5 Easy Steps For Adding a Thermostat To a Gas Fireplace

Adding a thermostat to a gas fireplace is a wise decision. Why? Because, this amazing device will allow you to control the fireplace temperature, fuel flow, and liquid heat effortlessly and thus get perfect heat for your comfort.

adding a thermostat to a gas fireplace

Plus, it will ensure your safety. But, do you know the process of adding the thermostat to your gas fireplace? If not, keep on reading. 

This step-by-step, simple guide will show you the entire installation process. Further, we can assure you if you read the whole article, you will also learn:

  • Which kind of thermostat do you need for a gas fireplace?
  • How do you adjust the thermostat on a gas fireplace?
  • Remote thermostat for a gas fireplace.
  • What benefits of using a thermostat in a gas fireplace?

Note: Before knowing the installation process, it would be wise to know about the thermostat, its function, and which type of thermostat is good to install. Knowing all these issues will help you to add the thermostat perfectly. 

Okay? So, let’s start…

What is a Thermostat?

A thermostat is a device that maintains temperature within the given limits of an enclosed area. The thermostat produces signals when the temperature increases or decreases the desired value. 

what is a thermostat

It is usually used to control the electric current to heating or cooling a unit, the flow of fuel to a burner, and also control the gas or liquid heat in an area where it serves.

Which Kind of Thermostat do I Need for a Gas Fireplace?

There are many types of thermostats based on their structure. You can add any kind of digital thermostat and even add a remote to control the temperature without leaving the comfort of your bed or easy chair.

But in this section, we are suggesting a thermostat type that is best for a gas fireplace which is Millivolt thermostat.  

which kind of thermostat do i need for a gas fireplace

A Millivolt thermostat uses very low voltage usually about 750 millivolts. But for being low voltage, it doesn’t require a step-down transformer and is not connected to the household wiring system. 

Like other low-voltage systems, it has different features like programmable settings, digital displays, wireless remotes, touchscreens, and more. 

5 Steps for Adding a Thermostat to a Gas Fireplace

There are various types of thermostats available for adding to a gas fireplace. But it would be wise to check the owner’s manual to determine the correct type of thermostat system for your gas fireplace.

how to add a thermostat to a gas fireplace

However, the Nest thermostat is also a very famous one to use for a gas fireplace. Well, to add this one to your fireplace, you need to go through the following steps:

Step 1: Get a 24v AC Adapter

If your gas fireplace does not support using 24v AC, you have to use it via an adapter.

Step 2: Purchase Fan Relay

You will need a fan relay for the fireplace. While the Nest will switch the 24v source then this relay will switch the millivolt system in your gas fireplace.

Step 3: Install the Nest and Connect the Wiring

You need to disconnect the thermostat wires from your gas fireplace and install the AC adapter. Then, Connect one wire from the AC adapter to the Nest backplate’s RH terminal. Again, Connect the other lead of the AC adapter to the existing thermostat wire(Red).

Connect the thermostat wire(White) to the Nest backplate’s W1 terminal.

Step 4: Connect the Fan Relay

Install the relay near or within the gas fireplace. It may be useful to have some female spade terminals on hand for this step if you do not already have them. 

Put those on all of the Wires, including two wires from the Nest and the two in the fireplace. The wires from the Nest thermostat should be connected to terminals 1 and 3 on the relay. Connect terminals 2 and 4 on the relay to the thermostat that leads from the fireplace.

Step 5: Plug the Ac Adapter and Connect the Nest Thermostat

The AC adapter needs to be plugged in. To use your Nest thermostat, simply connect it to the backplate. If everything went well, your gas fireplace should now operate on a fully functional Nest thermostat. 

After charging the battery in the Nest fully, you will be able to configure the WiFi settings and control the thermostat via the app.

How Do I Adjust the Thermostat on a Gas Fireplace?

There are two moods available for adjusting the thermostat on a gas fireplace; these are TEMP (SUN) Mode and Timer mode.

SUN Mode:

  • Until you see the SUN Mode keep pressing the SET button
  • Hold down to the SET button until the TEMP flashes, then select your desired temperature using the small and large flame buttons
  • To complete programming press the OFF button or wait for 10 seconds

Timer Mode:

  • Until the TIMER mode is displayed in the lower right-hand corner press the SET button
  • Press and hold the SET button until the time flashes, use the high and low flame buttons to set your desired start time
  • Press the SET button for moving your next setting and program when you want the cycle and end

Most fireplaces can be operated by remote control to enhance simplicity and comfort. But it’s quite confusing what kind of remote control works well with your gas fireplace. 

