Gas Fireplace Switch Not Working – What To Do?

People who have wall switches for their gas fireplaces frequently have problems with the pilot flame not lighting even after the main burner is turned on. If you've ever encountered this problem and are looking for a solution, then keep reading. We've done some research and have answers right here for you!

There are two different approaches to repairing the wall switch that controls a gas fireplace. Also, the particular problems that it has are what will determine which of these solutions is best for you. Let's take a brief look at them:

  • The switch has malfunctioned. To fix this, you have to install a new millivolt switch.
  • The wiring may be faulty or rusted. Replacing the wiring can help fix this problem.

The good news is that each of these problems can be tested without much difficulty and can be resolved with surprisingly little effort. Read on to learn more about gas fireplaces and the possible fixes you can do if your gas fireplace switch is not working.

Woman turning on the switch for the gas fireplace, Gas Fireplace Switch Not Working - What To Do?

How Do Gas Fireplaces work?

For those unfamiliar with gas fireplaces, we will begin with the fundamentals. What does the wall switch do for a gas fireplace?

A fireplace wall switch is a simple toggle switch that opens or shuts the circuit between both the thermopile and gas valve. It runs at millivolts, allowing it to operate with extremely low-voltage electricity. Also, it is applied as a safety mechanism that prevents the gas valve from opening if the pilot light isn't functioning properly.

To give you a better understanding of its function, we also need to take a step back and examine the interaction between the thermopile, the pilot light, and the gas valve.

Thermopile is meant to generate around half a volt of power (between 650 and 850 millivolts) if it is heated for roughly two minutes. This heat is supplied by the pilot light, which is a little flame that burns continuously.

After the wall switch has been engaged, the electric current travels out from the thermopile to the gas valve, where it activates the gas valve.

If you do not flip the switch to the "off" position, the gas valve will not open, and the fireplace will not light.

Possible Fixes for Malfunctioning Gas Fireplace Switches

There are a variety of reasons why the wall switch on a gas fireplace is not functioning properly. The following is a list of these reasons and things that you can do to fix the problem.

The Switch Has Malfunctioned

A black stainless covered fireplace mantel

Checking to see if the switch has failed or not is the first step in troubleshooting. Wall switches for fireplaces aren't exactly high-priority items, so it's possible for them to break without much effort.

If this happens, turning on the fireplace will no longer be an option for you, because if the circuit that is located behind the wall switch is not closed, the pilot light will not transmit a "green" signal to the gas valve. As a result, the fireplace will not operate in any way.

To check whether or not the switch has failed, you need to find a way to operate the fireplace without using the wall switch.

If the circuits are shut and the thermopile continues to function normally, then the switch is confirmed to be "faulty."

Here is the step-by-step guide on how to accomplish that:

  • By removing the flat screws, you can detach the cover plate that was attached to the wall switch. 
  • Remove any more screws that may be securing the switch to the wall. When this is done, the switch will become accessible.
  • After the switch has been removed, you should verify whether or not it is the one for the fireplace wall. The electrical lines that connect to it will be considerably more slender than those typically used (in your fan, light, etc). If this is not the case, you have probably confused the switch for the fireplace with another control.
  • Unscrew the terminal screws that are holding the wire in place on the switch in order to separate the wire from the switch.
  • Connect the two wires and twist them many times while they are connected. This is done to ensure that the switch is not activated and that the circuit is closed.
  • Try to start the fireplace by using the pilot light and the ignition switch.

Just about the only alternative in this situation is to replace the fireplace switch. These switches, known as millivolt switches, are quite distinct from conventional wall switches.

But what is a millivolt switch?

As opposed to standard 120V wall switches, millivolt switches are made to operate on millivolt circuits such as gas fireplaces. Also, other electric appliance wires, the ones that link to a fireplace switch, are noticeably thicker. 

