Sensor to detect gas fireplace is on?

My first thought moving into a house with a gas fireplace was to install a smart switch to be able to turn it on and off automatically. But that seems to be unsafe, since phantom events could turn it on accidentally. The primary driver for me is to be able to turn it OFF if left on accidentally. Does anyone know of a way to passively sense whether the gas fireplace is on? Like a high heat or fire sensor that i could place nearby? I could then set up notifications that would alert me if the fireplace is on when I have put the house to sleep.

You can just use a temperature sensor or you can look for a VOC sensor (often called an air quality sensor) which measures particles in the air.

By the way, I have posted this a couple of dozen times in the forum in the past so I don’t really want to go into all the details, just search for “fireplace” and you can find the conversations, but in most places in the United States it will be illegal to have any gas fireplace control that can be operated from a phone app because they are generally limited By code to within about 40 feet of the fireplace. And in some jurisdictions to within line of sight.

It doesn’t matter whether you yourself know that you will never turn on the gas fireplace from your office 5 miles away, just the fact that you can is a safety violation.

Smartthings can and does glitch occasionally, and you can find posts in the forum from people who say their lights randomly turned on or their garage door randomly opened or their front door randomly unlocked. You don’t want that to happen with the gas fireplace when no one is aware of it. :scream: :rotating_light: :fire_engine: :ambulance:

(I personally don’t put anything on smartthings that would not be safe to run for 24 hours on attended.)

So the first thing is to check with your local township and make sure that it would be legal to have a phone app that can turn your fireplace on.

Fireplaces which are inset into the wall and qualified as thermostat controlled heating devices fall into a separate category. Those are usually fine. But your typical gas fireplace insert is not.

Anyway, just search the forum for fireplaces, you’ll find lots of discussion.

And of course just having a sensor to notify you that it’s on is fine. It’s putting the fireplace control itself into the app that is the problem.

Yup, your previous posts are what steered me away from that “bright” idea and led me to a purely passive sensor to trigger color notifications for alerting me i forgot to turn the fireplace off. So, thanks for that!

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I woke up with a new thought on this today. (I do some of my best work when I’m asleep! LOL! :sleeping: )

How much light does the fireplace give off?

The Problem with both the temperature sensor and a VOC air quality sensor is is that it takes a while for the room environment to change even after the fireplace is turned off.

But the light would be an immediate change. As soon as you switch off the fireplace, its light is gone.

So a good lux sensor might be a better choice for your bedtime check. The Fibaro multi would probably be good. :sunglasses: make sure you get the Z wave one, not the HomeKit one, so it works with smartthings.

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I used an Iris contact sensor on our gas fireplace at the old house and it worked great. The fireplace had a mantel and I mounted it under it. The temp would rise quickly when the fireplace was on . I had it set to turn on the ceiling fan in the living room. Would usually come on with a minute of turnign on the fireplace.


I use virtual thermostat smartapp on, with sonoff, Aoetec temp sensor and harmony for ceiling fan. Need to turn

Agreed, for events that you want to occur when the fireplace is turned on, The temperature sensor should be quick and accurate. And the light sensor probably wouldn’t help because it’s possible that there will be other lights on in the room at that time.

However, to get a reminder that the fireplace was left on after everyone is getting ready for bed, the Room temperature may not fall quickly enough to let you know before you’ve already gotten into bed. So that’s why I was thinking a light sensor might be better for that use case.

But it all depends on the details. Different rooms will have different conditions. :sunglasses:

So, I confirm that a temperature sensor does not work well for my use case because the temperature does not fall quickly enough to be useful. The lighting sensor won’t work well in my setup either. So, I am exploring a contact sensor.

In particular, I am protecting my gas fireplace switch from my young children using a child protective switch cover:
Child Be Safe, Baby and Toddler Resistant Electrical Safety Cover Guard for Modern Wide Light Switch and Outlet, Set of 3 (White)

I am thinking about embedding a recessed door sensor right next to the switch, immediately outside of the single-gang box yet still within the footprint of the switch cover/plate. With the magnet secured to the door of the child protective switch plate, the sensor should tell me whether the child protective door is open or closed. We can then just leave the door open when we have the fireplace on, and close it when we turn the fireplace off.

My question is this: would there be any issue with me embedding a zwave door sensor (with magnet) right next to the gas fireplace switch? It will be outside of the single-gang box, but just want to make sure it won’t like induce a current or something bad. I think those switches are dry switches in that they just complete a circuit rather than supplying voltage to a load, but don’t know enough about it. Anyone know for sure?

Or does anyone else know a safe and reliable smart gas fireplace product? First search engine hit I see is “iFlame”?

I added an additional wifi switch in line. So both switches need to be on for fireplace to light.

Interesting…So you have a double-gang box and just toggle both switches at once? That seems to address the safety concern of having phantom events accidentally turn on the fireplace.

Toggle each individually. So both have to be turned on for fireplace to operate. I use mainly in evening. Have one switch to turn off at 11pm.

Right. So I would have one dumb switch and one smart switch in a double gang box, wired in series. The smart switch would tell me the status of the fireplace and the dumb switch would require physical operation for safety reasons. Problem is I don’t know if I have a normal Romex over there for operating the smart switch. Might be back to the contact sensor if not.

Could use a smart switch with dry contacts and install in line from dumb switch. The smart switch would close the circuit. Most are low voltage in the US. I use Sonoff mini behind the existing switch.

I see. Would the smart switch be able to show the status of the fireplace actually being on or off? Or would it’s status only indicate the possibility of the fireplace being on or off, without being able to know the status of the dumb switch?

Ok I’m on board with this idea if it will work for my setup. Looks like I have just a single 22 gauge wire behind my switch. See pic. Not familiar with this sort of thing - would the sonoff mini work with this?

The 22ga wires go to the gas valve. Search YouTube for ‘smart plug fireplace control by Alexa’. Can’t copy the link here. This is the process that I used. I had an outlet under the fireplace to plug into. I have a blower on the fireplace that used the outlet. You basically install the switch in line of one of the 22ga wires.

Basically you need a dry contact switch. Most smart switches are not going to work, because they need line voltage and Neutral, that is what powers the radio in the switch. Not sure about a sonoff mini never used one.

Search here for dry contact. The first thing that popped up for me was this Those are low voltage wires but I am not sure what a gas fireplace uses. So maybe these would work. Looks like they are not battery operated so you still have the issue of getting power to them.

Qubino makes them too. I have a few of them for other automations in my home but it will work and nice thing is they are quite small and can fit in the back of a gang box.

Thanks for the link. Looking at the install manual, I’m not sure how it’s supposed to work with my setup. I have only the 22 gauge wire in the box connected to the switch for the gas fireplace. No 110v AC. I don’t know how gas fireplaces work. Is there a 24V DC source somewhere like pictured in the install manual for the garage door?