Question from Uxbridge: Why Does My Furnace’s Pilot Light Keep Going Off?

If you have an older furnace with a gas pilot light and it keeps going out, heating your Uxbridge home can become a frustrating process. Not only are you forced to trudge downstairs to light it every time you need heat, but you’re probably starting to worry that there is something wrong – either with your furnace or with your gas supply. Here are some possible reasons for your pilot light shutting off and what you can do about them.

  • Thermocouple – The thermocouple is used to generate electricity from the gas being burned by the pilot light to power the sensor that keeps the pilot light running. So, if the thermocouple goes bad or gets blocked in some way, the sensor won’t work properly and your pilot light won’t remain lit. Even a small problem with the thermocouple can lead to the valve closing and the pilot light going out.
  • Gas Pressure – If the gas pressure going to your furnace is too low, due to a leak, pipe problem or another appliance, the pilot light may not have enough gas to stay lit. While it is possible that the problem is not related to gas pressure, anything that affects the flow of gas into your home should be inspected by a professional. If you smell gas, leave the house and call your gas company immediately.
  • Mercury Sensor – The sensor in your pilot light that maintains the flow of gas to keep it lit can go bad. Keep in mind that these sensors almost always used to contain mercury (and often still do), so you should be careful with them. It’s best to call an Uxbridge professional who can replace and dispose of it properly.
  • Dirty Burners – Excess dust, lint, rust or sulfur build up can result in blockage of the burner holes. When this happens, gas will flood into the chamber but not light right away. When it does finally light, it will create a small boom or banging sound that will often put out the pilot light. Not only is this inconvenient, it is very dangerous. Fortunately, it can be avoided with annual cleanings of your furnace.

The best way to keep your pilot light lit at all times is to have someone inspect it once a year. If something happens in between, you can usually rule out cleanliness issues and call in a professional to check the thermocouple and sensor.