Diesel-Burner’s Controller and connect both plugs.
Figure 39a
Figure 39b
NOTE: The Diesel Burner’s Controller might have to be mounted onto the side of the diesel burner, before the
plugs are inserted into the control unit, otherwise it might not be possible to mount the control unit.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 9: DETACHING
AND
REATTACHING
THE
DIESEL BURNER
Step 4: Reinstall the Access Cover
NOTE: The access cover must be installed prior to operation as a safety switch exists, which will
prevent the Aqua-Hot from operating whenever the access cover is not properly installed.
Figure 40b
Figure 40a
1. Reinstall the Aqua-Hot’s access cover .
2. Securely tighten the three bolts securing the access cover in place.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 10: DIESEL-BURNER COMPONENTS
Figure 41
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 10: DIESEL-BURNER COMPONENTS
Diesel-Burner Motor:
The motor drives the combustion air blower and the
fuel pump. In order to perform the following procedures, it may be necessary to detach the dieselburner head.
NOTE: The Aqua-hot 600 Series is equipped with a 20A
Fast Blow Fuse, located on the red #20 wire, between the
electronic controller and the diesel burner controller’s BPlug, which is the diesel burner motor power wire.
If there is no 12 Volts D.C. present on the C-2 pin, continue.
2.
Verify the Electronic Controller is sending power
to the diesel burner motor.
A. Using a volt meter, check for 12 Volt-DC on the
JP4 plug, on the B4 + pin (red wire #3). If no
power is present verify the electronic controller is
receiving power from the batteries.
i.
Locate the main power terminals on the
bottom of the electronic controller.
ii.
Using a volt Meter, check for 12 Volt D.C. on the JP 8 terminal. If no voltage is
present, verify that either the jumper is in
place, that connects pins JP5 and JP8
together, or if there is a power wire
hooked up to the JP8 terminal verify that it
is receiving 12 Volt D.C. from the
Motor home’s batteries.
iii.
If the JP8 pin does have 12 Volt D.C. +,
but pin 3, on the JP4 terminal does not
have power, replace the electronic
controller.
Component Test:
1.
Locate the diesel-burner controller’s C-Plug and
insert the probes of a DC voltmeter into the C-2 (+)
and the C-5 (-) locations.
A. Turn the diesel switch ON and verify both the
diesel burner status light and the heating status
lights are illuminated on the electronic controller.
If either light is not illuminated, follow the trouble
shooting guide for that particular component.
B. Observe the voltage level. If a normal voltage
registers on the voltmeter and the motor is not
operating, inspect the C-Plug Harness for loose or
damaged wire connections. If the C-Plug harness
and connections are in good condition, but the
motor is not operation the motor must be
replaced.
NOTE: The motor may have a flat spot and will cause the
burner to work intermittently. When testing the motor be
sure to test it multiple times to find the intermittent problem.
Figure 42
12 Volt D.C. + / - from
coach house batteries.
Fuse for Webasto Blower
Motor
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SECTION 10: DIESEL-BURNER COMPONENTS
Diesel-Burner Motor (continued) -
RPM Test:
1.
Disconnect the ignition cables from the ignition
electrodes.
7.
Connect the motor’s wires directly to a 12 volt DC
power supply.
2.
Remove the four ignition coil screws that secure the
ignition coil to the protection cap.
8.
Turn the power supply ON and use a phototachometer to test for a proper RPM reading.
3.
Lift the ignition coil and disconnect its wires from
the C-Plug harness wires prior to removing.
9.
4.
Remove the protection cap from the diesel-burner
so that the motor and clutch halves are exposed.
At approximately 12 volts DC the RPM reading
should be 4500 RPM’s (+/- 300 RPM’s.) If the
motor’s RPM reading is not within the above specs,
the motor must be replaced.
NOTE: It may be necessary to remove the diesel-burner to
remove the bottom two screws securing the protection cap in
place. Follow the direction on detaching and reattaching the
diesel burner in section 9.
5.
Place a few wraps of black electrical tape around
the clutch halves and then place a small piece of
reflective tape over the black tape.
6.
Disconnect the motor’s black (+) and brown (-)
wires from the C-plug harnesses black (+) and
brown (-) wires.
NOTE: Test the diesel-burner’s bearings prior to reattaching the diesel-burner head or replacing the motor.
Worn bearings can cause lower than normal RPM
readings and premature motor wear. To properly
test for worn bearings, reference the bearings function test section.
Figure 43
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 10: DIESEL-BURNER COMPONENTS
Motor Replacement Procedure:
Be sure to move the Diesel-Burner switch on the Interior Switch Panel to the OFF position and disconnect the Diesel-Burner’s power supply before detaching the Diesel-Burner from the Aqua-Hot. Failure to turn off the Diesel-Burner and disconnect
power could result in serious bodily injury.
1.
2.
3.
Follow the directions for detaching the diesel burner
in section 9.
Remove the four ignition coil screws that secure the
ignition coil to the protection cap. Lift the ignition
coil to disconnect its wires from the C-plug harness
wires prior to removing. Remove the protection cap
from the diesel-burner so that the motor clutch
halves are exposed.
Remove the three hex head screws that secure the
motor and flange assembly to the blower housing.
Remove the motor and flange assembly along with
the clutch halves. Disconnect the motor’s black (+)
and brown (-) wires from the C-plug harness’ wires.
NOTE: Inspect the clutch halves for cracks and also ensure
that the flat portion in each shaft hole is free of
wear and tear. Too much play on the shaft produces a loud clacking noise. If any cracks or wear are
detected, the clutch half must be replaced.
NOTE: Be sure to test the diesel-burner’s bearings prior to
reinstalling the motor. Worn bearings can cause
lower than normal RPM readings and premature
motor wear.
6.
Reinstall a clutch half on both the new motor’s shaft
and the combustion air blower shaft. Attach the
motor and flange assembly, with the recessed edge
of the motor flange in-line with the wiring access
slot of the blower casing, to the blower housing
with the three hex head screws.
NOTE: Inspect the blower casing’s O-ring for damage or
wear prior to reinstalling the diesel-burner head’s
protection cap. If damage or wear exists, replace
the O-ring.
7.
Connect the black (+) and the brown (-) wires of the
new motor to the C-Plug harness’ yellow (+) and
brown (-) wires. Feed the C-plug harness’ yellow
and brown wires back through wiring access hole in
the protection cap.
8.
Reinstall the protection cap. Reconnect the black
(+) and brown (-) wires.
9.
Reinstall the ignition coil and secure to the protection cap with the four ignition coil screws.
10.
Follow the directions for reattaching the diesel
burner in section 9.
11. Test for proper operation
4. Detach the motor from the motor flange by removing
the two Phillips heads screws that fasten the two
parts together.
5. The motor must be mounted to the flange with the
wires and drain hole pointing downward and the
recessed edge of the motor flange pointing upward.
This will ensure a proper protection cap fit.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 10: DIESEL-BURNER COMPONENTS
Figure 44
Motor Replacement Procedure: (continued)
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SECTION 10: DIESEL-BURNER COMPONENTS
Flame Sensor:
The flame sensor is a photo resistive device which
supplies the diesel-burner’s controller with a DC
voltage signal when it detects a flame. When the
flame sensor senses the light of the flame, it will
shut the ignition coil off, and send a signal to the
diesel burner controller indicating that everything is
working properly. If the flame sensor does not
sense the flame, it will shut the diesel burner down
in a default after 20 seconds.
NOTE: In order to perform the following procedures it is
necessary to detach and reattach the diesel-burner
head. Be sure to review the detaching/attaching
instructions.
Component Test: Ohms
NOTE: Be sure to calibrate your ohmmeter prior to checking the flame sensor to proper resistance values.
1.
2.
In order to perform the following procedures it is
necessary to detach the diesel-burner. Be sure to
review the detaching/attaching instructions in section 9.
Once the diesel burner has been removed, Locate
and detach the flame sensor’s green and blue wires
from the C-plug harness wires.
3.
Connect the flame sensor’s green and blue wires to
an ohmmeter.
4.
Check resistance by placing a shop rag over the
flame sensor’s glass surface, to simulate a no flame
condition, and then remove the rag and expose to a
light source, to simulate a flame condition.
5.
If the flame sensor is operating properly, the ohmmeter should register high resistance, over 100K Ω
when the glass surface is covered, and less than 200
Ω when exposed to a light source.
6. If these resistance numbers cannot be obtained, verify the flame sensor’s glass surface is clean. If the
flame sensor is clean and the resistance numbers
cannot be obtained, the flame sensor must be replaced.
Flame Sensor Maintenance:
1.
For light dirt, dust, and/or carbon deposits, simply
wipe off the flame sensor with a soft cloth.
2.
Should heavy carbon deposits be present, completely remove the flame sensor from the photo disc and
clean with brake cleaner.
Figure 45
Flame Sensor
Green Wire
Blue Wire
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SECTION 10: DIESEL-BURNER COMPONENTS
Flame Sensor Replacement Procedure:
1.
In order to perform the following procedures it is
necessary to detach diesel-burner head. Be sure to
review the detaching/attaching instructions in section 9.
2.
Remove the screw that fastens the flame sensor to
the photo disc and detach the sensor’s green and
blue wires from the C-plug harness’ green and violet wires, and remove flame sensor.
3.
