A.O. Smith 1000 SERIES 100 Instruction manual

Service Handbook
COMMERCIAL BOILERS/WATER HEATERS
25589 Highway 1
McBee, SC 29101
FOR MODELS: XB/XWH
1000, 1300, 1700
2000, 2600, 3400
SERIES 100/101
INSTALLATION CONSIDERATIONS - PRE SERVICE CHECKS
- BOILER/WATER HEATER CONSTRUCTION OPERATION & SERVICE - TROUBLESHOOTING
SERVICING SHOULD ONLY BE PERFORMED BY A QUALIFIED SERVICE AGENT
PRINTED IN THE U.S.A. 0513
320822-003
2
Servicing should only be performed by a Qualified Service Agent
TABLE OF CONTENTS
TABLE OF CONTENTS�������������������������������������������������������������������������� 3
Burner Control Operation���������������������������������������������������������������� 40
INTRODUCTION������������������������������������������������������������������������������������ 4
General Operational Sequence������������������������������������������������������� 41
Qualifications������������������������������������������������������������������������������������� 4
Lead Lag������������������������������������������������������������������������������������������ 42
Service Warning�������������������������������������������������������������������������������� 4
Local operator interface: display system����������������������������������������� 44
Service Reminder������������������������������������������������������������������������������ 4
Installation Instructions (S7999D OI Display)���������������������������������� 45
Tools Required����������������������������������������������������������������������������������� 4
Page Navigation������������������������������������������������������������������������������ 48
INSTALLATION CONSIDERATIONS����������������������������������������������������� 5
TROUBLESHOOTING������������������������������������������������������������������������� 58
Instruction Manual����������������������������������������������������������������������������� 5
Poor Combustion - Ignition Failure - Rough Start/Operation����������� 58
Closed Water Systems���������������������������������������������������������������������� 5
TROUBLESHOOTING CODES������������������������������������������������������������ 60
Thermal Expansion���������������������������������������������������������������������������� 5
PIPING DIAGRAMS����������������������������������������������������������������������������� 75
Air Requirements������������������������������������������������������������������������������� 5
Contaminated Air������������������������������������������������������������������������������� 5
Venting����������������������������������������������������������������������������������������������� 6
General Venting Information�������������������������������������������������������������� 6
Water Piping�������������������������������������������������������������������������������������� 6
Temperature Rise & Flow Rate���������������������������������������������������������� 6
Boiler/Water Heater Controls������������������������������������������������������������� 7
Primary System Control��������������������������������������������������������������������� 7
Installation Checklist�������������������������������������������������������������������������� 8
FEATURES AND COMPONENTS��������������������������������������������������������� 9
OPERATION AND SERVICE����������������������������������������������������������������11
Modulating Fire Operation����������������������������������������������������������������11
Combustion Blower��������������������������������������������������������������������������11
Heat Exchanger Assembly�������������������������������������������������������������� 12
Venturi And Gas Train Assembly����������������������������������������������������� 14
Burner Assembly����������������������������������������������������������������������������� 15
Flame Sensor���������������������������������������������������������������������������������� 17
Spark Igniter������������������������������������������������������������������������������������ 18
Gas Valve���������������������������������������������������������������������������������������� 19
Temperature Sensors���������������������������������������������������������������������� 20
Air Filter Assembly��������������������������������������������������������������������������� 21
Control Panel Assembly������������������������������������������������������������������ 22
Control Board Assembly������������������������������������������������������������������ 25
Display System (Touch Screen Display)������������������������������������������ 29
Connector Terminals������������������������������������������������������������������������ 29
START UP AND OPERATIONS����������������������������������������������������������� 31
Prior To Start Up������������������������������������������������������������������������������ 31
General�������������������������������������������������������������������������������������������� 31
Filling And Purging of Boiler/Water Heater Installation�������������������� 31
Filling Boiler/Water Heater Installation��������������������������������������������� 31
Inlet Gas Pressure��������������������������������������������������������������������������� 31
Manifold Pressure Connections������������������������������������������������������� 32
Water Temperature Regulation�������������������������������������������������������� 32
Check/Control Water Hardness������������������������������������������������������� 33
Freeze Protection (Hydronic Heating Installation)��������������������������� 33
Inspect/Fill Condensate System������������������������������������������������������ 33
LIGHTING AND OPERATING INSTRUCTIONS���������������������������������� 34
Adjustment��������������������������������������������������������������������������������������� 35
Setting Of The Test Mode���������������������������������������������������������������� 35
CONTROL SYSTEM OPERATIONS���������������������������������������������������� 38
Burner Control System�������������������������������������������������������������������� 38
Overview������������������������������������������������������������������������������������������ 38
Servicing should only be performed by a Qualified Service Agent
3
INTRODUCTION
This Service Manual covers the models and series numbers listed on the front cover only. The instructions and illustrations contained
in this manual will provide you with troubleshooting procedures to verify proper operation and diagnose and repair common service
problems.
QUALIFICATIONS
QUALIFIED INSTALLER OR SERVICE AGENCY
Installation and service of this boiler/water heater requires ability equivalent to that of a Qualified Agency (as defined by ANSI below)
in the field involved. Installation skills such as plumbing, air supply, venting, gas supply and electrical supply are required in addition
to electrical testing skills when performing service.
ANSI Z223.1 2006 Sec. 3.3.83: “Qualified Agency” - “Any individual, firm, corporation or company that either in person or through
a representative is engaged in and is responsible for (a) the installation, testing or replacement of gas piping or (b) the connection,
installation, testing, repair or servicing of appliances and equipment; that is experienced in such work; that is familiar with all
precautions required; and that has complied with all the requirements of the authority having jurisdiction.”
If you are not qualified (as defined by ANSI above) and licensed or certified as required by the authority having jurisdiction to
perform a given task do not attempt to perform any of the procedures described in this Service Manual. If you do not understand the
instructions given in this manual do not attempt to perform any procedures outlined in this manual.
This product requires start-up certification by an qualified service agent that has been trained by the factory for this specific product.
Call 1-800-527-1953 to locate the nearest qualified service agency and arrange a factory certified start-up.
SERVICE WARNING
If you are not qualified (as defined by ANSI above) and licensed or certified as required by the authority having jurisdiction to perform
a given task do not attempt to perform any of the procedures described in this manual. If you do not understand the instructions given
in this manual do not attempt to perform any procedures outlined in this manual.
SERVICE REMINDER
When performing any troubleshooting step outlined in this manual always consider the wiring and connectors between components.
Perform a close visual inspection of all wiring and connectors to and from a given component before replacement. Ensure wires were
stripped before being crimped in a wire connector, ensure wires are crimped tightly in their connectors, ensure connection pins in
sockets and plugs are not damaged or worn, ensure plugs and sockets are mating properly and providing good contact.
Failure to perform this critical step or failing to perform this step thoroughly often results in needless down time, unnecessary parts
replacement, and customer dissatisfaction.
TOOLS REQUIRED
•
•
•
•
•
•
•
•
•
•
4
Instruction Manual that came with the boiler/water heater.
All hand tools common to installation and service of commercial water heaters and boilers such as torch, pipe wrenches etc.
TORX® T40 or 5 mm hex wrench - for setting gas mixture at gas valve.
3 mm or 7/64 inch hex (Allen) wrench - for setting gas mixture at gas valve.
6 mm allen key, Long (8-10”) T handle 1/8 inch hex (allen key) wrench for Blower removal and installation.
Hex (Allen) wrench sizes: 1/2”, 5/32”, 1/8”, 1/4” and 5/16" or TORX® T25/T40 - for Burner, and 24V Gas Valve removal and
installation.
Two Manometers or Pressure Gauges.
• One - U tube manometer or gauge for measuring supply gas pressure.
• One (optionally two) digital Manometer(s) range -20.00 to +20.00" W.C., resolution 0.01" W.C. Recommend UEI model
EM200, TPI model 620 or equivalent. Used to measure manifold gas pressures and to test performance of pressure
switches. Optional second digital manometer can be used in place of U tube manometer for measuring supply gas
pressures.
True RMS Digital Multi Meter DMM, recommend UEI model DL289 or Fluke equivalent. Capable of measuring:
• AC/DC Voltage.
• Ohms.
• DC micro amps (μA) - flame sensing current.
AC amp meter- recommend UEI model DL289 or equivalent.
Combustion analyzer capable of measuring:
• CO2 (carbon dioxide).
• CO (carbon monoxide).
• Draft Pressure.
• Exhaust Temperature (vent gases).
Servicing should only be performed by a Qualified Service Agent
INSTALLATION CONSIDERATIONS
This section of the Service Manual covers some of the critical installation requirements that, when overlooked, often result in
operational problems, down time and needless parts replacement. Costs to correct installation errors are not covered under the
limited warranty. Ensure all installation requirements and instructions contained in the Instruction Manual that came with the boiler/
water heater have been followed prior to performing any service procedures.
INSTRUCTION MANUAL
Have a copy of the Instruction Manual that came with the boiler/water heater on hand for the model and series number being serviced.
Installation information given in this Service Manual is not a complete installation instruction. Installation information given in this
manual has a limited focus as it applies to servicing the boiler/water heater. This Service Manual does not replace or supersede the
Instruction Manual that came with the boiler/water heater. Always refer to the Instruction Manual for complete installation instructions.
If the Instruction Manual is not on hand copies can be obtained from the manufacturer's web site or by calling the technical support
phone number shown on the back cover of this manual.
CLOSED WATER SYSTEMS
Water supply systems may, because of code requirements or such conditions as high line pressure, among others, have installed
devices such as pressure reducing valves, check valves, and back flow preventers. Devices such as these cause the water system
to be a closed system.
THERMAL EXPANSION
As water is heated, it expands (thermal expansion). In a closed system the volume of water will grow when it is heated. As the
volume of water grows there will be a corresponding increase in water pressure due to thermal expansion. This type of failure is not
covered under the limited warranty. Thermal expansion can also cause intermittent Temperature-Pressure Relief Valve operation:
water discharged from the valve due to excessive pressure build up. This condition is not covered under the limited warranty. The
Temperature-Pressure Relief Valve is not intended for the constant relief of thermal expansion.
A properly sized thermal expansion tank must be installed on all closed systems to control the harmful effects of thermal expansion.
Contact a local plumbing service agency to have a thermal expansion tank installed.
AIR REQUIREMENTS
Carefully review the requirements for combustion and ventilation air in the Instruction Manual that came with the boiler/water heater.
Failure to meet these requirements when the boiler/water heater is installed or overlooking their importance when servicing the boiler/
water heater often results in needless down time, unnecessary parts replacement, and customer dissatisfaction.
An inadequate supply of air for combustion and ventilation often causes operational problems. A lack of combustion and ventilation air
can create a negative ambient air pressure in the installed space which can lead to improper combustion and operational problems.
CONTAMINATED AIR
Combustion air that is contaminated can greatly diminish the life span of the boiler/water heater and the components such as Igniters
and Burners. Propellants of aerosol sprays, beauty shop supplies, water softener chemicals and chemicals used in dry cleaning
processes that are present in the combustion, ventilation or ambient air can cause such damage.
Vapors from volatile compounds such as solvents, cleaners, chlorine based chemicals and refrigerants in addition to being highly
flammable in many cases, can also react to form highly corrosive substances such as hydrochloric acid inside the combustion
chamber. The results can be hazardous and cause product failure.
If the boiler/water heater is installed in beauty shops, barber shops or laundries with dry cleaning equipment, it is imperative the boiler/
water heater be installed in a Direct Vent configuration so that air for combustion is derived directly from the outdoor atmosphere
through a sealed intake air pipe. See the venting installation section in the Instruction Manual that came with the boiler/water heater
for more information on Direct Vent installations.
Servicing should only be performed by a Qualified Service Agent
5
VENTING
This section of the Service Manual is not a complete venting installation instruction. Refer to the Instruction Manual that came with
the boiler/water heater; ensure the venting has been installed per all Instruction Manual requirements. Failing to install the factory
provided vent and/or intake air terminations, exceeding the maximum equivalent vent and/or intake air piping lengths, adding too
many elbows to the intake air and/or vent pipes, installing the wrong vent intake air pipe size, will cause operational problems,
improper combustion, rough starting/operation and Control System lock out costs to correct installation errors are not covered under
the limited warranty.
GENERAL VENTING INFORMATION
The boilers/water heaters covered in this manual are operationally equivalent to Category IV appliances and may be installed in
either a Power Vent or Direct Vent configuration.
Category IV Appliance
Category IV appliances operate with a positive vent (exhaust) static pressure and with vent gas temperatures low enough to produce
condensate in the vent piping.
Power Vent Configuration
Power Vent configurations derive all combustion air from the room where they are installed and discharge all flue gases to the outdoor
atmosphere through a sealed vent (exhaust) pipe. Power vent configurations have one vent pipe connected to the boiler/water heater
which can be terminated in a vertical or horizontal arrangement.
Direct Vent Configuration
Direct Vent configurations derive all combustion air directly from the outdoor atmosphere through a sealed intake air pipe and
discharge all flue gases to the outdoor atmosphere through a sealed vent (exhaust) pipe. Direct Vent configurations have two pipes
connected to the boiler/water heater, one vent pipe and one intake air pipe. Direct Vent configurations can also be terminated in a
vertical or horizontal arrangement.
WATER PIPING
Ensure all water piping requirements, diagrams and piping installation instructions contained in the Instruction Manual that came with
the boiler/water heater have been observed and followed. Factory installed pumps on XB boilers/XWH water heaters are sized for
up to a maximum of 25 equivalent feet (7.6 m)of outlet (supply) and inlet (return) piping; 50 equivalent feet (15.2 m) total. Exceeding
these limitations will lead to Control System lock outs and can permanently damage the boiler/water heater's heat exchangers. A
bypass line must be installed between the outlet and inlet piping of the boiler/water heater on the "system side" of the boiler/water
heater's circulation pump to prevent condensation on the copper heat exchanger.
TEMPERATURE RISE & FLOW RATE
Water flow rates through the boiler/water heater are critical. Flow rates that are too low may cause excessive lime/calcium accumulation
inside the heat exchanger; while flow rates that are too high can lead to velocity erosion that can eventually cause water leaks. Boiler/
water heater efficiency is also affected by flow rates. Measuring the actual water flow rate (gallons per minute) through the boiler/
water heater is often impractical in the field. Because the temperature rise through the boiler/water heater is directly linked to the flow
rate and is simple to measure, temperature rise is commonly used to confirm proper flow rates.
Temperature rise is calculated by subtracting the inlet water temperature from the outlet water temperature. Temperature rise is
commonly referred to as the "Delta T" and expressed as ΔT. The temperature rise through the boiler/water heater should be set
between 20° F and 30° F. Temperature rise (flow rate) is set by throttling a flow control valve installed in the boiler/water heater's outlet
(supply) water line with the boiler/water heater firing at 100%. Never attempt to throttle the outlet valve unless the boiler/water heater
is firing at 100%. Valves on the boiler/water heater's inlet (return) water line must never be throttled and left fully open at all times
except when servicing the boiler/water heater. The outlet temperature, inlet temperature are shwon on the display system. Delta T
(ΔT) must be below 75° F. If this is exceeded, the display will show an alert and the individual burner will lock out.
6
Servicing should only be performed by a Qualified Service Agent
BOILER/WATER HEATER CONTROLS
The controls that are improperly installed or configured can cause serious operational and service related problems such as short
cycling. This section provides information for how various controls can work together or independently to provide proper boiler/water
heater and system control.
PRIMARY SYSTEM CONTROL
All installations require a “Primary System Control” that senses and reacts to water temperature inside the storage tank on domestic
water applications or in the return line on primary/secondary hydronic heating systems. The Primary System Control will activate and
deactivate boiler/water heater heating cycles based on its setpoint and current system water temperature. There are three suitable
methods to configure a Primary System Control. One of these three methods must be used.
1. The Primary System Control can be the boiler/water heater’s control system working with the factory supplied Header Sensor,
installed inside the storage tank on domestic water applications or in the return line on primary/secondary hydronic heating
systems for XB.
2. Alternatively, on XWH water heater the Burner Control system can be used as a Primary System Control. It will also provide
water heater status and error reporting. Multiple water heaters can be joined together to heat a system instead of a single, larger
burner or boiler/water heater. Using boilers/water heaters in parallel is more efficient, costs less, reduces emissions, improves
load control, and is more flexible than the traditional large boiler/water heater.
3. MB2 and COM2 ports can be used for Building Management Systems.
FIELD WIRING
120 VAC Power Supply Wiring
A dedicated, single phase, 30/60 amp circuit breaker with a grounded neutral should be provided to supply power to the boiler/water
heater(s). Use #10 AWG wire for the 120 VAC power supply to the boiler/water heater. All 120 VAC power supply connections must
be made as shown in Figure 1. These connections should be made at the rear of the boiler/water heater where a wiring junction box
is provided. Field installed power supply wiring to the boiler/water heater should be installed in conduit. This conduit and wiring should
be separate from any other conduit/wiring to guard against EMI (electromagnetic interference).
Figure 1. FIELD WIRING
Power Supply Check
To reduce the possibility of electrical interference with the control system, the power supply voltage, polarity and ground must be
checked. Using an AC volt meter check the 120 VAC power supply wiring from the breaker prior to making power supply connections
at the boiler/water heater. Confirm the power supply voltage & polarity are correct and that an adequate ground connection is present
by performing the three voltage tests below. See Figure 1.
Confirm RMS voltage between:
• H and GND = 108 VAC minimum, 132 VAC maximum.
• N and H = 108 VAC minimum, 132 VAC maximum.
• N and GND = < 1 VAC maximum.
Servicing should only be performed by a Qualified Service Agent
7
INSTALLATION CHECKLIST
The list below represents some of the most critical installation requirements that, when overlooked, often result in operational
problems, down time and needless parts replacement. Before performing any troubleshooting procedures use the list below to
check for installation errors. Costs to correct installation errors are not covered under the limited warranty. Ensure all installation
requirements and instructions contained in the Instruction Manual that came with the boiler/water heater have been observed and
followed.
1. The vent (exhaust) pipe must not be combined or connected to any other appliance’s vent system or chimney.
2. The intake air pipe must not be combined or connected to any other appliance’s intake air piping.
3. The boiler/water heater(s) covered in this manual are condensing appliances. Condensate will form in the vent pipe during normal
operation, condensate can also form in the intake air piping in certain circumstances. Ensure the intake air and/or vent piping
is not installed in a manner that will allow water to be trapped in the piping. This will lead to blocked exhaust and/or blocked air
intake fault conditions and Control System lock outs.
4. Ensure the intake air and/or vent piping is the correct size for the installed length. See the venting requirements section in the
Instruction Manual that came with the boiler/water heater. Using smaller pipe than is required will lead to blocked exhaust and/or
blocked air intake fault conditions and Control System lock outs.
5. Ensure the intake air and/or vent piping are within the maximum equivalent lengths required in the Instruction Manual that came
with the boiler/water heater. Exceeding the maximum length or number of elbows allowed will also lead to blocked exhaust and/
or blocked air intake fault conditions and Control System lock outs.
6. Ensure there is a water trap formed in the condensate drain tube/line connected to the exhaust elbow on the boiler/water heater
and that the condensate drain is flowing freely. Condensate drain blockage will cause the heat exchanger to fill with water and
lead to blocked exhaust fault conditions and Control System lock outs.
7. Ensure the vent and intake air terminations have adequate clearances from each other and the terminations of other appliances.
Failure to maintain adequate clearances can cause the recirculation of flue gases between the vent and intake air piping.
Recirculation of flue gases will cause poor combustion, sooting, ignition failure, rough starts, rough operation, premature failure
of the heat exchanger and icing of the combustion air intake during severe cold weather.
8. Direct vent terminations being installed in dead air spaces such as alleys, atriums, and inside corners can also cause the
recirculation of flue gases between the vent and intake air piping. To prevent the recirculation of flue gases, maintain as much
distance as possible between the intake air and vent terminations.
9. Ensure the screens in the factory supplied terminations are securely installed to prevent blockage in the intake air and/or vent
piping.
10.On Direct Vent installations ensure the screen at the intake air connection on the water heater was removed before the intake air
piping was connected.
11.Ensure the power supply connections to the water heater are polarity correct. Use the Digital Multi Meter to verify correct polarity
and ground at an outlet the water heater is plugged into. Reversed polarity (neutral and hot wires reversed) will cause the AC
Reversed fault condition and Control System lock out.
12.Ensure the boiler/water heater and the burner are properly grounded. The Control System requires an adequate earth ground
for flame sensing (verification). Inadequate grounding to the water heater and/or the burner will cause the Ignition Failure fault
condition and Control System lock out.
