RheosTM
Installation and Operation Instructions
Document 1170F
Installation and Operation
Instructions for
Rheos
TM
Modulating Boiler
Model RHCH
Modulating Water Heater
Model RHCV
U.S. Patent No. 6,644,393
Canada Patent Pending
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualified in hot water boiler installation and maintenance. Improper installation and/or operation could
create carbon monoxide gas in flue gases which could cause serious injury, property damage, or death.
Improper installation and/or operation will void the warranty.
WARNING
If the information in this manual is not
followed exactly, a fire or explosion may
result causing property damage, personal
injury or loss of life.
Do not store or use gasoline or other
flammable vapors and liquids in the vicinity
of this or any other appliance.
H2300300F
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not
use any phone in your building.
• Immediately call your gas supplier from a
nearby phone. Follow the gas supplier's
instructions.
• If you cannot reach your gas supplier, call
the fire department.
Installation and service must be performed
by a qualified installer, service agency, or gas
supplier.
AVERTISSEMENT
Assurez-vous de bien suivres les instructions
données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion
ou pour éviter tout dommage matériel, toute
blessure ou la mort.
Ne pas entreposer ni utiliser d’essence ni
d’autres vapeurs ou liquides inflammables dans
le voisinage de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ:
• Ne pas tenter d’allumer d’appareils.
• Ne touchez à aucun interrupteur. Ne pas vous
servir des téléphones dansle bâtiment où vous
vous trouvez.
• Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions
du fournisseur.
• Si vous ne pouvez rejoindre le fournisseur de
gaz, appelez le sservice des incendies.
L’installation et l’entretien doivent être assurés par
un installateur ou un service d’entretien qualifié ou
par le fournisseur de gaz.
Page 2
LAARS Heating Systems
TABLE OF CONTENTS
SECTION 1.
General Information
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
Introduction......................................................... 3
Model Identification............................................. 3
Warranty............................................................. 4
Dimensions......................................................... 4
Outdoor Installations........................................... 6
Locating the Appliance........................................ 6
Locating Pump-Mounted Water
Heater with Respect to Storage Tank(s)............. 6
Locating Pump-Mounted Boiler with
Respect to Return/Supply Header...................... 6
Locating Appliance for Correct Vent Distance
From Outside Wall or Roof Termination.............. 6
SECTION 2.
Venting and Combustion Air
2.1 Combustion Air................................................... 7
2.1.1Combustion Air From Room............................... 7
2.1.2Intake Combustion Air......................................... 7
2.2 Venting................................................................ 9
2.3 Locating Vent & Combustion Air Terminals......... 9
2.3.1Side Wall Vent Terminal...................................... 9
2.3.2Side Wall Combustion Air Terminal....................11
2.3.3Vertical Vent Terminal........................................11
2.3.4Vertical Combustion Air Terminal...................... 15
2.4 Common Vent Test – Boilers............................. 15
SECTION 3.
Gas Supply and Piping
3.1 Gas Supply and Piping..................................... 15
SECTION 4A.
Water Connections – Rheos Boiler
4A.1Heating System Piping:
Hot Supply Connections – Boiler...................... 18
4A.2Cold Water Make-Up – Boiler........................... 18
4A.3Water Flow Requirements – Boiler................... 18
4A.4Freeze Protection – Boiler................................ 19
SECTION 4B.
Water Connections – Rheos Water Heater
4B.1Water System Piping – Water Heater............... 19
4B.2Hot Water Supply Piping – Water Heater.......... 19
4B.3Water Flow Requirements – Water Heater....... 20
4B.4Combined Water (potable)
Heating and Space Heating.............................. 20
4B.5Freeze Protection — Water Heater................... 20
SECTION 5.
Electrical Connections
5.1 Main Power....................................................... 21
5.2 Pump Connections........................................... 21
5.3 Temperature Control – Boiler............................ 21
5.4 Temperature Control – Water Heater................ 21
5.4.1Remote Water Heater Temperature Control..... 21
5.4.2Internal Water Heater Temperature Control...... 22
5.5 Temperature Control Features.......................... 22
5.5.1Temperature Setpoint....................................... 24
5.5.2Differential Setting............................................. 24
5.5.3Offset................................................................ 24
5.5.4Throttling Range............................................... 24
5.5.5Minimum Output Setting................................... 24
5.5.6Integration Constant......................................... 24
5.6 External Control Connections........................... 25
5.7 Wiring Diagrams............................................... 25
SECTION 6.
Operating Instructions
6.1
6.2
6.3
6.4
Filling the Boiler System................................... 38
Operating the Burner and Set Up..................... 38
Shutting Down the Rheos................................. 40
To Restart the Rheos........................................ 40
SECTION 7.
Maintenance
7.1 System Maintenance........................................ 40
7.2 Appliance Maintenance and
Component Description.................................... 40
7.2.1Burner............................................................... 41
7.2.2Filter.................................................................. 41
7.2.3Modulating Gas Valve....................................... 41
7.2.4Safety Gas Valve.............................................. 41
7.2.5Manual Reset High Limit Control...................... 41
7.2.6Temperature Control......................................... 41
7.2.7Ignition Control.................................................. 41
7.2.8Ignitor / Flame Sensor Assembly...................... 42
7.2.9Transformers..................................................... 42
7.2.10 Blower............................................................ 42
7.2.11 Flow Switch..................................................... 42
7.2.12 Heat Exchanger Coil...................................... 42
7.2.13 Normally Open Vent Valve.............................. 43
7.2.14 Motorized Safety Valve................................... 43
7.2.15 Gas Pressure Switches.................................. 44
SECTION 8.
Trouble Shooting
8.1 Sequence of Operation..................................... 45
8.2 Resolving Lockouts........................................... 45
8.3 Delayed Ignition – Possible Causes................. 45
8.3.1High Lockup Pressure (LP Appliances)
- Occurs on Start-up......................................... 45
8.3.2Gas Valve Regulation....................................... 45
8.3.3Defective Burner - Occurs on
Startup or at Burner Shutdown......................... 46
8.4 Short Cycling – Boiler....................................... 46
8.5 Short Cycling – Water Heater........................... 46
8.6 High Gas Consumption..................................... 46
SECTION 9.
Replacement Parts
9.1 General Information.......................................... 46
9.2 Parts List........................................................... 47
Tables Listing ................................................................. 56
Figures Listing . ............................................................. 56
Rheos Boiler and Water Heater
Page 3
SECTION 1.
General Information
with the installation. Consult the Laars Heating
Systems factory, or local factory representative, with
any problems or questions regarding this equipment.
Experience has shown that most operating problems
are caused by improper installation.
The Rheos appliance is protected against over
pressurization. A pressure relief valve is fitted to all
appliances. It is installed inside the jacket, at the water
outlet of the unit.
USING THIS MANUAL – Because the Rheos
Boilers and Rheos Water Heaters are identical
appliances, with the exception of materials of
manufacture, labels and ultimate use application,
this manual provides information for the proper
installation, operation and maintenance of both
products. Where differences exist between the
application of the appliances and their operation,
the sections pertinent to only one appliance or the
other will be so identified.
IMPORTANT: The inlet gas pressure to the appliance
must not exceed 13" W.C. (3.2kPa).
All installations must be made in accordance
with 1) American National Standard Z223.1/NFPA54Latest Edition “National Fuel Gas Code” or 2) CSA
B149.1 “Natural Gas and Propane Installation Code”
and with the requirement of the local utility or other
authorities having jurisdiction. Such applicable
requirements take precedence over the general
instructions contained herein.
All electrical wiring is to be done in accordance
with the local codes, or in the absence of local codes,
with: 1) The National Electrical Code ANSI/NFPA No.
70-latest Edition, or 2) CSA STD. C22.1 “Canadian
Electrical Code - Part 1”. This appliance must be
electrically grounded in accordance with these codes.
WARNING
The Rheos hydronic, boiler or water heater must be
installed in accordance with the procedures detailed
in this manual, or the Laars Heating Systems
warranty will be voided. The installation must
conform to the requirements of the local jurisdiction
having authority, and, in the United States, to the
latest edition of the National Fuel Gas Code, ANSI
Z223.1/NFPA54. In Canada, the installation must
conform to the latest edition of CSA B149.1 Natural
Gas and Propane Gas Installation Code, and/or
local codes. Where required by the authority having
jurisdiction, the installation of Rheos boilers must
conform to the Standard for Controls and Safety
Devices for Automatically Fired Boilers, ANSI/ASME
CSD-1. Any modifications to the boiler, its gas
controls, or wiring may void the warranty. If field
conditions require modifications, consult the factory
representative before initiating such modifications.
1.2 Model Identification
Consult the rating plate on the unit. The
following information describes the model number
structure.
(1-2) Model Series Designation
R H = Rheos mid-sized commercial
(3) Model Efficiency
C = Mid Efficiency (non-condensing)
H = High Efficiency (condensing)
(4) Usage
H = Hydronic
V = Volume Water
(5-8) Size
1 2 0 0 = 1,200,000 BTU/hr input
1 6 0 0 = 1,600,000 BTU/hr input
2 0 0 0 = 2,000,000 BTU/hr input
2 4 0 0 = 2,400,000 BTU/hr input
1.1 Introduction
This manual provides information necessary for
the installation, operation, and maintenance of Laars
Heating Systems Rheos (copper tube or cupronickel
tubes) appliances. Read it carefully before installation.
All application and installation procedures
should be reviewed completely before proceeding
3
1
2
6
7
8
R
H
0
0
FUEL
ALTITUDE
LOCATION
0
0
N
A
I
P
SERIES
R
H
4
5
Model Designation
USAGE
C
H
H
V
SIZE
1
1
2
6
0
0
2
0
0
0
2
4
0
0
9
10
11
A
C
12
13
14
15 16
HEAT
EXCHANGER
OPTION
CODES
X
X
A
H
B
N
C
S
D
E
F
G
F
FIRING
MODE
REVISION
F
2
1
E
F
Page 4
(9) Fuel
N = Natural Gas
P = Liquid Propane
(10) Altitude
A = Universal Altitude (0' to 10,000') (0m to 3050m)
(11) Location
C = Indoor and Outdoor (for non-condensing units)
I = Indoor (for condensing units)
(12) Firing Mode
F = Modulating
(13) Revision
1 = First version
2 = Second version
(14) Heat Exchanger
E = Glass-lined steel with copper tubes
F = Glass-lined steel with cupronickel tubes
(15) Control Option Code
X = Standard, meets CSD-1 boiler standard
A = Control Pack A: CSD-1, CA, FM, IL, IRI,
Alarm Bell
B = Control Pack B: CSD-1, CA, FM, IL, LDS, MN
C = Control Pack C: with 200°F (93°C) max.
control (KY)
D = Control Pack A with 200°F (93°C) max. control
E = Control Pack B with 200°F (93°C) max. control
F = Non CSD-1
G = Non CSD-1 with 200°F (93°C) max. control
(16) Pump Options
X = No Pump
H = Pump mounted, hard water pump
N = Pump mounted, normal pump
S = Pump mounted, soft water pump (volume
water, high efficiency (condensing) model only)
LAARS Heating Systems
1.3 Warranty
Laars Heating Systems’ Rheos appliances are
covered by a limited warranty. The owner should fill
out the warranty registration card and return it to Laars
Heating Systems.
All warranty claims must be made to an
authorized Laars Heating Systems representative or
directly to the factory. Claims must include the serial
number and model (this information can be found
on the rating plate), installation date, and name of
the installer. Shipping costs are not included in the
warranty coverage.
Some accessory items are shipped in separate
packages. Verify receipt of all packages listed on
the packing slip. Inspect everything for damage
immediately upon delivery, and advise the carrier of
any shortages or damage. Any such claims should be
filed with the carrier. The carrier, not the shipper, is
responsible for shortages and damage to the shipment
whether visible or concealed.
1.4 Dimensions
The overall dimensions are 34.5" (88cm)
wide, 65.75" (167cm) tall, 55" (140cm) deep. Other
dimensions can be found in Figure 1.
Rheos Boiler and Water Heater
Page 5
"P" WATER INLET PUMP-MOUNTED UNIT
"G" GAS CONNECTION
"V" FLUE VENT (CAT. IV) OUTLET
"S" WATER OUTLET
"A" AIR INLET
WITH AIR FILTER
65.75
167
53
135
48
122
"W" WATER INLET
NON-PUMP-MOUNTED UNIT
30.5
77
C
B
D
13
33
Model
17.25
44
55
140
"V" Vent Outlet
Connection
"A" Air Inlet Connection
7.75
20
3.75
10
34.5
88
Dimensions shown in inches cm.
"W" Inlet Water
Connection NonPump-Mounted
"P" Inlet Water
Connection PumpMounted
"S" Outlet Water
Connection All
Models
1200
inches
6
cm
15
inches
6
cm
15
NPT
2-1/2"
NPT
2-1/2"
NPT
2-1/2"
1600
2000
2400
6
7
10
15
18
25
8
8
8
20
20
20
2-1/2"
3"
3"
3"
2-1/2"
3"
2-1/2"
3"
3"
Model
"G" Gas Connects. Std/Control
Pk A Nat/LP
Control
Pk B & E
Nat
Control
Pk B & E
LP
NPT
NPT
NPT
inches
cm
inches
cm
inches
cm
1200
1"
1-1/2"
1-1/2"
34-1/4
87
27-3/4
70
9-3/4
25
1600
2000
2400
1-1/2"
1-1/2"
1-1/2"
2"
2"
2"
2"
1"
2"
34-1/4
34-1/4
32
87
87
81
25-1/2
24-3/4
22-1/2
65
63
57
10-1/2
9-3/4
10-1/2
27
25
27
Figure 1. Dimensional Drawing.
"B"
"C"
"D"
Page 6
1.5 Outdoor Installations
Attach the appropriate termination and appliance
adaptor to the vent outlet (see Table 1). Units are
shipped with a louvered cover over the ducted air
connection. Do not remove this cover, and/or add any
piping to the ducted air connection. The unit will take
its combustion air through the louvers in the jacket.
WARNING
The outdoor terminal gets hot. Unit must be
installed in such a way as to reduce the risk of
burns from contact with the vent terminal.
Model (Size)
1200
1600
2000
2400
Termination
Appliance Adapter
D2008300
D2008300
D2008400
D2007500
D2008500
D2008500
D2008600
D2007600
Table 1. Terminals for Outdoor Installation.
In installations where the air temperature may
go below 15°F (-9°C), a valve heater kit, part number
R2010100, must be installed on the operating gas
valve. Instructions for the installation of the valve
heater are included with the kit.
NOTE: Units built with control packs B and E
have two actuators. Therefore, two heater kits must be
used.
1.6 Locating the Appliance
The appliance should be located to provide
clearances on all sides for maintenance and inspection.
It should not be located in an area where leakage of
any connections will result in damage to the area
adjacent to the appliance or to lower floors of the
structure.
When such a location is not available, it is
recommended that a suitable drain pan, adequately
drained, be installed under the appliance.
The appliance is design certified by CSAInternational for installation on combustible flooring;
in basements; in closets, utility rooms or alcoves.
Rheos Boilers or Water Heaters must never be
installed on carpeting. The location for the appliance
should be chosen with regard to the vent pipe lengths
and external plumbing. The unit shall be installed such
that the gas ignition system components are protected
from water (dripping, spraying, rain, etc.) during
operation and service (circulator replacement, control
replacement, etc.). When vented vertically, the Rheos
must be located as close as practical to a chimney
or gas vent. If the vent terminal and/or combustion
air terminal terminate through a wall, and there is
potential for snow accumulation in the local area, both
terminals should be installed at an appropriate level
above grade.
LAARS Heating Systems
The dimensions and requirements that are shown
in Table 2 should be met when choosing the locations
for the appliance:
Appliance
Surface
Piping Side
Opposite Side
Top
Back
Front
Vent
Required
Clearance From
Combustible Material
inches
cm
Suggested
Service
Clearance
inches
cm
1
2.5
24
1
2.5
24
1
2.5
24
1
2.5
36
1
2.5
36
per UL1738 venting system
supplier's instructions
61
61
61
91
91
Table 2. Clearances.
1.7 Locating Pump-Mounted Water Heater
with Respect to Storage Tank(s)
For best results a pump-mounted Rheos water
heater should be located within 15 feet (4.6m) of the
storage tank(s). The pump is sized for 30 feet (9.1m)
of piping.
