GSW Pilot Flame / Thermocouple Failure

GSW gas water heater pilot will not light or stay lit (standing pilot models)

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Dirty pilot orifice, Weak or failed thermocouple, Insufficient gas pressure, Drafts blowing out pilot

How to Fix / Troubleshooting

Safety: Turn the gas control knob to OFF and wait at least 5 minutes to clear any accumulated gas before relighting attempts.

  • Clean pilot assembly: Remove the burner access cover. Gently brush the pilot assembly and use compressed air to blow out dust and debris from the pilot orifice.
  • Check thermocouple position: Ensure the thermocouple tip is directly in the pilot flame. Adjust the bracket if needed so the flame engulfs the top 10–13 mm of the tip.
  • Test thermocouple: If the pilot lights but goes out when you release the control knob, the thermocouple is likely weak. Replace it with a GSW-compatible thermocouple kit.
  • Check for drafts: Look for open windows, vents, or furnace blower drafts that may blow out the pilot. Correct airflow issues.
  • Gas supply: If the pilot flame is very small or yellow, have a gas technician check inlet pressure and the gas control valve.
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Repair Difficulty

Medium 3/5

Required Part

Thermocouple
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