8
Servicing should only be performed by a Qualified Service Agent
FEATURES AND COMPONENTS
FRONT VIEW
BACK VIEW
VENT (EXHAUST)
HIGH VOLTAGE
CONNECTION BOX
AIR FILTER BOX
SENSOR/COMMUNICATION BOX
TOUCH SCREEN DISPLAY
PRESSURE RELIEF
VALVE
MAIN POWER
WATER OUTLET
SWITCH
SUPPLY
ALL BRONZE CIRCULATION PUMP.
FACTORY INSTALLED AT INLET
WATER CONNECTION
XB MODELS - OPTIONAL
XWH MODELS - STANDARD
CONDENSATE TRAP
SIDE VIEW
MAIN GAS SHUT
OFF VALVE
VENT (EXHAUST) CONNECTION
7 INCH AL29-4C STAINLESS STEEL
WATER OUTLET
WATER INLET
Figure 2. SINGLE HEAT EXCHANGER BOILER/WATER HEATER - 1000/1300/1700
Servicing should only be performed by a Qualified Service Agent
9
BACK VIEW
FRONT VIEW
SENSOR/COMMUNICATION BOX
AIR FILTER BOX
HIGH VOLTAGE
CONNECTION BOX
TOUCH SCREEN DISPLAY
WATER OUTLET
MAIN POWER
SUPPLY
SWITCH
VENT (EXHAUST)
ALL BRONZE CIRCULATION PUMP.
FACTORY INSTALLED AT INLET
WATER CONNECTION
XB MODELS - OPTIONAL
XWH MODELS - STANDARD
WATER INLET
SIDE VIEW
CONDENSATE TRAP
PRESSURE RELIEF
VALVE
VENT (EXHAUST) CONNECTION
7 INCH AL29-4C STAINLESS STEEL
WATER OUTLET
WATER INLET
Figure 3. DOUBLE HEAT EXCHANGER BOILER/WATER HEATER - 2000/2600/3400
10
Servicing should only be performed by a Qualified Service Agent
OPERATION AND SERVICE
MODULATING FIRE OPERATION
XB boilers & XWH water heaters are modulating systems. The control system modulates the firing rate of the burner to match system
load by controlling the speed of the combustion blower.
They do not have a gas orifice. The combustion blower "pulls" fuel gas from the outlet of the 24 VAC gas valve (when energized) into
a venturi that is connected to the inlet of the Combustion Blower. The firing rate is directly proportional to the speed of the combustion
blower motor. As the blower speed increases, the pressure inside the venturi falls creating a stronger vacuum which pulls more fuel
gas into the blower/burner assembly which increases the firing rate.
The control system controls the speed of the combustion blower in response to system temperature. As the system temperature falls
blower speed is increased to provide more heating capacity. The control system sends digital speed instructions to the electronic
speed control which is part of the combustion blower assembly.
COMBUSTION BLOWER
The combustion blower is an assembly that includes the blower motor, housing and an integral electronic speed control. The power
junction box sends 120 VAC and an earth ground from its J3 socket to the 120 VAC 3 pin socket on the combustion blower assembly
to power the electronic speed control. The control board sends a PWM (Pulse Width Modulation) signal, an instruction to start, stop
and control the blower motor speed from the J2 socket to the 5 pin wiring socket on the combustion blower assembly. Four wires from
the J2 socket on the control board carry this instruction to the 5 pin wiring socket on the combustion blower assembly, see Figure 4
below.
Table 1. COMBUSTION BLOWERS
XB/XWH MODELS
BLOWER PART NUMBERS
1000/2000
EBM RG-175
1300/1700/2600/3400
EBM G1G170-AB05-20
Service Note:
The 5 pin PWM signal plug must remain plugged in to the 5 pin socket on the blower assembly at all times. Disconnecting this plug
will cause the combustion blower to run at maximum speed continuously. This may cause rough starts, rough operation and control
system lock out. If the electronic speed control is functioning properly combustion blower speed should noticeably reduce during the
operating state. If blower speed reduction does not occur during the operating state ensure the 5 pin plug from the control board is
securely plugged into the matching 5 pin socket on the blower assembly and that the J2 plug is securely plugged into the J2 socket
on the control board. Perform a close visual inspection of the pins inside the plugs and sockets at the combustion blower and the
control board, replace any worn or damaged wiring harnesses as necessary.
Figure 4. COMBUSTION BLOWER ASSEMBLY
Servicing should only be performed by a Qualified Service Agent
11
HEAT EXCHANGER ASSEMBLY
The heat exchanger transfers heat from the hot flue gases to the heating system’s water. Combustion products including flue gas
condensate, which are formed in the heat exchanger are evacuated. The heat exchanger includes the following interfaces:
• 2x Burner doors
• Flue gas outlet connection
• Water inlet and outlet connection
• Condensate connection
• Bushes for sensor
Heat from the hot flue gases is transferred to the heating water through a spiral tube made from stainless steel. The heat exchanger
is equipped with an evacuation for the combustion products at the back side. The burner doors should integrate a double tightness:
a gasket insuring a thermal protection and a gasket tight to the condensates and flue gas. The burner door should be in contact
with the front panel of the heat exchanger in order to limit the risk of leakage from combustion products in case the gaskets are
incorrectly reinstalled. Bolts on the front of the boiler/water heater can withstand forces resulting from the weight of the front panel
and assembled parts (burner door, fan, gas valve, venturi, air-gas sleeve). Maximum nuts torque for assembling the burner door is
3.7 ft.lb.
Minimum working pressure rated capacity is 14.5 PSI (100 kPa) and the minimum water volume is 1.1 GPM (4.2 LPM) per tube.
Under these conditions the maximum temperature difference between the outgoing and returning water is 80°F (26.7°C). With a
Maximum Allowable Working Pressure of 160 PSI (1103.2 kPa), the exchanger’s hot water circuit system does not tolerate longlasting leaks or deformations. Minimum water pressure for a closed-loop system must not be lower than 14.5 PSI (100 kPa). Normal
Heating circuit water temperature is 41°F – 203°F (5°C - 85°C).
The ambient temperature around the product must not exceed 140°F (60°C) and the ambient relative humidity (RH) can vary from
0% to a maximum of 90%. In the extreme case of a safety component malfunctioning and causing the system to overheat to a
temperature higher than 203°F (85°C) (closed system), the water temperature shall not exceed 210°F (99°C) referring to the ASME
Code Section IV for austenitic stainless steel materials. The maximum surface temperatures for the casing, back panel and front
panel must not exceed 302°F (150°C).
The Trio ASME “H” Heat Exchangers are equipped with 2 water male connections with NPT threading, according to the ANSI/ASME
B1.20.1 standard, which are dimensioned according to the capacity of the heat exchanger. A female NPT 1/8” threaded connection
type, according to the ANSI/ASME B1.20.1 standard, is available on the water flow and on the water return header of each stage
in order to receive some NTC sensors able to control the water flow and return temperature and/or to use its as a limiter and safety
thermostat.
Figure 5. HEAT EXCHANGER ASSEMBLY
12
Servicing should only be performed by a Qualified Service Agent
Water Connection
Heat Exchangers are equipped with 2 water male connections with NPT threading, according to the ANSI/ASME B1.20.1 standard,
which are sized according to the capacity of the heat exchanger.
Flue Gas Outlet Connection
The heat exchanger is equipped with an evacuation for the combustion products at the back side. Flue gas outlets are sized
according to the capacity of the heat exchanger.
A. O. Smith recommends the recovery and the evacuation of the flows coming from the chimney, mainly if there’s a risk of remains
in the chimney’s channel, in order to avoid that they return in the heat exchanger.
Burner Door/Plates Connection
A. O. Smith recommends that the burner doors should integrate a double tightness, a gasket insuring a thermal protection and a
gasket tight to the condensates and flue gas.
A. O. Smith recommends as well that the burner door should be itself in contact with the front panel of the heat exchanger in order to
limit the risk of leakage from combustion products in case of lack of remounting the gaskets.
Bolts on the front of the boiler/water heater can withstand forces resulting from the weight of the front panel and assembled parts
(burner door, fan, gas valve, venturi, air-gas sleeve). Maximum nuts torque for assembling the burner door is 3.7 ft.lb.
Operating Conditions - Installation factors
Heating units will be subject to the effects of corrosion from the moment they are filled with water. It is however essential that the
following installation factors are taken into account in order not to worsen the phenomenon of corrosion.
•
Combustion air must not contain chlorine, ammonia, or alkali agents. Installation of the product near a swimming pool, a washing
machine, or a laundry do expose combustion air to these contents.
•
The heat exchanger must be used filled with water within the temperature and pressure limits specified in its technical specification
booklet.
•
The water's pH must fall within the following limits: 7.5<pH<9.5 and if the system contains aluminium parts, it must be less
than 8.5. This pH value is achievable after steady state conditions after filling the mains network water (pH around 7) inside the
installation and the air bleeding operation has been done ( death water condition).
•
Water hardness must fall within the following limits:
• 5°F<TH<15°F
• 3 Grains/US gallon<TH<9 Grains/US gallon
•
To avoid to the maximum presence of oxygen in the system, it is advised to prevent as much as possible air intake and water
leakage during installation. Usual spots where air is most likely to seep in are: suction gasket, pump, air valve working as venting
pipe, O-rings gaskets in stuffing box. Using an automatic water refill system reduces some risk (as any fresh water is bringing
fresh oxygen in the system), like installing a water meter so that it is possible to evaluate the water volume in order to eliminate
any water leakage as early as possible.
•
A minimum water pressure, adapted to each exchanger type, is requested in order to allow good performances.
•
A. O. Smith recommends to the customers to carry out the drain of the heat exchanger after test or use in order to avoid
consequences on the product in the event of freezing ; the expansion of the water in case of freezing could cause degradations
or leakages.
Servicing should only be performed by a Qualified Service Agent
13
VENTURI AND GAS TRAIN ASSEMBLY
The gas train includes a venturi connected to the inlet of the combustion blower. The outlet of the 24 VAC gas valve is also connected
to the venturi by a manifold gas line. There is a shutoff valve installed in the manifold gas line for start up and service procedures. The
venturi contains a convergent/divergent nozzle (cone shaped restrictor) that constricts the air passage to the blower. As air enters the
constriction point its velocity increases. A pressure drop occurs at this point and creates a negative (vacuum) pressure in the cavity
between the nozzle and the venturi housing. This negative pressure “pulls” gas from the outlet of the 24 VAC gas valve into the blower
where it is mixed with combustion air and then supplied to the burner, see Figure 6.
As the combustion blower speed is increased the velocity of air flowing through the venturi is also increased. This increases the
vacuum created by the venturi and more fuel gas is pulled from the 24 VAC gas valve and supplied to the burner. This increases the
firing rate (input Btu/hr) of the boiler/water heater. As the blower speed is decreased less fuel gas is supplied to the burner and the
firing rate is reduced.
BURNER
FLAPPER
VENTURI
BLOWER
MANUAL GAS
SHUTOFF VALVE
DIFFERENTIAL MANIFOLD
PRESSURE TAP
MODULATING
GAS VALVE
Figure 6. VENTURI AND GAS TRAIN ASSEMBLY
14
Servicing should only be performed by a Qualified Service Agent
GAS PRESSURE
SWITCH
FLEX GAS
MANIFOLDS
BURNER ASSEMBLY
The burner is a stainless steel radial fire burner with a woven steel fiber surface. It is installed in the center of the horizontal heat
exchanger. The burner is mounted inside the recess of the heat exchanger.
The spark igniter on the boiler/water heater is a 120VAC igniter. The igniter receives power from the J5 socket on the Control Board.
The 110V from the board is then passed to an ignition transformer. From the ignition transformer the spark ignitier is energized.
A Low/High Gas Pressure Switch is installed on the gas manifold. The Low Pressure Gas Switch is a normally open switch that closes
on a rise in pressure. Switch contacts closes in between +4" W.C.(minimum) - +14" W.C.(maximum) on natural gas models and +4"
W.C.(minimum) - +14" W.C.(maximum) on propane gas models. The High Gas Pressure Switch is normally closed and is used to
detect excessive gas pressure.
Boilers/water heaters have only one flame sensor per individual burner. The flame sensor is mounted close to the burner to sense
the flame firing rates.
Figure 7. BURNER ASSEMBLY (1000/2000)
Servicing should only be performed by a Qualified Service Agent
15
Figure 8. BURNER ASSEMBLY (1300/2600)
Figure 9. BURNER ASSEMBLY (1700/3400)
16
Servicing should only be performed by a Qualified Service Agent
FLAME SENSOR
Ignition of the burner is controlled electronically. The principle of operation for electronic ignition relies on flame sensing voltage to
prove the fuel gas flowing to the burner has been ignited and is burning safely.
Flame sensing requires correct power supply polarity and an adequate earth ground to the boiler/water heater's burner. See Figure
7 on Page 15, Figure 8 and Figure 9 on Page 16 for the Burner Assembly.
Figure 10. FLAME SENSOR
Flame Sensing Operation
•
•
•
•
•
•
The Flame Sensor is a metal (conductor) rod mounted in a ceramic insulator.
The Control System applies an AC voltage to the Flame Sensor through a single wire.
The burner flame will conduct a small amount of electrical current.
The Burner must be grounded for current to flow from the Flame Sensor to the Burner.
During ignition the burner flame must make complete and continuous contact with the Flame Sensor.
As the AC voltage flows from the Flame Sensor through the burner flame to the (grounded) Burner, the AC voltage is "rectified"
and becomes a DC voltage.
• Flame sensing voltage can be measured with a Digital Multi Meter. See Tools Required on Page 4.
Flame Signal Processing
The flame signal processing will monitor the flame sensor. The flame signal voltage at the test jacks or on the bar graph on the display
is the measured voltage in the range from 0V to 30V. The display could show stronger numerical data.
The incoming flame signals are filtered to eliminate transient and spurious events. The flame failure response time (FFRT) is 4
seconds. Flame sensitivity is set by the Flame Threshold parameter, which will provide the ON/OFF threshold specified in volts.
Service Notes:
• Ensure you have identified the correct Flame Sensor wire before performing a flame sensing test to prevent damage to the test
meter.
• The most common cause of ignition failure is a corroded Flame Sensor. Rust/corrosion will accumulate on the Flame Sensor
over time. The Flame Sensor should be inspected and cleaned anytime the measured flame sensing voltaget is at a minimum
of 1 volt or the Burner has been removed. Clean the Flame Sensor with ultra fine steel wool. DO NOT use a coarse abrasive
material such as sand paper for cleaning. Inspect the ceramic insulator on the Flame Sensor for cracks, replace the Flame
Sensor if it is damaged. The Combustion Blower and Burner must be removed to access the Flame Sensor.
• An open flame sensing circuit caused by disconnected or loose connectors can also cause ignition failure. Check all wiring
connections between the Flame Sensor and the J1 connector on Control Board.
• The burner not being grounded will cause ignition failure. Ensure the boiler/water heater and the burner are properly grounded.
Servicing should only be performed by a Qualified Service Agent
17
SPARK IGNITER
The Spark Igniter is made of a ceramic composite material, see Figure 11 below. The Control System powers the Spark Igniter (120
VAC) from the pin 6, J5 connector on the Control Board to the External Spark Transformer.
Spark Igniters are service parts, over time Spark Igniters will wear out and must be replaced as they will no longer generate enough
spark to cause ignition.
Before troubleshooting the Spark Igniter it is recommended to check the reasons for ignition failure such as no gas, air in the gas line,
gas supply pressure being too low or improper air-gas mixture caused by incorrect gas valve setting. Only when it is identified that
ignition failure is not caused by these reasons, troubleshooting the Spark Igniter is recommended.
Figure 11. SPARK IGNITER
External Ignition System Components:
The three main components of the spark ignition system are the Burner Control Board, the Ignition Transformer and the Spark Igniter.
The Burner Control Board sends 120 VAC to the Ignition Transformer during the pre-ignition and startup cycle only. The Ignition
Transformer takes the input voltage and outputs the ignition voltage as high as 14 kV to the Spark Igniter for reliable ignition.
Service Notes/Troubleshooting the External Ignition System:
• Turn OFF all the gas supply valves internal and external to the unit (Turn ON only when safe and before ignition tests).
• Identify the pin 6 on the J5 connector block, using a voltmeter measure the volts on this terminal with reference to ground
during the pre-ignition/start up cycle of the boiler/water heater. Use the display to exactly time the ignition cycle (Burner state:
Pre-ignition, as the sparker does not operate continuously). This should read approximately 115-120 VAC. If the voltage range
matches, then the Ignition Transformer or the Spark Igniter could be causing the failure. If there is no voltage during the ignition
cycle, then check pin 7 on J5 connector for the supply voltage of 115-120 VAC. The pin 7 on J5 connector is connected to the
main power terminals.
• If there is voltage at pin 6 on J5 connector, replace the Ignition Transformer and retest. If it still fails, reaplce the Spark Igniter
and test.
18
Servicing should only be performed by a Qualified Service Agent
GAS VALVE
The 24 Volt Gas Valve on the XB Boilers/XWH water heaters is AC voltage valve. The Control Board sends 24 VAC to the gas valve.
See Figure 6 on Page 14.
Gas Valve Voltage Test
• Check for 24 VAC supplied to the 24 Volt Gas Valve at pin 2 of the J5 Connector on the Control Board. Using an "AC" volt
meter connect one lead to pin 2 of the J5 Connector and the other lead to ground. 24 VAC should be present.
Gas Valve Removal:
The outlet of the 24 Volt Gas Valve is connected by flange directly to the side of the Venturi and is secured by four - 5/32” hex head
screws. A gasket is fitted into the gas valve’s outlet flange. Ensure there is a new gasket on hand before removing the valve. Call the
toll free phone number on the back cover of this manual to order parts. Have the complete Model, Series and Serial number (located
on the boiler/water heater's rating label) for the boiler/water heater being serviced on hand before calling.
1. Turn off power to the boiler/water heater at the Main Power Supply switch.
2. Loosen the retaining screw for the wiring harness plug on the valve and disconnect the plug.
3. Turn off the supply gas to the boiler/water heater at the main gas shutoff valve.
4. Disconnect the supply gas line to the boiler/water heater at the boiler/water heater's 24 Volt Gas Valve.
5. If the boiler/water heater has been installed in a Direct Vent configuration, disconnect the intake air pipe at the intake air
connection on the boiler/water heater.
6. Remove the 4 gas valve mounting screws - 5/32” hex head screws.
7. Carefully lift the 24 Volt Gas Valve body off of the Venturi.
8. Follow these steps in reverse order to reinstall the 24 Volt Gas Valve.
9. Run the boiler/water heater through a complete cycle before leaving to ensure it is operating properly.
Gas Pressure
The boiler/water heater covered in this Service Manual is rated from 920,000 Btu/hr to 3,400,000 Btu/hr input. It is certified for
elevations up to 2000 feet (610 meters) for Propane and 10,100 feet (3079 m) for Natural gas. For higher elevations call the toll free
support phone number shown on the back cover of this manual for technical assistance.
Models
(XB/XWH)
1000, 1300, 1700
2000, 2600, 3400
Table 2. GAS PRESSURE
Manifold Pressure
Type of Gas
Natural
Propane
Maximum Supply Pressure Minimum Supply Pressure
Inches W.C.
kPa
Min Fire
-0.2 to - 0.3
-0.05 to - 0.07
Max Fire
-3.0 to -3.9
-0.75 to -0.97
Min Fire
-0.1 to - 0.3 -0.025 to -0.07
Max Fire
-3.6 to -4.9
-0.90 to -1.22
Inches W.C.
kPa
Inches W.C.
kPa
14.0
3.49
4.0
1.0
14.0
3.49
4.0
1.0
Service Notes:
• The manifold gas pressure is factory set and cannot be adjusted in the field.
• The manifold gas pressure and the supply gas pressure can be measured at two pressure test ports on the boiler/water
heater’s 24 Volt Gas Valve. The manifold pressure test port is closest to the Combustion Blower. There is a needle valve in
each test port that is opened/closed with a small slotted screwdriver. Turn the needle valve counter-clockwise to open the test
port valve and clockwise to close it.
• Manifold gas pressure will run close to 0” W.C. or lower (in a vacuum) depending on the current operating state. This
pressure will be considerably lower, -0.2” W.C. to -4.9” W.C. during the Pre- Purge and Post-Purge operating states when the
Combustion Blower is running at high speed and the 24 Volt Gas Valve is closed.
• There is usually a drop in supply gas pressure noticed when the boiler/water heater’s 24 Volt Gas Valve opens during ignition.
Seeing a corresponding rise in manifold pressure during ignition confirms the valve is opening and gas is flowing to the Burner.
• A sustained drop in supply gas pressure of 1.5" W.C. or more during boiler/water heater running may indicate the supply gas
line is undersized. If the boiler/water heater is experiencing a sustained drop in supply gas pressure of 1.5" W.C. or more and
the boiler/water heater is experiencing repeated Ignition Failure conditions, intermittent loss of flame or rough starting ensure
the supply gas line is sized in accordance with the current edition of National Fuel Gas Code (ANSI Z223.1/NFPA 54) or the
Natural Gas and Propane Installation Code (CAN/CSA B149.1).