When it comes to finding a remote control for a gas fireplace, you need to find out what kind of gas valve is used by your gas fireplace. Some popular remote models for a specific gas valve are given below:

  • Millivolt Gas Valve: SKY-3301, SKY-1001, SKY-5301
  • Latching Solenoid: SKY-CON, SKY-CON-TH
  • Maxitrol: SKY-MRCK-TH, SKY-MRCK, RCK-M

Benefits of Using a Thermostat in a Gas Fireplace

Gas fireplaces are used to make our living places warmer during the colder months of the year. But it is necessary to monitor the temperature and adjust it accordingly to ensure the safety of using a gas fireplace. 

benefits of using a thermostat in a gas fireplace

A thermostat brings many benefits to make our life a little easier and these are:

  • A thermostat is an easy way to monitor and control the heat according to the fireplace temperature which helps generate a more consistent room temperature by controlling the firing rate
  • The thermostat feature can help you reduce energy consumption while retaining the comfort of a continuous view on efficient fireplaces with a wide turndown range.

Why Is My Gas Fireplace Thermostat Not Working?

If your fireplace doesn’t work, it likely means there’s a problem that you should solve. There are a few things to consider that may help you locate the issue and solve the fireplace problems:

  • Make sure the thermostat is set correctly.
  • Since it is not getting a signal to do so, the fireplace will not light while the room is at a higher temperature than the set temperature on the thermostat.
  • Loose connections between the fireplace circuit panel and thermostat could also account for the problem.

How To Test a Gas Fireplace Thermostat?

Testing process of a gas fireplace thermostat:

  • Check the thermostat that you set if it is controlling the gas fireplace.
  •  Ensure the set point of the thermostat is higher than the room temperature. 
  •  Remove the cover of the thermostat and clean the inner dust, sometimes it doesn’t work properly because of the inner dust.
  •  Most thermostats have screw terminals that hold the wires. Remove the terminals with your screwdriver. Don’t let the wires fall into the cavity.
  •  Make sure the wires are twisted together.
  •  Turn on the fireplace and if it doesn’t work, there is another problem than the thermostat.


How to use a Wifi millivolt thermostat for a gas fireplace?

Turn your fireplace on/off from anywhere with your cell phone! A millivolt thermostat must be placed externally on the furnace. A millivolt thermostat is very simple, with 2 wires going to it, and it calls for heat by shunting them. Without a power source, the wifi millivolt thermostat will not work.

What is the thermostat switch?

A thermostatic switch is powered either by the thermal conductivity of the device it controls or by the thermal convection of the device itself. Thermostatic switches work solely by reading the temperature emitted from the devices they control the temperature accordingly.

What is a 750-millivolt thermostat?

Typically, millivolt systems are primarily used in direct-vent or top-vent wall furnaces. A standard low-voltage thermostat does not work for these systems, and they require a special thermostat. A millivolt thermostat uses a very low voltage, usually about 750 millivolts (mV) or 0.75 volts.

Is it cheaper to heat with wood or gas?

Generally, it depends on local costs for firewood, gas, and other fuels. The use of natural gas is usually quite cheap compared to firewood. When it comes to propane, is more expensive than firewood and electricity. In the case of a wood fireplace, you should also include the cost of cleaning the chimney with the cost of the firewood.


Hopefully, now you know all the simple processes of adding a thermostat to a gas fireplace. So, why will you hire a professional for thermostat installation and spend the money?

No need. Just follow the 5 simple steps to add the thermostat as we have shown you. And thus control your fireplace to get more heat or less for your ease and super comfort. 

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

6 thoughts on “5 Easy Steps For Adding a Thermostat To a Gas Fireplace”

  1. I need to change my gas valve on my fireplace and install a
    A wall thermostat unit.
    Do you have the material to make this happen ?

    • Hi Roy

      I don’t have one but I can recommend the best. Here you can get the Millivolt thermostat as it uses very low voltage but doesn’t require a step-down transformer. It has different features like programmable settings, digital displays, wireless remotes, and touchscreens. Nest thermostat is also famous.

      And in the case of a gas valve, you can pick the Millivolt Gas Valve: SKY-3301, SKY-1001, SKY-5301 or Latching Solenoid: SKY-CON, SKY-CON-TH. They are popular. Check which matches your fireplace and pick one.

      Will let me know if they could help you. Okay?


  2. Gas valve is a millivolt valve.
    It is now controlled on & off by a remote. Question: to install a wall low voltage thermostat (heat only) do you need only 2 wire thermometer wire run which
    terminals on gas valve? Are there in other steps. Thanks for your help.

    • Hi Mack
      Connect one wire to one of the hot wires which has come from your panel, and connect another one to the same color hot wire which is going to your gas furnace or heater. Hopefully, you are done.



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