Troubleshoot Standing Pilot Gas Water Heater – I am wondering how many people have had issues with lighting their pilot light on their water heater. I am sure it is many as I have responded to calls that turned out to simply going through the proper procedure to light the light and as complex as finding a bad gas valve to get someone’s hot water heater working again. I know it’s frustrating going without hot water especially when you don’t plan on lighting the pilot light and waiting the time it takes for the water heater to heat the water.

Troubleshoot Standing Pilot Gas Water Heater

This is especially true when you need to get to work on time. So you are tired of lighting and relighting the pilot light and you want to fix the water heater problem. First, you have to troubleshoot the standing pilot ignition system for your water heater. To most, it is a simple process but to a homeowner can create a little anxiety and be frustrating. If you are not confident about the troubleshooting process for your standing pilot gas water heater then my best advice is to call an HVAC contractor.

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Troubleshoot Standing Pilot Gas Water Heater

Troubleshoot Standing Pilot Gas Water Heater - How To Light a Pilot Light for water heaters

Pilot Burner

  • First is to make sure you have a gas supply. If you have any other gas appliances test to make you have gas available. Then you check the cut-off valves in the gas piping to make sure no one inadvertently turned a valve off in the gas piping. There should be one near the water heater as required by gas code and another near the gas meter which is outside somewhere. Check to make sure these valves are open. Once you have determined there is a gas supply then next you move to the water heater.
  • The next thing you need to is to follow the instructions for lighting the pilot light. The instructions are usually on the water heater itself near the gas valve. It typically involves turning the gas valve knob to the “Pilot” position and then pressing on the knob, however, each manufacturer can have different procedures for their gas valves and lighting the pilot so follow the instructions. You can also check our page on how to light a pilot light for further instructions if there are none on the water heater. You will also need some matches or a light for this procedure. The best is the long matches or the long lighters to give you extended reach to where the pilot light is located. So you try this and the pilot light stays lit but it has constantly been going out over time and this is the umpteenth time you’ve lit the pilot light.

There are many times the pilot light goes out because of a draft in the room where the pilot is located. Perhaps the water heater is located in a garage and the pilot light goes out when the garage door is opened. Or another door is opened when the light goes out. There are also occasions when high winds will blow down the flue and extinguish the pilot light. Check the top of the flue to make sure it has a rain cap. If you find this is the problem and it is common and frustrating you may have to have a special flue cap installed that will block the wind from causing downdrafts.

How to Troubleshoot Standing Pilot Gas Water Heater - The Thermocouple and Testing

thermocouple provides millivolts to the valve


So you light the pilot and it does not stay lit. At this point, it is probably best to call a professional HVAC company or even a plumber to check it further to make the fix. The fix will require special tools and a little know-how. The most common reason the pilot light will not stay lit is either a bad thermocouple or a pilot nozzle being plugged or clogged with debris such as dust or some other particle. Thermocouples are cheap and are purchased at most hardware stores and even online. If the pilot nozzle is plugged or clogged the pilot assembly needs to be disassembled and cleaned up and then reassembled and the pilot light lit.

The old thermocouple should be tested to make sure it is putting out the proper millivolts. That test will require a multimeter that can read millivolts. Minimum millivolts on the thermocouple should be 25 millivolts. Below that and you get the drop out voltage for the gas solenoid inside the gas valve. Many thermocouples that I have tested that were not bad read over 30 millivolts and as high as 60 millivolts. The maximum output of millivolts for a thermocouple for a water heater or gas furnace should never be over 100 millivolts.

How to Troubleshoot Standing Pilot Gas Water Heater | HVAC Heating

Related Link: How to Test a thermocouple with a multimeter (opens in a new window)

Troubleshoot Standing Pilot Gas Water Heater –¬†Other problems that can cause the pilot light from staying lit can be a bad gas valve. In that case, definitely, call a professional. It is important that gas valve is installed properly including making sure it is the correct gas valve, is it natural gas or LP gas, is the pilot adjusted properly for pressure and gas output and is the pilot light close to the burners in the proper position. It is important that this is done properly after it is gas we are talking about and gas has the potential to be dangerous. Don’t take any chances. Do it right and then don’t worry about it again.

High Performance HVACHow to Troubleshoot Standing Pilot Gas Water Heater