i have done this and it works great! the switch for my gas fireplace is under a flap that opens below the glass. i noticed that the switch was just a contact closure. i figured out that this does not need power(ac) because when a storm caused a power outage, my fireplace remained on. i have an open space under my fireplace insert that contained the AC for the blower. I used the x10 UM506 universal module and set it for a contact closure when activated. i then tapped into the two wires going to the fireplace switch and hooked them up the the um506 which is plugged into the blower AC outlet under the fireplace insert. viola. works like a champ. now i don't have to fight the hellfire winds from the blower to turn off my fireplace. i was going to get another x10 switch to control my blower fan speed but that is for another day. hope this helps.