10
305, 505, 705 Indoor Manual
Code
Fault
Remedy
14
Thermal Fuse
Check gas type of unit and ensure it matches gas type being used.
Check for restrictions in air flow around unit and vent terminal.
Check for low water flow in a circulating system causing short-cycling.
Ensure dip switches are set to the proper position.
Check for foreign materials in combustion chamber and/or exhaust piping.
Check heat exchanger for cracks and/or separations.
Check heat exchanger surface for hot spots which indicate blockage due to scale build-
up. Refer to instructions in manual for flushing heat exchanger.
Measure resistance of safety circuit.
Ensure high fire and low fire manifold pressure is correct.
Check for improper conversion of product.
16
Over Temperature
Warning
Check for restrictions in air flow around unit and vent terminal.
Check for low water flow in a circulating system causing short-cycling.
Check for foreign materials in combustion chamber and/or exhaust piping.
Check for clogged heat exchanger.
32
Outgoing Water
Temperature Sensor
Fault
Check sensor wiring for damage.
Measure resistance of sensor.
Clean sensor of scale build-up.
Replace sensor.
33
Heat Exchanger
Outgoing Temperature
Sensor Fault
Check sensor wiring for damage.
Measure resistance of sensor.
Clean sensor of scale build-up.
Replace sensor.
34
Combustion Air
Temperature Sensor
Fault
Check for restrictions in air flow around unit and vent terminal.
Check sensor wiring for damage.
Measure resistance of sensor.
Clean sensor of scale build-up.
Ensure fan blade is tight on motor shaft and is in good condition.
Replace sensor.
52
Modulating Solenoid
Valve Signal Abnormal
Check modulating gas solenoid valve wiring harness for loose or damaged terminals.
Measure resistance of valve coil.
61
Combustion Fan
Failure
Ensure fan will turn freely.
Check wiring harness to motor for damaged and/or loose connections.
Measure resistance of motor winding.
71
SV0, SV1, SV2, and
SV3 Solenoid Valve
Circuit Fault
Check wiring harness to all solenoids for damage and/or loose connections.
Measure resistance of each solenoid valve coil.
72
Flame Sensing Device
Fault
Ensure flame rod is touching flame when unit fires.
Check all wiring to flame rod for damage.
Remove flame rod and check for carbon build-up; clean with sand paper.
Check inside burner chamber for any foreign material blocking flame at flame rod.
Measure micro amp output of sensor circuit with flame present.
Replace flame rod.
LC
Scale Build-up in Heat
Exchanger (when
checking maintenance
code history, “00” is
substituted for “LC”)
Flush heat exchanger. Refer to instructions in manual.
Replace heat exchanger.
No
code
Nothing happens when
water flow is activated.
Clean inlet water supply filter.
On new installations ensure hot and cold water lines are not reversed.
Check for bleed over. Isolate unit from building by turning off hot water line to building.
Isolate the circulating system if present. Open your pressure relief valve; if water is
flowing, there is bleed over in your plumbing.
Ensure you have at least the minimum flow rate required to fire unit.
Ensure turbine spins freely.
Measure the resistance of the water flow control sensor.
Check for DC shorts at components.
Error
Code
Table
