Using a combination stacked 1 single pole $witch/1 3 way $witch(this device uses one space in a standard electrical box and uses the same trim plate as you average single duplex plug{resmbles an 8}), take three conductors from the attic fan Jbox to your desired remote location. Using the white wire in a three conductor w/ground non metallic cable(read 12/3 w/g romex @ local hardware) run the power going IN to the attic fans thermo control(you will have the incoming house power, the input to the fans control, and the new white wire in one wire nut) down to your remote $ and land it on one of the black (NOT GREEN) screws of the 3 way part of your $. Next, tie the black wire from the new romex to the fans control output AND LEAVE THE WIRE TO THE FAN MOTOR OUT OF THIS SPLICE. This wire ties to the other black screw on the 3 way part of your remote $. tie the red wire to the wire going to the fan motor in the fan Jbox. At the remote, land the red to switched screw of the single pole part of the $. Last, run a jumper from the brass screw of the 3 way part to the other screw of the single pole $witch. Here's what that'll do: With the single pole $ turned on, and the three way closing the white wire to the jumper, it'll send power to the fan motor as long as the circuit feeding the fan assembly is hot(hand or laymans, manual). With the three way turned the other way, it'll connect from the fans control to the jumper and the fan will only have power when its controller calls for it(auto). With the single pole $witch turned off, it won't matter what the power the three way is switching because none of it can get to the fans motor. This is a residential version of hand off auto switch, all readily available. couple of things to look for: First SHUT OFF POWER TO THE FANS CIRCUIT!!! Next, make certain it is the hot wire that the factory controller is operating-if not, then stop and re post here. Last, some of these combo stacked switches have a tab that connects the common sides of each switch together- I think that's only on the two single pole version and that the three ways don't have this tab- IF you have said tab, break it out. It is a fairly simple concept, just have to think of things w/o their "normal" order of events...BTW this switch being off will NOT kill power to the controls, just keep it from getting to the fan motor.