Water heater pumps are sized for water hardness;
7.6 to 17 grains per gallon for normal water, and
greater than 17 grains per gallon for hard water. If
the system has soft water (1 to 7.5 grains per gallon
hardness), but the Rheos has a normal water pump
mounted in it, please consult the factory for assistance.
If the appliance must be installed with longer
piping runs, then larger diameter pipe or tubing may be
able to be used, in some instances. Consult the factory
for assistance.
1.8 Locating Pump-Mounted Boiler with
Respect to Return/Supply Header
For the best results a pump-mounted Rheos
Boiler should be located within 15 feet (4.6m) of
the supply and return headers. The pump is sized for
30 feet (9.1m) of piping, in most cases, enough for
primary-secondary piping systems.
If the appliance must be installed with longer
piping runs, then larger diameter tubing may be able
to be used, in some instances. Consult the factory for
assistance.
1.9 Locating Appliance for Correct Vent
Distance From Outside Wall or
Roof Termination
The forced draft combustion air blower in the
appliance has sufficient power to vent properly when
the guidelines in Table 3 are followed.
NOTE: When located on the same wall, the Rheos
combustion air intake terminal must be installed
a minimum of 12" (30cm) below the exhaust vent
terminal and separated by a minimum of 36 inches
(91cm) horizontally.
Rheos Boiler and Water Heater
Model
1200
1600
2000
2400
Intake
Size
6" (15 cm) dia.
8" (20 cm) dia.
8" (20 cm) dia.
8" (20 cm) dia.
Page 7
Exhaust
Size
6" (15 cm) dia.
6" (15 cm) dia.
7" (18 cm) dia.
10" (25 cm) dia.
Intake
Maximum Run
50 linear feet with 5 elbows
50 linear feet with 5 elbows
50 linear feet with 5 elbows
50 linear feet with 5 elbows
Exhaust
Maximum Run
50 linear feet with 5 elbows
50 linear feet with 5 elbows
50 linear feet with 5 elbows
50 linear feet with 5 elbows
Table 3. Vent / Air Pipe Sizes.
Section 2.
Venting and Combustion Air
2.1 Combustion Air
Rheos boilers and water heaters must have
provisions for combustion and ventilation air in
accordance with section 5.3, Air for Combustion and
Ventilation, of the National Fuel Gas Code, ANSI
Z223.1, or Sections 7.2, 7.3 or 7.4 of CSA B149.1,
Installation Codes, and applicable provisions of the
local building codes.
A Rheos unit can take combustion air from the
space in which it is installed, or the combustion air can
be ducted directly to the unit. Ventilation air must be
provided in either case.
2.1.1 Combustion Air From Room
In the United States, the most common
requirements specify that the space shall communicate
with the outdoors in accordance with method 1 or 2,
which follow. Where ducts are used, they shall be of
the same cross-sectional area as the free area of the
openings to which they connect.
Method 1: Two permanent openings, one
commencing within 12" (300mm) of the top and one
commencing within 12" (300mm) of the bottom, of
the enclosure shall be provided. The openings shall
communicate directly, or by ducts, with the outdoors
or spaces that freely communicate with the outdoors.
When directly communicating with the outdoors, or
when communicating to the outdoors through vertical
ducts, each opening shall have a minimum free area
of 1 square inch per 4000 Btu/hr (550 square mm/kW)
of total input rating of all equipment in the enclosure.
When communicating to the outdoors through
horizontal ducts, each opening shall have a minimum
free area of not less than 1 square inch per 2000 Btu/hr
(1100 square mm/kW) of total input rating of all
equipment in the enclosure.
Method 2: One permanent opening, commencing
within 12" (300mm) of the top of the enclosure, shall
be permitted. The opening shall directly communicate
with the outdoors or shall communicate through a
vertical or horizontal duct to the outdoors or spaces
that directly communicate with the outdoors and shall
have a minimum free area of 1 square inch per 3000
Btu/hr (734 square mm/kW) of the total input rating of
all equipment located in the enclosure. This opening
must not be less than the sum of the areas of all vent
connectors in the confined space.
Other methods of introducing combustion and
ventilation air are acceptable, providing they conform
to the requirements in the applicable codes listed
above.
In Canada, consult local building and safety
codes or, in absence of such requirements, follow
CAN/CGA B149.
2.1.2 Intake Combustion Air
The combustion air can be taken through the
wall, or through the roof. When taken from the wall, it
must be taken from out-of-doors by means of the Laars
horizontal wall terminal, shown in Table 4. See Table 3
to select the appropriate diameter air pipe. When taken
from the roof, a field-supplied rain cap or an elbow
arrangement must be used to prevent entry of rain
water (see Figure 2).
Use single-wall galvanized pipe for the
combustion air intake (see Table 5), sized per Section
1.8. Route the intake to the heater as directly as
possible. Seal all joints with tape. Provide adequate
hangers. The unit must not support the weight of the
combustion air intake pipe. Maximum linear pipe
length allowed is 50 feet (15.2m). Up to five elbows
can be used with the 50 feet of pipe. Subtract 10
allowable linear feet for every additional elbow used.
Figure 2. Combustion Air and Vent Through Roof.
Page 8
LAARS Heating Systems
U.S. Installations (see note 1)
Canadian Installations (see note 2)
A= Clearance above grade, veranda, porch, 12 inches (30 cm)
12 inches (30 cm)
deck, or balcony
B= Clearance to window or door that may be 4 feet (1.2 m) below or to side of opening; 36 inches (91 cm)
opened
1 foot (30 cm) above opening
C= Clearance to permanently closed window
See note 4
See note 5
D= Vertical clearance to ventilated soffit located
above the terminal within a horizontal See note 4
See note 5
distance of 2 feet (61cm) from the center line
of the terminal
E= Clearance to unventilated soffit
See note 4
See note 5
F= Clearance to outside corner
See note 4
See note 5
G= Clearance to inside corner
See note 4
See note 5
H= Clearance to each side of center line
3 feet (91 cm) within a height 15 feet above
extended above meter/regulator assembly See note 4
the meter/regulator assembly
I= Clearance to service regulator vent outlet
See note 4
3 feet (91 cm)
J= Clearance to nonmechanical air supply inlet
to building or the combustion air inlet to
4 feet (1.2 m) below or to side of opening; 36 inches (91 cm)
any other appliance
1 foot (30 cm) above opening
K= Clearance to a mechanical air supply inlet 3 feet (91 cm) above if within 10 feet (3 m) 6 feet (1.83 m)
horizontally
Vent termination not allowed in this location for
Vent termination not allowed in this location category IV appliances. A vent shall not
L= Clearance above paved sidewalk or paved for category IV appliances. For Category III terminate directly above a sidewalk or paved
driveway located on public property
appliances, vent must terminate at least 7 driveway that is located between two single
feet (2.13m) above the sidewalk or driveway.family dwellings and serves both dwellings.
For Category III appliances that do not violate
the previous condition, vent must terminate at
least 7 feet (2.13m) above the sidewalk or
driveway.
M= Clearance under veranda, porch, deck, or balcony
See note 4
12 inches (30 cm) (see note 3)
Notes:
1. In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code.
2. In accordance with the current CAN/CGA-B149 Installation Codes.
3. Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
4. For clearances not specified in ANSI Z223.1 / NFPA 54, clearance is in accordance with local installation codes and the requirements of the
gas supplier.
5. For clearances not specified in CAN/CGA-B149, clearance is in accordance with local installation codes and the requirements of the gas
supplier.
Figure 3. Combustion Air and Vent Through Side Wall.
Rheos Boiler and Water Heater
Horizontal Combustion
Air Terminal
20260701
20260703
20260703
20260703
Model
1200
1600
2000
2400
Page 9
Horizontal Vent
Terminal
D2004500
D2004500
D2004600
D2006200
Table 4. Horizontal Vent and Air Terminals
For Indoor Installations.
Term
Pipe
Joint
Sealing
Description
Single-wall galvanized steel pipe, 24 gauge
minimum (sized per section 1.9)
Permanent duct tape or aluminum tape
Insulation Not required, but recommended R5 insulation
for cold installations (consult American Society
of Heating, Refrigerating, and Air Conditioning
Engineers (ASHRAE) handbook)
Table 5. Required Combustion Air Piping Material.
The connection for the intake air pipe is in the
back of the unit. Take the plate off the back to reveal
the collar on the filter box. Run a bead of silicone
around the collar and slide the pipe over the collar.
Secure with sheet metal screws.
In addition to air needed for combustion, air
shall also be supplied for ventilation, including all air
required for comfort and proper working conditions
for personnel. The Rheos loses less than 1 percent of
its input rating to the room, but other heat sources may
be present.
2.2 Venting
The Rheos is a Category IV appliance and must
be installed with a stainless steel venting system
that complies with the UL 1738 Standard (see Table
6). It must be installed per this installation manual
and the venting system manufacturer’s Installation
Instructions. The unit’s vent can terminate through the
roof, or through an outside wall. It can be installed
through walls that are from 3" (7.6cm) to 12" (30cm)
in thickness.
See Table 3 to select the appropriate vent pipe
diameter. The first section of venting attached to the
boiler must include a condensate drain fitting and
condensate trap. Route the vent pipe to the heater
as directly as possible. Seal all joints and provide
adequate hangers as required in the venting system
manufacturer’s Installation Instructions. Horizontal
portions of the venting system must be supported to
prevent sagging and may not have any low sections
that could trap condensate. The unit must not support
the weight of the vent pipe. Horizontal runs must slope
upwards not less than ¼ inch per foot (21mm/m) from
the unit to the vent terminal. Up to five elbows can
be used with the 50 feet (15.2m) of pipe. Subtract 10
allowable linear feet for every additional elbow used.
IMPORTANT NOTE ABOUT COMMON VENTING:
A single vent that is shared by multiple Rheos
units MUST be engineered by a competent venting
specialist, and involves the selection of draft inducing
equipment, hardware and controls to properly balance
flue gas pressures. Do not common vent Rheos
units unless the vent system meets this requirement.
Rheos units are never permitted to share a vent with
Category I applliances.
For outdoor applications, see Section 1.5.
Condensate Drain Connection: A condensate
drain connection shall be provided on the first section
of venting attached to the boiler. Connect a clear
plastic tube between that drain connection on the
vent and a floor drain (or optional condensate pump
if a floor drain is not accessible). The plastic tube
shall be formed into a loop (trap) to drain condensate
that collects in the vent system without permitting
flue gases to escape. The condensate drain must be
installed so as to prevent accumulation of condensate.
Consult local codes for disposal method.
Term
Description
Venting
System
Heat-Fab®, Inc. Saf-T Vent®GC or CI,
Metal-Fab®, Inc. Corr/Guard, or
equivalent sealed stainless steel
system certified to UL1738.
Insulation
Not required, but recommended R5 insulation with protective cover for cold installations (consult American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) handbook)
Table 6. Required Venting Material.
2.3 Locating Vent & Combustion Air
Terminals
2.3.1 Side Wall Vent Terminal
The appropriate Laars side wall vent hood must
be used, and is listed in the installation and operation
manual. The terminal provides a means of installing
the vent piping through the building wall, and must
be located in accordance with ANSI Z223.1/NFPA 54
and applicable local codes. In Canada, the installation
must be in accordance with CSA B149.1 or .2 and
local applicable codes. Consider the following when
installing the terminal:
1. The figure in this addendum shows the
requirements for mechanical vent terminal
clearances for the U.S. and Canada.
2. Vent terminals for condensing appliances or
appliances with condensing vents are not
permitted to terminate above a public walkway,
or over an area where condensate or vapor could
create a nuisance or hazard.
Page 10
3.
4.
5.
6.
7.
LAARS Heating Systems
Locate the vent terminal so that vent gases cannot
be drawn into air conditioning system inlets.
Locate the vent terminal so that vent gases cannot
enter the building through doors, windows,
gravity inlets or other openings. Whenever
possible, locations under windows or near doors
should be avoided.
Locate the vent terminal so that it cannot be
blocked by snow. The installer may determine
that a vent terminal must be higher than the
minimum shown in codes, depending upon local
conditions.
Locate the terminal so the vent exhaust does
not settle on building surfaces or other nearby
objects. Vent products may damage such
surfaces or objects.
If the boiler or water heater uses ducted
combustion air from an intake terminal located
on the same wall, locate the vent terminal at least
3 feet (0.9m) horizontally from the combustion
air terminal, and locate the vent terminal at least
1 foot (0.3m) above the combustion air terminal.
From Massachusetts Rules and Regulations
248 CMR 5.08:
(a) For all side wall horizontally vented gas
fueled equipment installed in every dwelling,
building or structure used in whole or inpart
for residential purposes, including those
owned or operated by the Commonwealth and
where the side wall exhaust vent termination
is less than seven (7) feet above finished grade
in the area of the venting, including but not
limited to decks and porches, the following
requirements shall be satisfied:
1.
INSTALLATION OF CARBON MONOXIDE
DETECTORS.
At the time of installation of the side wall
horizontal vented gas fueled equipment, the
installing plumber or gasfitter shall observe that
a hard-wired carbon monoxide detector with
Model and
Gas Type
1200 natural
1200 propane
1600 natural
1600 propane
2000 natural
2000 propane
2400 natural
2400 propane
Notes:
an alarm and battery back-up is installed on
the floor level where the gas equipment is to be
installed. In addition, the installing plumber or
gasfitter shall observe that a battery operated or
hard-wired carbon monoxide detector with an
alarm is installed on each additional level of the
dwelling, building or structure served by the side
wall horizontal vented gas fueled equipment.
It shall be the responsibility of the property
owner to secure the services of qualified licensed
professionals for the installation of hard-wired
carbon monoxide detectors.
a.
In the event that the side wall
horizontally vented gas fueled equipment is
installed in a crawl space or an attic, thehardwired carbon monoxide detector with alarm
and battery back-up may be installed on the
next adjacent floor level.
b.
In the event that the requirements of
this subdivision cannot be met at the time of
completion of installation, the owner shall
have a period of thirty (30) days to comply
with the above requirements; provided,
however, that during said thirty (30) day
period, a battery operated carbon monoxide
detector with an alarm shall be installed.
2.
APPROVED CARBON MONOXIDE
DETECTORS.
Each carbon monoxide detector as required
in accordance with the above provisions shall
comply with NFPA 720 and be ANSI/UL 2034
listed and IAS certified.
3.
SIGNAGE.
A metal or plastic identification plate shall be
permanently mounted to the exterior of the
building at a minimum height of eight (8) feet
Distance from Gas Meter or Last Stage Regulator
0-50 feet
2"
1-1/2"
2-1/2"
2"
2-1/2"
2-1/2"
2-1/2"
2"
0-15m
5.1cm
3.8cm
6.4cm
5.1cm
6.4cm
6.4cm
6.4cm
5.1cm
50-100 feet
2-1/2"
2"
2-1/2"
2"
3"
2-1/2"
3"
2-1/2"
15-31m
6.4cm
5.1cm
6.4cm
5.1cm
7.6cm
6.4cm
7.6cm
6.4cm
100-200 feet 31-61m
2-1/2"
6.4cm
2"
5.1cm
3"
7.6cm
2-1/2"
6.4cm
3"
7.6cm
2-1/2"
6.4cm
3"
7.6cm
2-1/2"
6.4cm
1. These figures are based on 1/2" 0.12kPa water column pressure drop.
2. Check supply pressure and local code requirements before proceeding with work.
3. Pipe fittings must be considered when determining gas pipe sizing.
Table 7. Gas Piping Sizes.
200-300 feet
3"
2-1/2"
3"
2-1/2"
3-1/2"
3"
3-1/2"
3"
61-91m
7.6cm
6.4cm
7.6cm
6.4cm
8.9cm
7.6cm
8.9cm
7.6cm
Rheos Boiler and Water Heater
above grade directly in line with the exhaust vent
terminal for the horizontally vented gas fueled
heating appliance or equipment. The sign shall
read, in print size no less than one-half (½) inch
in size, “GAS VENT DIRECTLY BELOW.
KEEP CLEAR OF ALL OBSTRUCTIONS”.
4. INSPECTION.
The state or local gas inspector of the side
wall horizontally vented gas fueled equipment
shall not approve the installation unless, upon
inspection, the inspector observes carbon
monoxide detectors and signage installed in
accordance with the provisions of 248 CMR
5.08(2)(a) 1 through 4.
(b) EXEMPTIONS: The following equipment is
exempt from 248 CMR 5.08(2)(a) 1 through 4:
1.
