So we have a gas log fireplace (Heatilator brand), and I wanted to set up the electronic ignition switch (which is just a standard 2 pole switch) to a z-wave GE on/off. When I opened the wall plate I knew I was in trouble. The wiring bundle is coming from the Heatilator rather than off the circuit. For the switch they only run line/load/ground. Neutral, along with the rest of the wiring bundle off the circuit, is run to the built-in Heatilator unit. Any ideas on how I can make this work? The only thing I can think of is that there’s an outlet almost directly below the switch which is on the same circuit. I could probably fish some romex between the two (I have some extra lying around), connect the neutral to the bundle in the outlet and to the z-wave at the switch, and cap the rest off. That seems like a total hack and probably not code. Only other option is to crack open the fireplace and see if there’s any way to get to the wiring in the back, pigtail off the neutral, connect the rest of the romex to the fireplace, and run the romex from the heatilator to the box in place of the bundle currently in there. Any other (preferably simple, non-rewiring) ideas would be welcome.
Thx!
Well first think long and hard about allowing remote control of an unattended gas appliance. Can you say kaboom!
If you are set on doing this then you just need a zwave switch with dry contacts out. Wire these in parallel with the LV wiring that controls the burner.
A cheap solution I use for garage door opening and irrigation control is a $20 zwave wall receptacle powering a salvage 12VDC wall wart transformer in turn powering a $4 automotive relay coil. The contacts of the relay can be used to switch all sorts of low voltage loads and because this is LV you have relaxed wiring requirements under the NEC.
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I just did this last week. Different brand fireplace, but nonetheless, same concept. The first thing I want to mention is that you may want to consider not modifying the switch you already have. That switch should work all of the time, even if your power goes out. So you want to keep that in place so you can still turn the fire place on if you power is out for an extended period of time. You don’t have to do this, it is just a thought.
The solution that curiousB wrote about is pretty much exactly what I did. For my setup, I was lucky because I actually had 2 switches, the one that turned the fireplace on and off, and one that turned a 120V outlet on and off below the fireplace. This outlet is intended for use with a blower. So I replaced the switch for the outlet with a z-wave switch. From there, I wired a 120V dry contact relay which I wired in parallel with the existing switch. This allows me to still operate the the fireplace with the manual switch or with my new z-wave switch. The only “problem” with this setup is that if the fireplace is turned on via the manual switch, it cannot be turned off by the z-wave switch and if it is turned on via z-wave, it cannot be turned off via the manual switch.
The relay I used is an “ice cube” style control relay that has a manual activation switch on it. I could use that switch to activate the relay in case of a power outage, but teaching my wife how to do that is a different story…which is why I left the existing switch in place.
Thinking about this more, the solution for you may be to replace the outlet with a z-wave outlet and then wire as described above. Another easy solution, would be the MimoLite (Smart Home - The Last You'll Ever Need - Ezlo Smart Home). That would just plug into your existing outlet and give you the relay you need. This is kind of overkill for what you want to do, but it is easy and has a “nice looking” plug that wouldn’t be an eyesore in your room. I used these on my garage doors and it is great! I was going to go this route myself, but since I had the spare switch to use, I just went that route.
Thanks for the replies! I’m looking into the various solutions proposed and will let you know which way I decide to go…and if the house blows up 
Same fireplace and setup here.
I left the wall switch the same to someone elses point of being able to use it in case of power outage.
I used this http://www.amazon.com/gp/product/B00913ATFI/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1 device and connected the relay portion to the ignition module (bridging the connections from the wall switch) and powered it with a 120v outlet that was already present in the fireplace.
Very easy setup, took me 30 minutes or so to connect. Only downside is as mentioned before you cant turn it on with one switch and then off with the other. Not a big deal for me.