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Relay Switch

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  • Relay Switch

    I am getting ready to install a alternate fuel furnace along side my LP forced air unit. I would like to wire it up so that when the "new" furnace blower comes on the "old" blower would also come on.
    Can someone recommend the proper relay and suggest a wiring diagram?

  • #2
    Re: Relay Switch

    hmm we interconnect the bathroom fan to the furnace so when the fan for the bathroom comes on the fan only comes on in the furnace.
    its been a while but at the furnace control board the green from the thermostat connects to green on the 18/3, red goes to red and black goes to green on the board. On the relay black is common and I forget which is normally open/closed. green NC comes to mind I think. Vanee says green is NC and red is NO schematic seems to be the way we usually do it.

    now the humidifier comes on when the fan comes on so unless someone else has an idea couldn't you run a second 2 wire from HUM and common to control the relay? The main furnace

    now are you having just the blower on the old run or is that a heating source as well?
    Last edited by intertan; 11-22-2008, 07:43 PM.