The equipment listed in Chapter 10 entitled
“Equipment Not Required To Be Vented” in the
most current edition of NFPA 54 as adopted by
the Board; and
2.
Product Approved side wall horizontal vented gas
fueled equipment installed in a room or structure
separate from the dwelling, building or structure
used in whole or in part for residential purposes.
(c) MANUFACTURER REQUIREMENTS
– GAS EQUIPMENT VENTING SYSTEM
PROVIDED. When the manufacturer of
Product Approved side wall horizontally
vented gas equipment provides a venting
system design or venting system components
with the equipment, the instructions provided
by the manufacturer for installation of the
equipment and the venting system shall
include:
1.
Detailed instructions for the installation of the
venting system design or the venting system
components; and
2.
A complete parts list for the venting system
design or venting system.
(d) MANUFACTURER REQUIREMENTS –
GAS EQUIPMENT VENTING SYSTEMNOT
PROVIDED. When the manufacturer of a
Product Approved side wall horizontally
vented gas fueled equipment does not
provide the parts for venting the fuel gases,
but identifies “special venting systems”, the
following requirements shall be satisfied by
Page 11
the manufacturer:
1.
The identification of each “special venting
system” shall include either the listing of the
website, phone number or manufacturer’s address
where the venting system installation instructions
can be obtained; and
2.
The “special venting systems” shall be Product
Approved by the Board, and the instructions
provided with that system shall include a parts
list and detailed installation instructions.
(e) A copy of all installation instructions for the
Product Approved side wall horizontally
vented gas fueled equipment, and all the
venting instructions, parts lists, and/or design
instructions for the venting system shall
remain with the appliance or equipment at the
completion of the installation.
Manufacturers' websites where venting system
installation instructions may be obtained is
located on the Laars website at: http://www.
laars.com.
2.3.2 Side Wall Combustion Air Terminal
The Laars side wall combustion air terminal (see
Table 4) must be used when the heater takes air from a
side wall. Consider the following when installing the
terminal:
1. Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning fluid,
chlorine compounds, etc.)
2. Locate the terminal so that it will not be subject
to damage by accident or vandalism. It must be at
least 7 feet (2.1m) above a public walkway.
3. Locate the combustion air terminal so that it
cannot be blocked by snow. The National Fuel
Gas Code requires that it be at least 12 inches
(30cm) above grade, but the installer may
determine it should be higher, depending upon
local conditions.
4. If the Rheos is side-wall vented to the same wall,
locate the vent terminal at least 3 feet (0.9m)
horizontally from the combustion air terminal,
and locate the vent terminal at least 1 foot (0.3m)
above the combustion air terminal (see Figure 3).
2.3.3 Vertical Vent Terminal
When the unit is vented through the roof, the
vent must extend at least 3 feet (0.9m) above the point
at which it penetrates the roof. It must extend at least
2 feet (0.6m) higher than any portion of a building
within a horizontal distance of 10 feet (3.0m), and high
enough above the roof line to prevent blockage from
snow. When the combustion air is taken from the roof,
the combustion air must terminate at least 12" (30cm)
below the vent terminal (see Figure 2).
Page 12
LAARS Heating Systems
OPTIONAL PUMP MOUNTED UNIT AVAILABLE
COLD WATER
MAKE-UP
BOILER CIRC.
PUMP
SYSTEM
SUPPLY
SYSTEM
RETURN
D
C
D
C
SYSTEM PUMP
LEGEND
EXPANSION TANK
THERMOMETER
WITH AIR SCOOP AND
AUTO AIR VENT
TEMPERATURE
SENSOR
PURGE
VALVE
GLOBE VALVE
3-WAY VALVE
INSTALL AIR VENTS AT HIGH POINTS IN SYSTEM
BOILER CIRC. PUMP SIZED FOR FLOW THROUGH BOILER
PIPING & SIZING OF EXPANSION TANK
PER TANK MANUFACTURER'S INSTRUCTIONS
BOILER CIRC. PUMP TO BE USED WITH EM 2
SYSTEM TEMP. INTERLOCK REQUIRED
DIMENSION ''D'' TO BE 18" MINIMUM
DOTTED DEVICES INDICATE ALTERNATE LOCATIONS
MULTIPLE STAGE BOILERS RECOMMENDED
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING. CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS.
PUMP
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
BOILER CIRCUIT PIPING MUST BE EQUAL TO
BOILER WATER CONNECTION SIZE
DIMENSION ''C'' TO BE 4 PIPE DIAMETERS
VALVE
CHECK VALVE
PRIMARY/SECONDARY MANDITORY FOR ALL
VARIABLE FLOW SYSTEMS
Figure 4. Hydronic Piping — Multiple Boilers, Primary Secondary System.
OPTIONAL PUMP MOUNTED
UNIT AVAILABLE
ADJUSTMENT PROCEDURE TO MAINTAIN 130° F INLET TEMP.
1. Turn on heater and open valves A & B
2. After steady-state operation, if T1 is less than
130° F, slowly close valve B until T1 climbs to 130° F
T1
3. If T1 is greater than 130° F, slowly
close valve A until T1 drops to 130° F
T1
4. Check after system operating temperature has
stabilized. Make final adjustments
BOILER CIRC.
PUMP
COLD WATER
MAKE-UP
SYSTEM
RETURN
A
D
B
B
D
C
A
SYSTEM
SUPPLY
B
C
SYSTEM PUMP
LEGEND
EXPANSION TANK
THERMOMETER
TEMPERATURE
SENSOR
GLOBE VALVE
WITH AIR SCOOP AND
AUTO AIR VENT
PURGE
VALVE
CHECK VALVE
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
3-WAY VALVE
VALVE
PUMP
PRIMARY/SECONDARY MANDITORY FOR ALL
VARIABLE FLOW SYSTEMS
BOILER CIRCUIT PIPING MUST BE EQUAL TO
BOILER WATER CONNECTION SIZE
INSTALL AIR VENTS AT HIGH POINTS IN SYSTEM
BOILER CIRC. PUMP SIZED FOR FLOW THROUGH BOILER
PIPING & SIZING OF EXPANSION TANK
PER TANK MANUFACTURER'S INSTRUCTIONS
BOILER CIRC. PUMP TO BE USED WITH EM 2
SYSTEM TEMP. INTERLOCK REQUIRED
DIMENSION ''C'' TO BE 4 PIPE DIAMETERS
DIMENSION ''D'' TO BE 18" MINIMUM
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING. CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS.
Figure 5. Hydronic Piping — Multiple Boilers, Low Temperature System.
DOTTED DEVICES INDICATE ALTERNATE LOCATIONS
MULTIPLE STAGE BOILERS RECOMMENDED
Rheos Boiler and Water Heater
Page 13
Model
(Size)
20°F
Flow
H/L
gpm
feet
Temperature Rise in Degrees (°F/°C)
11°C
25°F
14°C
Flow
H/L
Flow
H/L
Flow
H/L
lpm
m
gpm
feet
lpm
m
104
139
174
209
395
527
659
791
1200
1600
2000
2400
18
22
20
18
84
111
139
167
5.5
6.7
6.1
5.5
12
14
13
12
316
422
527
632
3.7
4.3
4.0
3.7
30°F
Flow
H/L
gpm
feet
17°C
Flow
H/L
lpm
m
70
93
116
139
264
351
439
527
8
10
9
8
2.4
3.0
2.7
2.4
NOTE: Maximum temperature rise is 30°F (17°C), as shown. Headloss is for boiler’s heat exchanger only.
Table 8. Water Flow Requirements, RHCH (Boiler).
OPTIONAL PUMP MOUNTED UNIT AVAILABLE
NOTES:
1. BOILER LOOP TO BE MAINTAINED AT 180° F.
2. ZONE THERMOSTATS TO BE INTERLOCKED WITH BOILER.
BOILER TO FIRE UPON CALL FOR HEAT FROM ANY ZONE.
3. ZONE PIPING AND INTERLOCK WIRING TO BE
DESIGNED BY SYSTEM DESIGNER.
COLD WATER
MAKE-UP
BOILER CIRC.
PUMP
120° F
D
180° F
C
D
SYSTEM PUMP
180° F
C
C
C
D
140° F
LEGEND
EXPANSION TANK
THERMOMETER
TEMPERATURE
SENSOR
GLOBE VALVE
WITH AIR SCOOP AND
AUTO AIR VENT
PURGE
VALVE
CHECK VALVE
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
3-WAY VALVE
VALVE
PUMP
PRIMARY/SECONDARY MANDITORY FOR ALL
VARIABLE FLOW SYSTEMS
BOILER CIRCUIT PIPING MUST BE EQUAL TO
BOILER WATER CONNECTION SIZE
INSTALL AIR VENTS AT HIGH POINTS IN SYSTEM
BOILER CIRC. PUMP SIZED FOR FLOW THROUGH BOILER
PIPING & SIZING OF EXPANSION TANK
PER TANK MANUFACTURER'S INSTRUCTIONS
BOILER CIRC. PUMP TO BE USED WITH EM 2
SYSTEM TEMP. INTERLOCK REQUIRED
DIMENSION ''C'' TO BE 4 PIPE DIAMETERS
DIMENSION ''D'' TO BE 18" MINIMUM
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING. CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS.
Figure 6. Hydronic Piping — One Boiler, Multi-Temperature System.
DOTTED DEVICES INDICATE ALTERNATE LOCATIONS
MULTIPLE STAGE BOILERS RECOMMENDED
Page 14
LAARS Heating Systems
OPTIONAL PUMP MOUNTED UNIT AVALIABLE
BOILER CIRC.
PUMP
COLD WATER
MAKE-UP
SYSTEM
SUPPLY
SYSTEM
RETURN
D
C
SYSTEM PUMP
LEGEND
EXPANSION TANK
THERMOMETER
TEMPERATURE
SENSOR
GLOBE VALVE
WITH AIR SCOOP AND
AUTO AIR VENT
PURGE
VALVE
3-WAY VALVE
INSTALL AIR VENTS AT HIGH POINTS IN SYSTEM
BOILER CIRC. PUMP SIZED FOR FLOW THROUGH BOILER
PIPING & SIZING OF EXPANSION TANK
PER TANK MANUFACTURER'S INSTRUCTIONS
BOILER CIRC. PUMP TO BE USED WITH EM 2
SYSTEM TEMP. INTERLOCK REQUIRED
DOTTED DEVICES INDICATE ALTERNATE LOCATIONS
DIMENSION ''D'' TO BE 18" MINIMUM
MULTIPLE STAGE BOILERS RECOMMENDED
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING. CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS.
PUMP
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
BOILER CIRCUIT PIPING MUST BE EQUAL TO
BOILER WATER CONNECTION SIZE
DIMENSION ''C'' TO BE 4 PIPE DIAMETERS
VALVE
CHECK VALVE
PRIMARY/SECONDARY MANDITORY FOR ALL
VARIABLE FLOW SYSTEMS
PUT BOILER CONTROL SENSOR IN THE OUTLET
WHEN USING THIS PIPING STYLE
Figure 7. Hydronic Piping - Alternate System.
OPTIONAL PUMP MOUNTED UNIT AVALIABLE
ADJUSTMENT PROCEDURE TO MAINTAIN 130° F INLET TEMP.
1. Turn on heater and open valves A & B
2. After steady-state operation, if T1 is less than
130° F, slowly close valve B until T1 climbs to 130° F
3. If T 1 is greater than 130° F, slowly
close valve A until T1 drops to 130° F
4. Check after system operating temperature has
stabilized. Make final adjustments.
BOILER CIRC.
PUMP
COLD WATER
MAKE-UP
A
SYSTEM
RETURN
A
B
D
SYSTEM
SUPPLY
B
C
SYSTEM PUMP
LEGEND
EXPANSION TANK
THERMOMETER
TEMPERATURE
SENSOR
GLOBE VALVE
WITH AIR SCOOP AND
AUTO AIR VENT
PURGE
VALVE
CHECK VALVE
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
3-WAY VALVE
PRIMARY/SECONDARY MANDITORY FOR ALL
VARIABLE FLOW SYSTEMS
BOILER CIRCUIT PIPING MUST BE EQUAL TO
BOILER WATER CONNECTION SIZE
INSTALL AIR VENTS AT HIGH POINTS IN SYSTEM
BOILER CIRC. PUMP SIZED FOR FLOW THROUGH BOILER
PIPING & SIZING OF EXPANSION TANK
PER TANK MANUFACTURER'S INSTRUCTIONS
BOILER CIRC. PUMP TO BE USED WITH EM 2
SYSTEM TEMP. INTERLOCK REQUIRED
DIMENSION ''C'' TO BE 4 PIPE DIAMETERS
DIMENSION ''D'' TO BE 18" MINIMUM
VALVE
PUMP
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING. CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS.
Figure 8. Hydronic Piping - Alternate Low Temperature System.
DOTTED DEVICES INDICATE ALTERNATE LOCATIONS
MULTIPLE STAGE BOILERS RECOMMENDED
PUT BOILER CONTROL SENSOR IN THE OUTLET
WHEN USING THIS PIPING STYLE
Rheos Boiler and Water Heater
Page 15
2.3.4 Vertical Combustion Air Terminal
When combustion air is taken from the roof, a
field-supplied rain cap or an elbow arrangement must
be used to prevent entry of rain water (see Figure 2).
The opening on the end of the terminal must be at least
12" (30cm) above the point at which it penetrates the
roof, and high enough above the roof line to prevent
blockage from snow. When the vent terminates on the
roof, the combustion air must terminate at least 12"
(30cm) below the vent terminal.
NOTE: This section does not describe a method for common
venting Rheos units. It describes what must be done when a unit is
removed from a common vent system. Rheos units require special
vent systems and fan for common vent. Contact the factory if you
have questions about common venting Rheos units.
When an existing boiler is removed from a
common venting system, the common venting system
is likely to be too large for proper venting of the
appliances remaining connected to it.
At the time of removal of an existing boiler, the
following steps shall be followed with each appliance
remaining connected to the common venting system
placed in operation, while the other appliances
remaining connected to the common venting system
are not in operation.
1. Seal any unused openings in the common venting
system.
2. Visually inspect the venting system for proper
size and horizontal pitch and determine there is
no blockage or restriction, leakage, corrosion and
other deficiencies which could cause an unsafe
condition.
3. Insofar as it is practical, close all building doors
and windows and all doors between the space in
which the appliances remaining connected to the
common venting system are located and other
spaces of the building. Turn on clothes dryers
and any appliance not connected to the common
venting system. Turn on any exhaust fans, such
as range hoods and bathroom exhausts, so they
will operate at maximum speed. Do not operate a
summer exhaust fan. Close fireplace dampers.
4. Place in operation the appliance being
inspected. Follow the lighting instructions.
Model
(Size)
1200
1600
2000
2400
Note:
Hard Water
Flow H/L Temp
Flow
gpm feet Rise (°F) lpm
119
20
18
449
161 29
17
609
182 22
19
690
237 23
18
898
H/L Temp
m Rise (°C)
6.1
10
8.8
10
6.7
11
7.0
10
6.
7.
2.4 Common Vent Test — Boilers
5.
Adjust thermostat so appliance will operate
continuously.
Test for spillage at the draft hood relief opening
after 5 minutes of main burner operation. Use
the flame of a match or candle, or smoke from a
cigarette, cigar or pipe.
After it has been determined that each appliance
remaining connected to the common venting
system properly vents when tested as outlined
above, return doors, windows, exhaust fans,
fireplace dampers and any other gas burning
appliance to their previous conditions of use.
Any improper operation of the common venting
system should be corrected so that the installation
conforms to the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 and/or CSA B149.1, Installation
Codes. When resizing any portion of the common
venting system, the common venting system
should be resized to approach the minimum size
as determined using the appropriate tables in Part
II of the National Fuel Gas Code, ANSI Z223.1
NFPA 54 and/or CSA B149.1, Installation Codes.
Section 3.
Gas Supply and Piping
3.1 Gas Supply and Piping
Gas piping should be supported by suitable
hangers or floor stands, not the appliance.
Review the following instructions before
proceeding with the installation.
1. Verify that the appliance is fitted for the proper
type of gas by checking the rating plate. Laars
Heating Systems appliances are normally equipped
to operate at elevations up to 2000 feet (610m).
However, the appliance will function properly
without the use of high altitude modification at
elevations up to 10,000 feet (3050 m).