Servicing should only be performed by a Qualified Service Agent
19
TEMPERATURE SENSORS
Temperature sensors are 3/4 inch male threaded immersion probes. Temperature probes have embedded temperature sensors
(thermistors). The boiler/water heater’s control system monitors these sensors to determine water temperature at various points
in the system. Thermistors are thermally sensitive resistors; as the surrounding temperature rises the resistance of the thermistor
(measured in ohms) will decrease and as the surrounding temperature falls the resistance of the thermistor increases. The Boiler/
water heater’s Control System monitors these sensors to determine water temperature at various points in the system.
INLET / REMOTE TEMPERATURE PROBE
OUTLET TEMPERATURE PROBE
Figure 12. TEMPERATURE SENSORS
Inlet and Outlet Temperature Sensors
All boiler/water heater models have two inlet and two outlet temperature sensors for each heat exchanger, factory installed to monitor
the water temperature entering and leaving the boiler/water heater. The Inlet Temperature Probe is a temperature sensor only and
has two leads. The Outlet Temperature Probe also contains the manual reset high temperature limit switch and has four leads. The
control system displays the Inlet and Outlet water temperatures sensed from these two sensors on the default Temperatures screen.
Remote Sensors
All boiler/water heater models are supplied from the factory with a remote sensor. The remote sensor is used to control system water
temperature for a single boiler/water heater in a domestic hot water storage tank or in the return line from a primary/ secondary
hydronic heating system.
The boiler/water heater will modulate its firing rate in response to the actual system temperature and load conditions. The control
system displays the temperature sensed from the remote sensor as the “Lead Lag” temperature on the default Temperatures screen.
In addition to these sensors the XB hydronic boilers receive an outdoor sensor for monitoring the outdoor temperatures. The outdoor
reset functionality is disabled by default and can easily be turned ON at start up.
20
Servicing should only be performed by a Qualified Service Agent
AIR FILTER ASSEMBLY
Figure 13. AIR FILTER ASSEMBLY
Air Filter Assembly is mounted on the top panel of the XB boilers/ XWH water heaters. See Figure 2 on Page 9 and Figure 3 on
Page 10. The assembly includes a filter which slides inside the filter housing and filter brackets. The filter is made of of wire mesh
screen and is meant to block dust particles and other debris from entering through the air intake into the boiler/water heater.
Service Notes:
• Ensure the filter is cleaned and water washed every 3 months to avoid the dust and debris getting settled on the filter mesh
screen.
Servicing should only be performed by a Qualified Service Agent
21
CONTROL PANEL ASSEMBLY
Figure 14, Figure 15 on Page 23 and Figure 16 on Page 24 shows the Control Panels Assemblies for the XB boilers/XWH water
heaters. The main components include Control Boards (Master & Local), Display Power Supply, 24 VAC Terminal Block, Step Down
Transformer, Pump Relay, Fuse Block, Input Power 120 VAC Terminal Block, Low Water Cutoff Device and Interlock/Load Control
Input (ILK/LCI) Relays.
Figure 14. CONTROL PANEL ASSEMBLY (1000/1300/1700)
22
Servicing should only be performed by a Qualified Service Agent
Figure 15. UPPER CONTROL PANEL ASSEMBLY (2000/2600/3400)
Servicing should only be performed by a Qualified Service Agent
23
Figure 16. LOWER CONTROL PANEL ASSEMBLY (2000/2600/3400)
24
Servicing should only be performed by a Qualified Service Agent
CONTROL BOARD ASSEMBLY
The Control Board assembly provides heat control, flame supervision, circulation pump control, fan control, boiler/water heater
control sequencing, and electric ignition function. It will also provide boiler/water heater status and error reporting. The Control Board
may consist of Control Device, Touchscreen Display (required for setup and ModBus communication, but not required for the system
to operate once the Control Device is programmed), Local Operator Interface (which can set up and monitor the Control Device),
Local Keyboard Display Module, Flame Rod, Temperature Sensor (NTC Type 10KΩ at 77°F (25°C) or 12KΩ at 77°F (25°C)), Limit
Sensor (NTC Type 10KΩ at 77°F (25°C)) and Fans (VFD).
INPUTS
Analog Inputs:
1. NTC Sensor Imputs (10kohm or 12kohm)
NOTE: 12kohm and 10kohm single sensors cannot be used for Limit Application functions (10kohm dual sensors only).
2. Hydronic Control
• Outlet Limit and Temperature
• Stack Limit and Temperature
• Inlet Temperature
• Outdoor Temperature
3. Other Analog Inputs
• PWM Feedback
• Flame Signal from either a Flame Rod or Ultraviolet Detector
• 4-20mA Control Input, Remote Setpoint, Remote Firing Rate
Digital Inputs:
1. LCI (Load [or Limit] Control Input)
2. Interlock
3. Annunciation
OUTPUTS
Analog Outputs:
1. Modulation
• 4-20mA
• 0-10 VDC
• PWM for Variable Frequency Drives
Digital Outputs:
1. Auxiliary Output Control
• Hydronic Control for Pumps 3 outputs, 5 different programmable features
2. Combustion Blower
3. External Ignition
4. Gas Valve
5. Alarm
Servicing should only be performed by a Qualified Service Agent
25
Figure 17. CONTROL BOARD ASSEMBLY
26
Servicing should only be performed by a Qualified Service Agent
CONNECTORS
J1
J2
PINS
1
Not Used
2
FLAME SENSE1/2: SENSE
Flame Rod Input.
3
FLAME SENSE1/2: GND
Flame Rod Common.
4
Not Used
5
Not Used
6
Not Used
1
TACH
Tachometer Input (Tach).
2
25VDC
Electronic Blower Motor Power (25 VDC).
3
PWM
Digital modulation (PWM) Output Digital modulation signal out.
4
GND
Ground pin for Fan interface and power.
A
Modbus MB1 RS-485 +. Connects to Display.
B
Modbus MB1 RS-485 -. Connects to Display.
C
Modbus MB1 Ground (G). Connects to Display.
A
Modbus MB2 RS-485 +. Connects to Local Burner Control
Board for Lead lag application.
B
Modbus MB2 RS-485 -. Connects to Local Burner Control
Board for Lead lag application.
C
Modbus MB2 RS-485 Ground (G). Connects to Local Burner
Control Board for Lead lag application.
MB1
J3
Table 3. CONTROL BOARD CONTACTS/CONNECTIONS
TERMINOLOGY
DESCRIPTION AND RATING
MB2
1: Not Used
ECOM 2: Not Used
3: Not Used
J4
J5
J6
1
Not Used
2
Not Used
3
Not Used
4
Not Used
5
Not Used
6
PUMP1/PUMP Output
120 VAC Power output to Pump Relay.
7
H_PUMP/PUMP Input
120 VAC Power input from Power Distribution Block.
8
Not Used
9
Not Used
10
SOLA1_L_RTN
120 VAC Power Supply Neutral.
11
Not Used
12
G/EARTH GROUND
Earth Ground.
1
INTERLOCK/BFS
Blocked Flue Switch. Per Model Input Rating.
2
GV1
24VAC Power input to the Gas Valve.
3
Not Used
4
Not Used
5
Not Used
6
SPARK_G1
120 VAC Power output to Spark Generator.
7
H_BLOW_SPRK
120 VAC Power input from Power Distribution Block.
1
LWCO
Annunciator for LWCO Input.
2
Not Used
3
FLOW_SW
4
Not Used
5
Not Used
6
Not Used
7
Not Used
8
Not Used
Annunciator for Flow Switch Input.
Servicing should only be performed by a Qualified Service Agent
27
CONNECTORS
J7
J8
J9
J10
PINS
TERMINOLOGY
DESCRIPTION AND RATING
1
SIPHON
Condensation Switch Input.
2
F1
Flapper Switch Input.
3
Not Used
4
SYS_ENABLE
Annunciator for System Enable Switch.
5
LGP
Annunciator for Low Gas Pressure Switch.
6
HGP
Annunciator for High Gas Pressure Switch.
7
Not Used
1
SOLA1_PWR
24VAC Power Input form Terminal Block.
2
SOLA1_S_RTN
24VAC Return Input from Terminal Block.
3
Not Used
4
INLET TEMP
Supply for, and signal input from 10K or 12K Ohm NTC Inlet
Temperature sensor. Connects to Pin 2 on Inlet Temperature
Sensor.
5
INLET TEMP Common
Ground reference for the Inlet Temperature Sensor. Connects
to Pin 1 on Inlet Temperature Sensor.
6
Not Used
7
Not Used
8
OUTLET TEMP
Supply for, and signal input from 10K or 12K Ohm NTC Outlet
Temperature Sensor. Connects to Pin 2 on Outlet Temperature
Sensor.
9
OUTLET TEMP Common
Ground reference for the Outlet Temperature Sensor. Connects
to Pins 3 & 4 on Outlet Temperature Sensor.
10
OUTLET TEMP
Supply for, and signal input from 10K Ohm NTC Outlet
Temperature Sensor. Connects to Pin 1 on Outlet Temperature
Sensor.
11
HEADER +
Supply for, and signal input from 10K or 12K Ohm NTC
Header Sensor.
12
HEADER -
Ground reference for the Header Sensor.
1
Not Used
2
Not Used
3
Not Used
4
STACK TEMP
Supply for, and signal input from 10K or 12K Ohm NTC Flue
Sensor. Connects to Pin 2 on Flue Sensor.
5
STACK Common
Ground reference for the Flue Sensor. Connects to Pin 3 & 4
on Flue Sensor.
6
STACK TEMP/Heat Exchanger
Unit)
Supply for, and signal input from 10K Ohm NTC Flue Sensor.
Connects to Pin 1 on Flue Sensor.
7
Not Used
1
REMOTE RESET
Open/Ground Input that has functionality corresponding to
pushing/releasing the local reset.
2
TOD (Time of Day)
Open/Ground Input which switches operating set points.
3
TOD/REMOTE RESET COMMON
Ground reference for time of day and remote reset inputs.
4
MODULATION 4 - 20mA (+) (Out)
4 to 20 mA Current modulation signal out into a 600 Ohm.
5
MODULATION 0 - 10 VDC (+) (Out) 0 to 10 VDC Voltage modulation signal out, 10 mA max.
6
MODULATION COMMON (-)
7
Not Used
8
Not Used
Ground reference for voltage and current modulation signals.
SPECIAL CONNECTIONS
Flame +
Flame 28
FS +
Testpoint for Flame signal. 0 to 10
VDC
FS -
Testpoint for Flame signal - Ground
reference.
Servicing should only be performed by a Qualified Service Agent
DISPLAY SYSTEM (TOUCH SCREEN DISPLAY)
The Display System is a microprocessor-based color touchscreen Operator Interface (OI) display that provide an operator interface
for monitoring and configuring parameters such as burner control sequence, flame signal, diagnostics, historical files, and faults in
the Control System. It can be used to monitor an individual boiler/water heater but is primarily used for multiple boiler/water heater
applications in a lead/lag arrangement. Wiring connections to the Display System are through a removable 8-pin wiring header.
Electrical Ratings:
1. Input Voltage: 18 – 30 Vac (24Vac nominal), 50/60 Hz.
2. Input Current: 500 mA max.
3. Power consumption: 12W max.
4.
5.
6.
7.
8.
Operating Temperature: -4 to 158 ºF (-20 to 70 ºC)
Storage/Shipping Temperature: -22 to 176 ºF (-30 to 80 ºC)
Humidity: 90% RH, non-condensing.
Enclosure rating: IP10 / NEMA 1
Approvals:
• FCC Part 15, Class A Digital Device.
• Underwriter’s Laboratories, Inc. (UL) (cUL) Component Recognized (for non-continuous operation): File Number MH17367
(MJAT2, MJAT8).
CONNECTOR TERMINALS
Figure 18. DISPLAY CONNECTOR TERMINALS
The Display System must be appropriately wired for both power and communications.
The communication is done over two RS-485 bus:
• COM1 is connected directly to the Control Board J3 connector to either Modbus (MB1 or MB2).
• COM2: A bus to the Building Automation System.
Refer to the Table 4 for 8-pin Connector Terminals.
Table 4. 8-PIN CONNECTOR TERMINALS
PIN #
FUNCTION
1
COM1 A
2
COM1 B
3
COM1 C*
4
COM2 A
5
COM2 B
6
COM2 C*
7
24 VAC Common*
8
24 VAC Power
* These 3 terminals are connected internally and can be connected to earth ground.
Servicing should only be performed by a Qualified Service Agent
29
Figure 19. DISPLAY CONNECTOR TERMINALS SCHEMATIC DIAGRAM
Figure 20. DISPLAY CONNECTOR TERMINALS LEAD LAG DIAGRAM
30
Servicing should only be performed by a Qualified Service Agent
START UP AND OPERATIONS
PRIOR TO START UP
In addition to normal supplies and hand tools necessary for installing and servicing the boilers/water heaters, other tools and test
equipment should be on hand. See Tools Required on Page 4 for detailed tool requirements.
Only an A. O. Smith Certified Start-up agent must perform the initial firing of the boiler/water heater. At this time the user should not
hesitate to ask the start-up agent any questions regarding the operation and maintenance of the unit. If you still have questions,
please contact the factory or your local A. O. Smith representative. Contact Technical Support noted on the back cover for the name
of your closest Certified Start-up Agent.
GENERAL
Never operate the boiler/water heater without first making sure the boiler/water heater and system are filled with water, in addition:
• Make sure a temperature and pressure relief valve is installed in the storage tank for hot water supply installations.
• Make sure that the boiler/water heater and system have been purged of air and checked for leaks.
Also ensure to check the gas piping for leaks before beginning the initial firing of the boiler/water heater.
FILLING AND PURGING OF BOILER/WATER HEATER INSTALLATION
1. Fast fill system through bypass until pressure approaches desired system pressure. Close bypass valve and permit pressure to
be established by the pressure reducing valve.
2. Vent all high points in system to purge system of air.
Provisions should be made to permit manual venting of radiators or convectors. Gas line purging is required with new piping or
systems in which air has entered.
FILLING BOILER/WATER HEATER INSTALLATION
1. Close the system’s drain valve by turning handle clockwise.
2. Open a nearby hot water faucet to permit the air to escape.
3. Fully open the cold water inlet pipe valve allowing the boiler/water heater and piping to be filled.
4. Close the hot water faucet as water starts to flow.
INLET GAS PRESSURE
The inlet gas pressure is measured by removing the 1/8” NPT Plug located on the upstream side of the supply gas valve, and
inserting a 1/8” NPT hose barb fitting to be connected to a manometer or pressure gauge. Once pressure has been checked and/
or adjusted, replace the plug and check for leaks. The maximum value specified must not be exceeded. The minimum values must
be maintained under both load and no load conditions (static and firing conditions). Refer to Instruction Manual of this boiler/water
heater for pressure values. The combination gas valves supplied with the boiler/water heater are for low pressure service. If upstream
pressure exceeds 14.0” W.C., an intermediate gas pressure regulator of the lockup type must be installed.
BURNER
BLOWER
FLAPPER
VENTURI
MANUAL GAS
SHUTOFF VALVE
GAS PRESSURE
SWITCH
DIFFERENTIAL MANIFOLD
PRESSURE TAP
MODULATING
GAS VALVE
FLEX GAS
MANIFOLDS
Figure 21. GAS TRAIN ASSEMBLY
Servicing should only be performed by a Qualified Service Agent
31
MANIFOLD PRESSURE CONNECTIONS
Check the manifold pressure (refer to Table 2 on Page 19) by removing the pipe plug (located on the back of the boiler/water heater near
the main gas shutoff valve) and inserting a suitable 1/8” NPT hose barb for connection to the manometer/pressure gauge. Upon completion
of measurements and adjustments, remove the hose barb and replace the pipe plug. Check for gas leaks and insure all connections are
gas tight. The draft pressures can range in between 0.05" - 1.5" W.C. And the static to dynamic pressures may vary in the range of 2" - 5"
W.C. depending on the boiler/water heater models.
WATER TEMPERATURE REGULATION
HOT WATER CAN SCALD: Boilers/water heaters are intended to produce hot water. Water heated to a temperature which will
satisfy space heating, clothes washing, dish washing and other sanitizing needs can scald and permanently injure you upon contact.
Some people are more likely to be permanently injured by hot water than others. These include the elderly, children, the infirm or
physically/mentally disabled. If anyone using hot water in your home fits into one of theses groups or if there is a local code or state
law requiring a specific temperature water at the hot water tap, then you must take special precautions. In addition to using the lowest
possible temperature setting that satisfies your hot water needs, a means such as a mixing valve should be used at the hot water taps
used by these people or at the hot water supply tank. Mixing valves are available at plumbing supply or hardware stores. Follow the
manufacturer’s instructions for installation of the valves. Before changing the thermostat setting on the hot water system controller,
refer to Table 5.
Hot water temperatures required for automatic dishwasher and laundry use can cause scald burns resulting in serious personal injury
and/or death. The temperature at which injury occurs varies with the person’s age and time of exposure. The slower response time of
children, aged or disabled persons increases the hazards to them. Never allow small children to use a hot water tap, or to draw their
own bath water. Never leave a child or disabled person unattended in a bathtub or shower. The boiler/water heater should be located
in an area that is inaccessible to the general public.
Table 5. RISK OF SCALDS
Water Temperature ºF
Time for 1st Degree Burns
(Less Severe Burns)
Time for Permanent Burns
2nd & 3rd
(Most Severe Burns)
110
(normal shower temp.)
116
(pain threshold)
116
35 minutes
45 minutes
122
1 minute
5 minutes
131
5 seconds
25 seconds
140
2 seconds
5 seconds
149
1 second
2 seconds
154
instantaneous
1 second
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, Sept. 15,1978)
Should overheating occur or the gas supply fail to shut off, turn off the main manual gas shutoff valve to the boiler/water heater.
32
Servicing should only be performed by a Qualified Service Agent
CHECK/CONTROL WATER HARDNESS
XWH water heaters are approved for use in Domestic Water Heating Systems with a water supply hardness of 0 grains per gallon to a
maximim of 12 grains per gallon and a Total Dissolved Solids (TDS) not exceeding 350 PPM. Heating water having higher grains/TDS
specified here requires larger circulating pump. Consult manufacturer when heating water exceeding these specs. Refer to Table 6
for recommend flow rate to maintain scale free operation with up to a medium water hardness. For scale free operation in hard water
systems with a water hardness greater than 12 grains per gallon, a water softener must be installed and maintained.
Table 6. WATER HARDNESS MEDIUM (0-12 GRAINS PER GALLON)
XW MODEL
NO.
∆T ºF
GPM (LPM)
∆P FEET
1000
25
76 (287.6)
17.5
1300
25
99 (374.7)
22
1700
25
129 (488.2)
23
2000
25
152 (575.3)
17.5
2600
25
198 (749.4)
22
3400
25
258 (976.53)
23
∆T ºF = Temperature rise ºF at the specified GPM.
GPM = Flow rate in gallons per minute.
∆P = Pressure loss through the heat exchanger in feet of head.
For systems over 5 grains per gallon; and for scale free operation, boiler/water heater setpoint should not exceed 140 ºF.
Note: The factory installed/supplied pump on the above listed models of boilers/water heaters is sized to maintian a 25 ºF ∆T
through the boiler/water heater when the boiler/water heater is firing at 100% fire.
In addtion to the pressure loss through the heat exchanger, the factory supplied pump is sized for an additional 50 feet (15.2 m)
of equivalent feet of piping between the boiler/water heater and a storage tank. All piping between the boiler/water heater and the
storage tank must be of a pipe size equal to the inlet/outlet(s) of the boiler/water heater. Installation differences may slightly change
these parameters.
FREEZE PROTECTION (HYDRONIC HEATING INSTALLATION)
1. Determine freeze protection fluid quantity using system water content, following fluid manufacturer’s instructions.
2. Local codes may require a backflow preventer or actual disconnect from city water supply.
3. When using freeze protection fluid with automatic fill, install a water meter to monitor water makeup. Freeze protection fluid may
leak before the water begins to leak, causing concentration to drop, reducing the freeze protection level.
INSPECT/FILL CONDENSATE SYSTEM
Inspect/check condensate lines and fittings:
1. Inspect the condensate drain line, condensate PVC fittings and condensate trap. Repair any leaks.
Fill condensate trap with water:
1. Remove the 2 inch PVC cap with the switch located at the top of the trap.
2. Fill with fresh water until the water begins to pour out of the drain.
3. Replace the cap. Press the cap onto the trap until the cap makes contact with the drain.
The condensate trap must be filled with water during all times of boiler/water heater operation to avoid flue gas emission from the
condensate drain line. Failure to fill the trap could result in severe personal injury or death.
