Remotec ZFM-80 - Fireplace Project

Hello everyone. I’m working getting my fireplace connect for use in Smartthings and integration with Alexa. All the guides I have read thus far recommend the Remotec ZFM-80 Dry Contact Switch Module ( However, it appears that this item is out of stock (on Amazon as well).

My question is, does anyone have a recommendation for an alternative? One that you may have had success with for a fireplace or similar project?

I’m still not clear why a normal smart switch won’t work. It seems as though there is no difference than the one that’s on my wall, but I’ve seen people say you shouldn’t use them.

A normal smart switch didn’t work because the switch on your wall is almost never wired with 120 vac. Pop the cover and take a look.

Ahha! I will look at that. Thanks!

1 Like

Take a look at these two links. The first is to the entire thread. The second is to my finished project.

It works great. I can control it with the switch, the app, and via Alexa.

I thought the same thing, then I popped the cover and was like awww darn!

Thanks for the reply. Funny thing, throughout my searches I do remember reading your fireplace setup before…should have bookmarked it :slight_smile:

One question I do have for you: what is the purpose of the 110 vac Dpdt dry contact relay in your setup? Could you setup the fireplace to trigger on/off with just the Aeon labs G2 smart switch?

The Fireplace is ran by a low voltage module. The switch on the wall just open and closed a circuit between two contacts on the module. That circuit is normally a millivolt circuit.

-The G2 smart switch has 120 vac in to power it.
-The switch on the wall is then connected to the G2 external switch terminals. The external switch terminals are not controlled by the G2, it controls the G2. This means that you have remote control via the app to control the G2 as well as an external switch. The two together act just like a three way switch.

  • The G2 output terminals have 120 vac on them as well, therefore they can NOT be connected directly to the fireplace module.

This is where the dpdt relay comes in to play. It is powered by the 120 vac from the G2. It is a dry contact relay (no physical contact between the two sides). So, 120 vac on one side, and the low voltage module on the other.

Now you can safely power the low voltage fireplace from the ST app, from the wall switch, and from Alexa.

You do not have to connect the external switch, but I wanted a physical switch to kill the fireplace is I had two.

It really depends on your fireplace. Some are 110 while others are low voltage. Mine has both types of switches next to the the fireplace.

bamarayne i right you need to remove the switch and take a look.

A fireplace switch gets its millivolt power from the thermocouple in the fireplace.

Does one of your switches turn the fireplace fan on/off?

No, I have the same fireplace as you. My fan turns on once its warmed up and then turns off after it cools.

One switch kills the power for the entire unit. The other is the dry contact switch. I need both “on” for it to work.

My old house was just a 110v switch. A buddy of mine also just used a regular zwave switch on his 110v only switch. Neither have a dry contact switch in the setup.

Probably has to do with building codes if its dry contact only or with a power kill switch.

edit: added a comment about building codes.

Ok, you have it set up different than mine.

I was initially confused by the setup, until you worked on your zwave and I dove into it. Only been in the house for about 4 months.

It took me some time to wrap my head around it. I finally figured it out when I wired up the smart switch and checked it out with my fluke.

Wow. I’m using the exact setup you want, and it works great. I wonder why those switches aren’t available anywhere anymore. I even have a custom faceplate that was made when we were redoing the fireplace surround.

I had left a link here to something that I thought would work, but I was mistaken. There are a few others out there, I think.

This will work, but if you want a regular switch as well you’ll need a dual-gang junction box. Otherwise, you can just cover it up and the only control would be via z-wave.

Have you had any issues with Zwave control of the Remotec. I have an outdoor fireplace wired up exactly like yours. 120 to the switch and millivolt to the ignition via the Remotec. My fireplace alternates between 1) failing to switch at all, 2) coming on while the ST hub still reports the switch as off, or 3) coming on normally after two or three attempts. If #2, I can continue to hit the switch in the ST app over and over until it actually thinks it is on and, after that, switching it off will actually turn off the fireplace. Manual operation of the switch via the physical button works every time, as you’d expect. The outdoor patio has three other Zwave switches (2 GE outlets and 1 switch and there are two additional Zwave switches just inside the patio doors, so lots of Zwave repeaters in the vicinity. None of the other devices on the patio are behaving as such. I currently have a virtual switch configured to turn on the fireplace along with two overhead gas heaters. The two heaters come on every time and the fireplace has this random behavior as described above. Any thoughts from the group?

Nope, haven’t seen any issues. The only thing that annoys me a little is every time it gets polled the blue light on it blinks a few times, whether it’s on or off. But no issues with it responding to z-wave commands or randomly turning on or off.

BTW, it looks like there are actually a few ZFM-80s in stock at Amazon and other places again.

Can you show us how you wired the physical switch with the relay for that safety purpose?