2. The maximum inlet gas pressure must not exceed
13" W.C. (3.2kPa). The minimum inlet natural
gas pressure is 4" W.C. (1.0kPa) and minimum
inlet propane gas pressure is 6" (1.5kPa).
3. Refer to Table 7, size supply.
Normal Water
Flow H/L Temp
Flow
gpm feet Rise (°F) lpm
93
12
23
351
132 20
21
500
149 15
23
565
186 14
23
703
Soft Water: 1 to 7.5 grains per gallon
Normal Water: 7.6 to 17 grains per gallon
Hard Water: More than 17 grains per gallon
H/L Temp
m Rise (°C)
3.7
13
6.1
12
4.6
13
4.3
13
Soft Water
Flow H/L Temp
Flow
gpm feet Rise (°F) lpm
65
6.0
32
246
89
8.9
31
336
100 6.6
35
379
129 6.9
32
488
Note: Headloss is for heater’s heat exchanger only.
Table 9. Water Flow Requirements, RHCV (Water Heater).
H/L Temp
m Rise (°C)
1.8
18
2.7
17
2.0
19
2.1
18
Page 16
LAARS Heating Systems
5
1
SU
PP
KEY:
LY
WATER CATEGORY GRAIN
HARDNESS PER GALLON
S = SOFT
1 THROUGH 7.5
N = NORMAL 7.6 THROUGH 17
H = HARD
OVER 18
2
17.1 PARTS PER MILLION
= 1 GRAIN HARDNESS PER GALLON
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS
3
LEGEND
EXPANSION TANK
THERMOMETER
TEMPERATURE
SENSOR
GLOBE VALVE
WITH AIR SCOOP AND
AUTO AIR VENT
TPRV
PRV
CHECK VALVE
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
3-WAY VALVE
VALVE
NOTES:
1. OPTIONAL CWMU & RECIRC. LINE LOCATION.
RE
4
CW
MU
CIR
2
C.
2. WHEN USING INTERMITTENT PUMP AND EM LOCATE REMOTE AQUASTAT
WELL IN LOWER 1/3 OF TANK WITH HEAT SENCEING COMPOUND.
3. BACK FLOW PREVENTER MAY BE REQUIRED CHECK LOCAL CODES.
4. THERMAL EXPANSION TANK MAY BE REQUIRED CHECK LOCAL CODES.
5. WHEN USING OPTIONAL FACTORY MOUNTED PUMP, MAX PIPE LENGTH
30' TOTAL, 6-90° ELBOWS , FULL PIPE SIZE.
PUMP
6. THIS DRAWING DEPICTS A TWO-PASS HEAT EXCHANGER.
7. CAUTION: PUMP SIZING MUST BE BASED UPON WATER HARDNESS AT JOB SITE
Figure 9. Water Heater Piping — One Heater, One Tank.
5
5
7
3
4
1
MU
CW
N
.R
RC
KEY:
CI
UR
ET
WATER CATEGORY GRAIN
HARDNESS PER GALLON
S = SOFT
1 THROUGH 7.5
N = NORMAL 7.6 THROUGH 17
H = HARD
OVER 18
17.1 PARTS PER MILLION
= 1 GRAIN HARDNESS PER GALLON
LY
PP
SU
7
CAUTION: THIS DRAWING SHOWS SUGGESTED
2
PIPING CONFIGURATION AND VALVING CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS
NOTES:
1. OPTIONAL CWMU & RECIRC. LINE LOCATION.
2. WHEN USING INTERMITTENT PUMP AND EM2 LOCATE REMOTE AQUASTAT
WELL IN LOWER 1/3 OF TANK WITH HEAT SENCEING COMPOUND.
3. BACK FLOW PREVENTER MAY BE REQUIRED CHECK LOCAL CODES.
LEGEND
EXPANSION TANK
THERMOMETER
4. THERMAL EXPANSION TANK MAY BE REQUIRED CHECK LOCAL CODES.
TEMPERATURE
SENSOR
5. WHEN USING OPTIONAL FACTORY MOUNTED PUMP, MAX PIPE LENGTH
30' TOTAL, 6-90° ELBOWS , FULL PIPE SIZE.
GLOBE VALVE
WITH AIR SCOOP AND
AUTO AIR VENT
TPRV
PRV
6. THIS DRAWING DEPICTS A TWO-PASS HEAT EXCHANGER.
7. COMMON PIPING MUST BE SIZED FOR MAXIMUM COMBINED HEATER FLOW.
8. CAUTION: PUMP SIZING MUST BE BASED UPON WATER HARDNESS AT JOB SITE
Figure 10. Water Heater Piping — Multiple Heaters, One Tank.
CHECK VALVE
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
3-WAY VALVE
VALVE
PUMP
Rheos Boiler and Water Heater
Page 17
5
3
1
MU
CW
N
UR
ET
.R
RC
CI
4
2
LY
PP
KEY:
SU
WATER CATEGORY GRAIN
HARDNESS PER GALLON
S = SOFT
1 THROUGH 7.5
N = NORMAL 7.6 THROUGH 17
H = HARD
OVER 18
2
17.1 PARTS PER MILLION
= 1 GRAIN HARDNESS PER GALLON
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS
NOTES:
1. OPTIONAL CWMU & RECIRC. LINE LOCATION.
LEGEND
EXPANSION TANK
THERMOMETER
2. WHEN USING INTERMITTENT PUMP AND EM2
WELL IN LOWER 1/3 OF TANK WITH HEAT SENCEING COMPOUND.
WITH AIR SCOOP AND
AUTO AIR VENT
TEMPERATURE
SENSOR
3. BACK FLOW PREVENTER MAY BE REQUIRED CHECK LOCAL CODES.
4. THERMAL EXPANSION TANK MAY BE REQUIRED CHECK LOCAL CODES.
GLOBE VALVE
5. WHEN USING OPTIONAL FACTORY MOUNTED PUMP, MAX PIPE LENGTH
30' TOTAL, 6-90° ELBOWS , FULL PIPE SIZE.
CHECK VALVE
6. THIS DRAWING DEPICTS A TWO-PASS HEAT EXCHANGER.
TPRV
3-WAY VALVE
PRV
VALVE
PUMP
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
7. CAUTION: PUMP SIZING MUST BE BASED UPON WATER HARDNESS AT JOB SITE
Figure 11. Water Heater Piping — One Heater, Multiple Tanks.
5
7
5
3
1
MU
CW
N
UR
ET
.R
RC
CI
4
KEY:
WATER CATEGORY GRAIN
HARDNESS PER GALLON
S = SOFT
1 THROUGH 7.5
N = NORMAL 7.6 THROUGH 17
H = HARD
OVER 18
17.1 PARTS PER MILLION
= 1 GRAIN HARDNESS PER GALLON
2
LY
PP
SU
7
2
CAUTION: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND VALVING CHECK
WITH LOCAL CODES AND ORDINANCES FOR
ADDITIONAL REQUIREMENTS
NOTES:
1. OPTIONAL CWMU & RECIRC. LINE LOCATION.
LEGEND
EXPANSION TANK
2. WHEN USING INTERMITTENT PUMP AND EM2 LOCATE REMOTE AQUASTAT
WELL IN LOWER 1/3 OF TANK WITH HEAT SENCEING COMPOUND.
THERMOMETER
3. BACK FLOW PREVENTER MAY BE REQUIRED CHECK LOCAL CODES.
TEMPERATURE
SENSOR
4. THERMAL EXPANSION TANK MAY BE REQUIRED CHECK LOCAL CODES.
5. WHEN USING OPTIONAL FACTORY MOUNTED PUMP, MAX PIPE LENGTH
30' TOTAL, 6-90° ELBOWS , FULL PIPE SIZE.
GLOBE VALVE
6. THIS DRAWING DEPICTS A TWO-PASS HEAT EXCHANGER.
CHECK VALVE
7. COMMON PIPING MUST BE SIZED FOR MAXIMUM COMBINED HEATER FLOW.
8. CAUTION: PUMP SIZING MUST BE BASED UPON WATER HARDNESS AT JOB SITE
Figure 12. Water Heater Piping — Multiple Heaters, Multiple Tanks.
WITH AIR SCOOP AND
AUTO AIR VENT
TPRV
PRV
PRESSURE REDUCING VALVE
W/ FAST FILL BYPASS
3-WAY VALVE
VALVE
PUMP
Page 18
4.
Run gas supply line in accordance with all
applicable codes.
Note: If you have a boiler/water heater with a
normally open vent valve, install a vent line from
the vent valve to an outside location as required
by your installation code or IRI requirement. Do
not remove 3/4 inch pipe plug from the vent
valve if venting from the normally open vent
valve is not required by your installation code.
5. Locate and install manual shutoff valves in
accordance with state and local requirements.
6. A sediment trap must be provided upstream of
the gas controls.
7. All threaded joints should be coated with
piping compound resistant to action of liquefied
petroleum gas.
8. The appliance and its individual shutoff valve
must be disconnected from the gas supply piping
during any pressure testing of that system at test
pressures in excess of 1/2 PSIG (3.45kpa).
9. The unit must be isolated from the gas supply
system by closing its individual manual shutoff
valve during any pressure testing of the gas
supply piping system at test pressures equal to or
less than 1/2 PSIG (3.45kpa).
10. The appliance and its gas connection must be
leak tested before placing it in operation.
11. Purge all air from gas lines.
WARNING:
Open flame can cause gas to ignite and result in
property damage, severe injury, or loss of life.
NOTE: The Rheos appliance and all other gas
appliances sharing the gas supply line must be firing
at maximum capacity to properly measure the inlet
supply pressure. The pressure can be measured at
the supply pressure port on the gas valve. Low gas
pressure could be an indication of an undersized
gas meter, undersized gas supply lines and/or an
obstructed gas supply line. A bleed line from the
diaphragm-type automatic valve shall be vented per
local code requirements. Rheos units are equipped
with low and high gas pressure switches that are
integrally vent limited. These types of devices do not
require venting to atmosphere.
Section 4A.
Water Connections — Rheos Boiler
4A.1 Heating System Piping:
Hot Supply Connections — Boiler
LAARS Heating Systems
NOTE: This appliance must be installed in a closed
pressure system with a minimum of 12 psi (82.7kPa)
static pressure at the boiler.
Hot water piping should be supported by suitable
hangers or floor stands. Do not support piping with
this appliance. Due to expansion and contraction of
copper pipe, consideration should be given to the type
of hangers used. Rigid hangers may transmit noise
through the system resulting from the piping sliding in
the hangers. It is recommended that padding be used
when rigid hangers are installed. Maintain 1" (2.5cm)
clearance to combustibles for hot water pipes.
Pipe the discharge of the relief valve (full size)
to a drain or in a manner to prevent injury in the event
of pressure relief. Install an air purger, an air vent,
a diaphragm-type expansion tank, and a hydronic
flow check in the system supply loop. Minimum fill
pressure must be 12psig (82.7kPa). Install shutoff
valves where required by code.
Suggested piping diagrams are shown in Figures
4, 5, 6, 7 and 8. These diagrams are meant only as a
guide. Components required by local codes must be
properly installed.
4A.2 Cold Water Make-Up — Boiler
1.
2.
3.
Connect the cold water supply to the inlet
connection of an automatic fill valve.
Install a suitable back flow preventer between the
automatic fill valve and the cold water supply.
Install shut off valves where required.
NOTE: The boiler, when used in connection with a refrigeration
system, must be installed so the chilled medium is piped in parallel
with the boiler with appropriate valves to prevent the chilled
medium from entering the boiler.
The boiler piping system of a hot water heating
boiler connected to heating coils located in air
handling appliances where they may be exposed to
refrigerated air circulation must be equipped with flow
control valves or other automatic means to prevent
gravity circulation of the boiler water during the
cooling cycle.
A boiler installed above radiation level, or as
required by the authority having jurisdiction, must be
provided with a low water cutoff device either as a part
of the boiler or at the time of boiler installation.
4A.3 Water Flow Requirements — Boiler
A hydronic heating (closed loop) application
recirculates the same fluid in the piping system. As a
result, no new minerals or oxygen is introduced into
the system. To ensure a proper operating temperature
leading to long boiler life, a flow rate has been
established based on the fluid temperature rise for this
specific size boiler.
Pump-mounted boilers can be ordered for use in
primary secondary piping systems. The pumps used
are sized for the headloss through the heater, plus 30
Rheos Boiler and Water Heater
24V
COM
Page 19
Increase the head loss requirement by 20%.
Setpoint Adjustment
Dial
VDC
SEN
Module
Connector
Differential
Adjustment
Relay
Energized
LED Indicator
IMPORTANT NOTES: Different glycol products
may provide varying degrees of protection. Glycol
products must be maintained properly in a heating
system, or they may become ineffective. Consult the
glycol specifications, or the glycol manufacturer, for
information about specific products, maintenance
of solutions, and set up according to your particular
conditions.
Jumper Block
Position
Heating
Relay
Cooling
Note: Jumper must
be in “Heating” mode,
or Rheos will not
operate properly.
Figure 13. Temperature Control.
feet (9.1m) of full-sized piping and a normal number
of fittings.
Table 8 specifies water flow rates for boilers,
which will enable the user to size a pump. The
headloss shown is for the heater only, and the user
will need to add the headloss of the system piping to
properly size the pump.
The minimum inlet water temperature for the
Rheos is 130°F (54°C) to avoid condensing on the
copper coils.
4A.4 Freeze Protection – Boiler
Proper precautions for freeze protection are
recommended for boiler installations in areas where
the danger of freezing exists.
Power outage, interruption of gas supply, failure
of system components, activation of safety devices,
etc., may prevent a boiler from firing. Any time a
boiler is subjected to freezing conditions, and the
boiler is not able to fire, and/or the water is not able
to circulate, there is a risk of freezing in the boiler
or in the pipes in the system. When water freezes,
it expands. This can result in bursting of pipes in the
system, or damage to the boiler, which could result in
leaking or flooding conditions.
Do not use automotive anti-freeze. Maintaining
a mixture of minimum 50% water and maximum
50% properly inhibited HVAC glycol, which contains
an antifoamant, is the preferred method of freeze
protection for Rheos boilers. Percentage of glycol
used in the Rheos boiler must not exceed 50%.
Typically, this mixture will serve as burst protection
for temperatures down to approximately –35°F (30°C). To get the desired temperature rise across the
boiler when this mixture is used, increase the water
flow by 15% above the original recommendation.
Section 4B.
Water Connections —
Rheos Water Heater
4B.1 Water System Piping —
Water Heater
Hot water piping should be supported by suitable
hangers or floor stands. Do not support piping with
this appliance. Due to expansion and contraction of
copper pipe, consideration should be given to the type
of hangers used. Rigid hangers may transmit noise
through the system resulting from the piping sliding in
the hangers. It is recommended that padding be used
when rigid hangers are installed.
The Rheos can be used with several different
types of readily available storage tanks. A pump draws
water from the storage tank and pumps the water
through the heater and back into the tank. Pumpmounted units have a circulating pump built into the
water heater.
Pipe the outlet from the heater’s relief valve
such that any discharge from the relief valve will be
conducted to a suitable place for disposal when relief
occurs. Do not reduce line size or install any valves in
this line. The line must be installed to allow complete
drainage of both the valve and the line.
Suggested piping diagrams are shown in Figures
9, 10, 11 and 12. These diagrams are meant only as a
guide. Components required by local codes must be
properly installed.
The minimum inlet water temperature for the
Rheos is 130°F (54°C) to avoid condensing on the
copper coils.
4B.2 Hot Water Supply Piping —
Water Heater
Follow the tank manufacturer’s guidelines for
completion of the hot water system connections.
Page 20
NOTE: A listed temperature and pressure relief
valve listed as complying with the Standard for
Relief Valves and Automatic Gas Shutoff Devices
for Hot Water Supply Systems, 1). ANSI Z21.22
latest edition, or 2). CSA 4.4, of suitable discharge
capacity must be installed in the separate storage
tank system.
If the Rheos water heater is installed in a closed
water supply system, such as one having a backflow
preventer in the cold water supply line, the relief valve
may discharge periodically, due to thermal expansion.
Means (such as a properly-sized expansion tank) shall
be provided to control thermal expansion. Contact the
water supplier or local plumbing inspector on how to
control this situation.
LAARS Heating Systems
Cover Screws
(Quantity=4)
Integration
DIP Switch
is set to
“Medium” at
the factory.
See Section
5.5.6 for
descriptions
of other
settings.
