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    NorthernHeat's Avatar
    NorthernHeat Posts: 1,455, Reputation: 132
    Ultra Member

    Dec 5, 2006, 02:42 PM
    You've come to the right place for do-it-yourself heating and cooling maintenance, repair and troubleshooting. Browse and search the items in this thread, and in the other posts within this area... and if you don't find what you're looking for, feel free to click the "Ask About Heating & Air Conditioning" button at the top of any page.

    I'll use this space to post some answers & solutions to Frequently Asked questions

    1. Information to include with your question
    2. Common Thermostat Wiring Help
    3. Part identification

    ... more to come :)
    NorthernHeat's Avatar
    NorthernHeat Posts: 1,455, Reputation: 132
    Ultra Member

    Dec 5, 2006, 02:42 PM
    Thermostat wiring codes explained.

    Rh=24V. Hot from heat transformer.

    Rc=24V hot from cooling transformer.

    If there is just 1 transformer leave jumper in Rh-Rc

    W=heat relay

    W2=2nd stage heat relay

    Y=Condensing unit relay (out door air conditioner/heat pump relay)

    Y2=Second stage cooling

    B=reversing valve (heat pump) energizes on heat (mostly just Rheem/Ruud/Weatherking)

    O=reversing valve (heat pump) energizes on cool (Most all heat pumps)

    B/O= reversing valve (you need to go into the installer set up of stat to tell it energize valve on cool or heat)

    C=Common (grounded side of transformer)

    G=Fan on relay (just for circulating air) also helps air quality if you have a high efficiency air cleaner, and can help balance temperatures from room to room.

    L=heat code diagnostic light.

    E=Emergency heat (heat pump)

    If your current thermostat wire has only has 4 wires, Red, White, Blue and Green
    put the Blue wire on the yellow thermostat terminal for cooling.

    Note: Not all installers will use proper color codes. You may have to look in the furnace to see where these wires are connected at the PC board of fan center. Also look to see if the wires have been spliced anywhere.

    If the heat pump has a box on the side of the furnace with allot of thermostat wires going to it, this is a fossil fuel kit, these are many and varied by manufacturers. You may want a service tech to mess with it. Let him pull his hair out, you will lose yours soon enough. :D

    If I have forgotten anything please just let me know

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