Slide the tab of the new flame sensor into the provided slot in the photo disc and secure in place with
the screw. Connect the flame sensor’s green wire to
the green C-plug harness wire and the blue wire to
the C-plug harness’ violet wire.
4.
Follow the directions for reattaching the diesel
burner, in section 9 of this manual.
Figure 46
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 64 —
SECTION 10: DIESEL-BURNER COMPONENTS
Ignition Electrodes
The diesel-burner’s ignition coil produces a high
voltage ignition spark across the ignition electrodes,
which ignites the incoming air/fuel mixture.
Cleaning and Maintenance:
1.
Polish away any carbon deposits that may have
baked onto the metal tips of the ignition electrodes
with a course sponge.
2.
If the ignition electrode’s electrical insulator is
cracked or damaged, the ignition electrode must be
replaced.
NOTE: The electrode adjustment gauge is used to set the
gap between the ignition electrodes. The electrode
adjustment gauge is located on the outside surface
of the diesel-burner head on the left hand side.
Ignition Electrode Adjustment Procedure:
1.
Follow the directions for detaching/reattaching the
diesel burner in section 9 of this manual.
2. Using a 10mm socket, slightly loosen the retaining
clamp bolt.
3. Place the electrode adjustment gauge on the nozzle
manifold hex and insert the metal tips of the ignition
electrodes into the appropriate notches of the electrode adjustment gauge.
NOTE: Be sure not to over-tighten the retaining clamp bolt
when readjusting the ignition electrodes. Overtightening the retaining clamp bolt will bend the
retaining clamp and prevent the photo disc from
floating freely. Not allowing the photo disc to float
freely will cause poor combustion and result in a
smoky exhaust. A bent retaining clamp can be restraightened with a punch and hammer. Lay the
clamp’s beveled side down on a solid flat surface
and align the thick end of the punch at dead center.
Tap the punch lightly until the retaining clamp returns to proper form.
4.
Using a 10 mm socket, tighten the retaining clamp
bolt.
5. Remove the electrode adjustment gauge and reattach to the diesel-burner head.
Replacement Procedure:
1. Using a 10mm socket, loosen and remove the retaining clamp bolt, and the retaining clamp.
2.
Slide the electrode out of the photo disc.
3.
To remove the electrode, hold onto the orange electrode boot, and pull firmly on the electrode.
4. Once the electrode has been removed Inspect inside
the orange electrode boot for the retaining clip,
which holds the electrode in place. If it is missing,
replace the electrode boot.
Figure 47
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 10: DIESEL-BURNER COMPONENTS
Ignition Electrodes
2.
Replacement Procedure: (continued)
Hook the diesel burner up to an alternate fuel
source.
A. Disconnect the steel fuel lines from the diesel
burner.
5. Insert the new electrode into the orange electrode
boot, and snap into place. Pull firmly on the electrode to make sure the retaining clip has secured the
electrode in place.
B. Install the fuel line bypass adapter fitting onto
the diesel burner.
C.
6.
Slide the electrode into the photo disc.
7.
Install retaining clamp and retaining clamp bolt and
finger tighten.
8.
3.
Follow steps 2 - 5 to properly adjust the electrodes.
Install rubber fuel lines on both the supply and
return fuel pipes, and install the other end of the
rubber fuel lines into an adequate supply of
diesel fuel. Reference figure 48.
Remove both the ignition cables from the ignition
electrodes, or connect a jumper wire (with alligator
clips) across the metal tips of the electrodes.
Failure to connect a jumper wire across the ignition electrodes, or to remove the ignition cables from the ignition
electrodes will result in a HIGH VOLTAGE shock and/
or a fire. If the ignition cables are removed, be sure to
place a piece of electrical tape on the end of each cable.
Fuel Nozzle:
The fuel nozzle is simply a fuel atomizer. It reduces
the diesel fuel into a fine spray which is mixed with
incoming combustion air and is ignited within the
combustion chamber.
NOTE: In order to perform the following procedures it is
necessary to detach and reattach the diesel-burner
head. Be sure to review section 9 for detaching and
reattaching instructions.
4.
Remove the B-plug from the diesel-burner head’s
controller.
5.
Turn the diesel switch ON and then plug the B-plug
back into the diesel-burner controller to activate the
diesel-burner. After approx. 20 seconds the fuel
solenoid will “click” and a fine mist of fuel should
appear from the fuel nozzle in a cone shaped spray
pattern.
Fuel Nozzle Component Test:
1. Follow the directions for detaching the diesel burner,
in section 9, of this manual.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
Figure 48
— Page 66 —
SECTION 10: DIESEL-BURNER COMPONENTS
Fuel Nozzle:
2.
6.
Remove the B-plug from the diesel-burner controller.
7.
If the cone shaped spray pattern did not appear, fol
low the troubleshooting guides for the following
components and verify they are operating properly:
A. Fuel Solenoid
B. Fuel pump
C. D.C. High Limit thermostats
NOTE: An adjustment of the ignition electrodes may be
necessary after replacing the fuel nozzle. Follow
the ignition electrode adjustment procedure found
in the ignition electrode section of this manual.
3.
8. If the components listed above are operating properly, and there is still no fuel coming out of the nozzle,
replace the fuel nozzle.
Fuel Nozzle Cleaning and Maintenance:
The fuel nozzle is a precision calibrated part and
cannot be cleaned or serviced. A replacement
of the fuel nozzle is recommended annually.
Use a 3/4 in. wrench to hold the fuel nozzle stand
hex while loosening the fuel nozzle with a 5/8 in.
wrench and remove.
After replacing the fuel nozzle, reattach the dieselburner head.
Be sure to reattach the diesel-burner head prior to
switching the heater ON. Failure to do so may result in
ignition of the diesel-burner and serious bodily injury.
4.
Turn ON the diesel switch for 5 seconds, then turn
it OFF. This will activate the diesel-burner’s
prime-cycle and flush the fuel system of any potential contaminants. Perform this procedure twice.
5.
Test for normal operation.
Fuel Nozzle Replacement Procedure:
1.
When replacing the fuel nozzle, be sure to tighten
the nozzle, loosen it a 1/4 turn, and then firmly retighten. This will establish a seated fit and avoid
any leaks.
NOTE: Be sure to use care when handling the new fuel
nozzle. Oils and/or small dust or dirt particles from
your hands may plug the nozzle’s small orifice. A
partially plugged orifice will restrict fuel flow,
which will affect the combustion process of the
diesel-burner.
Figure 49
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SECTION 10: DIESEL-BURNER COMPONENTS
stand approximately 1/2”. Remove the fuel solenoid shaft from the nozzle manifold using a 16mm
wrench.. Discard the shaft and valve kit, as replacements are provided with the new fuel solenoid assembly.
Fuel Solenoid:
The fuel solenoid allows the flow of diesel fuel to
the diesel-burner’s fuel nozzle.
NOTE: If a long after-smoking condition exists during the
diesel-burner’s purge cycle, the fuel solenoid valve
kit may need to be replaced.
NOTE: In order to perform the following procedures it is
necessary to detach and reattach the diesel-burner
head. Be sure to review the detaching/attaching
instructions.
Fuel Solenoid Component Test:
NOTE: If the fuel solenoid is not working troubleshoot the
diesel burner’s hi-limit thermostats. If they are tripped they
will not allow the fuel solenoid to operate.
1.
Locate and detach the C-plug harness’ violet (+)
and Brown (-) wires from the fuel solenoid.
2.
Connect the (-) lead of a 12 volt DC power supply
to the fuel solenoid’s (-) electrical terminal.
3.
Intermittently apply the (+) lead of the power supply to the fuel solenoid’s (+) electrical terminal.
4.
Listen for the fuel solenoid to click (i.e. open and
close).
5.
If the fuel solenoid does not click, it must be replaced.
3.
Insert the contents of the new fuel solenoid valve kit
into the new fuel solenoid shaft. Slide the new fuel
solenoid onto the fuel solenoid shaft. Thread the
new fuel solenoid shaft with fuel solenoid to the
fuel nozzle manifold and tighten. Secure the fuel
solenoid in place with the new flat washer and lock
nut.
4.
Connect the C-plug harness’ violet (+) and
brown (-) wires to the fuel solenoid’s
(+) and (-) electrical terminals.
Figure 50
Fuel Solenoid Replacement Procedure:
1.
Disconnect the C-plug harness’ violet (+) and
brown (-) wires from the fuel solenoid.
2.
Using an 8mm wrench, remove the lock nut and flat
washer from the end of the fuel solenoid shaft and
then pull the fuel solenoid away from the nozzle
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SECTION 10: DIESEL-BURNER COMPONENTS
Fuel Pump:
The fuel pump draws diesel fuel from the vehicle’s
fuel tank and creates a preset pressure of 145 PSI,
which is required for proper fuel atomization. Reference the illustration below for a basic overview
and understanding of how the fuel pump functions.
7. If fuel does flow through the fuel pump when ran
off an external source inspect the following in the
motor home:
A. Check the motor home fuel tank for fuel. If the
fuel level is below 1/4 the Aqua-Hot diesel
burner will not operate.
Fuel Pump Testing Procedure:
Do not remove the diesel burner at this time. Failure to
do so may result in serious bodily injury.
1.
Clamp off and remove the fuel return and fuel supply lines coming into the Aqua-Hot unit.
2.