Module
Connector
THROT MIN OFFSET
RANGE OUTPUT
Reverse
Acting
LED Indicator
(Percent of
Output)
VC I
4B.3 Water Flow Requirements —
Water Heater
In a water heating application (an open system),
new water is constantly being introduced. With the
new water comes a fresh supply of minerals that can
be deposited on the unit’s heat exchanger. This is
commonly known as scaling. The amount of minerals
will depend upon the hardness of the water. Water can
also be aggressive, and can erode metals, including
copper, if the water is moved too quickly. The water
flow requirements for the Rheos water heater are based
upon the hardness of the water. The water flow is kept
high enough to prevent scaling, but low enough to
prevent tube erosion. For extremely soft or hard water,
cupro-nickel tubes are available. Contact a Laars
Representative if you have questions or concerns about
water quality.
Pump-mounted water heaters can be ordered
with standard pumps for soft or normal water or with
pumps for hard water. The pumps used are sized for
the headloss through the heater, plus 30 feet (9.1m) of
full-sized piping and a normal number of fittings.
Table 9 specifies water flow rates for water
heaters, which will enable the user to size a pump.
The headloss shown is for the heater only, and the user
will need to add the headloss of the piping system to
properly size the pump.
4B.4 Combined Water (potable) Heating
and Space Heating
NOTE: These systems are not allowed in the
Commonwealth of Massachusetts.
Piping and components connected to this water
heater for the space heating application shall be
suitable for use with potable water.
Toxic chemicals, such as used for boiler
treatment, shall not be introduced into the potable
water used for space heating.
This water heater when used to supply potable
water shall not be connected to any heating system
Direct
Acting
Operation Mode
Jumper Positions
Note: Jumper must be in “Reverse Acting” mode, or Rheos will not operate properly.
Figure 14. Proportional Control.
or component(s) previously used with a non-potable
water heating appliance.
When the system requires water for heating at
temperatures higher than required for other uses,
an anti-scald mixing or tempering valve shall be
installed to temper the water for those uses in order
to reduce scald hazard potential.
4B.5 Freeze Protection – Water Heater
Although Rheos water heaters are designcertified for outdoor installations, such installations
are not recommended in areas subject to freezing
temperatures unless proper precautions are taken.
Power outage, interruption of gas supply, failure
of system components, activation of safety devices,
etc., may prevent a heater from firing. Any time a
heater is subjected to freezing conditions, and the
heater is not able to fire, and/or the water is not
able to circulate, there is a risk of freezing in the
heater or in the pipes in the system. When water
freezes, it expands. This can result in bursting of pipes
in the system, or damage to the heater, which could
result in leaking or flooding conditions.
Rheos Boiler and Water Heater
Section 5.
Electrical Connections
WARNING
The appliance must be electrically grounded in
accordance with the requirements of the authority
having jurisdiction or, in the absence of such
requirements, with the latest edition of the National
Electrical Code, ANSI/NFPA 70, in the U.S. and
with latest edition of CSA C22.1 Canadian Electrical
Code, Part 1, in Canada. Do not rely on the gas
or water piping to ground the metal parts of the
boiler. Plastic pipe or dielectric unions may isolate
the boiler electrically. Service and maintenance
personnel, who work on or around the boiler, may
be standing on wet floors and could be electrocuted
by an ungrounded boiler. Electrocution can result in
severe injury or death.
Single pole switches, including those of safety
controls and protective devices must not be wired in a
grounded line.
All electrical connections are made in the field
wiring box that is located inside the appliance.
NOTE: All internal electrical components have been
prewired. No attempt should be made to connect
electrical wires to any other location except the wiring
box.
Wiring connections are shown in Figures 18
through 33.
5.1 Main Power
Connect a properly sized and fused, 120-volt
supply to the main power switch (hot leg is connected
directly to switch). Neutral leg is connected directly to
the white wire. Ground wire can be connected to the
grounding screw in the box or on the switch.
5.2 Pump Connections
The pump time delay relay will call the pump
to be energized upon a call for heat, and will keep the
pump energized for a delay period after the call for
heat has ended. The delay period is adjustable from
0.1 to 10 minutes.
Pump-mounted Rheos units have pumps that are
wired at the factory to the pump time delay through a
relay. Wiring to a separate 230V single phase circuit,
per the wiring diagrams in Figures 18 through 33 is
necessary.
Rheos units without the factory-mounted pump
also have the pump time delay relay. A 120V single
phase pump, which is no larger than 1hP, or 230V
single phase pump no higher than 3/4hP, can be wired
directly to pump time delay relay, as shown in the
unit’s wiring diagram (120V hot connection on the
pump to terminal 2 on the pump delay relay, and 120V
Page 21
neutral to the 120V neutral circuit of the unit.)
If the pump is 3-phase, higher voltage than 120V,
or higher horsepower than 1hP, the pump’s starter
or a separate relay can be connected to the unit’s
pump time delay relay, and the pump can be driven
indirectly.
Contact the factory if there are questions about
connecting a pump to the Rheos’ pump time delay
relay.
5.3 Temperature Control — Boiler
Connect boiler T-T wires to isolated contacts on
zone valves, circulator relays, sequencing controls
(multiple appliance applications) or other temperature
controlled devices. The Rheos boiler temperature
control measures temperature on the boiler inlet. Set
the temperature control such that the setpoint plus
the boiler temperature rise equals the desired boiler
outlet temperature. Also set the manual reset high limit
20°F above the outlet temperature to avoid nuisance
lockouts.
Example, Imperial units: If the desired outlet
temperature is 180°F, and the boiler temperature rise is
25°F, then set the boiler temperature at 155°F (180°F
– 25°F). Lastly, set the manual reset high limit to
200°F (180°F + 20°F).
Example, Metric units: If the desired outlet
temperature is 82°C, and the boiler temperature rise is
14°C, then set the boiler temperature at 68°C (82°C14°C). Lastly, set the manual reset high limit to 93°C
(82°C+11°C).
5.4 Temperature Control — Water Heater
5.4.1 Remote Water Heater
Temperature Control
The Rheos water heater can be used with a fieldsupplied tank aquastat, sequencing control, or other
temperature control device, which will call the unit for
heat when the temperature goes below the controller’s
setpoint. For the most efficient setting, set the tank
temperature at the lowest possible setting for adequate
hot water in the application.
Caution
If the tank temperature control is set too high, a
potential for hot water scalding may exist.
After a setting has been chosen for the tank
temperature control, set the heater temperature control
10°F (6°C) higher. The heater’s temperature control
senses the inlet water temperature to the heater. The
heater’s manual reset high limit senses heater outlet
temperature, and should be set 20°F (11°C) above the
outlet temperature to avoid nuisance lockouts.
Example, Imperial units: If the tank temperature
is set to 140°F, set the heater’s temperature control to
150°F (140°F+10°F). Further, if the temperature rise
Page 22
through the heater is 25°F, the outlet temperature will
be 175°F (150°F+25°F). Therefore, set the manual
reset high limit to 195°F (175°F + 20°F).
Example, Metric units: If the tank temperature
is set to 60°C, set the heater’s temperature control to
66°C (60°C+6°C). Further, if the temperature rise
through the heater is 15°C, the outlet temperature will
be 81°C (66°C+15°C). Therefore, set the manual reset
high limit to 92°C (81°C+11°C).
5.4.2 Internal Water Heater
Temperature Control
When an external control is not used, the
circulator between the heater and the storage tank
must run continuously, so that the heater’s temperature
control can detect and control the water temperature in
the storage tank. The Rheos water heater’s temperature
control is adjusted to its lowest temperature position
when shipped from the factory. This is the preferred
starting point for setting the temperature control. Set
the manual reset high limit 20°F (11°C) plus heater
temperature rise above the temperature control’s
setting.
Example, Imperial units: If the heater’s
temperature control is set to 130°F, and the
temperature rise through the heater is 25°F, the outlet
temperature will be 155°F. Set the manual reset high
limit to 175°F.
Example, Metric units: If the heater’s
temperature control is set to 55°C, and the
temperature rise through the heater is 14°C, the outlet
temperature will be 69°C. Set the manual reset high
limit to 80°C.
Figure 15. Control Parameter Graph.
LAARS Heating Systems
Caution
Should overheating occur or the gas supply fail to
shut off, turn off the manual gas control valve to the
appliance.
5.5 Temperature Control Features
The Rheos temperature control is versatile and
will allow the user to better match the modulating
control to the application. Settings that can be changed
are temperature setpoint, differential, offset, throttling
range, and minimum output.
The temperature setpoint is the setting at which
the unit will shut off, having satisfied the controller’s
call for heat.
The differential determines how far the
temperature in the Rheos can fall before energizing
again.
The offset determines where the throttling range
begins.
The throttling range is the temperature range
through which the unit will modulate from minimum
to maximum firing rate.
Important Note: These control parameters work
together. Therefore, setting one parameter may have
an affect on another. Figures 15, 16 and 17 show the
relationships between these settings. Figure 15 follows
the examples that are shown in the following sections,
and Figures 16 and 17 are examples of how the
parameters can interfere with each other.
Rheos Boiler and Water Heater
Figure 16. Control Parameter Possible Interference.
Figure 17. Control Parameter Possible Interference.
Page 23
Page 24
5.5.1 Temperature Setpoint
The temperature setpoint is the point at which the
temperature control relay will be de-energized and the
unit’s call for heat will end. The temperature setpoint
is adjusted with the setpoint dial on the A350 control
(see Figure 13). The temperature control’s sensor is in
the inlet of the unit.
5.5.2 Differential Setting
The differential is the difference in temperature
settings when the temperature control’s relay is
energized and de-energized. For instance, if the
temperature setpoint is 180°F (82°C) and the
differential is 20°F (11°C), the temperature control
will call the unit to energize at 160°F (71°C). (The
differential is the setpoint minus the differential
setting) The call for heat will end when the unit
reaches its setpoint of 180°F (82°C). The Rheos
differential is adjustable from 1°F to 30°F (1°C to
17°C). In general, the differential setting for a water
heater system will be low, so that when a storage tank
is drawing down, the heater will react to sustain a
minimum tank temperature. Boilers generally have
higher differentials than water heaters, to minimize
short cycling (see throttling range). The differential
is set by removing the cover of the A350 control
and adjusting the potentiometer marked “DIFF” (see
Figure 13).
5.5.3 Offset
The offset determines the temperature below the
controller’s setpoint where the throttling range begins.
It offsets the throttling range.
For instance, if the setpoint is 180°F (82°C) and
the offset is 5°F (3°C), then the unit’s throttling range
will begin at 175°F (79°C). Between 175°F (79°C) and
180°F (82°C), the Rheos will be in low fire.
The offset can be adjusted between 0°F and 30°F
(0°C and 17°C) by removing the cover of the S350P
control and adjusting the Offset dial (see Figure 14).
5.5.4 Throttling Range
The throttling range allows the Rheos to match
the BTU demands of varying systems, by allowing the
user to choose the temperature range through which
the unit will modulate. This will tell the controller how
fast to respond to a change in temperature. A small
throttling range keeps the unit in high fire more, and
quickens the response of the system. A larger throttling
range allows the Rheos to spread its modulating range
over a larger temperature range.
Example, Imperial units: Using a temperature
setpoint of 180°F, with a 20°F differential, a 5°F
offset, and a throttling range of 10°F, the unit will
come on at 160°F and shut off at 180°F. The offset
will set the top of the throttling range 5°F under the
setpoint, which is 175°F in this example. Therefore,
LAARS Heating Systems
the throttling range will cause the Rheos to modulate
between 50% and 100% of full fire between 175°F and
165°F. Between 175°F and 180°F, the unit will remain
at low fire. Between 160°F and 165°F, the unit will be
at full fire.
Example, Metric units: Using a temperature
setpoint of 82°C, with a 11°C differential, a 3°C offset,
and a throttling range of 5°C, the unit will come on at
71°C and shut off at 82°C. The offset will set the top
of the throttling range 3°C under the setpoint, which is
79°C in this example. Therefore, the throttling range
will cause the Rheos to modulate between 50% and
100% of full fire between 79°C and 74°C. Between
79°C and 82°C, the unit will remain at l02 fire.
Between 71°C and 74°C, the unit will be a t full fire.
The throttling range is adjustable between 2°F
and 30°F (1°C to 17°C). The range can be set by
removing the cover of the S350P control and adjusting
the “THROT RANGE” dial (see Figure 14).
5.5.5 Minimum Output Setting
The minimum output setting of the controller is
0% of full fire. However, the minimum output of the
Rheos is limited to 50% of full fire by the fan speed
controller, to ensure proper operation of the Rheos.
If a minimum desired output is higher than 50%, the
setting can be adjusted up by removing the cover of
the S350P control and adjusting the Min Output dial
(see Figure 14). Turning the dial clockwise increases
the minimum output. In most cases, this setting should
be left as shipped from the factory, with the arrow
pointing to the 5 o'clock position.
5.5.6 Integration Constant
The proportional control used on the Rheos has
internal circuitry that helps to minimize overshoot that
can sometimes be associated with proportional plus
integral (PI) controls. There are three field-selectable
integration constants (slow, medium and fast), and
an off position on the proportional control, which
are selected with the dipswitches on the control (see
Figure 14). In most cases, this setting will not need to
be changed
Off: Switch 1 to ON position and all others to
OFF. Setting the control to the “Off” position puts the
control into proportional only operation. This is not a
recommended setting for the Rheos.
Slow: Switch 2 to ON position and all others
to OFF. This is the slowest integration constant. It
allows the Rheos the most time to reach its setpoint.
In most cases, this is too slow for Rheos installations.
Medium: Switch 3 to ON position and all others
to OFF. The integration constant is set to “Medium”
at the factory, and in most cases, will not need to be
changed. This setting will be the best suited to most
Rheos installations.
Fast: Switch 4 to ON position and all others
to OFF. If the rate of system recovery to setpoint is
Rheos Boiler and Water Heater
sluggish with the control set to medium, the “Fast”
setting may be an improvement. The “Fast” setting
will only be used when the rate of change at the sensor
is very rapid. In most cases, this setting is too fast for
the Rheos.
5.6 External Control Connections
Rheos units are built with a selector switch and
a terminal strip to allow the Rheos to receive a 010VDC signal from an external controller (such as a
building automation system or multiple boiler control).
When the selector switch is in the “Rheos
Control” position, the Rheos will be modulated by the
unit’s factory-mounted modulating control.
When the switch is in the “External Control”
position, the unit look for a 0-10VDC signal from an
external (field-supplied) controller.
To interlock the external boiler control with the
Rheos, the call for heat signal MUST be connected to
the field interlock terminal strip on the Rheos (shown
in Figure 18). Be sure to remove the factory-installed
jumper between the field interlock terminals. The
0-10VDC modulating signal MUST be connected to
external control terminal strip, located to the right
of, and behind the front panel. The terminal strip is
labeled “0-10VDC +” and 0-10VDC –” to indicate
which terminal received the hot signal (+) and which
terminal receives the common signal (-) from the
controller.
The Rheos unit will modulate between 4.7V and
10V (for 50% and 100%, respectively). Anything less
than 4.7 volts will result in 50% of full fire.
For the external control to modulate the Rheos,
the selector switch on the front panel must be in the
“External Control” position.
Important Note: DO NOT MAKE/BREAK RHEOS
LINE VOLTAGE TO SIGNAL CALL FOR HEAT. A“call
for heat / end call for heat” MUST be connected to the
field interlock terminals. The Rheos does not recognize
0 volts as a signal to shut off. If the call for heat is not
connected between the field interlock terminals, the
Rheos will remain in low fire when it sees 0 volts as a
modulating signal.
Caution
Rheos supply voltage must not be disengaged,
except for service or isolation, or unless otherwise
instructed by procedures outlined in this manual. To
signal a call for heat, use the 24V field-interlock, as
shown in the wiring diagram(s).
Some Rheos components are designed to have
constant voltage during normal operation. If Rheos
supply voltage is toggled as a call for heat signal,
premature failure of these components may result.
Page 25
5.7 Wiring Diagrams
Caution
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing
Page 26
Figure 18. Wiring Diagram, Model 1200, Standard and Codes A, C, D, F and G.
LAARS Heating Systems
Rheos Boiler and Water Heater
Figure 19. Wiring Diagram, Models 1600, 2000 and 2400, Standard and Codes A, C, D, F and G.
Page 27
Page 28
Figure 20. Wiring Diagram, Model 1200, Codes B and E.
