No Heat – The good news is, it’s usually a pilot light problem on old furnaces and you can fix that.



Did you wake up this morning and your house was extremely cold? You go to turn up the heat at the thermostat but the furnace isn’t responding.

No heat calls to furnace service companies are all too common in Edmonton, one of the most common reasons is a pilot light that is not working. If you have a natural gas burning furnace the burner would be ignited by either a standing pilot flame which is most often found in older furnaces or an electronic ignition which is found in modern furnaces. If you have an older furnace and it’s a standing pilot you’ll see that the flame is lit all the time, if you have a newer furnace then you probably have electronic ignition and that flame is only lit when your furnace is calling for heat.

gas valve and pilot assemblyWith the standing pilot light you have two main parts the pilot burner and the thermocouple. The thermocouple works by sensing heat from the pilot burner, if it feels heat it allows the main gas valve to keep flowing, if the thermocouple does not sense heat it shuts off the main gas valve to the burners. This is a safety feature that will not allow gas to flow and build up if it is not being ignited.

Thermocouple works by producing a small amount of electricity when heated by the pilot assembly, The thermocouple is connected directly to the pilot valve body. By converting heat to electricity it tells the pilot valve to open or to close. If for some reason the pilot light goes out the thermocouple will cool down and will stop producing electricity and will tell the gas valve to shut off the gas supply to the pilot and the burners.

This is a great safety feature but can be very frustrating when your house is getting cold and it’s below freezing outside. This is one of the most common problems service companies face but it’s also one of the easiest to troubleshoot. Let me walk you through how to re-light your pilot.

How to re-light your furnace pilot light


  1. Start by going to the furnace and turning off the power also take the top door off the furnace, look for the pilot valve. It is a box shaped device with gas lines running into it and is typically located near the burners. It is a valve that usually has three settings “on”, “pilot” and “off”.
  2. Turn the gas valve to the off position, wait a few minutes for any gas that was left over in the burner area clear away.
  3. Find the pilot assembly, it’s where a silver colored line and a copper line come together. It will be located close to the burner assembly.
  4. The pilot light can be hard to reach, it’s a good idea to use a barbecue lighter or a fireplace match to reach safely. If you don’t either, tape the match to the end of the stick.
  5. Some gas valves will have a red reset button other gas valves will not, in both cases you need to turn the gas valve from the off setting to the pilot setting.
  6. Ignite your match or lighter and place close to the pilot assembly, push down on the red reset button or hold the gas valve knob down if there is no reset button. Hold the button or knob down for about 30 seconds. This will override the thermocouple control and allow gas to flow until the thermocouple is hot enough to produce an electrical current and open the main gas valve.
  7. After 30 seconds slowly release the button or knob and see if the pilot stays lit. If it doesn’t you will have to repeat the above steps. If it does stay lit you can now turn the gas valve from the pilot position to the on position. Replace the door on the furnace.
  8. Now turn on the power to your furnace and set the thermostat up to 22 degrees or to a setting that will make the furnace demand heat. Also make sure that your thermostat is on the heat setting, some thermostats have a heat setting, a cool setting and an off setting.
  9. The gas should now ignite in the burners and keep the flow of gas supplied as required when your thermostat calls for heat.
  10. Adjust your thermostat to the desired setting and you’re done.

If you find that you still have no pilot and you followed all the above steps or it did light but will not stay lit then you probably have a problem with your thermocouple or the pilot assembly needs to be adjusted. It might be time to call in the professional furnace repair company.

If you have a gas water heater the same steps can be followed to relight the pilot assembly.

We hope this tutorial helps and that you’re never trapped in the cold again do the pilot light going out.