Zwave for gas fireplace

I apologize if already posted somewhere, I saw a similar answer but was not sure if it is the same… I have replaced a number of lights and fan switches with zwave and connected them to smartthings and then to alexa. I wanted to do the same for my gas fireplace but have hit a snag and wanted to make sure I was not going to cause a problem. the switch on the wall for the fireplace is just a simple 2 wire switch that would turn the fire on and off (pilot always lit) so I suppose that would be a Millivolt system. now it looks like there are neutral, ground and a separate line coming in, all of which are not currently being used with the switch already at the box where I want to put the switch. my question is could I just connect a switch as I usually would for a normal light switch (neutral, ground and standard) and just put the two wires currently there as the lead whereI would normally put the wire going to lighting or would that not work/be dangerous. thanks for the help

It all depends on what travels through those two wires already connected to the switch. Find the manual? Safest bet would be using a dry micro relay switch and hiding it behind the existing switch. The switch would control the micro relay and that could also be controlled via ST.

You can do that, but your fireplace will probably fry… No really… I mean it.

Your fireplace is a milivolt system. You will need a dry contact relay, for safety to make this work.

Read this… Somewhere in there are the instructions I used.


Read the other project threads and bring in an electrician. You need to know exactly what you’re doing for this, and the Standard micro relay is intended for lighting control are not going to be appropriate here. At the very least you want something that has an automatic timer shut off in the hardware device itself (not depending on a smart app to do it).

Before you do anything else, though, check with your jurisdiction. In many places in the US it is illegal to put in any kind of remote control for a gas fireplace that can be used out of sight. You can’t even have a button upstairs in the bedroom to turn on the fireplace downstairs. This is for safety reasons. if you look at the remote controls for fireplaces which are sold nationally, you’ll see that they almost all have a range limit of about 20 feet which is intended to meet this requirement.

Any SmartThings device of any type that you use on a fireplace would violate this requirement because being able to be at your office and tap the device tile on your phone is obviously out of sight control of the fireplace.

If your jurisdiction does have this requirement and you install something which is not to code, Then you very likely void your homeowner’s insurance if there is a fire.


This device could work: Remotec Zwave Dry Contact Fixture Module

Me personally? Is the fire safe to leave on while not home indefinitely? If not, do not automate it without safety controls. Real ones. To me Zwave and ZigBee HA is not suitable for safety.


appreciate all of the replies! i am going to refrain attempting to automate the fireplace after reading the concerns


One thing I’m in the process of doing with mine, to add a layer of safety…

I have a Wemo switch that I’ve never taken out of the box. I’m going to make it a mobile plug in the wall switch, with an outlet.

I will use it via the Wemo app and Alexa. I will plug my ST smart switch into it. I will tell Alexa to turn on the fire place power, she will turn on the Wemo. I will then have a piston set up to turn on the fireplace.

So, it will be a two step process.

Alexa, turn on the fireplace power.
Alexa turn on the fireplace.

The problem is that if your piston can respond to the WeMo, then the WeMo is controlled by SmartThings. And as you know, there has been more than one report in the forum of SmartThings turning a device on randomly. So that might include your WeMo.

If you want a layer of safety, you would have to have the WeMo not known to SmartThings.

The Wemo would NOT be connected to the ST hub. I would use the Wemo app integrated with Alexa. Gotta keep it isolated from ST to prevent the random turn on events.

So what would trigger the piston?

The piston would control the ST connected microswitch that is plugged into the Wemo. Once the Wemo is turned on (not via ST in any way at all) the ST switch will then have power applied. I then tell Alexa to turn that one on.

2 step process.

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I used a CT-100 thermostat works great

I’ve started to think about trying to control my gas fireplace via Zwave and found this thread helpful I found a Reddit thread that offers a nice solution and includes photos that I’ll probably try out.

I know this is old but I just had to answer. The pilot generator is millivolt (DC) so breaking the circuit anywhere controls the operator in the gas valve.

Any low-voltage switch should work. Y’all are over-thinking this.

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Sorry for resurrecting the thread, but I’ve been thinking about doing something similar.
I agree with posters who point out the risks of being able to turn ON a fireplace remotely, but what if you only want to turn it OFF remotely (always turning it on manualy)…

I was thinking of something like this:

But cutting off the arm at the bottom that pushes the switch up. That way, it can never flip the switch on, only off. Do you see any holes in this plan?


How do you get the switch back to the on position without taking off the cover every time?

Yeah, I realized that after I posted. I thought the “hooks” on the left are what moved the switch on and off, but looking again, I think that’s just to detect the position.

FYI to everyone. I tried using a GE Z-wave smart switch on my fireplace just now and am pretty sure I fried it.

I hooked it up just as the original poster wanted to, with a neutral and live from Romex coming in for the adjacent light switches. I connected the red and white wires to the load terminal and the fireplace lit up. I thought, “Great it’s working!” Let me test the switch and turn it off… pressed the switch and all I heard was a discrete buzzing noise (like a bug zapper, zapping a bug) and then nothing. Sick feeling in stomach… Disconnected the switch, reconnected the original toggle switch and the fireplace is simply not responding. No on, no off. I probably fried the control box. @bamarayne

I had read the Heatilator manual stating that the fireplace used 110-120 VAC, no mention of a millivolt system. But I should have guessed it because the wires were too thin as opposed to typical copper wiring for wall switches. Also my non contact voltimeter picked up nothing. So yes, do not use a regular wall switch.

@ady624 I am curious as to why people have success with Remotec Dry Contact Module.

Someone even posted a YouTube video showing success with it.

Now going to cost me to replace my control box. A little knowledge is a dangerous (expensive) thing.

Sorry to hear that. But yeah, those thin wires are nothing but a signal wire. The regular wall switch is just there to act as a circuit interrupt.

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