LAARS Heating Systems
Rheos Boiler and Water Heater
Figure 21. Wiring Diagram, Models 1600, 2000 and 2400, Codes B and E.
Page 29
Page 30
LAARS Heating Systems
Figure 22. Wiring Diagram, Model 1200, Pump-Mounted, Standard and Codes A, C, D, F and G.
Rheos Boiler and Water Heater
Figure 23. Wiring Diagram, Models 1600, 2000 and 2400, Pump-Mounted, Standard and Codes A, C, D, F and G.
Page 31
Page 32
Figure 24. Wiring Diagram, Model 1200, Pump-Mounted, Codes B and E.
LAARS Heating Systems
Rheos Boiler and Water Heater
Figure 25. Wiring Diagram, Models 1600, 2000 and 2400, Pump-Mounted, Codes B and E.
Page 33
Page 34
Schematic Wiring Diagram
Figure 26. Wiring Schematic, Model 1200, Standard and
Codes A, C, D, F and G.
LAARS Heating Systems
Schematic Wiring Diagram
Figure 27. Wiring Schematic, Models 1600, 2000 and
2400, Standard and Codes A, C, D, F and G.
Rheos Boiler and Water Heater
Schematic Wiring Diagram
Figure 28. Wiring Schematic, Model 1200, Codes B
and E.
Page 35
Schematic Wiring Diagram
Figure 29. Wiring Schematic, Models 1600, 2000 and
2400, Codes B and E.
Page 36
Schematic Wiring Diagram
Figure 30. Wiring Schematic, Model 1200, Pump-Mounted, Standard and Codes A, C, D, F and G.
LAARS Heating Systems
Schematic Wiring Diagram
Figure 31. Wiring Schematic, Models 1600, 2000 and
2400, Pump-Mounted Standard and Codes A, C, D, F
and G.
Rheos Boiler and Water Heater
Schematic Wiring Diagram
Figure 32. Wiring Schematic, Model 1200, Pump-Mounted, Codes B and E.
Page 37
Schematic Wiring Diagram
Figure 33. Wiring Schematic, Models 1600, 2000 and
2400, Pump-Mounted Codes B and E.
Page 38
Section 6.
Operating Instructions
6.1 Filling the Boiler System
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Ensure the system is fully connected. Close all
bleeding devices and open make-up water valve.
Allow system to fill slowly.
If make-up water pump is employed, adjust
pressure switch on pumping system to provide
a minimum of 12 psi (81.8 kPa) at the highest
point in the heating loop.
If a water pressure regulator is provided on the
make-up water line, adjust the pressure regulator
to provide at least 12 psi (81.8 kPa) at the highest
point in the heating loop.
Open bleeding devices on all radiation units
at the high points in the piping throughout
the system, unless automatic air bleeders are
provided at such points.
Run system circulating pump for a minimum of
30 minutes with the boiler shut off.
Open all strainers in the circulating system,
check flow switch operation, and check for
debris. If debris is present, clean out to ensure
proper circulation.
Recheck all air bleeders as described in Step 4.
Check liquid level in expansion tank. With the
system full of water and under normal operating
pressure, the level of water in the expansion tank
should not exceed ¼ of the total, with the balance
filled with air.
Start up boiler according the procedure in this
manual. Operate the entire system, including the
pump, boiler, and radiation units for one (1) hour.
Recheck the water level in the expansion tank. If
the water level exceeds ¼ of the volume of the
expansion tank, open the tank drain, and drain to
that level.
Shut down the entire system and vent all
radiation units and high points in the system
piping, as described in Step 4.
Close make-up water valve and check strainer in
pressure reducing valve for sediment or debris
from the make-up water line. Reopen make-up
water valve.
Check gauge for correct water pressure and also
check water level in the system. If the height
indicated above the boiler insures that water is at
the highest point in the circulating loop, then the
system is ready for operation.
Refer to local codes and the make-up water
valve manufacturer’s instructions as to whether
the make-up water valve should be left open or
closed.
After placing the unit in operation, the ignition
system safety shutoff device must be tested. First,
shut off the manual gas valve, and call the unit
LAARS Heating Systems
for heat. Main gas terminals will be energized,
attempting to light, for seven (7) seconds, and
then will de-energize. The unit will go into
lockout mode. Second, turn the power off, press
the manual reset button shown in detail A of
Figure 30, open the manual gas valve and allow
the unit to light. While the unit is operating, close
the manual gas valve and ensure that power to
the main gas valve has been cut.
16. Within three (3) days of start-up, recheck all air
bleeders and the expansion tank as described in
Steps 4 and 8 above.
Important: The installer is responsible for
identifying to the owner/operator the location of all
emergency shutoff devices.
WARNING
Do not use this appliance if any part has been
under water. Immediately call a qualified service
technician to inspect the appliance
and to replace any part of the control system and
any gas control that may have been
under water.
6.2 Operating the Burner and Set Up
The Rheos modulating appliance utilizes an
advanced, state-of-the-art design. The setup must be
checked before the unit is put in operation. Problems
such as failure to start, rough ignition, strong exhaust
odors, etc. can be due to improper setup. Damage to
the boiler resulting from improper setup is not covered
by the limited warranty.
REQUIRED TOOLS:
Differential pressure gauge capable of reading
negative 0.01 inches W.C. (0.002kPa).
1. Using this manual, make sure the installation
is complete and fully in compliance with the
instructions.
2. Determine that the appliance and system are
filled with water and all air has been bled from
both. Open all valves.
3. Observe all warnings on the Operating
Instructions label and turn on gas and electrical
power to appliance.
4. There is a gas/air test panel to the left of the
control panel, at the front of the unit (see Figure
34). Ensure that all four valves on the test panel
are closed (see Figure 35).
5. Remove the two plugs from the + and – ports of
the air orifice taps, thread hose barbs into the
1/8" NPT connections, and attach the manometer
pressure lines to the barbs. Be sure all
connections are gas tight.
Rheos Boiler and Water Heater
Page 39
6.
7.
8.
9.
10.
11.
12.
13.
14.
Figure 34. Gas/Air Test Panel.
15.
16.
17.
Valve
Shown
Closed
Valve
Shown
Open
Figure 35. Test Panel Valves.
Switch on the appliance power switch located on
the front of the unit.
The Rheos will enter the start sequence. The
blower and pump come on for pre-purge, then
the ignitor warm-up sequence starts and after all
safety devices are verified, the gas valve opens. If
ignition doesn’t occur, check that there is proper
gas supply. Wait 5 minutes and start the unit
again.
Open air orifice test port valves. Check air
orifice differential at full fire, and make note of
the differential.
Switch the Rheos off.
Close air orifice valves, remove the barbs and
replace the plugs. Make sure the connections are
gas tight.
Remove the two plugs from the + and – ports of
the gas orifice taps, thread hose barbs into the
1/8" NPT connections, and attach the manometer
pressure lines to the barbs. Be sure all
connections are gas tight.
Switch on the appliance power switch located on
the front of the unit.
The Rheos will enter the start sequence. The
blower and pump come on for pre-purge, then
the ignitor warm-up sequence starts and after all
safety devices are verified, the gas valve opens.
Open gas orifice test port valves. Check gas
orifice differential at full fire, and make note of
the differential.
Close gas orifice valves, remove the barbs and
replace the plugs. Make sure the connections are
gas tight.
If gas and air orifice differentials match what
is shown in Table 10, and do not differ from
eachother by more than 0.1" w.c., the unit is
properly set up. If not, consult, the factory.
After placing the appliance in operation, the
Burner Safety Shutoff Device must be tested.
To test:
(a) Close gas shutoff valve with burner
operating.
(b) The flame will go out and blower will
continue to run for the post purge cycle.
One additional attempt to light will follow
including pre-purge, ignitor on, valve/flame
on and post purge. Ignition will not occur
as the gas is off. The ignition control will
lockout, and will have to be reset before the
unit will operate.
(c) Open gas shutoff valve. Restart the
appliance. The ignition sequence will
start again and the burner will start. The
appliance will return to its previous mode
of operation.
Page 40
Caution
Should any odor of gas be detected, or if the gas
burner does not appear to be functioning in a
normal manner, close main shutoff valve, do not
shut off switch, and contact your heating contractor,
gas company, or factory representative.
Gas Type
Natural
Propane
Air Orifice
Differential
4.0 to 4.5" W.C.
(1.0 to 1.1kPa)
4.5 to 5.0" W.C.
(1.1 to 1.2kPa)
Gas Orifice
Differential
4.0 to 4.5" W.C.
(1.0 to 1.1kPa)
4.5 to 5.0" W.C.
(1.1 to 1.2kPa)
Note: Long runs of vent or combustion air piping may
reduce the air and gas differential pressures. This is
acceptable, as long as the pressures are within 0.1"
(0.025kPa) w.c. of each other.
Table 10. Air and Gas Orifice Differentials at Full Fire.
6.3 Shutting Down the Rheos
1.
2.
3.
Switch off the main electrical disconnect switch.
Close all manual gas valves.
If freezing is anticipated, drain the Rheos and
be sure to also protect building piping from
freezing.
This step to be performed by a qualified
service person.
6.4 To Restart the Rheos
If drained, follow Section 6.1 in this manual
for proper filling and purging.
1. Switch off the main electrical disconnect switch.
2. Close all manual gas valves.
3. WAIT FIVE (5) MINUTES.
4. Set the aquastat or thermostat to its lowest
setting.
5. Open all manual gas valves.
6. Reset all safety switches (pressure switch,
manual reset high limit, etc).
7. Set the temperature controller to the desired
temperature setting and switch on electrical
power.
8. Burner will go through a prepurge period and
ignitor warm-up period, followed by ignition.
LAARS Heating Systems
SECTION 7.
Maintenance
WARNING
Disconnect all power to the appliance before
attempting any service to the appliance. Contact
with electricity can result in severe injury or death.
7.1 System Maintenance
1.
Lubricate the system water-circulating pump, if
required, per the instructions on the pump.
2. If a strainer is employed in a pressure reducing
valve or the piping, clean it every six months.
3. Inspect the venting system for obstruction or
leakage at least once a year. Periodically clean
the screens in the vent terminal and combustion
air terminal (when used).
4. Keep the appliance area clear and free from
combustible materials, gasoline, and other
flammable vapors and liquids.
5. If the appliance is not going to be used for
extended periods in locations where freezing
normally occurs, it should be isolated from the
system and completely drained of all water.
6. Low water cutoffs, if installed, should be
checked every 6 months. Float type low water
cutoff should be flushed periodically.
7. Inspect and clean the condensate collection and
disposal system yearly.
8. When a means is provided to neutralize
condensate, ensure that the condensate is being
neutralized properly.
9. Inspect flue passages, and clean with brushes/
vacuums, if necessary. Sooting in flue passages
indicates improper combustion. Determine the
cause and correct.
10. Inspect the vent system and air intake system,
and ensure that all joints are sealed properly. If
joints need to be resealed, completely remove
existing sealing material, and clean with alcohol.
Apply new sealing material, and re-assemble.
7.2 Appliance Maintenance and
Component Description
used.
Only genuine Laars replacement parts should be
Caution
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing.
Rheos Boiler and Water Heater
See Figures 36, 37 and 38 for location of gas
train and control components.
The gas and electric controls on the appliance
are engineered for long life and dependable operation,
but the safety of the equipment depends on their
proper functioning. It is strongly recommended that
a qualified service technician inspect the basic items
listed below every year.
a. Ignition control
b. Water temperature control
c. Automatic gas valve
d. Pressure switches
e. Blower
7.2.1 Burner
Check the burner for debris. Remove the fan
assembly to access the burner. Remove the 6 nuts,
which hold the burner in place. Pull burner up and out.
Clean burner, if necessary, by blowing compressed air
from the outside of the burner into the center of the
burner, and wipe the inside of the burner clean with
glass cleaner. A dirty burner may be an indication
of improper combustion or dirty combustion air.
Determine the cause, and correct. Always replace the
burner gasket when replacing the burner.
7.2.2 Filter
The filter used in the Rheos is washable with an
83% arrestance. Since the filter is washable, it will
only need replacement in very rare cases. If filter
replacement is needed, it should only be replaced with
factory parts. To access the filter, remove the unit’s
front panel. Disengage latch on top of filter box and
remove the filter box cover. Inspect the air filter. If
there is debris on the air filter, remove it from the filter
box, and wash it with mild soap and water. Ensure
that the filter is completely dry before re-installing, in
reverse order.
7.2.3 Modulating Gas Valve
The modulating gas valve consists of a valve
body and a pressure regulating electro-hydraulic
actuator. It provides the air/gas ratio control for the
unit. It is designed to operate with supply pressures of
4-13 inches w.c. (1.0 to 3.2 kPa).
To remove the valve actuator, shut off 120-volt
power and the gas shutoff valve. Remove the front
panel from the unit. Label the four pressure tubes
that are connected to the valve actuator, to ensure
that they will be replaced correctly. Remove the
four tubes from the barb connectors. Disconnect the
110-volt wires from the actuator. Remove the valve
actuator by taking out the four screws, and pulling the
actuator out. Re-install in reverse order. Turn on gas
shutoff valve and 120 volt power and check appliance
operation and tightness of gas valve connections.
The gas valve body will rarely have to be
removed. If there is a valve problem, and it has been
Page 41
determined the actuator is working properly, the gas
valve body may need to be replaced. To remove the
gas valve body, shut off 120-volt power and the gas
shutoff valve. Remove the front and right-side panels
from the unit. Disconnect the union between the
valve body and the blower. Label the four pressure
tubes that are connected to the valve actuator, to
ensure that they will replaced correctly. Remove
the valve actuator, per the instructions above. Unscrew
the valve body from the gas train. After the valve has
been removed, replace with a new valve in the reverse
order. Turn on gas shutoff valve and 120 volt power
and check appliance operation and tightness of gas
valve connections.
7.2.4 Safety Gas Valve
The safety gas valve is a 24-volt diaphragm
valve. It is designed to operate with supply pressures
of 4-14 inches w.c. (1.0 to 3.4 kPa). To remove the gas
valve, shut off 120-volt power. Shut off the main gas
supply to the unit. Disconnect the gas supply piping
from the back of the unit. Disconnect the electrical
wires from the valve, and unscrew the gas valve from
the gas train. Re-assemble in reverse order. A bleed
line from the diaphragm type automatic valve shall be
vented per local code requirements.
7.2.5 Manual Reset High Limit Control
The high limit switch is manual reset switch with
an adjustable set point, up to 240°F (116°C) on boiler
models and 200°F (93°C) water heater models. To
replace the switch, shut off the 120-volt power to the
appliance. Remove the cover from the switch to access
the mounting screws. Remove the screws, and pull the
switch off the control panel. Replace in reverse order.
7.2.6 Temperature Control
The temperature control consists of an adjustable
electronic control and digital display module. To
replace the control or the display, shut off the 120volt power to the appliance. Remove the cover from
the control panel, and remove the screws from the
DIN rail clip, to which the controls are mounted. Pull
the electrical connector from the controller. Slide the
controllers from the DIN rail clip. Replace in reverse
order.
7.2.7 Ignition Control
The ignition control ensures the proved
interrupted-type ignition system. It controls the
hot surface ignitor and proves that the flame signal
is appropriate for powering the gas valves. It also
controls the blower’s pre-purge and post-purge. To
replace the control, shut off the 120-volt power to the
appliance. Remove the cover from the control panel.
Remove the electrical connectors from the ignition
control. Take out the controller’s mounting screws, and
pull the controller out. Replace in reverse order.
Page 42
7.2.8 Ignitor / Flame Sensor Assembly
The ignitor is a 110v “Hot Surface” type. It
is energized whenever there is a call for heat and
switched off when ignition is established and the flame
has been sensed. To replace the ignitor, shut off the
120-volt power to the appliance, disconnect the Molex
connector, remove the two mounting screws on the
ignitor flange, and pull the ignitor out. Always install a
new ignitor gasket with the replacement ignitor.
Caution
Ignitor gets hot.
7.2.9 Transformers
There are three transformers in the Rheos
unit. One is 24v to 110v, the second is 110v to 24v,
and the third is 110v to 220v. Be sure to replace the
transformers with factory parts. These transformers are
not capable of supplying control voltage for external
devices such as zone valves, which must have their
own separate power supply. Should a transformer need
replacing, shut off the 120-volt power. Unplug the
transformer wires, remove the mounting screws and
remove the transformer. Replace transformer in the
reverse order.