Attach a short piece of fuel line to both the fuel return and fuel supply ports.
3.
Submerse the opposite end of the temporary fuel
supply line in a container of diesel fuel.
4.
Place the opposite end of the temporary fuel return
line in an empty container.
5.
Turn the diesel switch ON to activate the dieselburner, and wait ten seconds.
6.
If fuel does not flow out of the return line into the
empty container, the fuel pump must be replaced.
NOTE: Prior to replacing the fuel pump, be sure to inspect
the screen filter in the supply inlet of the fuel pump
for dirt particles. Clean and/or replace if necessary.
A plugged screen filter will restrict fuel from entering the fuel pump.
B.
Inspect the supply fuel line for kinks which
would prohibit fuel flow.
C.
Inspect the supply fuel line for cuts, which
would cause the diesel burner to suck air.
D. Inspect the fuel filter, to make sure all fittings
are tight, including hose clamps. Also, make
sure the fuel filter is tight.
E.
Inspect the Aqua-Hot for loose or cracked
fittings.
F. Inspect the supply fuel system for loose hose
clamps throughout
G. Inspect the fuel pick-up tube in the tank., for
loose connection and pin holes in the pick-up
tube
Fuel Pump Cleaning and Maintenance:
1.
Check all fuel connections for tightness.
2.
Check the screen filter located in the fuel supply
inlet of the fuel pump for dirt particles. Clean and/
or replace if necessary.
3.
To adjust the fuel pressure refer to Appendix C:
Fuel pressure check and adjustment..
Figure 51
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SECTION 10: DIESEL-BURNER COMPONENTS
Fuel Pump Replacement Procedure:
NOTE: To perform the following procedure it will be necessary to remove the diesel burner. Follow the section on
detaching and reattaching the diesel burner, section 9 of this
manual.
1.
2.
3.
4.
5.
6.
Locate and disconnect the C-Plug harness wires that
connect to the flame sensor and the fuel solenoid.
Also, disconnect the ignition cables from the ignition electrodes.
Remove the retaining clip that secures the photo
disc in place. Gently lift the photo disc so that it
releases from the nozzle stand and the ignition electrodes.
Loosen the supply and return banjo bolts to remove
the fuel supply and return pipes from the fuel pump.
Also, disconnect the high pressure fuel pipe from
both the fuel pump and the nozzle stand. Discard
the high pressure fuel pipe, gasket rings, and banjo
bolts , as replacements are provided in the new fuel
pump kit.
Remove the four nozzle stand plate screws that secure the nozzle stand plate in place. Remove the
nozzle stand plate by pulling on the nozzle stand
until the plate releases from the cast-aluminum
blower casing.
Remove the two pump mounting screws that secure
the fuel pump in place. Turn the nozzle stand plate
over and remove the snap ring from the fuel pump
shaft, using snap ring pliers. Remove the nylon
drive gear and then the fuel pump.
Attach the new fuel pump to the nozzle stand plate
with the two pump mounting screws. Turn the nozzle stand plate over to install the nylon drive gear on
the fuel pump’s shaft and secure in place with the
snap ring. Dab the teeth of the nylon drive gear
with white lithium grease (Isoflex LDS-18 is recommended.)
NOTE: Do not adjust the fuel pressure regulator of the new
fuel pump, as it has been factory preset.
Inspect the nylon drive gear’s cavity inside the cast aluminum blower casting for fuel stains. If fuel stains are present,
a replacement of the bearings and/or the entire blower casing may be necessary. Leaking fuel could cause bearing
seizure, resulting in potential damage to the internal bore/
bearing of the blower casing.
7.
Fit the nozzle stand plate inside the cast-aluminum
blower casing and secure in place with the four nozzle stand plate screws. Install the grommets on the
fuel return and supply banjo pipes and secure the
pipes to the fuel pump with the new banjo bolts and
gasket rings.
NOTE: Failure to use the new gasket rings or the correct
order placement could result in a fuel leak.
8.
Reconnect the C-plug harness’ violet (+) and brown
(-) wires to the fuel solenoid’s (+) and (-) electrical
terminals.
9.
Insert both the ignition cables into the rubber grommet and slide into the appropriate notch on the
blower casing.
10. Reconnect the ignition cables to the ignition electrodes.
11. Reinstall the photo disc and secure it in place with
the retaining clip.
12. Reconnect the flame sensor’s green wire to the
green C-plug harness and the blue wire to the Cplug harness’ violet wire. Install rubber grommet
around the harness wires, and set into place.
NOTE: Check the ignition electrodes for proper adjustment
prior to reattaching the diesel burner.
13. Follow the directions for reattaching the diesel
burner in section 9 of this manual.
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SECTION 10: DIESEL-BURNER COMPONENTS
Fuel Pump: (continued)
Figure 52
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SECTION 10: DIESEL-BURNER COMPONENTS
Bearings:
5.
Remove the three hex head screws that secure the
motor and motor flange to the blower housing. Re
move the motor and flange assembly along with the
clutch halves. Disconnect the motor’s black (+) and
brown (-) wires from the C-plug harness’ wires.
6.
Remove the four blower housing screws that secure
the blower housing to the blower casing. Remove
the blower housing so that the combustion air
blower is exposed.
7.
Spin the combustion air blower by hand. Placing
one of the clutch halves to the end of the shaft,
assists with the spinning of the bearings.
8.
If the combustion air blower rotates smoothly without any friction or noise, the bearings are in proper
working condition. If the combustion air blower
does not rotate smoothly and/or produces noise, the
bearings are worn and must be replaced.
The bearings support the combustion air blower’s
shaft and allows the blower to turn smoothly.
NOTE: In order to perform the following procedures it is
necessary to detach and reattach the diesel-burner
head. Be sure to review section 9 for detaching and
reattaching the diesel burner instructions
Bearing Test:
1.
2.
In order to perform the following procedure it is
necessary to detach and reattach the diesel-burner
head. Be sure to review the detaching and reattaching section for detaching and reattaching instructions.
Locate and disconnect the C-plug harness wires that
connect to the flame sensor and fuel solenoid. Also,
disconnect the ignition cables from the ignition
electrodes.
Replacement:
3.
Remove the four nozzle stand plate screws that secure the nozzle stand plate in place. Remove the
nozzle stand plate by pulling on the nozzle stand
until the plate releases from the cast-aluminum
blower casing.
1.
In order to perform the following procedure it is
necessary to detach and reattach the diesel-burner
head. Be sure to review the detaching and reattaching section for detaching and reattaching instructions.
4.
Remove the four ignition coil screws that secure the
ignition coil to the protection cap. Lift the ignition
coil and disconnect its black (+) and brown (-) wires
from the C-plug harness wires, prior to removing.
Remove the protection cap from the diesel-burner
so that the motor and clutch halves are exposed.
2.
Locate and disconnect the C-plug harness wires that
connect to the flame sensor and fuel solenoid. Also,
disconnect the ignition cables from the ignition
electrodes.
Figure 53
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SECTION 10: DIESEL-BURNER COMPONENTS
3.
Remove the four nozzle stand plate screws that secure the nozzle stand plate in place. Remove the
nozzle stand plate by pulling on the nozzle stand
until the plate releases from the cast-aluminum
blower casing.
NOTE: It is recommended to mark the internal components
of the diesel burner prior to disassembling of the burner.
Make a mark between the motor flange and the blower housing, and also between the blower housing and the blower
casing. If the burner is assembled improperly the protection
cap will not go on.
4.
5.
Remove the four ignition coil screws that secure the
ignition coil to the protection cap. Lift the ignition
coil and disconnect its black (+) and brown (-) wires
from the C-plug harness wires, prior to removing.
Remove the protection cap from the diesel-burner
so that the motor and clutch halves are exposed.
Remove the three hex head screws that secure the
motor and motor flange to the blower housing. Remove the motor and flange assembly along with the
clutch halves. Disconnect the motor’s black (+) and
brown (-) wires from the C-plug harness’ wires.
6.
Remove the four blower housing screws that secure
the blower housing to the blower casing. Remove
the blower housing so that the combustion air blower is exposed.
7.
Hold side-B of the blower casing and loosen the
retaining nut located in side-A of the blower casing.
Remove the retaining nut, steel drive gear and thick
flat washer from the combustion air blower’s shaft.
Lightly tap the threaded end of the shaft so that the
combustion air blower can be easily removed from
the blower casing.
NOTE: Be sure to inspect the blower casing’s bore/bearing
cavity for signs of damage due to potentially seized
bearings. If damage is present, the blower casing
must be replaced.
9.
Install a new snap ring into side-A of the blower
casing. Once the snap ring is in place, insert the
remaining contents of the new bearing kit into sideB of the blower casing, starting with the wave
washer. Secure the bearing kit assembly in place
with the remaining snap ring.
10. Inspect the combustion air blower for warping and/
or damage. If warping or damage is visible, the
combustion air blower must be replaced.
11. Reference Figure 54 for exact placement of the
three washers that slide over the threaded end of the
combustion air blower’s shaft prior to installation.
Failure to follow the correct order and direction of
the dished surfaces on the washers will result in a
restricted rotation of the combustion air blower.
12. Slide the combustion air blower’s shaft (with the
three washers) up through the bearing kit assembly
until the threaded portion appears on side-A of the
blower casing. Place the new thick flat washer and
steel drive gear on the threaded end of the combustion air blower’s shaft. Thread the new retaining
nut on the combustion air blower’s shaft until it is
finger tight (DO NOT TIGHTEN.)
