Why Won’t My Propane Hot Water Heater Stay Lit?

A propane hot water heater that won’t stay lit can be a frustrating issue, but with the right troubleshooting steps, you can often get it back up and running. The most common causes are a faulty thermocouple, a dirty or damaged pilot light assembly, a malfunctioning gas control valve, or a lack of combustible air.

Thermocouple Troubleshooting

The thermocouple is a critical safety device that senses the presence of a flame and shuts off the gas supply if the flame goes out. It consists of two dissimilar metal wires joined at one end, and when heated by the pilot light flame, it generates a small voltage (typically 20-30 millivolts) that keeps the gas control valve open.

To test the thermocouple:

  1. Set your multimeter to the millivolt range.
  2. With the gas valve in the “pilot” position, touch the probes of the multimeter to the terminals of the thermocouple.
  3. If the thermocouple is working properly, you should see a voltage reading between 20-30 millivolts.
  4. If the reading is low or zero, the thermocouple is likely faulty and needs to be replaced.

To replace the thermocouple, follow the instructions in the video linked at the end of this article.

Cleaning the Pilot Light Assembly

why won't my propane hot water heater stay lit

If the pilot light assembly is dirty or clogged, it may not be able to produce a strong enough flame to heat the thermocouple properly. To clean the pilot light assembly:

  1. Turn off the gas valve and wait for the appliance to cool down.
  2. Remove the access panel to expose the burner and pilot light assembly.
  3. Use a wire brush or compressed air to clean the tip of the pilot light and the surrounding area.
  4. Reassemble the appliance and try lighting the pilot light again.

Checking the Gas Control Valve

If the gas control valve is malfunctioning, it may not be able to supply enough gas to the pilot light or the burner. To test the gas control valve:

  1. Turn off the gas valve and wait for the appliance to cool down.
  2. Remove the access panel to expose the gas control valve.
  3. Locate the thermostat knob on the valve and turn it to the “pilot” position.
  4. Press the reset button on the valve (if equipped) and hold it down while lighting the pilot light.
  5. If the pilot light stays lit, turn the thermostat knob to the “on” position and observe the burner. If the burner does not light or goes out shortly after lighting, the gas control valve may be faulty and need to be replaced.

Checking for Adequate Combustible Air

If the appliance is located in a poorly ventilated area, it may not be able to get enough air to support combustion. Make sure the appliance is located in a well-ventilated area and that there is nothing blocking the air intake vents.

By following these troubleshooting steps and addressing any issues with the thermocouple, pilot light assembly, gas control valve, or combustible air, you should be able to get your propane hot water heater back up and running.

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