7.2.10 Blower
The combustion air blower is a high-pressure
centrifugal blower with a variable speed motor. The
speed of the motor is determined by the control logic.
If a blower change is required, turn off the 120-volt
power and gas supply to the unit. Take the front panel,
the two side access panels, and the top jacket panel
off. (If there is enough clearance on the side, the top
may not have to be removed.) Disconnect the gas
union between the blower and gas valves. Disconnect
the filter box assembly (at the air transition) from the
blower (six 8 mm bolts). Disconnect the two Molex
electrical connectors from the top right of the blower.
Remove the four nuts from the blower flange, and
pull the blower out. Replace blower in reverse order,
ensuring that all joints are made correctly and sealed.
After replacement, ensure that the unit operates
properly, by following the set-up procedure in this
manual.
7.2.11 Flow Switch
The Rheos uses a paddle-type flow switch to
ensure that the unit has water flow before ignition is
allowed.
7.2.12 Heat Exchanger Coil
Black carbon soot buildup on the external
surfaces of the heat exchanger is caused by one
or more of the following; incomplete combustion,
combustion air problems, venting problems and heater
LAARS Heating Systems
short cycling. Soot buildup or other debris on the heat
exchanger may restrict the flue passages.
If black carbon soot buildup is suspected,
disconnect electrical supply to the unit, and turn off
the gas supply by closing the manual gas valve on the
unit. Access the heat exchanger through the side access
panels, and inspect the finned copper tubing using a
flashlight. If there is a buildup of black carbon soot
or other debris on the heat exchanger, clean per the
following:
Caution
Black carbon soot buildup on a dirty heat exchanger
can be ignited by a random spark or flame. To
prevent this from happening, dampen the soot
deposits with a wet brush or fine water spray before
servicing the heat exchanger.
1.
2.
Disconnect the electrical supply to the unit.
Turn off the gas supply by closing the manual gas
valve on the heater.
3. Disconnect and remove the wires, conduit and
sensors from all components that are attached to
the inlet/outlet header.
4. Isolate the heat exchanger from the water supply.
5. Drain the heat exchanger from the drain located
on the bottom of the heat exchanger.
6. Disconnect the header flanges from the inlet and
outlet.
7. Remove the heat exchanger from the unit.
NOTE: The heat exchangers are heavy and may
require two people to remove to avoid personal
injury.
8. Clean the heat exchanger: A light accumulation
of soot or corrosion on the outside of the heat
exchanger can be easily removed. Use a wire
brush to remove loose soot and scale from the
heat exchanger. Do not use water or compressed
air for cleaning.
9. NOTE: While the heat exchanger is out of the
unit, inspect the firewall refractory insulation
blocks for cracks, wear and breakage. Replace if
necessary.
10. Inspect the inside of the copper tubes for scale
buildup. Scale can build up on the inner surface
of the heat exchanger tubes, which can restrict
water flow. If the tubes show signs of scaling,
clean the internal surface. Laars offers a tube
cleaning kit part number R2000700.
11. Reassemble in the reverse order.
If heat exchanger removal is necessary, consult
the factory for instructions.
NOTE: The Warranty does not cover damage
caused by lack of required maintenance, lack of
water flow, or improper operating practices.
Rheos Boiler and Water Heater
Page 43
Standard and Control Pack C Gas Train
Air Inlet
Transition
High Gas
Pressure Switch
Modulating Gas
Valve Actuator
Safety
Gas Valve
Manual
Gas Valve
Pressure
Switch
Gas Orifice
Manual
Gas Valve
Low Gas
Pressure
Switch
Modulating Gas
Valve Body
Control Packs A and D Gas Train
Air Inlet
Transition
High Gas
Pressure Switch
Modulating Gas
Valve Actuator
Normally Open
Vent Valve
Safety
Gas Valve
Pressure
Switch
Manual
Gas Valve
Gas Orifice
Manual
Gas Valve
Modulating Gas
Valve Body
Low Gas
Pressure Switch
Figure 36. Gas Trains.
7.2.13 Normally Open Vent Valve
Some Rheos models provide a normally open
vent valve for installations with IRI code requirements.
The valve opens when power is removed from the
safety valves. And the valve closes when the safety
valves are powered. See sections 3.1 Item #4 for
installation instructions.
7.2.14 Motorized Safety Valve
Control packs B and E have an additional
motorized safety valve. This valve is powered open
at the same time as the safety valve. To remove the
valve actuator, shut off the 120V power and the gas
shutoff valve. Remove the right side, or front panel.
Disconnect the 120V wires from the actuator. Remove
the valve actuator by taking out the four screws, and
pulling the actuator out. Re-install in reverse order.
Turn on gas shutoff valve and 120V power and
check appliance operation and tightness of gas valve
connections.
The gas valve body will rarely have to be
removed. If there is a valve problem, and it has been
Page 44
LAARS Heating Systems
Control Packs B and E Gas Trains
Modulating Gas
Valve Actuator
Modulating Gas
Valve Actuator
High Gas
Pressure Switch
Pressure
Differential
Tube Assembly
Air Inlet
Transition
On/Off Gas
Valve Actuator
Low Gas
Pressure Switch
Manual
Gas Valve
Air Inlet
Transition
High Gas
Pressure Switch
Pressure
Differential
Tube Assembly
Solenoid Safety
Gas Valve
Pressure
Switch
Gas Orifice
Modulating Gas
Valve Bodies
On/Off Gas
Valve Actuator
Low Gas
Pressure Switch
Manual
Gas Valve
Pressure
Switch
Gas
Orifice
Solenoid Safety
Gas Valve
Modulating Gas
Valve Body
Figure 37. Gas Train.
determined the actuator is working properly, the gas
valve body may need to be replaced. To remove the
gas valve body, shut off 120V power and the gas
shutoff valve. Remove the right side and front panels.
Remove the valve actuator. Unscrew the valve body
from the gas train. After the valve has been removed,
replace with a new valve in reverse order. Turn on gas
shutoff valve and 120V power and check appliance
operation and tightness of gas valve connections.
7.2.15 Gas Pressure Switches
The high and low gas pressure switches are 24V
manual reset switches that act to cut power to the gas
valves if the gas pressure is too low or too high for
proper operation. The gas pressure switches used are
integrally vent limited, and do not require venting to
atmosphere. To remove a switch, remove the screw
on the plastic housing and pull the clear cover off.
Disconnect the two wires from the screw terminals.
Twist the switch off the pipe nipple. Reassemble in
reverse order. For natural gas, set the low gas pressure
switch to 3" w.c. For propane, set the low gas pressure
switch to 5" w.c. For natural and propane, set the high
gas pressure switch to 14".
Figure 38. Control Panel.
Rheos Boiler and Water Heater
Page 45
Section 8.
Trouble Shooting
8.1 Sequence of Operation
The Rheos appliance is a cold start appliance
that should start only on a call for heat from a tank
aquastat, room thermostat, zone valve end switch or
other space temperature control device.
1. Upon a call for heat,
(a) The internal pump will start. (Pump is
optionally mounted on unit.)
(b) The blower will begin a 15 second prepurge.
2. Following the prepurge cycle the hot surface
ignitor will heat and will begin a 7 second trial
for ignition. The unit is allowed three attempts
for ignition.
3. The gas valve will then be energized and lowfire (50% of full fire) ignition will occur. The
unit will remain in a low-fire start-up period for 15
seconds.
4. After the low-fire start time is over, the unit
will be in normal operation firing rate and will
modulate based on the heating load via the
temperature controller settings and readings.
5. When the call for heat is complete, or the unit
reaches its setpoint temperature, the gas valve
will close, and the fan will continue to run for
its 30 second post-purge. If a pump time delay
is used, the pump will continue to run for the
specified amount of time (adjustable from 0.1 to
10 minutes).
8.2 Resolving Lockouts
There are many causes of lockouts. The three
most common causes are: (1) inadequate gas supply,
(2) poor combustion, (3) ignitor failure (4) combustion
air.
1. Inadequate gas supply: Before proceeding, ensure
that the gas supply has not been shutoff or the LP
tank (LP boilers) is not empty. Then, restart the
boiler and observe the operational cycle. After
the pre-purge time, the unit should light. If it
does not, consult the factory.
2. Poor Combustion: Poor combustion should be
suspected if there is a strong flue gas odor. The
odor may result from an improper gas/air ratio
(high or low O2 or CO2). If an improper gas/air
ratio is suspected, consult the factory.
3. Ignitor failure: If the boiler goes through a
normal start cycle but combustion does not
occur, ignitor failure should be suspected. Check
the ignitor by unplugging the ignitor plug and
measuring the ignitor resistance. It should be
50-80 (-) ohms. If the resistance is not 50-80
ohms (W), replace the ignitor. If the resistance is
4.
correct, reset the boiler and check for 120 VAC
at the ignitor plug during the start cycle. If there
is no voltage, replace the faulty ignitor wire
harness.
Inadequate combustion air: If the boiler goes
through a normal ignition cycle, and shuts off
after the blower ramps up to full speed, an
abnormal restriction in the air intake or exhaust
system should be suspected. Check the air filter
for buildup of debris and clean filter if necessary.
Inspect all exhaust venting and intake venting for
blockages. Remove any blockages and inspect
and replace any damaged vent sections. If the
unit still continues to lockout after igniting,
consult the factory.
Once the reason for the lockout has been
identified and resolved you can reset the unit by
pressing the manual reset button (see Detail A in
Figure 30. Control Panel).
8.3 Delayed Ignition - Possible Causes
8.3.1 High Lockup Pressure (LP
Appliances) - Occurs on Start-up
High lock up pressure is the most common
cause of delayed ignitions on LP fueled appliances. It
may result from an improper second stage regulator
selection or from a faulty regulator.
Lock up can be detected by measuring the gas
supply pressure to the appliance at the inlet pressure
port on the gas valve. The gas supply to the appliance
must be shut off before making any connections. To
check: use a water manometer or pressure gauge with
a scale reading of at least 25 in. W.C. or 15 oz/in2.
(6.2kPa). Attach the manometer to the gas valve inlet
pressure port. Turn on the gas supply. The Rheos
appliance is designed to operate with supply pressures
of 4-13 in. W.C. (2.3 - 7.5 oz/ in²) (0.1-3.2kPa). If
the supply pressure exceeds 13 in. W.C. (7.5 oz/ in²)
(3.2kPa) (with the appliance off) it is possible that this
may be the cause of the delayed ignitions and the inlet
pressure must be reset to between 4-13 in. W.C. (2.3
– 7.5 oz/in2) (0.1-3.2kPa). Restart the appliance and
then switch it off. If the inlet gas pressure exceeds 13
in. W.C. (7.5 oz/ in²) (3.2kPa) after the appliance is
switched off, correct the lock up problem.
8.3.2 Gas Valve Regulation
Gas valve regulation problems can also cause
delayed ignitions. If gas valve regulation problems
are suspected, consult the factory. Do not attempt field
adjustment or repair.
Page 46
8.3.3 Defective Burner - Occurs on
Startup or at Burner Shutdown
A defective burner can cause a delayed ignition.
If the gas supply pressure is proper, the gas valve is
functioning properly, the burner should be inspected.
There should be no distortion or perforations in the
burner. Replace if indicated.
8.4 Short Cycling — Boiler
Because the Rheos is a modulating boiler, and its
input will decrease when there is a reduction in heating
load, short cycling is greatly reduced. If the heating
load drops below the minimum input of the boiler for
an extended period, the boiler will have a tendency
to short cycle. This can be a symptom of improper
control strategy or setpoints, or a load distribution
problem. See Section 5.5 regarding controller setup.
Contact your Laars representative to discuss possible
remedies.
8.5 Short Cycling — Water Heater
Short cycling will generally occur only in
combination space heating and water heating
applications when the water heater is operating in
the space-heating mode. Because the Rheos is a
modulating water heater and its input will reduce when
there is a reduction in heating load, short cycling is
greatly reduced. If the heating load drops below the
minimum input of the water heater for an extended
period, the water heater will have a tendency to short
cycle. If short cycling is frequently experienced,
regardless of the control’s attempt to limit it, the
heating load should be redistributed to control it. See
Section 5.5 regarding controller setup.
If short cycling occurs in a water heater
application, it is probably caused by undersized
piping between the water heater and the storage tank
or by some other factor that restricts proper water
flow through the water heater. The cause should be
determined and corrected.
LAARS Heating Systems
8.6 High Gas Consumption
Appliances operating with an improper air/fuel
ratio are very inefficient and consequently, have
very high gas consumption. Because efficiency is
high when the CO2 is high (or O2 is low), appliances
operating with low CO2 or high O2 (especially LP
appliances) consume more gas. Adjust the CO2 or O2
for optimum efficiency. If no combustion analyzing
equipment (CO2 or O2) is available then a proper
adjustment of the air/fuel ratio (CO2 or O2) can not
be accomplished. However, by briefly sniffing the
flue gases it is possible to determine if the CO2 or
O2 is within the proper range. No significant flue gas
odor should be detected when combustion is proper.
A strong piercing smell indicates poor combustion
and generally a lean mixture - low CO2 or high O2 .
The CO2 should be 8 to 9% at all firing rates. Do not
attempt to correct combustion. Contact factory if the
CO2 is not within this range.
Section 9.
Replacement Parts
Only genuine Laars replacement parts should be used.
9.1 General Information
To order or purchase parts for the Laars Rheos,
contact your nearest Laars dealer or distributor. If
they cannot supply you with what you need, contact
Customer Service (see back cover for address,
telephone and FAX numbers).
