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    HatRock's Avatar
    HatRock Posts: 1, Reputation: 1
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    #1

    Dec 6, 2006, 08:52 PM
    Converting mercury bulb thermostat to digital
    I have a TRANE XL1200 Weathertron heat pump with auxiliary heat. It is controlled by a Trane 3AAT80A1A1 mercury bulb analog thermostat. I have purchased a RiteTemp 8050C digital programmable thermostat to replace it. The analog thermostat has wired terminals marked O,R,T,G,Y,X2,B,W and F. It also has a terminal marked U that is jumpered to the W wire. The RiteTemp digital has terminals C,W2,Rc,O,B,Rh,W,Y,G, and A. The digital thermostat has documentation suggesting how to connect the wires. The RiteTemp documentation maps the wires this way:

    Trane to RiteTemp

    Connect G wire to G terminal (this connects the fan)
    Jumper W terminal on RiteTemp to Y terminal on RiteTemp
    Connect Y wire to Y terminal (this connects the compressor)
    Connect O wire to O terminal (this connects chang over valve)
    Tape off the B wire
    Jumper Rc terminal on RiteTemp to Rh terminal on RiteTemp
    Connect R wire to Rc terminal (this connects to the 24vac power)
    Connect W wire to W2 terminal (this connects auxiliary heat)

    All of this is fine, but there are wires left over from the old thermostat connections. I don't have any documentation for the Trane thermostat so I don't know the function of each wire. The left over wires are T, X2 and F. The RiteTemp documentation implies that anything with an X is a control wire and should be connected to an AC (current) terminal so I guess I could connect that to the C terminal on the RiteTemp. That still leaves the T and F wires.

    Any advice? Thanks.
    NorthernHeat's Avatar
    NorthernHeat Posts: 1,455, Reputation: 132
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    #2

    Dec 7, 2006, 05:25 PM
    X is common, probably not needed. X2 I think is for a diagnostic light I=on old stat, not needed. F?? don't remember ever seeing that before, E maybe? I'm comfused about W to Y though. But I won't deal Rite temp stats, I've posted several messages about hardware store bargain stats.
    SuperTyphoon's Avatar
    SuperTyphoon Posts: 85, Reputation: 5
    Junior Member
    		  
    #3

    Dec 7, 2006, 05:26 PM
    I just got that tstat a week ago, but I live in Florida and only had to install it on a A/C unit with the indoor part of a heat pump. My only wires were W, Y, G, and RC.
    NorthernHeat's Avatar
    NorthernHeat Posts: 1,455, Reputation: 132
    Ultra Member
    		  
    #4

    Dec 7, 2006, 05:31 PM
    Quote Originally Posted by SuperTyphoon
    I just got that tstat a week ago, but i live in florida and only had to install it on a A/C unit with the indoor part of a heat pump. My only wires were W, Y, G, and RC.
    You have a completely different animal.
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