Condensing Water Heater Service Manual 8 100000354
73
Burner Sensor Circuit
Check sensor wiring and PC board to be sure they have not been damaged.
Replace sensor.
79
Water Leakage Detected Turn off water and gas supply.
Disconnect power to the unit.
Inspect the unit for leak.
Dry area around moisture sensing element.
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. Hard water must be treated to prevent
scale build up or damage to the heat exchanger.
Replace heat exchanger.
NOTE: The LC code is the only code that will allow the unit to keep running. The display will
alternate between the LC code and the temperature setting. The controller will continue to beep.
FF
Maintenance Performed Indicates a service provider performed maintenance or repair. Enter this code by pressing up,
down, and ON/OFF simultaneously.
No
code
Nothing happens when
water flow is activated.
On controller, verify if unit is sensing flow. If not then check the items below. If unit is
sensing flow then check the heat exchanger and outlet thermistors.
Clean inlet water supply filter.
On new installations ensure hot and cold water lines are not reversed.
Check for cold to hot cross over. Isolate circulating system if present. Turn off cold water to the
unit, open pressure relief valve; if water continues to flow, there is bleed over in your plumbing.
Verify you have at least the minimum flow rate required to fire unit.
Verify turbine spins freely.
Measure the resistance of the water flow control sensor.
If the display is blank and clicking is coming from the unit, disconnect the water flow servo motor.
If the display comes on then replace the water flow servo motor.
Diagnostic Codes
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