Rheos Boiler and Water Heater
Page 47
9.2 Parts List
COMBUSTION COMPONENTS
See Figure 39
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
20
21
Combustion chamber assembly
Base assembly
Panel, front cover, base frame
Panel, top, combustion chamber (with insulation)
Panel, bottom, combustion chamber
Panel, left, combustion chamber
Panel, right, combustion chamber
Panel, access, combustion chamber
Support, front, fan transition
Support, rear, fan transition
Hardware kit, combustion chamber
Burner, with gaskets
Gasket kit, burner
Tile kit (top & bottom of heat exchanger w/top insulation)
Tile support w/rods
Tile support protective liner
Flue collector kit (with gaskets)
Gasket kit, flue collector
Gasket kit, combustion chamber
Heat exchanger assembly, copper
Heat exchanger assembly, cupro-nickel
Baffle, flue
GAS TRAIN / COMBUSTION AIR COMPONENTS
See Figures 40 and 41
25 Gas train assembly, standard, Nat
25 Gas train assembly, standard, LP Nat
25 Gas train assembly, control pack A, Nat
25 Gas train assembly, control pack A, LP Nat
25 Gas train assembly, control pack B and E, Nat
25 Gas train assembly, control pack B and E, LP Nat
26 Gas valve, safety
27 Gas valve, solenoid safety, for control packs B & E
28 Gas valve, mod valve actuator
29 Gas valve, mod valve body
29 Gas valve, mod valve body, size 2000, Nat
29 Gas valve, mod valve body, size 2000, LP
30 Gas valve, mod complete (body and actuator)
30 Gas valve, mod complete (body and actuator) size 2000, Nat
30 Gas valve, mod complete (body and actuator) LP gas
size 2000, LP
31 Gas valve, manual
32 Double valve body / Actuator
33 Double valve body
34 On/Off Actuator
35 Normally open vent valve
36 Gas orifice kit (orifice in holder), Nat
36 Gas orifice kit (orifice in holder), LP
37 Gas orifice, Nat
37 Gas orifice, LP
38 Pressure switch, high gas
1200
1600
2000
2400
R2010800
R2001100
R2001200
R2001300
R2001400
R2001500
R2001600
R2001700
R2010200
R2010300
R2002200
R2013200
R2002400
R2002500
R2010900
R2016900
R2011000
R2002900
R2003000
R2013300
R2013301
R2017300
R2016300
R2001100
R2001200
R2001300
R2001400
R2001500
R2001600
R2001700
R2010200
R2010300
R2002200
R2016500
R2002400
R2002500
R2016700
R2016900
R2011000
R2002900
R2003000
R2017100
R2017101
not used
R2016400
R2001100
R2001200
R2001300
R2001400
R2001500
R2001600
R2001700
R2010200
R2010300
R2002200
R2016600
R2002400
R2002500
R2016800
R2016900
R2017000
R2002900
R2003000
R2017200
R2017201
not used
R2001000
R2001100
R2001200
R2001300
R2001400
R2001500
R2001600
R2001700
R2010200
R2010300
R2002200
R2002300
R2002400
R2002500
R2002600
R2002700
R2002800
R2002900
R2003000
R2003100
R2003101
not used
R2011100
R2011200
R2017800
R2018200
R2018600
R2019000
R2011300
R2019400
R2003400
R2011400
not used
not used
R2011500
not used
R2017400
R2017600
R2017900
R2018300
R2018700
R2019100
R2003300
R2019500
R2003400
R2011400
not used
not used
R2011500
not used
R2017500
R2017700
R2018000
R2018400
R2018800
R2019200
R2003300
R2019500
R2003400
not used
R2003500
R2011400
not used
R2003600
R2003200
R2010400
R2018100
R2018500
R2018900
R2019300
R2003300
R2019500
R2003400
R2003500
not used
not used
R2003600
not used
not used
not used
R2011500
not used
R2011600
not used
not used
R2019800
R2014400
R2011700
R2011800
R2011900
R2012000
R2004000
R2003700
not used
not used
R2019800
R2014400
R2019900
R2020100
R2020300
R2020500
R2004000
R2003700
R2019600
R2019700
R2019800
R2014400
R2020000
R2020200
R2020400
R2020600
R2004000
R2003700
R2019600
R2019700
R2019800
R2014400
R2003800
R2010500
R2003900
R2010600
R2004000
Page 48
39
40
41
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
Pressure switch, low gas
Tubing/Fittings (gas train repair kit)
Air filter box assembly (with gasket and hardware) Nat
Air filter box assembly (with gasket and hardware) LP
Air filter Gasket kit, air filter
Air filter box cover
Air filter felt gasket
Air filter air inlet vent w / gasket
Blower
Blower gasket kit
Air orifice, Nat
Air orifice strip, LP
Air orifice, LP
Air restrictor, LP
Air transition (filter box to blower)
Blower adapter transition
Ignitor kit (with gasket)
Sight glass Pressure switch, air
ELECTRICAL COMPONENTS
See Figure 42
60 Transformer, 115/24V, 40VA step down, 60 Transformer, 115/24V, 80VA step down, for control pack B & E only
62 Transformer, 24/115 step up
63 Fuse kit, 2 Amp, 5 pack (not shown)
63 Fuse kit, 5 Amp, 5 pack (Control packs B and E) (not shown)
64 Fuse holder (qty of 5)
65 Diagnostic lights kit
66 Ignition control (Single Trial)
66 Ignition control (Three Trial, Control packs F and G)
67 High limit, manual reset, RHCH boiler
67 High limit, manual reset, RHCV water heater
68 Temperature control, RHCH boiler
69 Module, proportional control
70 Relay, DPDT, 24V coil
71 Relay, Time Delay on Make
72 Relay, DPDT, 120V coil
73 Relay, EM2 kit
74 Relay, 115VAC SPST
75 Voltage regulator
76 Terminal block, 2 position
77 Terminal block, 4 position
78 Sensor, temperature control (not shown)
79 Switch, toggle, 3-way SPDT
80 Switch, toggle, DPDT
81 Control signal converter
82 Bell, alarm, 24V
83 Cover, control panel top
84 Cover, control panel bottom
85 Enclosure, control panel
86 Voltage divider panel, Std and control pack options
A, C, and D
86 Voltage divider panel, control pack options B and E
87 Support, control panel bottom
LAARS Heating Systems
1200
1600
2000
2400
R2004100
R2020700
R2020800
R2020800
R2004500
R2004600
R2004700
R2004800
R2021300
R2012100
R2012200
R2012300
not used
R2026400
R2026500
R2012500
R2022300
RW2002300
R2005300
R2022400
R2004100
R2020700
R2020900
R2021000
R2004500
R2004600
R2004700
R2004800
R2021400
R2004900
R2005000
R2021500
not used
R2021600
R2022100
R2005200
not used
RW2002300
R2005300
R2022400
R2004100
R2020700
R2004400
R2021100
R2004500
R2004600
R2004700
R2004800
R2021400
R2004900
R2005000
R2021700
R2022000
R2021700
R2022200
R2005200
not used
RW2002300
R2005300
R2022400
R2004100
R2020700
R2004400
R2021200
R2004500
R2004600
R2004700
R2004800
R2021400
R2004900
R2005000
R2005100
R2022000
R2005100
not used
R2005200
not used
RW2002300
R2005300
R2022400
1200
R0021300
R2022500
1600
R0021300
R2022500
2000
R0021300
R2022500
2400
R0021300
R2022500
R2005500
RE2043600
RE2043500
R2005500
RE2043600
RE2043500
R2005500
RE2043600
RE2043500
R2005500
RE2043600
RE2043500
RE2000300
R2005600
R2014100
R2022600
RE0015900
RE2217800
R2005800
R2005900
R2006000
R2006100
R2006200
RE2077700
R2014200
R2006300
R2006400
R2006500
R2006600
R2007700
R2015000
R2012700
R2014200
R2006700
R2007000
R2006800
R2006900
RE2000300
R2005600
R2014100
R2022600
RE0015900
RE2217800
R2005800
R2005900
R2006000
R2006100
R2006200
RE2077700
R2014200
R2006300
R2006400
R2006500
R2006600
R2007700
R2015000
not used
R2014200
R2006700
R2007000
R2006800
R2006900
RE2000300
R2005600
R2014100
R2022600
RE0015900
RE2217800
R2005800
R2005900
R2006000
R2006100
R2006200
RE2077700
R2014200
R2006300
R2006400
R2006500
R2006600
R2007700
R2015000
not used
R2014200
R2006700
R2007000
R2006800
R2006900
RE2000300
R2005600
R2014100
R2022600
RE0015900
RE2217800
R2005800
R2005900
R2006000
R2006100
R2006200
RE2077700
R2014200
R2006300
R2006400
R2006500
R2006600
R2007700
R2015000
not used
R2014200
R2006700
R2007000
R2006800
R2006900
R2015200
R2007100
R2015200
R2007100
R2015200
R2007100
R2015200
R2007100
Rheos Boiler and Water Heater
88
89
90
91
92
Panel, diagnostic lights
Bracket, mounting, diagnostic panel
Standoff
Hardware kit, control panel
Bracket, support, control panel top
Page 49
1200
1600
2000
2400
R2007300
R2007400
R2007500
R2007600
R2007800
R2007300
R2007400
R2007500
R2007600
R2007800
R2007300
R2007400
R2007500
R2007600
R2007800
R2007300
R2007400
R2007500
R2007600
R2007800
HEAT EXCHANGER / WATER PATH
See Figure 43
1200
1600
2000
2400
93 Header cover
R2012800
R2022700
R2022800
R2007900
93 Header cover, pump mount
R2022900
R2023000
R2023100
R2023200
94 Water barrier assembly
R2012900
R2023300
R2023400
R2008000
95 Gasket kit, heat exchanger cover
R2013000
R2023500
R2023600
R2008200
96 Hardware kit, heat exchanger cover
R2013100
R2023700
R2023800
R2008300
97 Gauge, temperature/pressure
RA0079000
RA0079000
RA0079000
RA0079000
98 Pressure relief valve, RHCH boiler
A0063600
A0063600
A0002700
A0002700
98 Pressure relief valve, RHCV boiler
A0001200
A0064400
A0000400
A0000400
100 Immersion well, high limit
RE2058300
RE2058300
RE2058300
RE2058300
101 Immersion well, temperature control
RE2074000
RE2074000
RE2074000
RE2074000
102 Tube cleaning kit (not shown)
R2000700
R2000700
R2000700
R2000700
103 Flow switch (with paddle)
R2008400
R2008400
R2008400
R2008400
104 Low water cutoff, manual reset
RE2075100
RE2075100
RE2075100
RE2075100
105 Pump, circulator (normal water)
R2023900
R2024100
R2024300
R2024100
105 Pump, circulator (hard water)
R2024000
R2024200
R2024400
R2024200
106 Bracket, pump mounting (normal water)
R2024600
R2024500
R2024500
R2024500
106 Bracket, pump mounting (hard water)
R2024600
R2024600
R2024600
R2024600
107 Flange, pump, gaskets / hardware
R2024700
R2024800
R2024700
R2024800
108 Shims, pump bracket (10 ea)
R2013600
R2013600
R2013600
R2013600
109 Gaskets (10 pk)
R2013800
R2013800
R2013800
R2013800
110 Temperature switch, bi-metal disc
R2024900
R2024900
R2024900
R2024900
JACKET
See Figure 44
1200
1600
2000
2400
115 Panel, upper front access
R2015101
R2015101
R2015101
R2015101
116 Panel, lower front access
R2015102
R2015102
R2015102
R2015102
117 Panel, waterway access
R2025000
R2025100
R2025200
R2025300
117 Panel, waterway access, pump
R2025400
R2025400
R2025400
R2025500
118 Panel, waterway cover
R2025600
R2025600
R2025600
R2025600
119 Panel, pump access
R2025700
R2025800
R2025800
R2025800
120 Panel, PRV access
R2025900
R2025900
R2025900
R2025900
121 Panel, rear access
R2008600
R2008600
R2008600
R2008600
122 Panel, front left
R2008700
R2008700
R2008700
R2008700
123 Panel, front right
R2008800
R2008800
R2008800
R2008800
124 Panel, rear left
R2008900
R2008900
R2008900
R2008900
125 Panel, rear right
R2009000
R2009000
R2009000
R2009000
126 Panel, common access
R2009100
R2009100
R2009100
R2009100
127 Panel, top
R2009200
R2009200
R2009200
R2009200
128 Panel, support
R2009300
R2009300
R2009300
R2009300
129 Panel, flue vent access
R2026000
R2026000
R2026100
R2026300
130 Panel, ducted air cover
R2009500
R2009500
R2009500
R2009500
131 Jacket trim kit
R2009600
R2009600
R2009600
R2009600
132 Hardware kit, jacket
R2009700
R2009700
R2009700
R2009700
133 Window, control / display
R2009800
R2009800
R2009800
R2009800
134 Window guide
R2009900
R2009900
R2009900
R2009900
135 Window latch
R2010000
R2010000
R2010000
R2010000
136 Jacket retro-fit kit (standard)
R2026400
R2026500
R2026600
R2026700
137 Jacket retro-fit kit (mounted pump)
R2026800
R2026900
R2027000
R2027100
Page 50
LAARS Heating Systems
12
13
10
4
18 OR 19
18 OR 19
9
14
17
14
19
19
14
6
19
19
18 OR 19
19
19
20
8
14
19
19
5
7
16
15
14
Figure 39. Combustion Components.
21
1 - Complete Combustion
Component Assembly
11 - Hardware Kit,
Combustion Chamber
3
2 (ASSEMBLY)
Rheos Boiler and Water Heater
Page 51
41
51
46
49
50
43
47
45
42
44
48
52
48
48
48
54
55
48
Figure 40. Gas Train/Combustion Air Components.
56
Page 52
40
53
38
LAARS Heating Systems
28 OR 30
26
31
Standard and
Control Pack C
Gas Train
57
36 OR 37
39
29 OR 30
31
40
28 OR 30
38
53
26
35
31
Control Packs
A and D
Gas Train
57
36 OR 37
53
40
38
28 OR 30
34
29 OR 30
31
39
39
27
31
Control Packs B and E Gas Train
53
57
28 OR 32
29
36 OR 37
31
40
34
27
38
29 OR 30
For sizes 1200, 1600 and
2000 Propane gas
57
36 OR 37
31
32 OR 33
For sizes 2000 Natural gas and 2400
Figure 41. Gas Train Components.
39
31
Rheos Boiler and Water Heater
Figure 42. Electrical Components.
Page 53
Page 54
93
95
LAARS Heating Systems
98
96
103
100
104
97
101
94
110
106
107 OR 109
107
105
106 OR 108
106
106
106
Figure 43. Heat Exchanger / Water Path Components.
Rheos Boiler and Water Heater
Page 55
134
133
132 - Jacket Hardware Kit
136 - Jacket Retro-fit Kit (standard)
137 - Jacket Retro-fit Kit (mounted pump)
127
131
135
130
128
115
124
128
126
129
121
120
118
122
131
125
126
117
123
116
Figure 44. Jacket Components.
119
Page 56
Tables Listing
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Terminals for Outdoor Installation...................... 6
Clearances.........................................................6
Vent / Air Pipe Sizes...........................................7
Horizontal Vent and Air Terminals
For Indoor Installations.......................................9
Required Combustion Air Piping Material.......... 9
Required Venting Material..................................9
Gas Piping Sizes..............................................10
Water Flow Requirements – RHCH (Boiler)..... 13
Water Flow Requirements – RHCV
(Water Heater)..................................................15
Air & Gas Orifice Differentials at Full Fire......... 40
Figures Listing
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Dimensional Drawing.........................................5
Combustion Air and Vent Through Roof............. 7
Combustion Air and Vent Through Side-Wall..... 8
Hydronic Piping – Multiple Boilers,
Primary Secondary System..............................12
Hydronic Piping – Multiple Boilers,
Low Temerature System...................................12
Hydronic Piping – One Boiler,
Multi-Temperature System...............................13
Hydronic Piping - Alternate System.................. 14
Hydronic Piping - Alternate Low
Temperature System........................................14
Water Heater Piping – One Heater, One Tank..... 16
Water Heater Piping – Multiple Heaters,
One Tank..........................................................16
Water Heater Piping – One Heater,
Multiple Tanks...................................................17
Water Heater Piping – Multiple Heaters,
Multiple Tanks...................................................17
Temperature Control........................................19
Proprotional Control.........................................20
Control Parameter Graph.................................22
Control Parameter Possible Interference......... 23
Control Parameter Possible Interference......... 23
Wiring Diagram, Model 1200,
Standard and Codes A, C, E, F and G............. 26
LAARS Heating Systems
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figure 29
Figure 30
Figure 31
Figure 32
Figure 33
Figure 34
Figure 35
Figure 36
Figure 37
Figure 38
Figure 39
Figure 40
Figure 41
Figure 42
Figure 43
Figure 44
Wiring Diagram, Models 1600, 2000 and 2400,
Standard and Codes A, C,E, F and G.............. 27
Wiring Diagram Model 1200,
Codes B and E.................................................28
Wiring Diagram, Models 1600, 2000 and 2400,
Codes B and E.................................................29
Wiring Diagram, Model 1200, Pump-Mounted,
Standard and Codes A, C, E, F and G............. 30
Wiring Diagram, Models 1600, 2000 and 2400,
Pump-Mounted,
Standard and Codes A, C, E, F and G............. 31
Wiring Diagram, Model 1200, Pump-Mounted,
Codes B and E.................................................32
Wiring Diagram, Models 1600, 2000 and 2400,
Pump-Mounted, Codes B and E...................... 33
Wiring Schematic, Model 1200,
Standard and Codes A, C, E, F and G............. 34
Wiring Schematic, Models 1600, 2000 and 2400,
Standard and Codes A, C,E, F and G.............. 34
Wiring Schematic, Model 1200,
Codes B and E.................................................35
Wiring Schematic, Models 1600, 2000 and 2400,
Codes B and E.................................................35
Wiring Schematic, Model 1200, Pump-Mounted,
Standard and Codes A, C, E, F and G............. 36
Wiring Schematic, Models 1600, 2000 and 2400,
Pump-Mounted,
Standard and Codes A, C, E, F and G............. 36
Wiring Schematic, Model 1200, Pump-Mounted,
Codes B and E.................................................37
Wiring Schematic, Models 1600, 2000 and 2400,
Pump-Mounted, Codes B and E...................... 37
Gas/Air Test Panel............................................39
Test Panel Valves.............................................39
Gas Trains........................................................43
Gas Train..........................................................44
Control Panel...................................................44
Combustion Components................................. 50
Gas Train/Combustion Air Components........... 51
Gas Train Components....................................52
Electrical Components.....................................53
Heat Exchanger / Water Path........................... 54
Jacket Components.........................................55
Rheos Boiler and Water Heater
Page 57
Page 58
LAARS Heating Systems
Rheos Boiler and Water Heater
Page 59
H2300300F
®
800.900.9276 • Fax 800.559.1583 (Customer Service, Service Advisors)
20 Industrial Way, Rochester, NH 03867 • 603.335.6300 • Fax 603.335.3355 (Applications Engineering)
1869 Sismet Road, Mississauga, Ontario, Canada L4W 1W8 • 905.238.0100 • Fax 905.366.0130
www.Laars.com
Litho in U.S.A. © Laars Heating Systems 1010 Document 1170F
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