Servicing should only be performed by a Qualified Service Agent
33
LIGHTING AND OPERATING INSTRUCTIONS
34
Servicing should only be performed by a Qualified Service Agent
ADJUSTMENT
There must be sufficient load to operate the boiler/water heater at high fire to perform the following adjustments. Start the boiler/water
heater and observe proper operating parameters for the system.
Required Tools:
• TORX® T40 or 5 mm hex wrench
• 3 mm or 7/64 inch hex wrench
• Combustion analyzer
These boilers/water heaters are equipped with a Honeywell combined gas/air control and gas safety shut off control valves. The
valve functions in parallel with the variable speed combustion blower to supply the correct gas air ratio for optimum performance and
efficiency. The combustion blower speed is controlled automatically and determines the amount of negative pressure experienced
by the gas safety shut off/control valves. The gas/air regulator adjusts gas flow to maintain the proper pressure at the outlet nozzle
of the associated valve.
SETTING OF THE TEST MODE
On the Burner Home screen, select any individual boiler/water heater which will guide to Burner Information screen.
Figure 22. BURNER HOME SCREEN
Figure 23. BURNER INFORMATION SCREEN
Click on Operation button, and under the Modulation Menu, set the required Firing rate (High/Low) by setting the RPM.
On the Firing Rate page, set the Firing rate RPM by selecting the Manual in Run check box.
Servicing should only be performed by a Qualified Service Agent
35
Figure 24. OPERATION SCREEN
Figure 25. FIRING RATE PAGE
HIGH FIRING RATE SETTING
Set the boiler/water heater to the high firing rate by setting the High Firing Rate RPM as described below. Check combustion readings
using a combustion analyzer. If combustion readings are not in accordance with the chart below adjust the gas valve as follows:
remove the flat, round, blue plastic cap from the cover. For more information, refer to the Instruction Manual. Using a 3 mm (7/64”)
hex wrench, turn the adjustment screw counterclockwise to increase or clockwise to decrease gas flow and achieve the desired CO2
level. Refer to the Table 7 for correct settings. There will be a slight time delay between the adjustment and the response of the CO2
measuring instrument. Adjust the settings in small increments and allow the combustion readings to stabilize before readjusting.
When desired adjustments are complete, reinstall the blue plastic cap on the cover. Combustion samples should be taken in the stack
within two feet of the boiler/water heater. The carbon monoxide (CO) values in the combustion sample should not exceed 150 PPM
under any circumstances. Contact OEM for any abnormal conditions leading to excessive CO above 150 PPM.
Table 7. HIGH FIRE RATE SETTING
MODELS (XB/XW)
36
RPM
(APPROXIMATE FACTORY SET)
CO2
*MANIFOLD PRESSURE
INCHES W.C (KPA)
NATURAL
GAS
PROPANE
NATURAL
GAS
PROPANE
NATURAL GAS
PROPANE
1000
4450
4750
8.5 - 9.2%
9.3 - 10.2%
-3.5 (-0.87)
-4.7 (-1.17)
1300
4850
5100
8.5 - 9.2%
9.3 - 10.2%
-3.0 (-0.75)
-3.6 (-0.89)
1700
5700
5700
8.5 - 9.2%
9.3 - 10.2%
-3.6 (-0.89)
-4.4 (-1.09)
2000
4700
4750
8.5 - 9.2%
9.3 - 10.2%
-3.9 (0.97)
-4.9 (-1.22)
2600
5200
5100
8.5 - 9.2%
9.3 - 10.2%
-3.3 (-0.82)
-3.6 (-0.89)
3400
5700
5700
8.5 - 9.2%
9.3 - 10.2%
-3.5 (-0.87)
-4.4 (-1.09)
Servicing should only be performed by a Qualified Service Agent
LOW FIRING RATE SETTING
Set the boiler/water heater to the low firing rate by setting the Low Firing Rate RPM as described below. Check combustion readings
using a combustion analyzer. If combustion readings are not in accordance with the chart shown below adjust as follows: remove
the cap on the gas regulator using a slotted screwdriver. For more information, refer to the Instruction Manual. This will expose the
offset adjustment screw. Using a TORX® T40 or a 5 mm hex wrench, carefully adjust the low fire gas setting to achieve the CO2 level
prescribed in Table 8.
Adjustments to the offset pressure regulators should not exceed 1/4 turn at a time before allowing the readings to respond and
stabilize.
After proper low fire offset adjustment is made, reinstall the slotted cap on the regulator.
Following all gas valve adjustments, check for proper light-off and verify correct fuel/air mix and combustion quality throughout the
entire firing range (from lowest to highest fan speed).
Note: The rotation of the Low Fire adjustment is opposite of the High Fire as follows: Clockwise rotation increases gas flow,
counterclockwise rotation decreases gas flow. Make sure the Manual Mode is set back to Automatic Mode to each of the burners,
once the required settings are done. Turn off the individual burner before proceeding to the next burner settings. Depending on the
boiler/water heater size and capacity, the flame voltage will be between 10-15 volts for low fire and 25-32 volts for high fire settings.
Check for gas valve settings and combustion for varied voltage levels.
Table 8. LOW FIRE RATE SETTING
MODELS (XB/XW)
RPM
(APPROXIMATE FACTORY SET)
CO2
*MANIFOLD PRESSURE
INCHES W.C (KPA)
NATURAL
GAS
PROPANE
NATURAL
GAS
PROPANE
NATURAL GAS
PROPANE
1000
1650
1540
7.3 - 8.2%
8.4 - 8.8%
-0.3 (-0.07)
-0.25 (-0.06)
1300
1650
1600
7.3 - 8.2%
8.4 - 8.8%
-0.2 (-0.05)
-0.14 (-0.03)
1700
1700
1700
7.3 - 8.2%
8.4 - 8.8%
-0.2 (-0.05)
-0.23 (-0.05)
2000
1550
1540
7.3 - 8.2%
8.4 - 8.8%
-0.3 (-0.07)
-0.31 (-0.07)
2600
1700
1600
7.3 - 8.2%
8.4 - 8.8%
-0.2 (-0.05)
-0.14 (-0.03)
3400
1700
1700
7.3 - 8.2%
8.4 - 8.8%
-0.2 (-0.05)
-0.23 (-0.05)
* NOTE: Values listed in Table 7 and Table 8 are tested under laboratory conditions with minimum vent length. Values may slightly vary
depending on ambient conditions and field equipment accuracy.
TURNING THE BOILER/WATER HEATER OFF
NEVER TURN OFF POWER TO THE BOILER/WATER HEATER WHILE IT IS FIRING unless an emergency shut down is required.
Repeated sudden stops while firing can damage the boiler/water heater. To shut down the boiler/water heater safely do one of the
following so the boiler/water heater can go through a normal shut down sequence with post purge cycles that cool down the Heat
Exchanger and purge the combustion chamber:
• Lower the Operating Set Point to it’s lowest setting.
• Lower the set point of the external Primary System Control in use to it’s lowest setting.
• Then turn the boiler/water heater off using the Lead Lag Master switch on the display.
Servicing should only be performed by a Qualified Service Agent
37
CONTROL SYSTEM OPERATIONS
BURNER CONTROL SYSTEM
Figure 26. R7910A1138 CONTROL SYSTEM
The R7910A1138 is a burner control system that provide heat control, flame supervision, circulation pump control, fan control, boiler/
water heater control sequencing, and electric ignition function. It will also provide boiler/water heater status and error reporting.
Multiple boiler/water heaters can be joined together to heat a system instead of a single, larger burner or boiler/water heater. Using
boiler/water heaters in parallel is more efficient, costs less, reduces emissions, improves load control, and is more flexible than the
traditional large boiler/water heater.
Control System consists of:
• R7910A1138 Control Device.
• S7999D Touchscreen Display—required for setup and ModBus communication but not required for the system to operate
once the R7910A1138 is programmed.
• S7910A Local Keyboard Display Module.
• Flame Sensor.
• Temperature Sensor, NTC Type 10KΩ at 77°F (25°C) or 12KΩ at 77°F (25°C).
• Limit Sensor, NTC Type 10KΩ at 77°F (25°C).
• 24V Digital I/O.
OVERVIEW
Functions provided by the R7910A1138 include automatic boiler/water heater sequencing, flame supervision, system status indication,
firing rate control, load control, CH/DHW control, limit control, system or self-diagnostics and troubleshooting.
The R7910 maximum version of the controller offers:
1. NTC-temperature sensor for:
•
•
•
•
2.
Outlet Limit And Temperature.
Stack Temperature Limit and Temperature.
Inlet Temperature.
Outdoor Temperature (R7910 only).
Modulating output PWM-driven rotation speed controlled DC-fan for optimal modulation control.
3. Three Pump Outputs with 5 selectable operation modes.
4. 24VAC:
• Output control of gas valve (Pilot and Main) and External Ignition Transformer.
• Digital inputs for room limit control, high limit control, Gas pressure switch, low water cutoff.
5. External spark transformer.
6. Flame sensor.
7. Test jacks for flame signal measurement from a flame sensor.
8. Alarm Output.
38
Servicing should only be performed by a Qualified Service Agent
COMMUNICATIONS AND DISPLAYS
Two modes of communications are available to the R7910.
1. The R7910 has two RS485 communication ports for ModBus that allows for interfacing to one or all R7910s of a system
and presents them individually to the user. The S7999D System Operator interface is a color touchscreen display used for
configuration and monitoring of the R7910A. Though configuration can be done through the display, it is not recommended as
all the parameters are pre-configured by the manufacturer. Any custom configuration required by the field should be done in
consultation with the A. O. Smith qualified service technician. Control Operation and display status in both test and graphical
modes can be shown along with the ability to setup. The R7910 can also be remotely reset through the S7999D display.
2. Either ModBus RS485 communication port can be used to allow configuration and status data to be read and written to the
R7910. Support a Master S7999D or a Building Automation master to control the R7910 to respond to a single ModBus address
to service the requests of the ModBus master in a Lead/Lag arrangement.
SPECIFICATIONS
1. Electrical Ratings:
Operating voltage
• 24VAC (20 to 30 VAC, 60 Hz ±5%)
• 30 amps (Single Heat Exchanger)
• 60 amps (Double Heat Exchanger)
Connected Load for Valve and annunciator functions:
•
•
•
2.
24VAC, 60Hz
120VAC (+10%/-15%), 60Hz (±5%)
Model Specific
Corrosion:
• R7910A must not be used in a corrosive environment.
3. Operating Temperature: -4°F to 150°F (-20°C to 66°C)
4. Storage/Shipping Temperature: -40°F to 150°F (-40°C to 66°C).
5. Humidity:
• Up to 95% Relative Humidity, noncondensing at 104°F for 14 days. Condensing moisture may cause safety shutdown.
6. Vibration: 0.0 to 0.5g Continuous (V2 level)
7. Enclosure: Nema 1/IP40.
8. Approvals:
Underwriters Laboratories, Inc. (UL): Component Recognized: File No. MP268 (MCCZ)
• R7910 is certified as UL372 Primary Safety Controls.
• The R7910 is certified as UL353 Limit Rated device when using part number 50001464 dual element limit rated NTC sensors.
CSD-1 Acceptable.
Meets CSD-1 section CF-300 requirements as a Primary Safety Control.
Meets CSD-1 section CW-400 requirements as a Temperature Operation control.
Meets CSD-1 section CW-400 requirements as a Temperature High Limit Control when configured for use with 10 kohm NTC sensors.
Federal Communications Commission, Part 15,
Class B. Emissionss.
Servicing should only be performed by a Qualified Service Agent
39
BURNER CONTROL OPERATION
Safety Shutdown of Burner Control Functions
Safety Shutdown (Lockout) occurs if any of the following occur during the indicated period:
1. INITIATE PERIOD:
a. A/C line power errors occurred.
b. Four minute INITIATE period has been exceeded.
2. STANDBY PERIOD:
a. Flame signal is present after 240 seconds.
b. Main Valve Terminal is energized.
c. Internal system fault occurred.
3. PREPURGE PERIOD:
a. Flame signal is detected for 10 seconds accumulated time during PREPURGE.
b. Purge Rate Fan RPM or High Fire Switch fails to close within four minutes and fifteen seconds after the firing rate motor is
commanded to drive to the high fire position at the start of PREPURGE.
c. Light off Rate Fan RPM or Low Fire Switch fails to close within four minutes and fifteen seconds after the firing rate motor is
commanded to drive to the low fire position at the end of PREPURGE.
d. Lockout Interlock (if programmed) does not close within 10 seconds.
e. Lockout Interlock opens during PREPURGE.
f. Main Valve terminal is energized.
g. Internal system fault occurred.
4. PRE-IGNITION TIME:
a. Lockout Interlock opens.
b. IAS Purge and Ignition enabled and the Interlock opens.
c. Preignition Interlock opens.
d. Pilot Valve terminal is energized.
e. Main Valve terminal is energized.
5. PILOT FLAME ESTABLISHING PERIOD. (PFEP):
a. Lockout Interlock opens (if enabled).
b. Pilot Valve terminal is not energized.
c. No flame is present at the end of the PFEP, or after programmed number of retry attempts.
d. Main valve terminal is energized.
e. Internal system fault occurred.
6. MAIN FLAME ESTABLISHING PERIOD. (MFEP):
a. Lockout Interlock opens (if enabled).
b. Pilot valve terminal is not energized.
c. Main valve terminal is not energized.
d. No flame present at the end of MFEP.
e. Internal system fault occurred.
7. RUN PERIOD:
a. No flame is present, or flame is lost (if enabled-lockout).
b. Lockout Interlock opens) if enabled).
c. IAS Purge and Ignition enabled and the Interlock opens.
d. Pilot terminal energized (if programmed as Interrupted Pilot).
e. Main valve terminal is not energized.
f. Internal system fault occurred.
8. POSTPURGE PERIOD:
a. Preignition Interlock does not close in five seconds.
b. Pilot Valve terminal is energized.
c. Main Valve terminal is energized.
d. Internal system fault occurred.
e. Flame sensed 240 seconds accumulated time after the RUN period.
40
Servicing should only be performed by a Qualified Service Agent
Safety Shutdown:
1. If the lockout interlocks open or a sensor designated as a safety limit are read as defective, Control System will lockout and
the blower motor will be de-energized.
If these open during the firing period, all fuel valves will be de-energized, the system will complete postpurge, and will lockout
indicated by an alarm.
2. If the main flame is not detected at the end of the last recycle attempt of the main flame establishing period, all fuel valves will
be de-energized, the device will complete postpurge, and will lockout indicated by an alarm.
3. If the flame sensing signal is lost during the run period (if lockout is selected), all fuel valves will be de-energized within 4 seconds
after the loss of the flame signal, the device will complete postpurge, and will lockout indicate by an alarm.
4. Manual reset is required following any safety shutdown. Manual reset may be accomplished by pressing the push button on the
device, pressing the remote reset wired into connector J10, or through an attached display.
Interrupting power to Control System will cause electrical resets, but does not reset a lockout condition.
GENERAL OPERATIONAL SEQUENCE
Initiate
The R7910 enters the Initiate sequence on Initial Power up or:
• Voltage fluctuations vary less than 20VAC or greater than 30VAC.
• Frequency fluctuations vary +/-5% (57 to 63 Hz).
• If Demand, LCI, or Stat interrupt (open) during the Prepurge Period.
• After the reset button is pressed or fault is cleared at the displays.
The Initiate sequence also delays the burner motor from being energized and de-energized from an intermittent AC line input or
control input.
If an AC problem exists for more than 240 seconds a lockout will occur.
Hydronic/Central Heating (XB Boilers)
Start-up sequence central heating request (system in standby):
1. Heat request detected (On Setpoint - On Hysteresis).
2. The CH pump is switched on.
3. After a system Safe Start Check, the Blower (fan) is switched on after a dynamic ILK switch test (if enabled).
4. After the ILK switch is closed and the purge rate proving fan RPM is achieved (or High Fire Switch is closed) - prepurge time is
started.
5. When the purge time is complete, the purge fan RPM is changed to the Lightoff Rate or if used, the damper motor is driven to
the Low Fire Position.
6. As soon as the fan-rpm is equal to the light-off rpm (or the Low Fire Switch closes), the Trial for Ignition or Pre-Ignition Time is
started.
7. Pre-Ignition Time will energize the ignitor and check for flame.
8. Trial for Ignition. Specifics for timings and device actions are defined by A. O. Smith.
9. The ignition and the gas valve are switched on.
10. The ignition is turned off at the end of the direct burner ignition period, or for a system that does use a pilot, at the end (or
optionally at the middle) of the Pilot Flame Establishing Period (PFEP). For an interrupted pilot system this is followed by a Main
Flame Establishing Period (MFEP) where the pilot ignites the main burner. For an intermittent pilot there is no MFEP.
11. The fan is kept at the lightoff rate during the stabilization timer, if any.
12. Before the release to modulation, the fan is switched to minimum RPM for the CH Forced Rate and Slow Start Enable, if the
water is colder than the threshold.
13. At the end of the CH-heat request the burner is switched off and the fan stays on until post purge is complete.
14. A new CH-request is blocked for the forced off time set by the Anti Short Cycle (if enabled).
15. The pump stays on during the pump overrun time.
16. At the end of the pump overrun time the pump will be switched off.
Servicing should only be performed by a Qualified Service Agent
41
Domestic Hot Water
Start-up sequence DHW-request (system in standby):
1. Heat request detected (Tank Sensor below Setpoint).
2. The pump is switched on.
3. After a system Safe Start Check, the Blower (fan) is switched on after a dynamic ILK switch test (if enabled).
4. After the ILK switch is closed and the purge rate proving fan RPM is achieved (or High Fire Switch is closed) - prepurge time is
started.
5. When the purge time is complete, the purge fan RPM is changed to the Lightoff Rate or if used, the damper motor is driven to
the Low Fire Position.
6. As soon as the fan-rpm is equal to the light-off rpm (or the Low Fire Switch closes), the Trial for Ignition or Pre-Ignition Time is
started (depending on configuration).
7. Pre-Ignition Time will energize the ignitor and check for flame.
8. Trial for Ignition. Specifics for timings and device actions are defined by the OEM or installer.
9. The ignition and the gas valve are switched on.
10. The ignition is turned off at the end of the direct burner ignition period, or for a system that does use a pilot, at the end (or
optionally at the middle) of the Pilot Flame Establishing Period (PFEP). For an interrupted pilot system this is followed by a Main
Flame Establishing Period (MFEP) where the pilot ignites the main burner. For an intermittent pilot there is no MFEP.
11. The fan is kept at the lightoff rate during the stabilization timer, if any.
12. Before the release to modulation, the fan is switched to minimum RPM for the DHW Forced Rate and Slow Start Enable, if the
water is colder than the threshold.
13. At the end of the DHW-heat request the burner is switched off and the fan stays on until post purge is complete.
14. The pump stays on during the pump overrun time.
15. At the end of the pump overrun time the pump will be switched off.
LEAD LAG
Burner Control System devices contain the ability to be a stand-alone control, operate as a Lead Lag Master control (which also uses
the Burner Control System function as one of the slaves), or to operate solely as a slave to the lead lag system.
Burner Control System devices utilize two ModBus™ ports (MB1 and MB2) for communications. One port is designated to support a
system S7999D display and the other port supports communications from the LL Master with its slaves.
The Lead Lag master is a software service that is hosted by a Burner Control System. It is not a part of that control, but is an entity
that is “above” all of the individual Burner Controls (including the one that hosts it). The Lead Lag master sees the controls as a set
of Modbus devices, each having certain registers, and in this regard it is entirely a communications bus device, talking to the slave
Buner Control Systems via Modbus.
The LL master uses a few of the host Burner Control System's sensors (header temperature and outdoor temperature) and also the
STAT electrical inputs in a configurable way, to provide control information.
LEAD LAG (LL) MASTER GENERAL OPERATION
The XP product is a multiple burner application and it works on the basis of the Lead Lag Operation. The XB Boiler is factory
configured for Hydronic/Central Heating application, whereas the XWH Water Heater is factory configured for Domestic Hot Water
application. The LL master coordinates the firing of its slave Burner Control Systems. To do this it adds and drops stages to meet
changes in load, and it sends firing rate commands to those that are firing.
The LL master turns the first stage on and eventually turns the last stage off using the same criteria as for any modulation control loop:
•
When the operating point reaches the Setpoint minus the On hysteresis, then the first Burner Control System is turned on.
•
When the operating point reaches the Setpoint plus the Off hysteresis then the last slave Burner Control (or all slave Burner
Controls) are turned off.
The LL master PID operates using a percent rate: 0% is a request for no heat at all, and 100% means firing at the maximum
modulation rate.
This firing rate is sent to the slaves as a percentage, but this is apportioned to the slave Burner Controls according to the rate
allocation algorithm selected by the Rate allocation method parameter.
For some algorithms, this rate might be common to all slave Burner Controls that are firing. For others it might represent the total
system capacity and be allocated proportionally.