Figure 54
NOTE: Be sure to observe the placement of the three washers of the bearing kit. To ensure proper tension, the
same order and direction of the dished surfaces of
the washers must be followed when reassembling.
8.
With a pair of snap-ring pliers, remove the snap
rings from both side-A and side-B of the blower
casing. Push all the contents of the bearing kit out
of the blower casing’s bore/bearing cavity. Discard
the retaining nut, steel drive gear, snap rings, bearings, spacer tube, and washers, as replacements are
provided in the new bearing kit.
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SECTION 10: DIESEL-BURNER COMPONENTS
12. Place a feeler gauge between the combustion air
blower and the flat surface of the blower casing.
Slowly tighten (or loosen) the retaining nut, holding
the combustion air blower, until a .018 - .020 gap is
achieved. Remove feeler gauge. Reference Figure
55a.
13. Spin the combustion air blower to ensure a friction
free rotation.
NOTE: If the combustion air blower is rubbing, loosen the
retaining nut slightly and lightly tap on the combustion air blower’s shaft (opposite side) then readjust
the gap.
14. Reattach the blower housing to the blower casing
using the four blower housing screws. Reinstall the
clutch half on both the motor’s shaft and the combustion air blower’s shaft. Attach the motor and
flange assembly, with the recessed edge of the motor flange in-line with the wiring access slot of the
blower casing, to the blower housing with the three
hex head screws. Reconnect the black (+) and
brown (-) wires of the motor to the C-plug harness’
black (+) and brown (-) wires. Feed the C-plug
harness’ yellow and brown wires back through the
wiring access hole in the protection cap.
NOTE: Inspect the clutch halves’ for cracks and also ensure
that the flat portion in each shaft hole is free of
wear and tear. Too much play on the shaft produces a loud clacking noise. If any cracks or wear are
detected, the clutch half must be replaced.
15. Reinstall the protection cap. Reconnect the black
(+) and brown (-) wires of the ignition coil to the Cplug harness’ yellow (+) and brown (-) wires. Reinstall the ignition coil and secure to the protection
cap with the four ignition coil screws. Reconnect
the ignition cables to the ignition electrodes.
16. Fit the nozzle stand plate inside the cast aluminum
blower casing and secure in place with the four nozzle stand plate screws. Reattach the fuel supply and
return lines to the diesel-burner head.
17. Reconnect the blue (+) and brown (-) wires to the
fuel solenoid’s (+) and (-) electrical terminals. Also, reconnect the flame sensor’s green wire to the
green C-plug harness wire and the blue wire to the
C-plug harness’ violet wire.
18. Follow the instructions for reattaching the diesel
burner, in the detaching/reattaching section in this
manual.
Figure 55b
Figure 55a
.018 - .020
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SECTION 10: DIESEL-BURNER COMPONENTS
Ignition Coil:
The ignition coil produces a high voltage ignition
spark (approx. 8000 volts), which is released across
the metal tips of the ignition electrodes during the
initial diesel-burner start-up.
Use extreme care when testing the ignition coil, as a High
Voltage Shock may result.
NOTE: In order to perform the following procedures it is
necessary to detach and reattach the diesel-burner
head. Be sure to review the section for detaching
and reattaching the diesel burner..
Component Test:
1.
Remove the four ignition coil screws that secure the
ignition coil in place.
2.
Disconnect the ignition coil’s black (+) and brown
(-) wires from the C-plug harness’ yellow (+) and
brown (-) wires.
3.
Connect the ignition coil wires directly to a 12 volt
DC power supply (i.e. black (+) wire to (+) lead and
brown (-) wire to (-) lead).
4.
Turn the power supply ON and watch for a spark to
appear across the metal tips of the ignition electrodes. If a spark does not appear, the ignition coil
must be replaced.
NOTE: Some ignition coils are intermittent and will need
to be tested numerously. If the Ignition Coils tests good and
it still will not operate it is possible the Electronic Controller
is defective.
Before replacing the ignition coil:
1. Verify the ignition electrodes are not cracked or broken.
2. Verify that the ignition electrodes are adjusted properly.
3. Ensure the electrode boots are securely holding the
electrodes in place.
4. Ensure the electrode boots are not broken inside the ignition coil wires.
Figure 56
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SECTION 10: DIESEL-BURNER COMPONENTS
Ignition Coil:
2.
NOTE: In order to perform the following procedures it is
necessary to detach and reattach the diesel-burner
head. Be sure to review the section for detaching
and reattaching the diesel burner..
Replacement Procedure:
1.
Disconnect the ignition cables from the ignition
electrodes. Remove the four ignition coil screws
that secure the ignition coil to the protection cap.
Lift the ignition coil and disconnect its wires from
the C-plug harness wires, prior to removing.
Connect the new ignition coil’s black (+) and brown
(-) wires to the C-plug harness’ yellow (+) and
brown (-) wires. Attach the ignition coil to the protection cap with the four ignition coil screws, then
reconnect the ignition cables to the ignition electrodes.
NOTE: If the new ignition coil does not function, check
wire connections and ensure they are properly connected.
3.
Follow the instructions for reattaching the diesel
burner and test for proper operation.
Figure 57
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 10: DIESEL-BURNER COMPONENTS
Diesel-Burner Controller:
NOTE: Before troubleshooting the Diesel Burner Controller, verify that the Aqua-Hot’s Electronic Controller has
voltage at both the C1(orange) & C7(white) wires on the JP4
Plug. Both the C1 & C7 wires will only have power when
both the Diesel Burner Status Light and the Heating Status
Light are illuminated.
The diesel-burner controller operates all the components of the diesel-burner head and safely shuts the
heater OFF in the event of an overheat, flameout,
and low voltage condition. It also receives dieselburner operation status signals from the flame sensor, VDC control thermostat, and VDC high-limit
thermostat.
Component Test:
The following conditions must exist prior to performing the diesel-burner controller circuit tests on
the following page. If one of the conditions below
does not exist, please contact our technical support
department at 1-800-685-4298 for additional assistance.
Condition #1
A battery voltage level between 11.5 to 14.0 volts
DC must be present at the diesel-burner controller
during all testing. It may be necessary to perform a
voltage check to ensure that this condition exists.
To perform the voltage check, locate the dieselburner controller’s B-plug, and insert the probes of
a DC voltmeter into the B-4 (+) and B-2 (-) locations.
Condition #2
A voltage level of between 11.5 to 14.0 volts must
be present at the diesel ON/OFF switch circuit of
the diesel-burner controller during all testing. It
may be necessary to perform a voltage check to
ensure that this condition exists. To perform the
voltage check, locate the diesel-burner controller’s
B-plug, and insert the probes of a DC voltmeter into
the B-1 (+) and B-2 (-) locations. Turn the diesel
switch ON and observe the voltage level.
Ground Circuit Test:
Locate the diesel-burner controller’s B-plug and Cplug. Insert the probes of a DC voltmeter into the B
-4 (+) and C-5 (-) locations and turn the diesel
switch ON. If a voltage reading does not register on
the voltmeter, the diesel-burner controller must be
replaced. If voltage is present, proceed to the next
circuit test.
VDC/VAC Control Thermostat Circuit Test:
Locate the diesel-burner controller’s B-plug and Cplug. Insert the probes of a DC voltmeter into the C
-1 (+) and B-2 (-) locations and turn the diesel
switch ON. If a voltage reading does not register on
the voltmeter, the diesel-burner controller must be
replaced. If voltage is present, proceed to the next
circuit test.
VDC High-Limit Thermostat Circuit Test:
Locate the diesel-burner controller’s B-plug and Cplug. Insert the probes of a DC voltmeter into the C
-4 (+) and B-2 (-) locations and turn the diesel
switch ON. If a voltage reading does not register on
the voltmeter, the diesel-burner controller must be
replaced. If voltage is present, proceed to the next
circuit test.
Motor Circuit Test:
Locate the diesel-burner controller’s B-plug and Cplug. Use a jumper wire to make a connection from
the C-1 location to the C-7 location. Turn the diesel
switch ON and insert the probes of a DC voltmeter
into the C-2 (+) and C-5 (-) locations. If no voltage
reading registers on the voltmeter, the diesel-burner
controller must be replaced. If voltage is present,
proceed to the next circuit test.
Be sure to remove the jumper wire that was used to make the
connection from the C-1 location to the C-7 location. A failure to do so will result in an overheating condition during
normal operation.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 10: DIESEL-BURNER COMPONENTS
Ignition Coil Circuit Test:
Turn the diesel switch OFF and locate the dieselburner controller’s C-plug. Also, locate the VDC
high-limit thermostat and disconnect it’s 2-way
male plug from the (white plastic) 6-way female
connector. Insert the probes of a DC voltmeter into
the C-8 (+) and C-5 (-) locations and turn the diesel
switch ON. If a voltage reading does not register on
the voltmeter 18-25 seconds after the initial start-up
the diesel-burner controller must be replaced.
NOTE: Be sure to reconnect the VDC high-limit thermostat’s 2-way male plug to the 6-way female plug.
The diesel-burner will not ignite during normal
operation if the VDC high-limit thermostat is left
disconnected.
