9 Tips on How to Relight a Furnace

Winter is just around the corner, and the chill has already set in. It’s not uncommon that a furnace pilot light would choose the exact wrong time to go out. Older furnaces have a standing pilot light. This means that the pilot light burns all the time. When the furnace needs to create more heat, the pilot light ignites the burner.

When there is enough heat, the burner goes out, but the pilot light remains lit, waiting for the burner to need it again. Follow these steps to get your furnace back up in running in record time, and keep your family warm and safe this winter. Below are nine tips on how to relight a furnace:

1. Why does the pilot light go out?

There are several issues that could be causing your pilot light to go out. For instance, if the thermocouple is broken, dirty, or out of place, it will malfunction, causing the pilot light to go out. It could also be an issue with the home’s gas regulator, which will require furnace repair services for a more technical diagnosis.

If there isn’t enough gas supplied to the unit, it can’t stay lit. Among other things, it could also just have been blown out by a gust of air.

2. Find the pilot

To relight a furnace, start on the outside of your furnace by locating the gas line. The gas line will lead to the furnace’s gas valve that will have a switch with three options: on, pilot, and off.

On the other side of the gas valve, there will be a small tube. Follow that tube down, and at the end you will see the pilot.

3. Turn off the gas

Before doing anything, you need to stop the gas from flowing into the furnace. First, turn the switch to “off”. This will stop any more gas from coming in. Next, you need to wait for three to five minutes before moving to the next step.

This allows any of the gas that was already in the furnace to escape. This step is extremely important, as you’ll be bringing fire into the mix later. As you know, an uncontrolled mixture of fire and gas can be extremely dangerous.

4. Don’t mess with gas

Remember, in a fight between you and a gas-fire mix, the gas and fire will win. If you smell gas, if you think there is a gas leak, or if you don’t feel comfortable or safe, then do consider calling a professional. It might be a little more expensive, but it will be worth it if you’re safe.

5. Time to relight the furnace

Now that the area is safe, turn the knob on the gas valve to “pilot” and push down on the knob. This is the bypass button. By pushing it, you are allowing some gas into the valve. As you hold the button down, hold a flame to the pilot.

The easiest thing to use is a BBQ lighter, since the space is fairly small and can be difficult to reach. However, you can use a match as well if you don’t have a BBQ lighter on hand. Don’t let go of the button, even once the pilot is lit – let the thermocouple heat up for about 30 seconds before letting go.

6. Check the pilot’s appearance

Your pilot light should burn blue, with a yellow/orange tip. If the flame does not look like this, even after holding the bypass button down for 30 seconds or more, you may consider calling in a professional to check it out, as there may be a more serious issue.

7. Turn on the furnace

The last step is to set the gas valve to “on” and stand back to see if your handiwork has had the desired outcome. If the flame looks good and the pilot stays lit, then you’re in the clear. However, if it continues to go out on a regular basis, then there is probably a deeper issue at hand.

8. Clean & replace the thermocouple

If the pilot light continues to go off, it could be a simple fix, like cleaning or replacing the thermocouple. The thermocouple is located next to the pilot. Before removing it, turn off the gas line, and shut off the power to the furnace. Just as you did when lighting the pilot, wait three to five minutes before moving to the next step.

Disconnect the thermocouple from the gas valve, and then use a slightly abrasive emery cloth to gently clean the thermocouple. If you’re replacing it, simply remove the old, and install the new one in its place.

9. Remove & replace the thermocouple

When removing the thermocouple, remove the end that is attached to the gas valve first, and then remove the other end. When replacing it, do the exact same thing in reverse – attaching the end closest to the pilot light first, followed by the end attached to the gas valve.