What I did...

The wall switch for fireplaces is just a low voltage or dry contact.

I left the cable in the wall and replaced the on/off switch with a Leviton momentary switch ($3) which always rocks back to off.

The cable connects up with the igniter under the fireplace.  I placed an IOLinc  in the outlet in my fireplace (installed so I could install an FK24 blower kit) and then moved the cable from the igniter to the IOLinc input.

I then ran a new piece of cable from the IOLinc output to the igniter.

 

Now my fireplace is controlled by the ISY.  If it sees a toggle of the momentary switch it toggles the fireplace on/off.  Doing it this way always me to setup my Harmony to control the fireplace as well and also set a time limit on fireplace runtime.  I also turn it off automatically when I set my alarm or see too much increase in my main floor thermostat (or delta with my one-wire sensors).

My plan is very similar to this, with the addition to adding an old fashion round mercury thermostat in between the ignitor and the i/olinc output as a safety break if the fireplace were to turn on when i wasn't home and get too hot. This seems the cleanest and cheapest way to accomplish post 12's point and if I ever abandon Insteon, I can easily just replace the levity with an on /off or a thermostat.

 

Any thoughts on this? thanks!

My PLM is the latest (no ALL_ON), I've never had one, I have the fireplace on a 30m ISY program timer, and my fireplace has a blower to prevent internal overheating anyway.

 

I lose sleep due to a number of things, that's not one of them.