Be sure to remove the jumper wire that was used to make the
connection from the C-1 location to the C-7 location. Failure
to do so will result in an overheating condition during normal
operation.
NOTE: If the Control Box is replaced and the Ignition
Coils still will not operate, it is possible the Electronic Controller is defective.
Figure 58a
Replacement Procedure:
1. Remove both the B-plug and the C-plug from the
diesel-burner controller. Gently pry away each side
of the diesel-burner controller bracket from the diesel-burner controller’s locking posts with a flat-head
screw driver. Once the locking posts have been
released, pull on the diesel-burner controller to remove it from the diesel-burner head.
Figure 58b
2. Slide the new diesel-burner controller into the diesel
-burner controller bracket. Push down on the diesel
-burner controller until the locking posts snap into
the bracket slots.
3. Reconnect the B-plug and the C-plug.
NOTE: Be sure to install the diesel-burner controller with
it’s C-plug and B-plug ports facing downward.
Failure to do so, will result in moisture collecting in
the ports and potential damage to the diesel-burner
controller’s internal circuitry.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 11: TROUBLESHOOTING
IF THE AQUA-HOT
IS
BLACK SMOKING:
1. Things to check before opening up heater
1. Low Voltage - Fire up generator/plug coach into shore power
2. Damaged or Restricted exhaust pipe - Inspect exhaust pipe for damage
2. Access cover must be removed to check the following:
1.
2.
3.
4.
Air Intake Closed off - on the bottom of the burner is the air adjustment, set at the half way point.
Broken Protection Cap - Check cap for cracks or missing pieces.
Worn OUT Grommets – run hands over grommets, on top and bottom, and feel for excessive air
Burner not seated properly or Loose - run hands along the seal of the burner, and check for excessive air
5. Air Intake Sleeve collapsed
3. Diesel Burner must be removed to check the following:
1.
2.
3.
4.
Photo Disc Bent or Tight – The photo disc must be loose, so it will seal on the combustion chamber properly
Combustion Chamber Warped/Melted – Inspect for signs of warping/melted aluminum.
Bad Nozzle - If nozzle is spraying poorly, it must be replaced
Fuel Pressure not at 145 PSI – Check fuel pressure with fuel pressure gauge
4. Diesel Burner must be torn down to check the following:
1. Slow Motor (Less Than 4500rpms at 12v) -
a slow motor acts the same as low voltage. Check motor rpm
with an rpm tester, under full load.
2. Bearings are worn out - Bearings should spin freely, and sound smooth.
If they are starting to seize up, they will
slow the motor down.
3. Impeller Fan Not Gapped Properly – The impeller needs to be gapped at 3-5 thousands or tighten fan down
until it rubs, back it off ¼ turn.
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SECTION 11: TROUBLESHOOTING
IF THE AQUA-HOT
IS
BLUE/WHITE SMOKING:
1. If The Heater Smokes on Start up/Shut down.
a. Fuel solenoid
- plunger worn out
- plastic/metal in the way of plunger
- fuel solenoid intermittent.
b. Nozzle Tower
- cracked
- poorly machined
c. Short cycling
- control t-stat bad
- someone turned heater off/on repeatedly
d. Return Fuel Check Valve
- heaters manufactured before 2001
NOTE: It is normal for the heater to blue/white
smoke for 3-5 seconds on start up and shut down.
2. If The Heater Smokes During The Burn Cycle.
a. Electrodes out of adjustment
b. Air in the fuel system
c. Bad nozzle
d. Fuel pressure
e. Fuel Pump
f.
Intermittent Ignition Coil
- If the coil doesn’t turn on, the fuel sprays for 20 seconds, before the photo eye shuts the fuel off.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
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SECTION 11: TROUBLESHOOTING
IF ONE
OF
THE AQUA-HOT HEATING ZONES
WILL NOT GET HOT:
1. General Problems
A. Diesel/Electric not operating
(antifreeze cold)
B.
Heater is Not up to operating Temperature
(antifreeze is cold)
C. Interior Zone Thermostat Not calling for heat
D. Zone Circulation Pump Not Operating
E.
Heat Exchanger Fans Not Operating
E.
The Low Temp Cut-Off status light is not illuminated on the
Electronic Control Board.
G. The Electronic Control Board is wired wrong
(i.e.) the fans for the bedroom come on but the pump for the
living room comes on.
H. Not enough Heat Exchangers installed
I.
Heat Exchangers improperly installed.
2. If Fans and Pumps are Running
A. Stuck Check Valve
B.
Kinked Line
C. No Antifreeze in system
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 81 —
SECTION 11: TROUBLESHOOTING
IF THERE IS A LACK
OF
DOMESTIC HOT WATER:
1: General information
1. The heater is only rated for water flow of 1.5 GPM
2. The heater is only rated for a 55*F temperature Rise on the cold water coming into
the unit
3. The diesel burner must be on for continuous hot water, the electric element is for limited use only.
2: Things to test for a lack of hot water problem.
1. Aqua-Hot Heater Bypassed
2. Outside Water Faucet is left on.
3. Washing Machine Valve has gone bad
4. Antifreeze Concentration is incorrect.
a. 30%-50% antifreeze concentration
5. Operating Range of the heater (I.E. Control Thermostat) is incorrect
a. 155° F - 185° F
6. Water Flow is too fast
a. Must be 1.5 GPM or Less.
7. Mixer Valve is stuck (knob does not turn freely)
8. Low Temperature Cut-off Thermostat is not functioning properly
a. Needs to trip within 1 – 2 Minutes when running hot water
b. Needs to turn the stir pump on, if the diesel burner switch is on as well.
9. Stir Pump is not functioning properly
a. Needs to be running when the diesel burner switch is on, and the Low Temperature Cut-Off
thermostat is Tripped.
b. Hold onto both upper and lower hose to make sure both get hot
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 82 —
SECTION 11: TROUBLESHOOTING
IF THERE IS ANTIFREEZE LEAKING:
NOTE: To find an antifreeze leak, the system must be Hot (up to operating temperature)
Or pressurized to 15PSI.
Inspect the following components on the Aqua-Hot Heating System for Leaks:
1. On the Front-Side of Aqua-Hot 1. Fluid Level Sensor
a. It might be necessary to cut away some of the insulation around the fluid level sensor, to locate
the leak.
2. Control Thermostat
b. It might be necessary to cut away some of the insulation around the Control Thermostat, to locate the leak.
3. Drain Valve and Hose going to the drain valve
4. Electric element
5. Circulation/Stir pump
c. Hoses
d. Tank ports
- It might be necessary to cut away some of the insulation around the tank ports to locate
the leak.
e. Pump
6. Burn Chamber Leak
a. If Antifreeze is running out of the tip of the exhaust pipe remove the burner, and combustion
chamber and inspect inside the burn chamber for leaks.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 83 —
SECTION 11: TROUBLESHOOTING
IF THERE IS ANTIFREEZE LEAKING: (CONTINUED)
2. On the Top-Side of Aqua-Hot 1. Expansion Tank Connection
a. Cracked expansion tank tubing
b. Loose air release valve
c. Brass hose barb fitting defective or loose
2. Return Ports
A. Defective fitting
B. Leaking fitting
3. On the Rear-Side of Aqua-Hot
1. Copper Pipes
a. The copper pipes come out of the tank, so they are possible points of antifreeze leaks. Either
where the brass fittings go into the tank, or at the copper pipes where they go through the brass
fittings.
Note: If no leaks are found on the Aqua-Hot, it is possible
that there is a leak within the motor home. Check all Heat
exchangers, connections, and tubing for leaks.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 84 —
APPENDIX A: WIRING DIAGRAM -
MANUFACTURED BEFORE JANUARY
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
2011
— Page 85 —
APPENDIX A: WIRING DIAGRAM –
MANUFACTURED
BETWEEN JANUARY 2011
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
THRU
AUGUST 2011
— Page 86 —
APPENDIX A: WIRING DIAGRAM –
MANUFACTURED
AFTER 09/01/2011
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 87 —
APPENDIX B: WIRE GAUGE INFORMATION
Because all Aqua-Hot heating systems are designed to operate only when there is an adequate supply of DC (Direct Current) voltage,
it is imperative that the proper wire gauge be determined and used for the DC power supply and ground wires. This bulletin addresses how to determine the DC amperage draw of the heating system, including heat exchangers, then, how to determine the proper wire
gauge based upon those findings for a specific application.
Determining the DC Amperage Draw of the Heating System:
1. Review the chart below for the amperage draw of each Aqua-Hot heater (excludes heat exchangers).
2. Determine the number of heat exchangers installed with the Aqua-Hot Heating System.
NOTE:
Each heating zone “FAN” circuit can supply up to 2.0 amps of direct current.
3. Consult the heat exchanger’s manufacturer for amp-draw information.
NOTE:
Each Aqua-Hot Cozy heat exchanger draws .23 amps of direct current.
Each Aqua-Hot Whisper heat exchanger draws .38 amps of direct current.
4. Determine the total amperage draw for all heat exchangers installed.
For example, if six Aqua-Hot Cozy heat exchangers have been installed, multiply the amperage draw of
each heat exchanger (.23 amps) by the number of heat exchangers (6). The total amperage draw in this
scenario would be 1.38 amps.
