Yeah I believe it had/has some issues, not sure if they worked it all out. My point was the manufacturer feels it is safe enough to allow remote/Alexa control.
Wiring the wall switch in series as shown in the first diagram would achieve this. The disadvantage is that the switch must be in the on position for the "smart" switch to work.
Could always add another emergency switch in the basement or to the side somewhere.
But you would not be able to use a momentary switch like this, it would need to be on/off and the state would be correct, switch would need to on for fireplace to work.
I will probably use a Zen 58 on my home heater which is a propane fueled simulated wood stove by Lopi.
It currently has a thermostat to control it, but I was going to add an additional thermostat for the lowest temperature setting 45°F then use the Zen58 relay to choose which thermostat to use.
Safety would not be a concern as the propane stove is controlled by 1 of 2 thermostats limiting high temperature.
Another option (if not enough low voltage wires) would be to use the existing physical switch as as the emergency disable switch, and an RF button controller device (Z-Wave, Zigbee, Lutron, etc…) as the manual trigger to turn on/off the fireplace.
I think what @ogiewon is talking about is something like a zen 34 which is a remote battery powered switch. Use it to control the relay in the Zen 16. It has a battery life of a few years so far. I have several of them.
Then use the switch as a override to disable the entire setup. Basically instead of it being wired in to to the switch input on the Zen 16, it would need to be wired inbetween the transformer and the control box or the control box and one side of the zen16 relay. That would be the only way to really have an override. It is a interesting idea
That is taking things even a bit further then even the fireplace manufacturer.
The more that I thought about this, the better a AA battery transformer sounded. With the Zen16, I would have to have a power supply. I have a plug on the junction box in the base of the fireplace that I was going to use for the Zen16. My current z-wave device that is placed over the fireplace wall switch works well. But it struggles when the AAx2 batteries get low. So I end up replacing the batteries often. But with the AA transformer that I linked above, all I have to do is run the power cord up into the switch box with the switch wires and use the artificial batteries. Initially, I did not want to run a new wire into the switch box. But it may be just as easy to do that as it would to incorporate the Zen16. Plus, the wall switch will stay in sync with the smart switch. The Zen16 will not. So I have ordered the AA transformer that I linked above and will put the Zen16 on hold for the moment. I'll report back to everyone.
So you think you have enough access through the wall and cabinet to fish a wire with plug? If you think do you can go ahead now and fish a pull string you will use later to pull the battery adapter wire through.
I use a zoo zwave switch with a cellphone charger plugged into it, connected by a scavenged USB cable connected to a 5volt relay with SPDT contacts with the relay coil, connected relay contacts in parallel with the low voltage toggle switch, defaulted the switch to power off after loss.
My Vermont Castings propane stove has a safety feature that shuts the gas line if the stove gets too hot. I am not sure, though, what the "too-hot" number is. I have the smart control set so the room never gets above 70/72.
Well, after all of the very helpful advice here, I could not get a wire pulled from the fireplace to the wall switch. So, I have abandon this project and will be complacent with changing batteries often. Thanks for all of the great help!