For example, if there are 4 slaves and the LL master's percent rate is 30%, then it might satisfy this by firing all four slaves at 30%,
or by operating the first slave at 80% (20% of the system’s capacity) and a second slave at 40% (10% of the system’s capacity).
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Servicing should only be performed by a Qualified Service Agent
The LL master may be aware of slave Burner Control’s minimum firing rate and use this information for some of its algorithms, but
when apportioning rate it may also assign rates that are less than this. In fact, the add-stage and drop-stage algorithms may assume
this and be defined in terms of theoretical rates that are possibly lower than the actual minimum rate of the Burner Control. A Burner
Control that is firing and is being commanded to fire at less than its minimum modulation rate will operate at its minimum rate: this is
a standard behavior for a Burner Control in stand-alone (non-slave) mode.
If any slave under LL Master control is in a Run-Limited condition, then for some algorithms the LL master can apportion to that stage
the rate that it is actually firing at. Additionally when a slave imposes its own Run-limited rate, this may trigger the LL Master to add
a stage, if it needs more capacity, or drop a stage if the run-limiting is providing too much heat (for example if a stage is running at a
higher-than commanded rate due to anti-condensation).
By adjusting the parameters in an extreme way it is possible to define add-stage and drop-stage conditions that overlap or even
cross over each other. Certainly it is incorrect to do this, and it would take a very deliberate and non-accidental act to accomplish it.
But there are two points in this:
1. LL master does not prevent it, and more important;
2. It will not confuse the LL master because it is implemented as a state machine that is in only one state at a time;
For example:
— If its add-stage action has been triggered, it will remain in this condition until either a stage has been added, or
— The criteria for its being in an add-stage condition is no longer met; only then will it take another look around to see what state it
should go to next.
ASSUMPTIONS
Modulating stage The modulating stage is the Burner Control that is receiving varying firing rate requests to track the load.
First stage: This is the Burner Control System that was turned on first, when no slave Burner Controls were firing.
Previous stage: The Burner Control that was added to those stages that are firing just prior to the adding of the Burner Control that
is under discussion.
Next stage: The Burner Control that will or might be added as the next Burner Control to fire.
Last stage: The Burner Control that is firing and that was added the most recently to the group of slaves that are firing. Typically this
is also the modulating stage, however as the load decreases then the last-added stage will be at its minimum rate and the previous
stage will be modulating.
Lead boiler/water heater: The Lead boiler/water heater is the Burner Control that is the first stage to fire among those stages which
are in the equalize runtime (Lead/Lag) group. If a boiler/water heater is in the “Use first” group it may fire before the Lead boiler/water
heater fires.
First boiler/water heater: A Burner Control may be assigned to any of three groups: “Use First”, “Equalize Runtime”, or “Use Last”.
If one or more Burner Controls are in the “Use First” category, then one of these (the one with the lowest sequence number) will
always be the first boiler/water heater to fire. If there is no Buner Control System in the “Use First” category and one or more are in
the “Equalize Runtime” category, then the First boiler/water heater is also the Lead boiler/water heater.
Servicing should only be performed by a Qualified Service Agent
43
LOCAL OPERATOR INTERFACE: DISPLAY SYSTEM
Figure 27. S7999D DISPLAY SYSTEM
The S7999D is a microprocessor-based touchscreen Operator Interface (OI) display that provide an operator interface for monitoring
and configuring parameters in the Burner Control system.
The S7999D is used to monitor an individual burner on the XB Boilers/XWH Water Heaters applications in a lead/lag arrangement. It
consists of 2 RS485 ports (COM 1 & COM 2) and USB port. The S7999D display can be flush front or behind mounted into a panel
cutout. Wiring connections to the S7999D are through a removable 8-pin wiring connector.
FEATURES
•
Individual boiler/water heater status, configuration, history, and diagnostics.
•
Allows configuration and monitoring of the Burner Control Controls burner control sequence, flame signal, diagnostics, historical
files, and faults.
•
S7999D OI Display only:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Allows switching view between multiple burners.
Allows viewing Lead-Lag Master.
Real-time data trending analysis and transferring saved trend data to Excel spreadsheet.
7” 800 x 480, 24 bit high resolution color LCD touch screen for clarity.
Audio output with integral speaker for sound output.
Adjustable backlight control.
Real time clock with coin-cell battery back up (CR2032).
S7999D has Black Border.
Volume control.
Screen Capture function to capture screen images.
USB port for file transfers and software updates
2 RS-485 (COM1 & 2) ports for Modbus™ interface to Burner controls and BAS Gateway.
Windows® CE 6.0 Operating System.
8-pin connector, back-up battery and mounting hardware are provided.
SPECIFICATIONS
1. Electrical Ratings:
• Input Voltage: 18 – 30 Vac (24Vac nominal), 50/60 Hz
• Input Current: 500 mA max.
• Power consumption: 12W max.
2. Operating Temperature: -4 to 158 ºF (-20 to 70 ºC)
3. Storage/Shipping Temperature: -22 to 176 ºF (-30 to 80 ºC)
4. Humidity: 90% RH, non-condensing.
5. Enclosure rating: IP10 / NEMA 1
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Servicing should only be performed by a Qualified Service Agent
6. Approvals:
FCC Part 15, Class A Digital Device
Underwriter’s Laboratories, Inc. (UL) (cUL) Component Recognized (for non-continuous operation): File Number MH17367 (MJAT2,
MJAT8).
INSTALLATION INSTRUCTIONS (S7999D OI DISPLAY)
Mounting the S7999D OI Display and Power Supply
The OI Display can be mounted on the door panel of an electrical enclosure.
1. Select the location on the door panel to mount the display; note that the device will extend into the enclosure at least one inch
past the mounting surface.
2. Provide an opening in the panel door 8" wide X 5 1/2" high (for front panel mount) or 7 1/8" wide X 4 11/16" high (for rear panel
mount).
3. Place the OI Display in the opening and use it as a template to mark the location of the four mounting screw holes. Remove
the device.
4. Using pilot holes as guides, drill 1/4 in. holes through the door panel.
5. Place the display in the opening, aligning the mounting holes in the device with the drilled holes in the panel.
6. Secure the display to the panel with four #6-32 screws and nuts provided.
7. Wire the 24VAC power supply and the RS-485 cables.
8. Ensure the 8-pin connector plug is aligned with the header pins when inserting the 8-pin connector plug back onto the Display.
Secure firmly.
9. Please make sure resistive spark cable is used with the display system, and route the wires away from the display as much as
possible.
Figure 28. S7999D OI DISPLAY CONNECTOR TERMINALS
QUICK SETUP (S7999D OI DISPLAY)
1. Make sure the S7999D 8-pin connector is properly aligned and pressed firmly in place.
2. Make sure the wires between the 8-pin connector and the controller are properly wired and secure.
WARNING: Electrical Shock Hazard. It can cause severe injury, death or equipment damage. Line voltage is present at the 120
VAC power supply.
3. Make sure the power supply is connected securely to the 120 VAC power source.
Servicing should only be performed by a Qualified Service Agent
45
STARTING UP THE S7999D OI DISPLAY
Power-up Validation
The Home page will appear when the device is properly powered. Select the Setup button to adjust the contrast and sound as desired.
If the screen is dim, check the pin 7 and 8 wiring connections.
A “camera” icon on the left top corner is for screen snapshot use. Up to 16 snapshots can be stored in the display and can be copied
to a USB memory stick.
Note: An Advanced Startup screen displays for five seconds after power-up before the Home page displays. This screen allows the
user to upgrade the software in the System Display and should normally be bypassed.
Three LEDs exist for I/O traffic: one for the Ethernet network port and two for Modbus™ ports. Modbus Com Port 2 is not active on
this device.
1. Make sure the Power and COM1 LEDs are blinking.
2. If the LEDs are not blinking:
• Make sure the proper connections have been made between the Modbus COM1 Port and the first controller device in the
Modbus network.
• Ensure proper wiring of the OI Display 9-pin Header Connections.
3. If connected to a BAS application, COM2 LED will blink indicating BAS traffic.
HOME PAGE (S7999D OI DISPLAY)
Make sure a screen similar to Figure 29 appears after the OI Display has completely powered up.
Figure 29. S7999D HOME PAGE
(BOILER/WATER HEATER 1 IN NORMAL OPERATION)
Figure 30. S7999D LEAD LAG HOME PAGE
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Servicing should only be performed by a Qualified Service Agent
Figure 31. S7999D DISPLAY PAGE FLOW
Servicing should only be performed by a Qualified Service Agent
47
On System applications, each Burner Control is represented on the Home page by an icon and name. Pressing the icon allows the
user to zoom in on that burner and see its specific details. These details are provided on a new page, which can include additional
buttons that display additional detail and operation information, which itself leads to other pages. The pages are traversed in a tree
structure method, as shown in Figure 31 on Page 47.
The Control System icons will appear in one of four colors indicating the boiler/water heater status.
• Blue: Normal operation
• Red: Lockout condition
• Gray: Communication error (disconnected or powered off)
• Yellow: Holding mode
Up to 8 Systems can be displayed on the Home page. The name of each burner is displayed next to the Control System icon button.
When Lead Lag is enabled, the system header temperature and firing rate are displayed for each System. When the burner is in
standby or not firing the firing rate is not displayed.
Note: The boiler/water heater name may be cut off on the Home page when all icons are present.
The Home page also includes buttons for Lead Lag configuration when lead lag master and slave in the Burner control is enabled.
Pressing the Setup button on the Home page displays miscellaneous setup and diagnostic functions. It also contains the setup
configuration for BAS applications.
The “Control snapshot” button allows the user to dump the current status and/or configuration settings of any Burner controller into
a text document. The text document can be viewed on the display, saved to flash for later viewing, and can be written to a USB stick
for viewing on a PC or file transfer. Pressing the Burner control icon opens that control’s status page. Go to “Configure” button to
continue.
PAGE NAVIGATION
The Burner Control OI Displays present information and options in a paged manner. Pages are displayed in a tree structure in
which the user navigates up and down to arrive at the desired Function. The page descriptions are provided below so that you can
understand the purpose of each and view the selections, parameters, and information that is available or required on each.
COMMON OI DISPLAY PAGE SYMBOLS
Most pages have a Home button in the top-left corner of the screen and a Back button in the top-right corner of the screen. The
Home button returns the user to the Home page and terminates any operation in progress. The Back button returns the user to the
previous page.
Two other icons may be noticed near the boiler/water heater name.
A camera button is for screen snapshot use. Up to 16 snapshots can be stored in the display and can be copied to a USB memory
stick.
A padlock indicates the operator is not currently logged in (may have been timed out) and a password is needed to change the
setting. An unlocked padlock indicates the password has been entered and the operator has logged into system successfully.
STATUS OR HOME PAGE
A status (summary) page (Figure 32 on Page 49) is displayed when the S7999D display is connected. This status page appears
on the S7999D when the Burner Control icon is pressed on the “Home” page. The status page displays the current condition of the
burner control and displays some of the more important configuration settings.
The initial status page displayed contains summary status information as shown in Figure 32 on Page 49. Any status information not
applicable for the installation is grayed/blanked out on the screen.
Buttons on this screen include:
• Configure: used to configure the burner control (password protected and all pre-configured).
•
•
•
•
•
•
48
Operation: used to perform daily or frequent functions with the burner control, such as setpoint adjustment, etc.
Diagnostic: used to view burner control diagnostic information (for servicing and temperature setting purpose only).
Details: used to view burner control detail status information.
History: used to view burner control history.
Pump: used to expand the pump status information.
Modulation: used to toggle between status displays: pump, setpoints, and modulation.
Servicing should only be performed by a Qualified Service Agent
Figure 32. SUMMARY STATUS PAGE (HYDRONIC CONTROL)
CONFIGURE BUTTON
The configuration page allows the user to view and set parameters that define how the connected Burner Control System R7910A
functions.
The configuration page allows the user to view and set parameters that define how the connected R7910A functions in the hydronic
heating system. All parameters are factory configured and only a qualified service technician must perform the configuration settings).
Figure 33. CONFIGURATION MENU PAGE
Figure 34. SAMPLE CONFIGURATION PAGE
Servicing should only be performed by a Qualified Service Agent
49
CONFIGURATION PASSWORD
Some parameters require a valid configuration password be entered by the user before the parameter can be changed. The password
need only be entered once while the user remains on the configuration pages and stays active. The display times out after 10 minutes
of inactivity. User will have to login again if another secure parameter needs to be changed by pressing the Padlock button.
Three levels of access to Burner Control parameters are permitted. Each access level has defined rights when interfacing with
configuration and status parameters within the controls.
• End user: The end user can read or view the control parameters and be allowed to change some operating parameters, CH
setpoint as an example. (The end user does not need password).
• Installer: The installer can read all control parameters and change default allowed parameters. This access level is used to
customize the control for a particular installation.
• OEM: The OEM can read and change all parameters, change sensor limits and burner control safety parameters.
Different passwords exist in the Burner Control for each access level. The end user level requires no password, but the installer and
OEM levels have unique passwords defined for them.
The installer and OEM passwords can be changed in the Burner Control after logging in with the current password. When the
password is changed, it is saved for all future logins.
Note: For the S7999D System OI display, each boiler/water heater in a multi-boiler/water heater configuration has its own set of
installer and OEM passwords. To avoid user confusion, the passwords should be changed to the same password in each control, but
there is no requirement to do so. Make sure to record your password.
The user is notified that a new password is needed to change a parameter (or until a password is entered successfully)—see Figure
35. The user can continue viewing the configuration parameters regardless of whether a password is entered successfully.
The Burner Controls maintain a password time-out that limits the scope of the password entry. Once a password is successfully
entered, the control starts an internal timer that expires after 10 minutes of inactivity. After the timer expires, the user is required to
re-enter a password before a parameter can be changed.
The user is not required to enter a configuration password for a parameter that has a lower access level than the access level
achieved by an earlier password entry for any configuration group (as long as the user stays in the configuration pages). The user
only needs to enter a password once until a parameter that has a higher access level is selected.
Figure 35. LOGIN REQUIRED
KEYBOARD
Some pages request user entry of characters. When this type of input is required, a keyboard page appears, as shown in Figure 36
on Page 51. The text box at the top of the screen displays the current (or default) setting of the user input. The user can add to this
text, clear it, or change it.
The Shift key on the left side of the screen shifts between upper and lowercase characters. Pressing the Shift key toggles the
keyboard from one mode to the other (continuous pressing of the Shift button is not required). The OK button should be pressed when
the user is done entering the text input. The Cancel button on the bottom of the screen allows the user to ignore any text changes
that have been made and keep the original text value. Pressing the OK or Cancel buttons returns the user to the page displayed prior
to the keyboard page.
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Servicing should only be performed by a Qualified Service Agent
LOGIN
Pressing the Login button allows entering the password from a keyboard as shown in Figure 36. After the password is entered, the
OK button is selected. The Cancel button aborts the password login.
Figure 36. DEVICE LOGIN SCREEN
WARNING: Explosion Hazard. Improper configuration can cause fuel buildup and explosion. Improper user operation may result in
property loss, physical injury or death.
Using the OI Displays to change parameters must be attempted by only experienced and/or licensed burner/boiler/water heater
operators and mechanics.
CHANGE PARAMETER SETTINGS
Change parameter settings by selecting the parameter on the page. A dialog box displays for the parameter with controls allowing
the user to change the value (see Figure 37). After changing the setting to a new value, press the OK button. Pressing the Cancel
button leaves the parameter unchanged. The changed setting is reflected on the screen and sent to the control when the OK button
is pressed.
Figure 37. EXAMPLE OF CHANGE CONFIGURATION PARAMETER PAGE
VERIFY
Pressing the Verify button displays safety configuration parameters for an additional verification step to commit the changes.
Safety parameters are grouped into blocks that include only safety parameters, not a mixture of safety data and non-safety data. All
parameters within the safety group undergo a verification process. A safety parameter group is identified on the display to indicate
when the configuration parameters are safety-related. Each safety parameter group is verified one at a time until all have been
verified. See Figure 38 on Page 52.
Like operating parameters, safety parameters can be viewed without the need to enter a password.
Safety parameter blocks that have been changed require verification. The verification steps do not have to be completed immediately;
the installer can move between and change parameter groups before the verification is done. A Verify button is enabled that allows
the installer to conduct verification sessions (the example of the Verify button in Figure 33 on Page 49 is not yet enabled because
the installer hasn’t logged in).
Servicing should only be performed by a Qualified Service Agent
51
Figure 38. SAFETY VERIFICATION
Figure 39. EDIT SAFETY DATA
NOTE: When the installer proceeds with the safety parameter configuration, the control unlocks the safety parameters in this group
and marks them unusable. Failure to complete the entire safety configuration procedure leaves the control in an un-runnable state
(lockout 2).
All safety configuration parameters in the group should have the same access level. If this condition isn’t so, the user is asked to enter
another password when a higher access level is needed.
Successful login is noted by the lock icon, which changes to “unlocked” on the page. The installer may begin to change safety
parameters (or any other parameters) at that time (see Figure 39). If the Burner Control is in an unconfigured (or new) state, then this
warning doesn’t appear. All parameters that need changes should be changed during the login.
If the safety configuration session is terminated after it has started (in the Edit or Verify stages), the Burner Control is left in an
unconfigured (unrunnable) state.
The installer can terminate the session by pressing the Menu button or by attempting to leave the Verification page with the Home or
Back buttons (top-left and top-right screen corners, respectively). However, leaving the session at this point leaves the control in an
unrunnable state and confirms whether the installer still wants to do so.
The settings of all parameters in each safety block must be verified to save them in the control.
When the installer is done changing safety parameters, pressing the Verify button on the configuration screen begins the Verification
process. The settings for all safety parameters in each changed block are presented and Verified by the installer (see Figure 40).
Figure 40. SAFETY PARAMETER CONFIRMATION
Figure 41. SAFETY PARAMETER RESET
Press the Yes button to confirm each safety parameter block. If the No button is selected, the safety parameter block remains
unconfirmed and the Configuration menu page is displayed. The control remains in an unconfigured state in this case.
After all safety parameter blocks have been confirmed, the installer is asked to press and hold the Reset button on the Burner Control
to complete the safety verification session (see Figure 41).
When the Reset button is pressed and held for 3 seconds the confirmed safety parameters are saved in the control. The above Reset
dialog box automatically closes when this step is completed. If this step is not performed, the control remains in a safety lockout state
until the installer resolves the unverified safety parameters.
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Servicing should only be performed by a Qualified Service Agent
FAULT/ALARM HANDLING
Each Burner Control reports to the OI display when a safety lockout or an Alert occurs.
Safety lockouts are indicated on each configuration page as an alarm bell symbol. At the status page (for S7999D), the History button
turns red. If the S7999D is displaying the system status icons, the control in alarm will turn red.
The lockout history can be displayed by pressing on the History button. The state information about each lockout is displayed along
with the date/time that the lockout occurred (refer to Table 9). Current date/time stamp is a display setup feature.
NOTE: In the event of a power interruption, the date/time must be reset. The OI Display does NOT have a backup means.
Table 9. BURNER CONTROL LOCKOUT HISTORY
DATA
COMMENT
Lockout time
Set by display.
Fault Code
Unique code defining which
lockout occurred.
Annunciator first out
First interlock in limit string
results in a shutdown.
Description
Fault description.
Burner Lockout/Hold
Source/reason
hold.
for
lockout/
Burner control state
Sequence time
Burner control state timer at
time of fault.
Cycle
Burner control cycle.
Run Hours
Burner control hours.
I/O
All digital I/O status at time of
fault.
Annunciator 1-8 states
All annunciator I/O status at
time of fault.
Fault data
Fault dependent data.
An alert log can be displayed for each control by pressing the Alert button on the bottom of the history status page. A description of
the alert is displayed along with the time when the alert occurred (refer to Table 10).
Table 10. BURNER CONTROL ALERT LOG
DATA
COMMENT
Alert Line
Set by display.
Alert Code
Unique Code defining which
fault occured.
Description
Alert description.
HISTORY BUTTON
The History button on the Home page serves not only as a button, but also displays Burner Control lockouts, holds, and alerts as they
occur. The History button can be selected at any time, regardless of which type of information is displayed, to view history information.
Pressing the History button displays a dialog box (see Figure 42 on Page 54) that allows the user to select the type of history to view.
The user can also silence an audible alarm generated by the control during a lockout or alert by alarm condition.
This History dialog box provides an exploded view of the status information displayed in the History button (the font is larger). One of
the four buttons (OK, Lockouts, Alerts, or Silence) can be selected. If none of these buttons are selected the dialog box closes after
30 seconds.
Servicing should only be performed by a Qualified Service Agent
53
Figure 42. EXAMPLE OF HISTORY BUTTON
Two types of historical data can be displayed on the history page: lockout history and alert log.