To replace the fireplace switch with a new one, follow the instructions below:

  • Switch off the fireplace's pilot and ignition.
  • Find the proper location for the switch. Make sure you can access the switch from the gas valve using a 15-foot wire. Skip this step if you're replacing a switch with preinstalled wire.
  • Remove the wires by unscrewing the terminal screws that hold the wire.
  • If you have the ability to attach a spade terminal, you should do so because they provide a secure connection. In that case, simply give the ends of the wires a twist and insert them into the appropriate terminal screws.
  • After reattaching the switch to the wall, connect both sets of flat screws. One set should be used for the switch frame, and the other should be used for the switch cover.

Check out this millivolt switch on Amazon.

The Wiring May Be Faulty or Rusted

A modern gas fireplace with black tile cladding

If the issue with the fireplace switch has not been resolved, the next step is to determine whether or not there is a problem with the wire. Either a damaged wire or a wire with a loose lead could be the cause of the problem.

The following are the measures that need to be taken in order to locate a loose wire:

  • Using a flat screwdriver, remove the screws holding the switch cover plate and the switch itself.
  • Examine the terminals to see if there is a wired connection that is not secure.
  • After you have ensured that the connections are secure, check to see if the fireplace is operational.
  • Finish tightening the flat screws, then reinstall the wall switch in its original location.

That wraps it up! There is no need for any additional repairs.

However, if the wire is defective, the method will be entirely different and more difficult. You will need to cut the wire that is connected to the gas valve. Performing it involves the following steps:

  • Open the gas valve's control panel.
  • Two terminals, known as "TH" and "TP," can be found.
  • Take a small insulated wire, a jumper wire, or a paperclip. Connect the bare ends to the terminals mentioned above.
  • Turn on the fireplace. If it works, a faulty wire has been identified.

If you are able to determine that a wire is faulty in this manner, you should remove the faulty wire and replace it with a new one.

Take note that the wire gauge that is used to connect the fireplace wall switch must be 18 AWG. Nothing larger or smaller can be used. If you haven't already done so, we strongly suggest that you purchase the following wires:

Check out this Hook Up Wire Kit on Amazon.

Check out this 18 AGW Silicone Wire on Amazon.

Once you get the wires, follow the steps below for replacing faulty wiring in a gas fireplace switch:

  • To ensure the proper operation of your fireplace, make sure the wires are connected to both the "TH" and "TP" terminals.
  • Using the fireplace grommet, insert the wire's opposite end. This is where the wire will be inserted.
  • Using a hacksaw, cut a hole in the drywall/wall and insert the wire. Rather than using gang boxes, switches can be installed directly instead.
  • Use flat screws to connect the wires to the switch.
  • Turn the fireplace on once to ensure the connection is correct.
  • Finally, screw the switch into the wall to close it up.


Man hand flipping the switch on

Can I use a regular switch for a fireplace?

A thermopile in a fireplace only generates millivolts, which is a far cry from the 120V that the light switch was intended to handle. Probably all that needs to be done is locate a switch that has a resistance that is sufficiently low.

It could most likely be accomplished with a low-voltage switch purchased at a local electronics retailer or salvaged from a child's toy, such as a 12V SPST.

Does a gas fireplace need electricity to ignite?

A spark from an electric source is needed to light the pilot light. If there is no power, the fireplace won't light.

Many IPI ignition systems for gas fireplaces use a battery-powered backup module to start the unit when the power goes out in the house.

In Closing

Woman turning on the switch for the gas fireplace

The reason why your gas fireplace wall switch isn't working could be due to a malfunctioning switch or a faulty wire. You can easily troubleshoot these issues.

If you are doubtful as to whether or not you will be able to perform the repair on your own, you should contact the manufacturer in order to be sent to a local specialist. If the work on the thermopile was performed by an authorized specialist, there is a possibility that a defective thermopile will be covered by the warranty.

Check out these articles below for more HVAC-related information:

Which Direction Should Ceiling Vents Point? 

How To Fix Low Superheat And Low Subcool In HVAC 



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