5. Add the total heat exchanger amperage draw to the amperage of the installed Aqua-Hot.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 88 —
APPENDIX B: WIRE GAUGE INFORMATION
For example, an Aqua-Hot 600-D with six Aqua-Hot Cozy heat exchangers has a total amperage draw of
23.38 amps.
Determining the Proper Wire Gauge:
1. Measure the total length of the wire required for the distance between the vehicle’s battery and the electronic controller for Aqua-Hot models 450-DE, 450-DM, 525-D, 600-D, and 675-D and the heater itself for
the Aqua-Hot 375-D model.
2. Using the determined length and total amperage draw, consult the wire gauge chart included in this bulletin. Round up to the closest amp draw listed on the left, then round up to the closest length at the top of the
chart.
For example, an Aqua-Hot 600-D heater with six Aqua-Hot Cozy heat exchangers with the electronic controller placed 15 feet from the vehicle’s battery would require an 8-gauge wire.
Wire Gauge Chart:
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 89 —
APPENDIX C: FUEL PRESSURE CHECK
AND
ADJUSTMENT
Instructions for Checking Fuel Pressure
NOTE:
A fuel pressure gauge is used to properly check the fuel pump’s pressure setting. The fuel pump is preset to 145 PSI. Perform the
following procedures to check for a proper fuel pressure setting.
NOTE: In order to perform the following procedure it is necessary to detach and
reattach the diesel-burner head. Be sure to review the detaching/attaching instructions.
Step 1: Remove the diesel-burner
Figure C1
1. Refer to the section on detaching/reattaching the diesel burner, to detach the diesel burner.
Step 2: Install fuel line bypass fittings onto the diesel burner.
Figure C2
1/4” Fuel
Tube unions
1. Locate the 1/4 “ fuel tube unions on the bottom side of diesel burner.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 90 —
APPENDIX C: FUEL PRESSURE CHECK
AND
ADJUSTMENT
Instructions for Checking Fuel Pressure
Step 2: Install fuel line bypass fittings onto the diesel burner. (continued)
Figure C3
2. Using a 13mm and a 9/16” wrench remove Steel Fuel lines from the diesel Burner
Figure C4
3. Using a 13mm and a 9/16” wrench install the fuel bypass fittings onto the diesel Burner
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 91 —
APPENDIX C: FUEL PRESSURE CHECK
AND
ADJUSTMENT
Instructions for Checking Fuel Pressure
Step 3: Installing the fuel pressure gauge
Figure C5
1. Using a 5/8” and a 3/4” wrench remove the fuel nozzle.
Figure C6
2. Using a 5/8” and a 3/4” wrench install the fuel pressure gauge.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 92 —
APPENDIX C: FUEL PRESSURE CHECK
AND
ADJUSTMENT
Instructions for Checking Fuel Pressure
Step 3: Running the burner off of an external fuel source
Figure C7
1. Using an external fuel source and rubber fuel line, hook the Webasto burner supply and return fuel
lines up to run off of the external fuel source.
WARNING!
A spark will appear across the ignition electrodes for a brief moment after the diesel burner has been activated.
DO NOT attempt to make any fuel pressure adjustments until the spark has disappeared. Failure to do so may
result in serious bodily injury. In some installations it may be necessary to shine a light on the flame sensor to
simulate a flame condition to shut of the ignition coil.
Figure C8
2. Turn the diesel burner switch to the on position. A pressure will register on the fuel pressure gauge
once the fuel solenoid opens (after approx. 10-20 seconds.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 93 —
APPENDIX C: FUEL PRESSURE CHECK
AND
ADJUSTMENT
Instructions for Adjusting Fuel Pressure
Step 1: Follow the directions for Checking the Fuel Pressure in this section.
Figure C9
1. Using an external fuel source and rubber fuel line, hook the Webasto burner supply and return fuel
lines up to run off of the external fuel source.
WARNING!
A spark will appear across the ignition electrodes for a brief moment after the diesel burner has been activated.
DO NOT attempt to make any fuel pressure adjustments until the spark has disappeared. Failure to do so may
result in serious bodily injury. In some installations it may be necessary to shine a light on the flame sensor to
simulate a flame condition to shut of the ignition coil.
Figure C10
2. Turn the diesel burner switch to the on position. A pressure will register on the fuel pressure gauge
once the fuel solenoid opens (after approx. 10-20 seconds.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 94 —
APPENDIX C: FUEL PRESSURE CHECK
AND
ADJUSTMENT
Instructions for Adjusting Fuel Pressure
Step 2: Adjust the Fuel pressure to 145 PSI.
Figure C11
1. Once the fuel solenoid has been activated, and the fuel pressure gauge is registering a pressure, the
fuel pressure can be adjusted. To increase the fuel pressure turn the pressure adjustment screw clockwise, and to reduce the fuel pressure, turn the pressure adjustment screw counter clockwise.
NOTE: If the fuel pressure cannot be adjusted refer to the fuel pump section in section ? Of this manual for troubleshooting tips.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 95 —
APPENDIX D: EXTREME COLD WEATHER OPERATION
Diesel-Burner
When storing the Motor home: Not winterizing the AquaHot when freezing temperatures are present will result in
serious damage to the Aqua-Hot’s Domestic Water Heating
System. Also, be sure to use an FDA approved, “GRAS”
rated antifreeze for winterization.
1. If the Diesel burner Fails to operate:
NOTE: The Aqua-Hot can continue to be used for interior
zone heating once the domestic water heating system
has been drained and winterized.
A. Is the Diesel Fuel in the motor home winter
fuel or summer fuel?
B. Is the Diesel Fuel liquid or Jelled?
C. Are the electrodes properly adjusted?
D. When was the last time an Annual Service
was performed?
120 Volt-A.C. Electric Heating Element
Please note that the 120 Volt-AC Electric Heating Element is
the Aqua-Hot’s secondary heat source for heating both the
interior and/or the domestic hot water during low heating demand situations (such as when moderate ambient temperatures
exist and/or when there is a low demand for domestic hot water).
If the 120 Volt-AC Electric Heating Element is not providing
enough heat, turn the Diesel-Burner on, in conjunction with the
120 Volt-AC Electric Heating Element.
Figure D1
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 96 —
APPENDIX D: EXTREME COLD WEATHER OPERATION
If there is a lack of interior Heat:
Note:
The 120 Volt-AC Electric Heating Element is
the Aqua-Hot’s secondary heat source for heating both
the interior and/or the domestic hot water during low heating demand situations (such as when moderate ambient
temperatures exist and/or when there is a low demand for
domestic hot water). If the ambient temperature is ex-
1. Is the Diesel Burner activated?
2. Is the Diesel Burner operating Properly?
3. What is the antifreeze concentration, inside of the
Aqua-Hot Boiler Tank?
4. Was the heating system properly installed, following the
450D installation manual?
Figure D2
A. Are there at least 5 heat exchangers installed in the
Interior of the motor home?
B. Are there cold air returns installed for every heat
exchanger? Reference Figure ??
C. Are the heat exchangers mounted as close to the
hot air outlet grill as possible? Reference
Figure ??.
Figure D3
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 97 —
APPENDIX E: AQUA-HOT MAINTENANCE
Monthly Maintenance:
Annual Maintenance:
Check the antifreeze and water heating solution to ensure
that it is at the proper level by visually checking the solution
level in the expansion tank. The level of the antifreeze and
water heating solution within the expansion tank should only
be checked when the Aqua-Hot is at maximum operating
temperature.
If additional antifreeze and water heating solution is required, fill the expansion tank to the “HOT” level mark. Be
sure to reference Section 2 of this manual to ensure that the
proper type of antifreeze is selected and mixed with highquality water at the correct mixture ratio.
Additionally, it is recommended that the diesel-burner be
fired and allowed to run monthly to keep it in good working
order.
FAILURE TO DISCONNECT ALL POWER SUPPLIES AND/OR
TO ALLOW THE HEATER TO COOL BEFORE SERVICING
COULD CAUSE SERIOUS DAMAGE OR PERSONAL INJURY.
To keep the Aqua-Hot running smoothly, it is recommended
to have the diesel-burner tuned up annually. A tune-up
should consist of a new fuel nozzle and fuel filter, along with
a thorough cleaning of the combustion chamber. To ensure
maximum diesel-burner performance, always use the recommended fuel nozzle and fuel filter when replacing these
parts.
NOTE: Be sure to use care when handling the fuel nozzle.
Oils and/or small dust or dirt particles from the
hands may plug the nozzle’s small orifice. A partially plugged orifice will restrict fuel flow, which
will affect the combustion process of the dieselburner.
Figure E1
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 98 —
APPENDIX E: AQUA-HOT MAINTENANCE
Aqua-Hot Maintenance Procedure:
Note: Before performing an annual
maintenance, it is recommended to test run
the Diesel-Burner. While testing inspect
exhaust for smoke.
Step 1: Test Run the Diesel Burner
1. Turn the Diesel-Burner Switch to the on position.
2. After the Diesel-Burner has ignited, inspect
the exhaust for smoke.
3. Shut the Diesel-Burner off, and wait for unit
to completely shut off.
NOTE: The diesel-burner can either be shut off by:
1. Turning the Diesel Burner switch to the off position.
2. Disconnecting the control thermostat wires
3. Unplugging the diesel burner controller.
Reference Figure E3
Step 2: Replace the Fuel Filter
1. Locate Fuel Filter.
2. Using hose pinch off pliers, clamp off both
fuel lines going to the fuel filter. Reference
figure E2.