The entire 15 fault code history is displayed in a scrollable list with the most recent fault displayed first followed by the next most
recent fault. Summary information is displayed for each fault entry, including the burner cycle count, fault code, and fault number with
description. Detailed information for a specific fault entry that also includes burner control sequence state, burner run-time hours,
annunciation status, etc., is viewed by selecting (touching the History line) the lockout entry in the list.
The date and time that each fault occurred is displayed in the lockout history. The lockout timestamp displays in both the lockout
summary and detail information.
The Burner Control does not maintain date or time of day information. The date and time stamp is assigned by the OI display. When
the OI display first obtains the lockout and alert history from the control (during the display data synchronization), no timestamps are
assigned since the times that the lockouts occurred are unknown. All new lockouts that occur after the synchronization are assigned
timestamps.
NOTE: The system time can be set in the OI display to ensure that correct timestamps are given to the controls’ lockouts and alerts.
Power interruptions will require the time to be reset as the display does not have a time backup means.
The Clear Lockout button allows the user to acknowledge and clear (reset) the lockout when in lockout state, much the same as
pressing the reset button on the front of the Burner Control.
The user can toggle between displaying the controls’ lockout history and alert log by pressing the Alerts or Lockouts button on the
bottom of the pages.
Figure 43. EXAMPLE OF LOCKOUT HISTORY
Figure 44. EXAMPLE OF ALERT SHOWN
To see additional detail about a lockout or alert, touching on the lockout or alert in the list expands the view of that lockout or alert,
as shown in Figure 43 and Figure 44.
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Servicing should only be performed by a Qualified Service Agent
Figure 45. CONTROL EXPANDED LOCKOUT DETAIL
Figure 46. CONTROL EXPANDED ALERT DETAIL
OPERATION BUTTON
The operation button displays the Burner Control running operation, including setpoint and firing rate values. From this page the user
can change setpoints, manually control the boiler/water heater’s firing rate, manually turn pumps on, view annunciation information,
and switch between hydronic heating loops (Central Heat and Domestic Hot Water), as shown in Figure 47. If a password is required
to change any of the settings on this page, the user can press the Login button to enter the password.
Annunciation information is shown in Figure 48 and Figure 49.
Figure 47. OPERATION PAGE
Figure 48. PROGRAMMABLE ANNUNCIATION
Figure 49. PROGRAMMABLE ANNUNCIATION CONT.
Servicing should only be performed by a Qualified Service Agent
55
DIAGNOSTICS BUTTON
The Diagnostics button displays analog and digital I/O status of the Burner Control and is meant only for diagnostics and troubleshooting
purposes. A snapshot of the diagnostic status is displayed and updated once per second as it changes in the control.
The digital I/O data is displayed as LEDs that are either on (green) or off (red) (see Figure 50). Not all digital I/O can be displayed at
the same time on the page, so a horizontal scroll bar is used to move the view left and right to show all digital I/O data.
Figure 50. DIAGNOSTICS PAGE (DIGITAL I/O)
Figure 51. DIAGNOSTIC PAGE (ANALOG I/O)
The control analog I/O can also be viewed on the OI Display. A snapshot of the diagnostic status is displayed and updated as it
changes in the control.
The analog I/O data is displayed as bar charts with I/O level represented in the I/O range (see Figure 51) Analog I/O that is not
enabled for the installation displays a blank I/O level. Not all analog I/O can be displayed at the same time on the page, so a horizontal
scroll bar is used to move the view left and right to show all analog I/O status.
SYSTEM CONFIGURATION (S7999D OI DISPLAY ONLY)
The OI Display has some functions related to general configuration for the control in the end user installation. Pressing the Display
Refresh button invokes a search procedure (see Figure 52). A new R7910A Hydronic Control is identified by “Unknown” status next
to its name in the boiler/water heater system list (see Figure 53). “Unknown” indicates that configuration data has not been retrieved
from the control yet.
Figure 52. SYSTEM REFRESH
Figure 53. SYSTEM CONFIGURATION PAGE
The control connected to the Modbus network is indicated to the user after the search procedure has concluded.
Once the control is located it must be synchronized with the OI Display before it can be displayed. New controls are not displayed on
the Home page until this synchronization is performed.
56
Servicing should only be performed by a Qualified Service Agent
SYSTEM SYNCHRONIZATION (S7999D OI
DISPLAY ONLY)
The user can manually synchronize configuration data from the
connected controls at any time.
A new control is visible when configuration and status data is
gathered from it. This collection procedure takes a few minutes.
The control is marked as “Unknown” when no configuration
information exists. Normally, control configuration data collection
only needs to be performed when the control is initially installed.
However, a re synchronization is necessary after the OI Display
is reset. See Figure 54.
The user presses the Synchronize button to begin synchronization
with the control.
CONFIGURATION
The Burner Control can be configured from the OI Display. The
control configuration is grouped into the functional groups as
shown in Table 11.
Table 11. FUNCTIONAL CONFIGURATION GROUPS
HYDRONIC CONTROL
System Identification and
Access
CH - Central Heat
Outdoor Reset
DHW - Domestic Hot Water
DHW Storage
DHW Plate
Warm Weather Shutdown
Demand Priority
Modulation Configuration
Pump Configuration
Statistics Configuration
High Limit
Stack Limit
Delta T Limits
T-Rise Limit
Heat Exchanger High Limit
Anti-condensation
Frost Protection Configuration
Figure 54. SYSTEM SYNCHRONIZATION
Status of the synchronization is reflected in the dialog box. The
synchronization can be aborted by selecting the Cancel button.
Annunciation Configuration
Burner Control Interlocks
Burner Control Timings and Rates
Burner Control Ignition
Burner Control Flame Failure
System Configuration
Fan Configuration
Sensor Configuration
Lead Lag Slave Configuration
Lead Lag Master Configuration
Most of this configurations are already performed by either the
contractor/installer or at A. O. Smith. Each functional group is
displayed on the Configuration menu page.
Parameters in functional groups that are not applicable for
the installation can be ignored. In some cases, features in a
functional group are disabled by default and are enabled when
needed for the installation.
Servicing should only be performed by a Qualified Service Agent
57
TROUBLESHOOTING
The Control System performs exhaustive self diagnostics and displays detected fault conditions in plain English errors/fault messages
on the Display System when there is a problem. When the Control System declares a fault condition it will “lock out” and disable
boiler/water heater operation.
POOR COMBUSTION - IGNITION FAILURE - ROUGH START/OPERATION
• Ensure the correct type of fuel gas, natural gas or propane, is supplied to the boiler/water heater., see the boiler/water heater's
rating label.
• Check supply gas and manifold pressure.
• Inspect the Burner for debris or damage.
If the high and/or low fire CO2 combustion readings are not in accordance with Table 7 on Page 36 and Table 8 on Page 37, or the
CO readings are high, or if the boiler/water heater is experiencing ignition failure or rough starting/operation perform the following
procedures:
ADEQUATE COMBUSTION AIR - PROPER VENTING
Combustion Air: Carefully review the requirements for combustion and ventilation air in the Instruction Manual that came
with the boiler/water heater. Ensure there is an adequate supply of fresh air for combustion and the boiler/water heater is vented
properly. Do not overlook this step. Lack of combustion air and improper venting is often the root cause for poor combustion,
ignition failure and Control System lock out. Ensure all air requirements listed in the Instruction Manual that came with the boiler/
water heater have been observed and followed.
Direct Vent Installations: If the boiler/water heater is using outdoor air for combustion (direct vent) ensure the intake air
or the vent pipe is not restricted and neither has exceeded the maximum equivalent feet or maximum number of elbow limitations
given in the Instruction Manual that came with the boiler/water heater. Ensure the specified (check parts list) vent and intake
air termination fittings have been installed. The factory supplied terminations are critical, failure to install required vent system
components will result in operation problems.
If the boiler/water heater is in an equipment room with a door to the outdoors, temporarily disconnect the intake air pipe and prop
open the equipment room door. Take combustion readings again to see if this corrects the problem. If the combustion readings
improve with the intake air pipe disconnected, the intake air pipe is either restricted or has too many equivalent feet or too many
elbows installed.
Conventional Vent Installations: If the boiler/water heater is using room air for combustion (conventional vent) ensure the
vent pipe is not restricted and has not exceeded the maximum equivalent feet or maximum number of elbow limitations given in the
Instruction Manual that came with the boiler/water heater. Ensure the specified (check parts list) vent termination fitting has been
installed. The required termination are critical, failure to install required vent system components will result in operation problems.
Ensure the fresh air openings in the equipment room are adequately sized for the combined input Btu/hr rating of all conventionally
vented fuel burning appliances in the room. If the boiler/water heater is in an equipment room with a door to the outdoors - prop
open the equipment room door. Take combustion readings again to see if this corrects the problem. If the combustion readings
improve with the door open the fresh air openings may be undersized, refer to Air Requirements in the Instruction Manual to correct
the problem.
Service Note
If the Instruction Manual that came with the boiler/water heater is not on hand or there is any questions regarding the Air Requirements
or Venting instructions; call the toll free support phone number on the back cover of this manual for further assistance. Costs to
correct installation errors are not covered under the limited warranty.
VENT GAS RECIRCULATION
Vent gases recirculating from the vent termination into the intake air termination on direct vent installations is a serious installation
problem that MUST BE corrected. It will cause poor combustion, high Carbon Monoxide (CO) levels, delayed ignition, rough starting/
operation and ignition failure. Costs to correct installation errors are not covered under the limited warranty.
Vent and intake air terminations on direct vent installations may be allowing the recirculation of vent gases to the intake air pipe.
Ensure both terminations on direct vent installations have been installed with adequate clearances. See the Instruction Manual that
came with the boiler/water heater for venting instructions and vent/intake air termination clearance requirements.
58
Servicing should only be performed by a Qualified Service Agent
RESTORE GAS FLOW SETTINGS TO DEFAULT
Each XB boiler/XWH water heater is fired and the optimal combustion set before leaving the factory. The High and Low Fire gas flow
adjustment screws on the 24 VAC Gas Valve have been set to maximize the boiler/water heater performance. When performing the
on site Start-up, gas flow can be improperly adjusted to the point the boiler/water heater will not light. This may require the valve to
be reset to a minimum gas flow (default) setting that will allow the unit to safely fire and perform the necessary adjustments outlined
in the Start-up procedure to ensure proper combustion and performance. Follow these steps to reset the gas flow settings to the
minimum gas flow (default) settings:
• With the boiler/water heater turned off. Use the correct size TORX® and/or Allen wrench to adjust the high fire and low fire
adjustment screws on the 24 VAC Gas Valve. Turn the High Fire adjustment screw clockwise and the Low Fire adjustment
screw counter-clockwise until they will not turn any more. This will close both gas flow adjustment screws. Do not overtighten or
use excessive force, turn the adjustment screws until they stop with minimal force applied.
• With both adjustment screws closed, turn the High Fire adjustment screw counter-clockwise 2 1/2 turns and the Low Fire
adjustment screw clockwise 2 1/2 turns. The gas flow settings are now reset to the minimum gas flow (default) setting.
• The boiler/water heater should light off with these minimum gas flow (default) settings. Make final gas flow adjustments and
ensure proper combustion and performance. If the boiler/water heater will not light off with the gas flow adjustment screws reset
as described above call the toll free support phone number on the back cover of this manual for further assistance.
BURNER INSPECTION
The stainless steel radial fire Burner used in XB boilers/XWH water heaters can trap debris drawn into the combustion air intake. This
can cause poor combustion, rough starting/operation and ignition failure. When cutting the intake air pipe sections during installation,
carefully remove all plastic debris left on the ends of each pipe section before installation to avoid this problem.
•
•
•
•
Turn off the power supply. Disconnect the Venturi from the Combustion Blower. See Figure 7 on Page 15.
Unplug the 3 pin and 5 pin plugs to the Combustion Blower Assembly. See Figure 4 on Page 11.
Remove the Combustion Blower to get access to the Burner.
Remove the Burner and inspect the burner for any signs of damage or debris inside. If the burner is damaged or contaminated
with debris - replace the burner. Check all gaskets in the burner/blower assembly for wear or damage. Replace any worn or
damaged gaskets.
Service Note
If the boiler/water heater is still experiencing poor combustion, rough starting/operating or ignition failure after all the steps in this
section have been performed call the toll free support phone number on the back cover of this manual for further assistance.
THINGS TO CHECK BEFORE SERVICING:
• Using the Instruction Manual that came with the boiler/water heater as reference, verify the water piping, gas line, venting and
electrical have all been properly installed.
• Ensure the power supply connections to the boiler/water heater are polarity correct and are properly grounded.
• Ensure supply gas pressure is within the minimum and maximum requirements.
• Review the Installation Considerations on page 3 and the Installation Check List on Page 8.
NOTE: Poor installations account for many service problems. Costs to correct installation errors are not covered under the limited
warranty.
RESETTING THE CONTROL SYSTEM
To reset the Control System from a lock out/fault condition; turn the power supply off for approximately 20 seconds and then back on.
Keep in mind if the condition that caused the lock out has not been corrected the Control System will continue to lock out.
IMPORTANT SERVICE REMINDER
When performing any troubleshooting step outlined in this manual always consider the wiring and connectors between components.
Perform a close visual inspection of all wiring and connectors to and from a given component before replacement. Ensure wires
were stripped before being crimped in a wire connector, ensure wires are crimped tightly in their connectors, ensure connection
pins in sockets and plugs are not damaged or worn, ensure plugs and sockets are mating properly and providing good contact.
Failure to perform this critical step or failing to perform this step thoroughly often results in needless down time, unnecessary parts
replacement, and customer dissatisfaction.
Servicing should only be performed by a Qualified Service Agent
59
TROUBLESHOOTING CODES
To support the recommended Troubleshooting, the R7910 has an Alert File. Review the Alert history for possible trends that may have
been occurring prior to the actual Lockout.
Note Column: H= Hold message; L=Lockout message; H or L= either Hold or Lockout depending on Parameter Configuration.
Table 12. TROUBLESHOOTING CODES
CODE
DESCRIPTION
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
NOTE
Safety Data Faults
1
Unconfigured safety data
1. New Device, complete device configuration and
safety verification.
2. If fault repeats, replace module.
L
2
Waiting for safety data verification
1. Device in Configuration mode and safety
parameters need verification and a device needs
reset to complete verification.
2. Configuration ended without verification, re enter
configuration, verify safety parameters and reset
device to complete verification.
3. If fault repeats, replace module.
L
Internal Fault.
1. Reset Module.
2. If fault repeats, replace module.
H
Internal Operation Errors
3
Internal fault: Hardware fault
4
Internal fault: Safety Relay key feedback error
5
Internal fault: Unstable power (DCDC) output
6
Internal fault: Invalid processor clock
H
7
Internal fault: Safety relay drive error
H
8
Internal fault: Zero crossing not detected
H
9
Internal fault: Flame bias out of range
H
10
Internal fault: Invalid Burner control state
L
11
Internal fault: Invalid Burner control state flag
L
12
Internal fault: Safety relay drive cap short
H
13
Internal fault: PII shorted to ILK
H or L
14
Internal fault: HFS shorted to LCI
H or L
15
Internal fault: Safety relay test failed due to
feedback ON
L
16
Internal fault: Safety relay test failed due to safety
relay OFF
L
17
Internal fault: Safety relay test failed due to safety
relay not OFF
L
18
Internal fault: Safety relay test failed due to
feedback not ON
L
19
Internal fault: Safety RAM write
L
20
Internal fault: Flame ripple and overflow
H
21
Internal fault: Flame number of sample mismatch
H
22
Internal fault: Flame bias out of range
H
23
Internal fault: Bias changed since heating cycle
starts
H
24
Internal fault: Spark voltage stuck low or high
H
25
Internal fault: Spark voltage changed too much
during flame sensing time
H
26
Internal fault: Static flame ripple
H
27
Internal fault: Flame rod shorted to ground
detected
H
28
Internal fault: A/D linearity test fails
H
29
Internal fault: Flame bias cannot be set in range
H
60
Servicing should only be performed by a Qualified Service Agent
H
H
CODE
DESCRIPTION
30
Internal fault: Flame bias shorted to adjacent pin
31
Internal fault: SLO electronics unknown error
32 - 46
Internal fault: Safety Key 0 through 14
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
Internal Fault.
1. Reset Module.
2. If fault repeats, replace module.
NOTE
H
H
L
System Errors
47
Flame Rod to ground leakage
H
48
Static flame (not flickering)
H
49
24VAC voltage low/high
1. Check the Module and display connections.
2. Check the Module power supply and make sure
that both frequency, voltage and VA meet the
specifications.
H
50
Modulation fault
H
51
Pump fault
52
Motor tachometer fault
Internal sub-system fault.
1. Review alert messages for possible trends.
2. Correct possible problems.
3. If fault persists, replace module.
53
AC inputs phase reversed
1. Check the Module and display connections.
2. Check the Module power supply and make
sure that both frequency and voltage meet the
specifications.
3. On 24Vac applications, assure that J4-10 and
J8-2 are connected together.
L
54
Safety GVT model ID does not match application's
model ID
Contact the qualified service technician.
L
55
Application configuration data block CRC errors
Contact the qualified service technician.
L
56 - 57
RESERVED
58
Internal fault: HFS shorted to IAS
Internal Fault: Mux pin shorted
Internal Fault.
1. Reset Module.
2. If fault repeats, replace module.
L
59
Normal Event Status
H
H
L
60
Internal Fault: HFS shorted to LFS
61
Anti short cycle
L
62
Fan speed not proved
63
LCI OFF
1. Check wiring and correct any faults.
2. Check Interlocks connected to the LCI to assure
proper function.
3. Reset and sequence the module; monitor the LCI
status.
4. If code persists, replace the module.
H
64
PII OFF
1. Check wiring and correct any faults.
2. Check Preignition Interlock switches to assure
proper functioning.
3. Check the valve operation.
4. Reset and sequence the module; monitor the PII
status.
5. If code persists, replace the module.
H or L
65
Interrupted Airflow Switch OFF
Interrupted Airflow Switch ON
1. Check wiring and correct any possible shorts.
2. Check airflow switches to assure proper
functioning.
3. Check the fan/blower operation.
4. Reset and sequence the module; monitor the
airflow status.
5. If code persists, replace the module.
H or L
66
Will not be a lockout fault. Hold Only.
H
H
Servicing should only be performed by a Qualified Service Agent
H or L
61
CODE
DESCRIPTION
67
ILK OFF
68
ILK ON
69
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
NOTE
1. Check wiring and correct any possible shorts.
2. Check Interlock (ILK) switches to assure proper
function.
3. Verify voltage through the interlock string to the
interlock input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H or L
Pilot test hold
1. Verify Run/Test is changed to Run.
2. Reset Module.
3. If fault repeats, replace module.
H
70
Wait for leakage test completion
1. Internal Fault. Reset Module.
2. If fault repeats, replace module.
H
71 - 77
RESERVED
78
Demand Lost in Run
1. Check wiring and correct any possible errors.
2. If previous steps are correct and fault persists,
replace the module.
H
79
Outlet high limit
1. Check wiring and correct any possible errors.
2. Replace the Outlet high limit.
3. If previous steps are correct and fault persists,
replace the module.
H or L
80
DHW high limit
1. Check wiring and correct any possible errors.
2. Replace the DHW high limit.
3. If previous steps are correct and fault persists,
replace the module.
H or L
81
Delta T limit
1. Check Inlet and Outlet sensors and pump circuits
for proper operation.
2. Recheck the Delta T Limit to confirm proper
setting.
3. If previous steps are correct and fault persists,
replace the module.
H or L
82
Stack limit
1. Check wiring and correct any possible errors.
2. Replace the Stack high limit.
3. If previous steps are correct and fault persists,
replace the module.
H or L
83
Delta T exchanger/outlet limit
Not Applicable.
H or L
84
Delta T inlet/exchanger limit
Not Applicable.
H or L
85
Inlet/outlet inversion limit
Not Applicable.
H or L
86
Exchanger/outlet inversion limit
Not Applicable.
H or L
87
Inlet/exchanger inversion limit
Not Applicable.
H or L
88
Outlet T-rise limit
1. Check for adequate flow.
H or L
89
Exchanger T-rise limit
Not Applicable.
H or L
90
Heat exchanger high limit
Not Applicable.
H or L
H or L
Sensor Faults
91
Inlet sensor fault
1. Check wiring and correct any possible errors.
2. Replace the Inlet sensor.
3. If previous steps are correct and fault persists,
replace the module.
H
92
Outlet sensor fault
1. Check wiring and correct any possible errors.
2. Replace the Outlet sensor.
3. If previous steps are correct and fault persists,
replace the module.
H
93
DHW sensor fault
1. Check wiring and correct any possible errors.
2. Replace the DHW sensor.
3. If previous steps are correct and fault persists,
replace the module.
H
62
Servicing should only be performed by a Qualified Service Agent
CODE
DESCRIPTION
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
NOTE
94
Header sensor fault
1. Check wiring and correct any possible errors.
2. Replace the header sensor.
3. If previous steps are correct and fault persists,
replace the module.
