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HomeRepair HelpLennox Water Heater RepairLennox Water heater not lighting Repair
Lennox Water heater not lighting
01 - Tripped Limit Switch or Thermostat
Most limit switches are resettable. If the limit switch or thermostat has a reset button on the back you should be able to reset it. If the button is popped out the limit switch or thermostat has tripped. You can try resetting it by pressing the button. You should hear a click when it resets. You can check the limit switch or thermostat for electrical continuity with a multimeter.
Top Solution
02 - Lennox Water Heater Gas Valve and Thermostat Assembly
The gas valve opens to allow gas to enter the burner. If the gas valve does not open, the burner will not light. First, ensure that the ignition source is working properly. Second, ensure that the gas valve has pressure. If the ignition source is working, and the gas valve has pressure, consider replacing the gas valve and thermostat.
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Highly Likely
03 - Remove flammable vapors from the area
Flammable vapors can be drawn into the water heater from paint cans, staining cans, or fuel containers stored too close to the water heater. This can cause the flammable vapor sensor to trip. Make sure any paint cans or other containers that can produce flammable vapors are stored far away from the water heater and vent the area of the water heater if necessary.
Highly Likely
04 - Lennox Water Heater Gas Valve Assembly
The gas valve opens to allow gas to enter the burner. If the gas valve does not open, the burner will not light. First, ensure that the ignition source is working properly. Second, ensure that the gas valve has pressure. If the ignition source is working, and the gas valve has pressure, consider replacing the gas valve assembly.
Common
05 - Lennox Water Heater Temperature Sensor
Flammable vapors should always be kept away from the water heater. If your water heater has a flammable vapor system (FVIR), sometimes identified as a temperature sensor, the sensor may have tripped which will prevent the burner from lighting. It is recommended to replace a tripped sensor rather than reset it. See owner's manual for more information.
Common
06 - Lennox Water Heater Igniter
Some water heaters use an igniter to ignite the gas. If the igniter fails, the burner will not light. To determine if the igniter is defective, first make sure the igniter is getting voltage. If the igniter is getting voltage, but it doesn’t glow, this indicates that the igniter is defective and should be replaced.
Common
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