3. Replace fuel filter, with proper replacement
canister.
NOTE: It is recommended that the replacement fuel filter
be filled with clean diesel fuel, prior to installation
4. Remove hose pinch off pliers.
Step 3: Run the Diesel Burner
1. Turn the Diesel-Burner Switch to the on position.
2. After the Diesel-Burner has ignited, let it
burn for 1 - 2 minutes to purge the old fuel
out of the nozzle holder, to prevent contamination of the replacement nozzle.
3. Shut the Diesel-Burner off, and wait for unit
to completely shut off.
NOTE: The diesel-burner can either be shut off by:
1. Turning the Diesel Burner switch to the off position.
2. Disconnecting the control thermostat wires
3. Unplugging the diesel burner controller.
Reference Figure E3
Thermostat
Connector
Figure E3
Figure E2
Diesel Burner
Controller Plugs
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 99 —
APPENDIX E: AQUA-HOT MAINTENANCE
Aqua-Hot Maintenance Procedure:
Step 4: Remove The Diesel Burner
CAUTION!
Be sure to clamp off the Fuel Supply and Return lines at the ports on top of the Aqua-Hot prior to beginning this
replacement procedure.
Figure E4a
Figure E4b
1. Locate the Diesel-Burner’s Controller and disconnect both plugs.
Figure E4c
2. Using an 7/16 wrench, loosen the nuts securing
each fuel line to the Aqua-Hot.
Figure E4d
3. The Diesel-Burner is secured to the Aqua-Hot with two nuts that can be loosened, and swung out of
the way by using a 10mm socket wrench with a 10 inch long extension.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 100 —
APPENDIX E: AQUA-HOT MAINTENANCE
Aqua-Hot Maintenance Procedure:
Step 4: Remove The Diesel Burner (continued)
Figure E4e
Diesel Burner’s white
Thermostat Plug
4. Carefully pull the Diesel-Burner away from the Aqua-Hot 4 to 5 inches before
rotating the burner, and then remove.
NOTE: To remove the diesel burner, it may be necessary to disconnect the control and hi limit thermostats from the diesel-burner’s white thermostat plug.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 101 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 5: Clean and Inspect the Combustion Chamber and Heat Transfer Tabs.
Use caution when handling the combustion chamber, it may be extremely
hot, and serious burns could result from touching a hot combustion chamber.
Figure E5a
Combustion Chamber
Assembly
Combustion Chamber
Gasket
Air Swirler
Nut Securing the
Combustion Chamber
1. Remove the combustion chamber by loosening and
removing the 4 nuts, securing the combustion chamber
to the boiler tank and pulling it straight out, approximately 16 inches.
2. Once the combustion chamber has been removed.
Use a long handled wire brush, and brush the heat transfer tabs, to loosen soot deposits. Failure to do so will
reduce the Aqua-Hot’s heat transfer capabilities.
NOTE: If the heat transfer tabs are excessively sooty, it may be necessary to vacuum the soot out of the heat transfer
tabs. If there is a minimal amount of soot, it may be left in the heat transfer tabs, and will be evacuated out the exhaust
pipe, upon start up of diesel burner.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 102 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 5: Clean and Inspect the Combustion Chamber and Heat Transfer Tabs
(continued)
Combustion Chamber
Assembly
Figure E5b
Back side of air
swirler
Outer ring that the photo
disc seats against
3. Inspect the Combustion Chamber Assembly and Air Swirler for damage or signs of warping.
1. Remove and Inspect the aluminum Air Swirler for signs of warping. If any part of the Air Swirler is
warped the Air Swirler must be replace.
A. Inspect the outer ring that the photo disc seats against for signs of warping.
B. Inspect the back side of the Air Swirler for signs of warping between screws.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 103 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 6: Reinstall the Combustion Chamber
CAUTION!
Failure to reinstall the combustion chamber will result in serious damage to the diesel burner.
Combustion Chamber
Assembly
Figure E6
Combustion Chamber
Gasket
Air Swirler
1. Reinstall the Combustion Chamber Assembly and the Air Swirler into the Aqua-Hot. Please note: It will
be necessary to replace the combustion chamber gasket, anytime the combustion chamber is removed.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 104 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 7: Inspect Diesel-Burner
Figure E7
Electrode
Fuel Nozzle
Fuel Pump
Grommet
Photo Disc
Ear
Flame Sensor
Inspect the following:
1.
Electrodes
- damaged
- improperly adjusted
2.
Fuel Pump
- leaks
3.
Photo disc
- warped
- bent
4.
Harness & Ignition Coil Wires
- crack or bare wires
- Hard or brittle wires
5.
Flame Sensor
- cracked
- overheated (purple color)
- melted wires
- dirty
6.
Rubber Grommets
- hard/brittle
- rubber has been cut out
- right/left
7.
Broken or cracked “Ears”
- due to over tightening of eyebolts.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 105 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 8: Clean Ignition Electrodes and Flame Sensor
Electrode Tips
Figure E8
Flame Sensor
1.
Ignition electrodes A. Polish away any carbon deposits that may have baked onto the metal tips of the ignition
electrodes with a course sponge.
2.
Flame Sensor A. For light dirt, dust, and/or carbon deposits, simply wipe off the flame sensor with a soft
cloth.
B. Should heavy carbon deposits be present, completely remove the flame sensor from the
photo disc and clean with brake cleaner.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 106 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 9: Replace The Fuel Nozzle
Figure E9
1. Use a 3/4 in. wrench to hold the fuel nozzle manifold hex, while loosening the fuel nozzle with a 5/8 in. wrench and remove.
NOTE: Be sure to use care when handling the new fuel nozzle. Oils and/or small dust or dirt particles from your hands may plug
the nozzle’s small orifice. A partially plugged orifice will restrict fuel flow, which will affect the combustion process of
the diesel-burner.
2.
When replacing the fuel nozzle, be sure to tighten the nozzle, loosen it a 1/4 turn, and then firmly retighten. This will establish a seated fit and avoid any leaks.
Be sure to reattach the diesel-burner head prior to switching
the heater ON. Failure to do so may result in ignition of the
diesel-burner and serious bodily injury.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 107 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 10: Adjust Ignition Electrodes
Figure E10
1.
Using a 10mm socket, slightly loosen the retaining clamp bolt.
2. Place the electrode adjustment gauge on the nozzle manifold hex and insert the metal tips of the ignition electrodes into the
appropriate notches of the electrode adjustment gauge.
3.
Using a 10 mm socket, tighten the retaining clamp bolt.
NOTE: Be sure not to over-tighten the retaining clamp bolt when readjusting the ignition electrodes. Over-tightening the retaining
clamp bolt will bend the retaining clamp and prevent the photo disc from floating freely. Not allowing the photo disc to
float freely will cause poor combustion and result in a smoky exhaust. A bent retaining clamp can be re-straightened with a
punch and hammer. Lay the clamp’s beveled side down on a solid flat surface and align the thick end of the punch at dead
center. Tap the punch lightly until the retaining clamp returns to proper form.
4. Remove the electrode adjustment gauge.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 108 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 11: Inspect Photo Disc
Figure E11
Photo Disc
1.
If the photo disc is not free floating, the electrode clamp bolt has been over-tightened, and has bent the electrode clamp. Using a
10mm socket remove the electrode clamp, and re-straighten.
-Lay the clamp’s beveled side down on a solid flat surface and align the thick end of the punch at dead center. Tap the
punch lightly until the retaining clamp returns to proper form.
Step 12: Re-Install Diesel Burner
Figure E12a
Figure E12b
NOTE: When reinstalling the diesel burner be careful not to damage the photo disc or bend the electrodes.
Also, be careful to not pinch any wires between the burner and the Aqua-Hot Tank.
1. Align the Diesel-Burner with the Aqua-Hot, using the alignment tabs welded on the Aqua-Hot.
2. Swing the Eye Bolts around the “Ears” on the diesel burner and securely tighten, using a 10mm socket with a 10
inch long extension.
Use extreme caution when tightening down the eye-bolt nuts, over tightening of the eye-bolt nuts can
cause the aluminum blower casing to crack. (Torque Specifications = Approximately 20-40 in. lbs.)
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 109 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 13: Reconnect the Fuel Lines
Figure E13a
Figure E13b
1. Align the fuel lines on the diesel burner with the fittings on the Aqua-Hot, and using a 7/16 inch
wrench, tighten down both the supply and return fuel fittings.
CAUTION!
Be sure to remove the clamps, off of the Fuel Supply and Return lines at the ports on top of the Aqua-Hot prior to starting the diesel burner, or serious damage will occur to the diesel-burner’s fuel pump.
Step 14: Plug in the diesel-burner’s controller and mount
Figure E14a
Figure E14b
1. Locate the Diesel-Burner’s Controller and connect both plugs.
NOTE: The Diesel Burner’s Controller might have to be mounted onto the side of the diesel burner, before the
plugs are inserted into the control unit, otherwise it might not be possible to mount the control unit.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 110 —
APPENDIX E: AQUA-HOT MAINTENANCE
Step 15: Re-Install the Aqua-Hot Access Cover
NOTE: The access cover must be installed prior to operation as a safety switch exists, which will prevent the
Aqua-Hot from operating whenever the access cover is not properly installed.