H
95
Stack sensor fault
1. Check wiring and correct any possible errors.
2. Replace the stack sensor.
3. If previous steps are correct and fault persists,
replace the module.
H
96
Outdoor sensor fault
1. Check wiring and correct any possible errors.
2. Replace the outdoor sensor.
3. If previous steps are correct and fault persists,
replace the module.
H
97
Internal Fault: A2D mismatch
L
98
Internal Fault: Exceeded VSNSR voltage
99
Internal Fault: Exceeded 28V voltage tolerance
Internal Fault.
1. Reset Module.
2. If fault repeats, replace module.
100
Pressure Sensor Fault
1.
2.
3.
4.
5.
H
101-104
RESERVED
Verify the Pressure Sensor is a 4-20ma source.
Check wiring and correct any possible errors.
Test Pressure Sensor for correct operation.
Replace the Pressure sensor.
If previous steps are correct and fault persists,
replace the module.
L
L
Flame Operation Faults
105
Flame detected out of sequence
1. Check that flame is not present in the combustion H or L
chamber. Correct any errors.
2. Make sure that the flame detector is wired to the
correct terminal.
3. Make sure the F & G wires are protected from
stray noise pickup.
4. Reset and sequence the module, if code
reappears, replace the flame detector.
5. Reset and sequence the module, if code
reappears, replace the module.
106
Flame lost in MFEP
Flame lost early in run
108
Flame lost in run
109
Ignition failed
1. Check pilot valve (Main Valve for DSI) wiring and
operation - correct any errors.
2. Check the fuel supply.
3. Check fuel pressure and repeat turndown tests.
4. Check ignition transformer electrode, flame
detector, flame detector siting or flame rod
position.
5. If steps 1 through 4 are correct and the fault
persists, replace the module.
L
107
110
Ignition failure occurred
Hold time of recycle and hold option. Will not be a
lockout fault. Hold Only.
H
111
Flame current lower than WEAK threshold
Internal hardware test. Not a lockout.
H
112
Pilot test flame timeout
Interrupted Pilot or DSI application and flame lost
when system in “test” mode.
1. Reset the module to restart.
L
113
Flame circuit timeout
Flame sensed during Initiate or off cycle, hold 240
seconds, if present after 240 seconds, lockout.
L
114-116
RESERVED
117
Condensate Fault
1. Check the condensate trap at the back of the
boiler/water heater for any blockage.
2. Check the exhaust vent piping for any blockage.
L
118-121
RESERVED
L
L
L
Rate Proving Faults
Servicing should only be performed by a Qualified Service Agent
63
CODE
DESCRIPTION
122
Lightoff rate proving failed
123
Purge rate proving failed
124
High fire switch OFF
125
High fire switch stuck ON
126
Low fire switch OFF
127
Low fire switch stuck ON
128
Fan speed failed during prepurge
129
Fan speed failed during preignition
130
Fan speed failed during ignition
131
Fan movement detected during standby
132
Fan speed failed during run
133-135
RESERVED
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
NOTE
1. Check wiring and correct any potential wiring
errors.
2. Check VFDs ability to change speeds.
3. Change the VFD.
4. If the fault persists, replace the module.
L
1. Check wiring and correct any potential wiring
errors.
2. Check High Fire Switch to assure proper function
(not welded or jumpered).
3. Manually drive the motor to the High Fire position
and adjust the HF switch while in this position
and verify voltage through the switch to the HFS
input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H
L
H
1. Check wiring and correct any potential wiring
H
errors.
H or L
2. Check Low Fire Switch to assure proper function
(not welded or jumpered).
3. Manually drive the motor to the High Fire position
and adjust the LF switch while in this position and
verify voltage through the switch to the LFS input
with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
1. Check wiring and correct any potential wiring
errors.
2. Check VFDs ability to change speeds.
3. Change the VFD.
4. If the fault persists, replace the module.
H or L
H or L
H or L
H
H
Start Check Faults
136
Interrupted Airflow Switch failed to close
1. Check wiring and correct any possible wiring
errors.
2. Check Interrupted Airflow switch(es) to assure
proper function.
3. Verify voltage through the airflow switch to the
IAS input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H
137
ILK failed to close
1. Check wiring and correct any possible shorts.
2. Check Interlock (ILK) switches to assure proper
function.
3. Verify voltage through the interlock string to the
interlock input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H
138-142
RESERVED
FAULT CODES 149 THROUGH 165 ARE
OEM SPECIFIC FAULT CODES
143
Internal fault: Flame bias out of range 1
Contact the qualified service technician.
L
144
Internal fault: Flame bias out of range 2
Contact the qualified service technician.
L
145
Internal fault: Flame bias out of range 3
Contact the qualified service technician.
L
146
Internal fault: Flame bias out of range 4
Contact the qualified service technician.
L
147
Internal fault: Flame bias out of range 5
Contact the qualified service technician.
L
148
Internal fault: Flame bias out of range 6
Contact the qualified service technician.
L
64
Servicing should only be performed by a Qualified Service Agent
CODE
DESCRIPTION
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
NOTE
149
Flame detected
OEM Specific.
1. Holds if flame detected during Safe Start check
up to Flame Establishing period.
H or L
150
Flame not detected
OEM Specific.
1. Sequence returns to standby and restarts
sequence at the beginning of Purge after the HF
switch opens. If flame detected during Safe Start
check up to Flame Establishing period.
H
151
High fire switch ON
OEM Specific.
1. Check wiring and correct any potential wiring
errors.
2. Check High Fire Switch to assure proper function
(not welded or jumpered).
3. Manually drive the motor to the High Fire position
and adjust the HF switch while in this position
and verify voltage through the switch to the HFS
input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
H or L
152
Combustion pressure ON
H or L
153
Combustion pressure Off
OEM Specific.
1. Check wiring and correct any errors.
2. Inspect the Combustion Pressure Switch to make
sure it is working correctly.
3. Reset and sequence the relay module.
4. During STANDBY and PREPURGE, measure
the voltage between Terminal J6-5 and L2 (N).
Supply voltage should be present. If not, the
lockout switch is defective and needs replacing.
5. If the fault persists, replace the relay module.
154
Purge Fan switch On
H or L
155
Purge Fan switch Off
OEM Specific.
1. Purge fan switch is on when it should be off.
156
Combustion pressure and Flame ON
157
Combustion pressure and Flame OFF
158
Main valve ON
159
Main valve OFF
160
Ignition ON
161
Ignition OFF
162
Pilot valve ON
163
Pilot valve OFF
H or L
H
OEM Specific.
H or L
1. Check that flame is not present in the combustion L
chamber. Correct any errors.
2. Make sure that the flame detector is wired to the
correct terminal.
3. Make sure the F & G wires are protected from
stray noise pickup.
4. Reset and sequence the module, if code
reappears, replace the flame detector.
OEM Specific.
L
1. Check Main Valve terminal wiring and correct any L
errors.
2. Reset and sequence the module. If fault persist,
replace the module.
OEM Specific.
1. Check Ignition terminal wiring and correct any
errors.
2. Reset and sequence the module. If fault persist,
replace the module.
L
OEM Specific.
1. Check Pilot Valve terminal wiring and correct any
errors.
2. Reset and sequence the module. If fault persist,
replace the module.
L
Servicing should only be performed by a Qualified Service Agent
L
L
65
CODE
DESCRIPTION
164
Block intake ON
165
Block intake OFF
166-171
RESERVED
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
NOTE
OEM Specific.
1. Check wiring and correct any errors.
2. Inspect the Block Intake Switch to make sure it is
working correctly.
3. Reset and sequence the module.
4. During Standby and Purge, measure the voltage
across the switch. Supply voltage should
be present. If not, the Block Intake Switch is
defective and needs replacing.
5. If the fault persists, replace the relay module.
L
Internal Fault.
1. Reset Module.
2. If fault repeats, replace module.
L
L
Feedback
172
Main relay feedback incorrect
173
Pilot relay feedback incorrect
174
Safety relay feedback incorrect
175
Safety relay open
L
176
Main relay ON at safe start check
L
177
Pilot relay ON at safe start check
L
178
Safety relay ON at safe start check
L
179-183
RESERVED
L
L
Parameter Faults
184
Invalid BLOWER/HSI output setting
185
Invalid Delta T limit enable setting
186
Invalid Delta T limit response setting
187
Invalid DHW high limit enable setting
188
Invalid DHW high limit response setting
L
189
Invalid Flame sensor type setting
L
190
Invalid interrupted air switch enable setting
L
191
Invalid interrupted air switch start check enable
setting
L
192
Invalid igniter on during setting
L
193
Invalid ignite failure delay setting
L
194
Invalid ignite failure response setting
195
Invalid ignite failure retries setting
196
Invalid ignition source setting
197
Invalid interlock open response setting
198
Invalid interlock start check setting
L
199
Invalid LCI enable setting
L
200
Invalid lightoff rate setting
L
201
Invalid lightoff rate proving setting
L
202
Invalid Main Flame Establishing Period time
L
203
Invalid MFEP flame failure response setting
L
204
Invalid NTC sensor type setting
L
205
Invalid Outlet high limit response setting
L
206
Invalid Pilot Flame Establishing Period setting
L
207
Invalid PII enable setting
L
208
Invalid pilot test hold setting
L
209
Invalid Pilot type setting
L
210
Invalid Postpurge time setting
L
211
Invalid Power up with lockout setting
L
66
1. Return to Configuration mode and recheck
selected parameters, reverify and reset module.
2. If fault repeats, verify electrical grounding.
3. If fault repeats, replace module.
1. Return to Configuration mode and recheck
selected parameters, reverify and reset module.
2. If fault repeats, verify electrical grounding.
3. If fault repeats, replace module.
Servicing should only be performed by a Qualified Service Agent
L
L
L
L
L
L
L
L
CODE
DESCRIPTION
RECOMMENDED TROUBLESHOOTING OF
LOCKOUT CODES
1. Return to Configuration mode and recheck
selected parameters, reverify and reset module.
2. If fault repeats, verify electrical grounding.
3. If fault repeats, replace module.
NOTE
212
Invalid Preignition time setting
213
Invalid Prepurge rate setting
214
Invalid Prepurge time setting
215
Invalid Purge rate proving setting
216
Invalid Run flame failure response setting
L
217
Invalid Run stabilization time setting
L
218
Invalid Stack limit enable setting
L
219
Invalid Stack limit response setting
L
220
Unconfigured Delta T limit setpoint setting
L
221
Unconfigured DHW high limit setpoint setting
L
222
Unconfigured Outlet high limit setpoint setting
L
223
Unconfigured Stack limit setpoint setting
L
224
Invalid DHW demand source setting
L
225
Invalid Flame threshold setting
L
226
Invalid Outlet high limit setpoint setting
L
227
Invalid DHW high limit setpoint setting
L
228
Invalid Stack limit setpoint setting
L
229
Invalid Modulation output setting
L
230
Invalid CH demand source setting
L
231
Invalid Delta T limit delay setting
L
232
Invalid Pressure sensor type setting
L
233
Invalid IAS closed response setting
L
234
Invalid Outlet high limit enable setting
Contact the qualified service technician.
L
235
Invalid Outlet connector type setting
Contact the qualified service technician.
L
236
Invalid Inlet connector type setting
Contact the qualified service technician.
L
237
Invalid DHW connector type setting
Contact the qualified service technician.
L
238
Invalid Stack connector type setting
Contact the qualified service technician.
L
239
Invalid S2 (J8-6) connector type setting
Contact the qualified service technician.
L
240
Invalid S5 (J8-11) connector type setting
Contact the qualified service technician.
L
241
Exchanger sensor not allowed with stack
connector setting
Not Applicable.
L
242
Invalid DHW auto detect configuration
Not Applicable.
L
243
Invalid UV with spark interference not compatible
with Ignitor on throughout PFEP
Contact the qualified service technician.
L
244
Internal fault: Safety relay test invalid state
Contact the qualified service technician.
L
245
Invalid Outlet connector type setting for Trise
Contact the qualified service technician.
L
246
4-20mA cannot be used for both modulation and
setpoint control
Contact the qualified service technician.
L
247
Invalid ILK bounce detection enable
Not Applicable.
L
248
Invalid forced recycle interval
Not Applicable.
L
249
STAT cannot be demand source when Remote
Stat is enabled
Not Applicable.
L
250
Invalid Fan speed error response
1. Check fan cables secured properly. If fault
persists contact the qualified service technician.
L
251-255
RESERVED
Servicing should only be performed by a Qualified Service Agent
L
L
L
L
67
Table 13. ALERTS
CODE
DESCRIPTION
CODE
DESCRIPTION
37
Program Module application parameter revision
differs from application processor
Alert PCB was restored from factory defaults
38
2
Safety configuration parameters were restored
from factory defaults
Program Module safety parameter revision differs
from safety processor
39
3
Configuration parameters were restored from
factory defaults
PCB incompatible with product contained in
Program Module
40
4
Invalid Factory Invisibility PCB was detected
Parameter PCB in Program Module is too large for
product
5
Invalid Factory Range PCB was detected
41
6
Invalid range PCB record has been dropped
Range PCB in Program Module was too large for
product
7
EEPROM lockout history was initialized
42
Alert PCB in Program Module was too large for
product
8
Switched application annunciation data blocks
43
IAS start check was forced on due to IAS enabled
9
Switched application configuration data blocks
10
Configuration was restored from factory defaults
44
Low voltage was detected in safety processor
11
Backup configuration settings was restored from
active configuration
45
High line frequency occurred
Annunciation configuration was restored from
factory defaults
46
Low line frequency occurred
47
Invalid subsystem reset request occurred
48
Write large enumerated Modbus register value
was not allowed
49
Maximum cycle count was reached
50
Maximum hours count was reached
51
Illegal Modbus write was attempted
52
Modbus write attempt was rejected (NOT
ALLOWED)
53
Illegal Modbus read was attempted
54
Safety processor brown-out reset occurred
55
Application processor watchdog reset occurred
56
Application processor brown-out reset occurred
57
Safety processor watchdog reset occurred
58
Alarm was reset by the user at the control
EE Management Faults
0
None (No alert)
1
12
13
Annunciation configuration was restored from
backup
14
Safety group verification table was restored from
factory defaults
15
Safety group verification table was updated
16
Invalid Parameter PCB was detected
17
Invalid Range PCB was detected
System Parameter Errors
System Operation Faults
18
Alarm silence time exceeded maximum
19
Invalid safety group verification table was detected
20
Backdoor Password could not be determined
21
Invalid safety group verification table was not
accepted
22
CRC errors were found in application configuration
data blocks
59
Burner control firing rate was > absolute max rate
23
Backup Alert PCB was restored from active one
60
Burner control firing rate was < absolute min rate
24
RESERVED
61
Burner control firing rate was invalid, % vs. RPM
25
Lead Lag operation switch was turned OFF
62
Burner control was firing with no fan request
26
Lead Lag operation switch was turned ON
63
27
Safety processor was reset
Burner control rate (nonfiring) was > absolute max
rate
28
Application processor was reset
64
29
Burner switch was turned OFF
Burner control rate (nonfiring) was < absolute min
rate
30
Burner switch was turned ON
65
Burner control rate (nonfiring) was absent
31
Program Module (PM) was inserted into socket
66
32
Program Module (PM) was removed from socket
Burner control rate (nonfiring) was invalid, %
vs.RPM
33
Alert PCB was configured
67
Fan off cycle rate was invalid, % vs. RPM
34
Parameter PCB was configured
68
Setpoint was overridden due to sensor fault
35
Range PCB was configured
69
Modulation was overridden due to sensor fault
36
Program Module (PM) incompatible with product
was inserted into socket
70
No demand source was set due to demand priority
conflicts
71-73
RESERVED
68
Demand/Rate Command Faults
Servicing should only be performed by a Qualified Service Agent
CODE
DESCRIPTION
Fan Parameter Errors
74
Periodic Forced Recycle
75
Absolute max fan speed was out of range
76
Absolute min fan speed was out of range
77
Fan gain down was invalid
78
Fan gain up was invalid
79
Fan minimum duty cycle was invalid
80
Fan pulses per revolution was invalid
81
Fan PWM frequency was invalid
82-83
RESERVED
Modulation Parameter Errors
84
Lead Lag CH 4-20mA water temperature setting
85
No Lead Lag add stage error threshold was
configured
86
No Lead Lag add stage detection time was
configured
87
No Lead Lag drop stage error threshold was
configured
88
No Lead Lag drop stage detection time was
configured
89
RESERVED
90
Modulation output type was invalid
91
Firing rate control parameter was invalid
92
Forced rate was out of range vs. min/max
modulation
93
Forced rate was invalid, % vs. RPM
94
Slow start ramp value was invalid
95
Slow start degrees value was invalid
96
Slow start was ended due to outlet sensor fault
97
Slow start was end due to reference setpoint fault
98
CH max modulation rate was invalid, % vs. RPM
99
CODE
114
DESCRIPTION
MIX modulation range (max minus min) was too
small (< 4% or 40 RPM)
Modulation Operation Faults
115
Fan was limited to its minimum duty cycle
116
Manual rate was > CH max modulation rate
117
Manual rate was > DHW max modulation rate
118
Manual rate was < min modulation rate
119
Manual rate in Standby was > absolute max rate
120
Modulation commanded rate was > CH max
modulation rate
121
Modulation commanded rate was > DHW max
modulation rate
122
Modulation commanded rate was < min
modulation rate
123
Modulation rate was limited due to outlet limit
124
Modulation rate was limited due to Delta-T limit
125
Modulation rate was limited due to stack limit
126
Modulation rate was limited due to
anticondensation
127
Fan Speed out of range in RUN
128
Modulation rate was limited due to IAS was open
129
Slow start ramp setting of zero will result in no
modulation rate change
130
No forced rate was configured for slow start ramp
CH parameter Errors
131
CH demand source was invalid
132
CH P-gain was invalid
133
CH I-gain was invalid
134
CH D-gain was invalid
135
CH OFF hysteresis was invalid
136
CH ON hysteresis was invalid
CH max modulation rate was > absolute max rate
137
CH sensor type was invalid
100
CH modulation range (max minus min) was too
small (< 4% or 40 RPM)
138
CH hysteresis step time was invalid
139
CH remote control parameter was invalid
101
DHW max modulation rate was invalid, % vs.RPM
140
CH ODR not allowed with remote control
102
DHW max modulation rate was > absolute max
rate
141
Steam P-gain was invalid
103
DHW modulation range (max minus min) was too
small (< 4% or 40 RPM)
142
Steam I-gain was invalid
143
Steam D-gain was invalid
144
Steam OFF hysteresis was invalid
145
Steam ON hysteresis was invalid
104
Min modulation rate was < absolute min rate
105
Min modulation rate was invalid, % vs. RPM
106
Manual rate was invalid, % vs. RPM
107
Slow start enabled, but forced rate was invalid
108
Analog output hysteresis was invalid
109
Analog modulation output type was invalid
110
IAS open rate differential was invalid
111
IAS open step rate was invalid
112
MIX max modulation rate was invalid, % vs. RPM
113
MIX max modulation rate was >absolute max or <
absolute min rates
CH Operation Faults
146
CH control was suspended due to fault
147
CH header temperature was invalid
148
CH outlet temperature was invalid
149
CH steam pressure was invalid
CH Parameter errors (continued)
150
Steam setpoint source parameter was invalid
151
Minimum water temperature parameter was
greater than setpoint
Servicing should only be performed by a Qualified Service Agent
69
CODE
DESCRIPTION
