I think what your wanting to do has never before been attempted. Given that, I feel the price of two switches, cutting them in wall, possible drywall repair, wire, and not to mention the fire place uses mili amps for ignition circuit, and furnace uses 24volt a.c. Your far better off getting a separate t-stat for fire place. Check with your local f.p. dealer for correct type, then go to the cheap place and get one. Remember this is just one man's opinion, good luck....
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Last edited by triple D; 02-18-2008 at 05:49 PM.