Figure E15a
Figure E15b
1. Reinstall the Aqua-Hot’s access cover .
2. Securely tighten the three bolts securing the access cover in place.
Step 15: Test for Normal Operation
A. Turn the Diesel-Burner switch on, and let the diesel burner run for a complete cycle, until it shuts
off on it’s own..
B. After the Diesel-Burner has shut off, turn on the interior heat/run hot water, until the Diesel
Burner cycles back on. When the diesel burner cycles back on, check the exhaust for signs of
smoke.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 111 —
APPENDIX F: WINTERIZATION PROCCESS
Not winterizing the Aqua-Hot when freezing temperatures
are present will result in serious damage to the Aqua-Hot’s
Domestic Water Heating System. Also, be sure to use an
FDA approved, “GRAS” rated antifreeze for winterization.
NOTE: The Aqua-Hot can continue to be used for interior
zone heating once the domestic water heating system
has been drained and winterized.
The Aqua-Hot’s Domestic Water Heating System must be
completely drained of domestic water, and properly winterized
any time the heater is stored where freezing temperatures may
be experienced.
Winterizing the Domestic Water Heating System:
Please follow these instructions when winterizing the AquaHot’s Domestic Water Heating System; reference Figure F1:
Completely drain the fresh water storage tank.
2.
Disconnect the domestic water demand pump’s suction
line from the fresh water storage tank.
3.
Attach an adequate piece of hose onto the suction side of
the domestic water demand pump.
4.
Place the opposite end of the hose into an adequate supply
of FDA-approved “GRAS” RV Antifreeze, and turn on the
demand water pump.
Open and close all interior and exterior water faucets, one at
a time, until only pure RV Antifreeze is present. Perform
this procedure for both the hot and cold faucets.
6.
Turn off Demand Water pump and remove the hose and reconnect the domestic water demand pump’s suction line to
the fresh water storage tank.
An FDA approved “GRAS” rated winterization antifreeze
must be used. YOU CANNOT BLOW DOMESTIC WATER
COIL OUT WITH AIR TO WINTERIZE AQUA-HOT.
De-Winterizing the Domestic Water Heating System:
For de-winterization, completely fill the fresh water storage tank.
Turn on demand water pump and open and close all interior and
exterior water faucets, one at a time, until only clear water is
present/visible. Reference Figure F1.
If disinfecting the potable water system after de-winterizing, be
sure to follow RVIA’s “Instructions for Disinfection of Potable
Water Systems on Recreation Vehicles.” These instructions
can be obtained by contacting the Recreational Vehicle Industry
Association at (703) 620-6003, visiting them online at
www.rvia.com, or writing to them at the following address:
Recreation Vehicle Industry Association
1896 Preston White Drive
P.O. Box 2999
Reston, VA 20195-0999
Figure F1
1.
5.
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 112 —
APPENDIX G: FILLING/DRAINING
THE
Only propylene glycol based “boiler” type antifreeze
deemed “GRAS” (Generally Recognized as Safe) by the
FDA shall be used in the Aqua-Hot’s hydronic heating
system. Failure to use the above specified antifreeze type
could result in serious injury or death.
AQUA-HOT
WITH HEATING SOLUTION
If assistance is needed in selecting an appropriate antifreeze,
please contact the Aqua-Hot Heating Systems Product Application Department at 1-800-685-4298.
NOTE: To Fill the Aqua-Hot it is recommended to use a
fluid transfer pump, and pump the antifreeze into the Boiler
Tank, thru the drain valve on the Aqua-Hot.
Ensure that the overflow tube is connected from the AquaHot’s expansion tank connection to the expansion tank’s
bottom connection and from the expansion tank’s top connection through the overflow tube hole in the motor home’s
bay floor prior to beginning this antifreeze and water heating
solution fill procedure. Failure to do so could result in an
antifreeze spill in the motor home’s bay.
1.
Locate the Aqua-Hot’s Drain Valve located at the front
of the heater. Reference Figure G1.
2.
Connect a piece of 1/2 inch PEX-type tubing to the
drain valve. This piece should be long enough to trans
port the antifreeze and water heating solution from its
source to the Aqua-Hot.
Filling The Aqua-Hot Heating System with
Boiler Antifreeze:
3.
Connect the other end of the 1/2 inch PEX-type tubing
to the fluid transfer pump.
4.
Open the Aqua Hot’s Drain Valve and turn the fluid
transfer pump on, and fill the Aqua-Hot with the 50/50
mixture of antifreeze and water heating solution until the
Low Tank-Level Cutoff Light, on the Electronic Control Board is extinguished, reference Figure G2. This
will take approximately four gallons.
5.
Turn the fluid transfer pump off, and close the drain
valve.
In order to provide the best freeze protection, boil-over protection, anti-corrosion and rust protection, a 50/50 mixture of
“GRAS” approved propylene glycol boiler antifreeze and
water is required.
Reference the owners manual for additional information regarding the antifreeze and water heating solution. Be sure to
use a “GRAS” Boiler-Type Propylene Glycol based antifreeze rather than an RV and Marine antifreeze or an automotive antifreeze/coolant.
Figure G1
Figure G2
Low Tank-Level
Cutoff
Drain Valve
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 113 —
APPENDIX G: FILLING/DRAINING
THE
AQUA-HOT
WITH HEATING SOLUTION
6. Locate the heating zone circulation pumps. Reference Figure G3.
11. Turn the fluid transfer pump off, and close the drain
valve.
7. Take the circulation pump’s blue (negative) wire
and disconnect it from the connector of the opposing wire. Be sure to purge both circulation heating
loops simultaneously. Reference Figure G4.
12. Repeat steps 10 and 11 until all air has been completely bled from the entire heating system.
8. Connect an alligator clip to the spade terminal on
the circulation pump’s blue (negative) wire and clip
the opposite end of the cable to a ground source.
NOTE: The circulation pump will activate as soon as the
pump is connected to a ground source.
9. Allow the circulation pumps to operate for the remainder of the purging process in order to purge all
the air out of the heating loops and boiler tank.
NOTE: Once the Purging Process has begun it will be necessary to refill the Aqua Hot’s Boiler tank with the appropriate antifreeze and water heating solution.
NOTE: All air is bled from the heating system when both
plumbing lines are free of air and there is fluid in
the expansion tank.
13. Continue to fill the Aqua Hot Heating System until
the fluid level remains at the “Cold” mark on the
Expansion Tank Bottle.
14. Once the systems have been purged, reconnect the
pump’s wires as originally configured. Reference
Figure G4.
15. Ensure that each circulation pump’s wiring has been
returned to its original configuration. Reference
Figure G4.
10. Open the drain valve and Turn the fluid transfer
pump on, and fill the Aqua-Hot with the 50/50
mixture of antifreeze and water heating solution
until the Low Tank-Level Cutoff Light, on the
Electronic Control Board is extinguished, reference
Figure 2.
Figure G3
Pump 1
Pump 2
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 114 —
APPENDIX G: FILLING/DRAINING
THE
AQUA-HOT
WITH HEATING SOLUTION
Figure G4
Zone 1
Circulation Pump
Zone 2
Circulation Pump
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 115 —
APPENDIX G: FILLING/DRAINING
Only propylene glycol based “boiler” type antifreeze
deemed “GRAS” (Generally Recognized as Safe) by the
FDA shall be used in the Aqua-Hot’s Hydronic heating
system. Failure to use the above specified antifreeze type
could result in serious injury or death.
Ensure that the overflow tube is connected from the AquaHot’s expansion tank connection to the expansion tank’s
bottom connection and from the expansion tank’s top connection through the overflow tube hole in the motor home’s
bay floor prior to beginning this antifreeze and water heating
solution fill procedure. Failure to do so could result in an
antifreeze spill in the motor home’s bay. Reference Figure
30.
In order to provide the best freeze protection, boil-over protection, and anti-corrosion and rust protection, a 50/50 mixture of “GRAS” approved propylene glycol boiler antifreeze
and water is recommended.
THE
AQUA-HOT
WITH HEATING SOLUTION
If assistance is needed in selecting an appropriate antifreeze,
please contact the Aqua-Hot Heating Systems Product Application Department at 1-800-685-4298.
TO DRAIN THE AQUA-HOT
1.
Connect a piece of 1/2 inch PEX-type tubing or rubber
hose to the drain valve. This piece should be long
enough to transport the antifreeze and water heating
solution from the Aqua-hot to a bucket.
2.
Open the Aqua-Hot’s drain valve located at the front of
the heater. Reference Figure G5.
Note: The Aqua-Hot 450 holds approximately 5 gallons of the antifreeze and water heating
solution.
Reference Section 1: Antifreeze and Water Heating Solution
for additional information regarding the antifreeze and water
heating solution. Be sure to use a “GRAS” boiler-type propylene glycol based antifreeze rather than an RV and Marine
antifreeze or an automotive antifreeze/coolant.
Figure G5
Drain Valve
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 116 —
© March 2012 Aqua-Hot® 450-DE4 Hydronic Heating System Service Manual—Rev. E
— Page 117 —
AHE-450-DE4
SERVICE MANUAL
15549 East Highway 52 | Fort Lupton, CO 80621
Toll free: 800.685.4298 | phone: 303.659.8221 | fax:303.857.7881
www.aquahot.com
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