CODE
DESCRIPTION
152
Minimum water temperature parameter was
greater than time of day setpoint
191
Lead Lag base load common setting was invalid
153
Minimum pressure parameter was greater than
setpoint
192
Lead Lag DHW demand switch setting was
193
Lead Lag Mix demand switch setting was invalid
154
Minimum pressure parameter was greater than
time of day setpoint
194
Lead Lag modulation sensor setting was invalid
195
155
CH modulation rate source parameter was invalid
Lead Lag backup modulation sensor setting was
invalid
156
Steam modulation rate source parameter was
invalid
196
Lead Lag slave mode setting was invalid
197
Lead Lag rate allocation setting was invalid
198
Lead selection setting was invalid
199
Lag selection setting was invalid
200
Lead Lag slave return setting was invalid
201
Lead Lag add stage method setting was invalid
202
STAT may not be a Lead Lag CH demand source
when Remote Stat is enabled
203
Lead Lag base load rate setting was invalid
DHW Parameter Errors
157
DHW demand source was invalid
158
DHW P-gain was invalid
159
DHW I-gain was invalid
160
DHW D-gain was invalid
161
DHW OFF hysteresis was invalid
162
DHW ON hysteresis was invalid
163
DHW hysteresis step time was invalid
164
DHW sensor type was invalid
165
Inlet sensor type was invalid for DHW
166
Outlet sensor type was invalid for DHW
167
DHW Storage OFF hysteresis was invalid
168
DHW Storage ON hysteresis was invalid
169
DHW modulation sensor type was invalid
170
DHW modulation sensor was not compatible for
AUTO mode
DHW Operation Faults
Lead Lag Operation Faults
204
Lead Lag master was suspended due to fault
205
Lead Lag slave was suspended due to fault
206
Lead Lag header temperature was invalid
207
Lead Lag was suspended due to no enabled
Program Module installed
208
Lead Lag slave session has timed out
209
Too many Lead Lag slaves were detected
210
Lead Lag slave was discovered
211
Incompatible Lead Lag slave was discovered
212
No base load rate was set for Lead Lag slave
213
Lead Lag slave unable to fire before demand to
fire delay expired
214
Adding Lead Lag slave aborted due to add
requirement change
171
DHW control was suspended due to fault
172
DHW temperature was invalid
173
DHW inlet temperature was invalid
174
DHW outlet temperature was invalid
175
DHW high limit must be disabled for AUTO mode
215
No Lead Lag slaves available to service demand
176
DHW sensortype was not compatible for AUTO
mode
216
No Lead Lag active service was set due to
demand priority conflicts
177
DHW priority source setting was invalid
217
No Lead Lag add stage method was specified
178
DHW priority method setting was invalid
218
No Lead Lag drop stage method was specified
CH Operation Faults (continued)
219
Using backup lead lag header sensor due to
sensor failure
179
CH S5 (J8 terminal 11) sensor was invalid
180
CH inlet temperature was invalid
181
CH S10 (J10 terminal 7) sensor was invalid
182
Lead Lag CH setpoint source was invalid
Lead Lag Parameter errors
183
Lead Lag P-gain was invalid
184
Lead Lag I-gain was invalid
185
Lead Lag D-gain was invalid
186
Lead Lag OFF hysteresis was invalid
187
Lead Lag ON hysteresis was invalid
188
Lead Lag slave enable was invalid
189
Lead Lag hysteresis step time was invalid
190
No Lead lag Modbus port was assigned
70
Frost Protection Faults
220
Lead Lag frost protection rate was invalid
221
Lead Lag drop stage method setting was invalid
222
CH frost protection temperature was invalid
223
CH frost protection inlet temperature was invalid
224
DHW frost protection temperature was invalid
225-226
RESERVED
227
DHW priority override time was not derated due to
invalid outdoor temperature
228
Warm weather shutdown was not checked due to
invalid outdoor temperature
229
Lead Lag slave communication timeout
230
RESERVED
Servicing should only be performed by a Qualified Service Agent
CODE
DESCRIPTION
231
Lead Lag CH setpoint was invalid
232
Lead Lag CH time of day setpoint was invalid
233
LL outdoor temperature was invalid
234
Lead Lag ODR time of day setpoint was invalid
235
Lead Lag ODR time of day setpoint exceeded
normal setpoint
236
Lead Lag ODR max outdoor temperature was
invalid
237
Lead Lag ODR min outdoor temperature was
invalid
238
CODE
DESCRIPTION
274
Abnormal Recycle: Demand off during Pilot Flame
Establishing Period
275
Abnormal Recycle: LCI off during Drive to Purge
Rate
276
Abnormal Recycle: LCI off during Measured Purge
Time
277
Abnormal Recycle: LCI off during Drive to Lightoff
Rate
278
Abnormal Recycle: LCI off during Pre-Ignition test
279
Abnormal Recycle: LCI off during Pre-Ignition time
Lead Lag ODR low water temperature was invalid
280
239
Lead Lag ODR outdoor temperature range was
too small (minimum 12°C/22°F)
Abnormal Recycle: LCI off during Main Flame
Establishing Period
281
Abnormal Recycle: LCI off during Ignition period
240
Lead Lag ODR water temperature range was too
too small (minimum 12°C/22°F)
282
Abnormal Recycle: Demand off during Drive to
Purge Rate
241
Lead Lag DHW setpoint was invalid
283
242
Lead Lag Mix setpoint was invalid
Abnormal Recycle: Demand off during Measured
Purge Time
243
Lead Lag CH demand switch was invalid
284
244
Lead Lag CH setpoint source was invalid
Abnormal Recycle: Demand off during Drive to
Lightoff Rate
245
RESERVED
285
Abnormal Recycle: Demand off during Pre-Ignition
test
246
CH setpoint was invalid
286
247
CH time of day setpoint was invalid
Abnormal Recycle: Demand off during Pre-Ignition
time
248
CH outdoor temperature was invalid
287
249
CH ODR time of day setpoint was invalid
Abnormal Recycle: Flame was on during Safe
Check
250
CH ODR time of day setpoint exceeds normal
setpoint
288
Abnormal Recycle: Flame was on during Drive to
Purge Rate
251
CH max outdoor setpoint was invalid
289
252
CH min outdoor setpoint was invalid
Abnormal Recycle: Flame was on during
Measured Purge Time
253
CH min water setpoint was invalid
290
Abnormal Recycle: Flame was on during Drive to
Lightoff Rate
254
CH outdoor temperature range was too small
291
255
CH water temperature range was too small
Abnormal Recycle: Flame was not on at end of
Ignition period
256
Steam setpoint was invalid
292
257
Steam time of day setpoint was invalid
Abnormal Recycle: Flame was lost during Main
Flame Establishing Period
258
Steam minimum pressure was invalid
293
Abnormal Recycle: Flame was lost early in Run
259
CH ODR min water temperature was invalid
294
Abnormal Recycle: Flame was lost during Run
260
RESERVED
295
Abnormal Recycle: Leakage test failed
261
DHW setpoint was invalid
296
Abnormal Recycle: Interrupted air flow switch was
off during Drive to Purge Rate
262
DHW time of day setpoint was invalid
297
263
DHW storage setpoint was invalid
Abnormal Recycle: Interrupted air flow switch was
off during Measured Purge Time
264
STAT may not be a DHW demand source when
Remote Stat is enabled
298
Abnormal Recycle: Interrupted air flow switch was
off during Drive to Lightoff Rate
265-266
RESERVED
299
267
STAT may not be a CH demand source when
Remote Stat is enabled
Abnormal Recycle: Interrupted air flow switch was
off during Pre-Ignition test
300
268
CH 4mA water temperature setting was invalid
Abnormal Recycle: Interrupted air flow switch was
off during Pre-Ignition time
269
CH 20mA water temperature setting was invalid
301
270
Steam 4mA water temperature setting was invalid
Abnormal Recycle: Interrupted air flow switch was
off during Main Flame Establishing Period
271
Steam 20mA water temperature setting was invalid
302
Abnormal Recycle: Ignition failed due to
interrupted air flow switch was off
272
Abnormal Recycle: Pressure sensor fault
303
273
Abnormal Recycle: Safety relay drive test failed
Abnormal Recycle: ILK off during Drive to Purge
Rate
Servicing should only be performed by a Qualified Service Agent
71
CODE
DESCRIPTION
CODE
DESCRIPTION
304
Abnormal Recycle: ILK off during Measured Purge
Time
341
Abnormal Recycle: Hardware SLO electronics
305
Abnormal Recycle: ILK off during Drive to Lightoff
Rate
342
Abnormal Recycle: Hardware processor clock
343
Abnormal Recycle: Hardware AC phase
306
Abnormal Recycle: ILK off during Pre-Ignition test
344
Abnormal Recycle: Hardware A2D mismatch
307
Abnormal Recycle: ILK off during Pre-Ignition time
345
Abnormal Recycle: Hardware VSNSR A2D
308
Abnormal Recycle: ILK off during Main Flame
Establishing Period
346
Abnormal Recycle: Hardware 28V A2D
347
Abnormal Recycle: Hardware HFS IAS shorted
309
Abnormal Recycle: ILK off during Ignition period
348
Abnormal Recycle: Hardware PII INTLK shorted
310
Run was terminated due to ILK was off
349
Abnormal Recycle: Hardware HFS LCI shorted
311
Run was terminated due to interrupted air flow
switch was off
350
Abnormal Recycle: Hardware HFS LFS shorted
351
Abnormal Recycle: Invalid zero crossing
312
Stuck reset switch
352
Abnormal Recycle: fault stack sensor
313
Run was terminated due to fan failure
353
Abnormal Recycle: stack limit
314
Abnormal Recycle: Fan failed during Drive to
Purge Rate
354
Abnormal Recycle: delta T limit
315
Abnormal Recycle: Fan failed during Measured
Purge Time
355
Abnormal Recycle: fault outlet sensor
356
Abnormal Recycle: outlet high limit
357
Abnormal Recycle: fault DHW sensor
358
Abnormal Recycle: DHW high limit
359
Abnormal Recycle: fault inlet sensor
360
Abnormal Recycle: Check Parameters Failed
316
Abnormal Recycle: Fan failed during Drive to
Lightoff Rate
317
Abnormal Recycle: Fan failed during Pre-Ignition
test
318
Abnormal Recycle: Fan failed during Pre-Ignition
time
319
Abnormal Recycle: Fan failed during Ignition
period
320
Abnormal Recycle: Fan failed during Main Flame
Establishing Period
321
Internal Errors
361
Internal error: No factory parameters were
detected in control
362
Internal error: PID iteration frequency was invalid
363
Abnormal Recycle: Main Valve off after 10
seconds of RUN
Internal error: Demand-Rate interval time was
invalid
364
322
Abnormal Recycle: Pilot Valve off after 10 seconds
of RUN
Internal error: Factory calibration parameter for
modulation was invalid
365
Internal error: CH PID P-scaler was invalid
323
Abnormal Recycle: Safety Relay off after 10
seconds of RUN
366
Internal error: CH PID I-scaler was invalid
367
Internal error: CH PID D-scaler was invalid
324
Abnormal Recycle: Hardware flame bias
368
Internal error: DHW PID P-scaler was invalid
325
Abnormal Recycle: Hardware static flame
369
Internal error: DHW PID I-scaler was invalid
326
Abnormal Recycle: Hardware flame current invalid
370
Internal error: DHW PID D-scaler was invalid
327
Abnormal Recycle: Hardware flame rod short
371
328
Abnormal Recycle: Hardware invalid power
Internal error: Lead Lag master PID P-scaler was
invalid
329
Abnormal Recycle: Hardware invalid AC line
372
330
Abnormal Recycle: Hardware SLO flame ripple
Internal error: Lead Lag master PID I-scaler was
invalid
330
Abnormal Recycle: Hardware SLO flame sample
373
Internal error: Lead Lag master PID D-scaler was
invalid
332
Abnormal Recycle: Hardware SLO flame bias
range
374
Abnormal Recycle: Hardware flame bias high
333
Abnormal Recycle: Hardware SLO flame bias heat
375
Abnormal Recycle: Hardware flame bias low
334
Abnormal Recycle: Hardware SLO spark stuck
376
Abnormal Recycle: Hardware flame bias delta high
335
Abnormal Recycle: Hardware SLO spark changed
377
Abnormal Recycle: Hardware flame bias delta low
336
Abnormal Recycle: Hardware SLO static flame
378
Abnormal Recycle: Hardware flame bias dynamic
high
337
Abnormal Recycle: Hardware SLO rod shorted
379
338
Abnormal Recycle: Hardware SLO AD linearity
Abnormal Recycle: Hardware flame bias dynamic
low
339
Abnormal Recycle: Hardware SLO bias not set
380
Abnormal Recycle: Fan Speed Not Proven
340
Abnormal Recycle: Hardware SLO bias shorted
381
Abnormal Recycle: Fan Speed Range Low
72
Servicing should only be performed by a Qualified Service Agent
CODE
DESCRIPTION
CODE
DESCRIPTION
382
Abnormal Recycle: Fan Speed Range High
482
Internal error: Safety key bit 4 was incorrect
383-450
RESERVED
483
Internal error: Safety key bit 5 was incorrect
Circulator Errors
484
Internal error: Safety key bit 6 was incorrect
451
Circulator control was invalid
485
Internal error: Safety key bit 7 was incorrect
452
Circulator P-gain was invalid
486
Internal error: Safety key bit 8 was incorrect
453
Circulator I-gain was invalid
487
Internal error: Safety key bit 9 was incorrect
454
Circulator temperature was invalid
488
Internal error: Safety key bit 10 was incorrect
455
Circulator outlet temperature was invalid
489
Internal error: Safety key bit 11 was incorrect
456
Circulator inlet temperature was invalid
490
Internal error: Safety key bit 12 was incorrect
457
Circulator outdoor temperature was invalid
491
Internal error: Safety key bit 13 was incorrect
458
Circulator sensor choice was invalid
492
Internal error: Safety key bit 14 was incorrect
459
Circulator PID setpoint was invalid
493
Internal error: Safety key bit 15 was incorrect
Debug Faults
494
Internal error: Safety relay timeout
460
LCI lost in run
495
Internal error: Safety relay commanded off
461
Abnormal Recycle: Demand lost in run from
application
496
Internal error: Unknown safety error occurred
462
Abnormal Recycle: Demand lost in run due to high
limit
497
Internal error: Safety timer was corrupt
498
Internal error: Safety timer was expired
463
Abnormal Recycle: Demand lost in run due to no
flame
499
Internal error: Safety timings
500
Internal error: Safety shutdown
RESERVED
464
LCI lost in Combustion Pressure Establishing
Period
501
465
LCI lost in Combustion Pressure Stabilization
Period
502
Mix setpoint was invalid
466
RESERVED
503
Mix time of day setpoint was invalid
504
Mix outdoor temperature was invalid
505
Mix ODR time of day setpoint was invalid
506
Mix ODR time of day setpoint exceeds normal
setpoint
Internal Data Faults
MIX Errors
467
Internal error: EEPROM write was attempted
before EEPROM was initialized
468
Internal error: EEPROM cycle count address was
invalid
507
Mix ODR max outdoor temperature was invalid
469
Internal error: EEPROM days count address was
invalid
508
Mix ODR min outdoor temperature was invalid
509
Mix ODR low water temperature was invalid
Mix ODR outdoor temperature range was invalid
470
Internal error: EEPROM hours count address was
invalid
510
511
Mix ODR water temperature range was invalid
471
Internal error: Lockout record EEPROM index was
invalid
512
Mix demand switch was invalid
Internal error: Request to write PM status was
invalid
513
Mix ON hysteresis was invalid
514
Mix OFF hysteresis was invalid
515
Mix ODR min water temperature was invalid
516
Mix hysteresis step time was invalid
517
Mix P-gain was invalid
Mix I-gain was invalid
472
473
Internal error: PM parameter address was invalid
474
Internal error: PM safety parameter address was
invalid
475
Internal error: Invalid record in lockout history was
removed
518
519
Mix D-gain was invalid
476
Internal error: EEPROM write buffer was full
520
Mix control was suspended due to fault
477
Internal error: Data too large was not written to
EEPROM
521
Mix S10 (J10-7) temperature was invalid
478
Internal error: Safety key bit 0 was incorrect
522
Mix outlet temperature was invalid
479
Internal error: Safety key bit 1 was incorrect
523
Mix inlet temperature was invalid
480
Internal error: Safety key bit 2 was incorrect
524
Mix S5 (J8-11) temperature was invalid
481
Internal error: Safety key bit 3 was incorrect
525
Mix modulation sensor type was invalid
526
Mix ODR min water temperature setpoint was
invalid
Servicing should only be performed by a Qualified Service Agent
73
CODE
DESCRIPTION
CODE
DESCRIPTION
527
Mix circulator sensor was invalid
571
Heat exchanger high limit response was invalid
528
Mix flow control was invalid
572
Heat exchanger high limit was exceeded
529
Mix temperature was invalid
573
530
Mix sensor was invalid
Heat exchanger high limit wasn't allowed due to
stack limit setting
531
Mix PID setpoint was invalid
574
532
STAT may not be a Mix demand source when
Remote Stat is enabled
Heat exchanger high limit wasn't allowed due to
stack connector setting
575
533-539
RESERVED
Heat exchanger high limit delay was not
configured for recycle response
540
Delta T inlet/outlet enable was invalid
541
Delta T exchanger/outlet enable was invalid
542
Delta T inlet/exchanger enable was invalid
543
Delta T inlet/outlet degrees was out of range
544
Delta T exchanger/outlet degrees was out of range
545
Delta T inlet/exchanger degrees was out of range
546
Delta T response was invalid
547
Delta T inversion limit response was invalid
548
Delta T rate limit enable was invalid
549
Delta T exchanger/outlet wasn't allowed due to
stack limit setting
Pump Errors
576
CH pump output was invalid
577
DHW pump output was invalid
578
Boiler/water heater pump output was invalid
579
Auxiliary pump output was invalid
580
System pump output was invalid
581
Mix pump output was invalid
582-589
RESERVED
DHW Plate Heat Exchanger Errors
590
DHW plate preheat setpoint was invalid
591
DHW plate preheat ON hysteresis was invalid
592
DHW plate preheat OFF hysteresis was invalid
593
Tap detect degrees was out of range
594
Tap detect ON hysteresis was invalid
595
Inlet - DHW tap stop degrees was out of range
596
Outlet - Inlet tap stop degrees was out of range
550
Delta T inlet/outlet limit was exceeded
551
Delta T exchanger/outlet limit was exceeded
552
Delta T inlet/exchanger limit was exceeded
553
Inlet/outlet inversion occurred
554
Exchanger/outlet inversion occurred
555
Inlet/exchanger inversion occurred
597
DHW tap detect on threshold was invalid
556
Delta T exchanger/outlet wasn't allowed due to
stack connector setting
598
DHW plate preheat detect on threshold was invalid
599
DHW plate preheat detect off threshold was invalid
557
Delta T inlet/exchanger wasn't allowed due to
stack limit setting
558
Delta T inlet/exchanger wasn't allowed due to
stack connector setting
559
Delta T delay was not configured for recycle
response
T Rise Errors
560
Outlet T-rise enable was invalid
561
Heat exchanger T-rise enable was invalid
562
T-rise degrees was out of range
563
T-rise response was invalid
564
Outlet T-rise limit was exceeded
565
Heat exchanger T-rise limit was exceeded
566
Heat exchanger T-rise wasn't allowed due to stack
limit setting
567
Heat exchanger T-rise wasn't allowed due to stack
connector setting
568
Outlet T-rise wasn't allowed due to outlet
connector setting
569
T-rise delay was not configured for recycle
response
Heat Exchanger High Limit Errors
570
74
Heat exchanger high limit setpoint was out of
range
Servicing should only be performed by a Qualified Service Agent
Servicing should only be performed by a Qualified Service Agent
AIR SEPARATOR
MODEL
XB-1000
XB-1300
XB-1700
XB-2000
XB-1600
XB-3400
EXPANSION
TANK
INLET DIA.
2”
2”
2.5”
3”
3”
4”
MAKE-UP
WATER
Figure 55. PRIMARY/SECONDARY PIPING SYSTEM
SYSTEM RETURN
WATER FLOW SWITCH
TEMPERATURE GAGE
CHECK VALVE
FULL PORT BALL VALVE
FINISHED FLOOR
SECONDARY BOILER PUMP - OPTIONAL
LOOP TEMPERATURE PROBE
DRAIN
TANK TEMPERATURE CONTROL
CIRCULATING PUMP
PRESSURE RELIEF VALVE
TEMPERATURE & PRESSURE
RELIEF VALVE
PLACES TEES AS CLOSE TOGETHER AS PRACTICAL
OUTLET DIA.
2”
2”
2.5”
3”
3”
4”
NOTES:
1. Preferred piping diagram.
2. The temperature and pressure relief valve setting shall not exceed pressure rating of any component in the system.
3. Service valves are shown for servicing unit. However, local codes shall govern their usage.
4. The boiler is shown with the optional factory installed and sized secondary boiler pump that is available on all XB models.
SYSTEM PUMP
SYSTEM SUPPLY
WARNING: THIS DRAWING SHOWS SUGGESTED
PIPING CONFIGURATION AND OTHER DEVICES;
CHECK WITH LOCAL CODES AND ORDINANCES
FOR ADDITIONAL REQUIREMENTS.
XB BOILERS (1000-3400) - ONE BOILER PRIMARY / SECONDARY HYDRONIC
PIPING SYSTEM
LEGEND
PIPING DIAGRAMS
75
Figure 56. HOT WATER SUPPLY WATER HEATER WITH VERTICAL TANK
76
Servicing should only be performed by a Qualified Service Agent
NOTES
Servicing should only be performed by a Qualified Service Agent
77
NOTES
78
Servicing should only be performed by a Qualified Service Agent
NOTES
Servicing should only be performed by a Qualified Service Agent
79
25589 Highway 1, McBee, SC 29101
Technical Support: 800-527-1953 • Parts: 800-433-2545 • Fax: 800-644-9306
www.hotwater.com
Copyright © 2013 A. O. Smith Water Heater Company, All rights reserved.