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    rfl4's Avatar
    rfl4 Posts: 2, Reputation: 1
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    #1

    Aug 24, 2008, 01:06 PM
    Thermostat wiring
    I just purchased a Honeywellrth7400 thermostat. I have connected this except for one wire. I have a T wire but cannot figure out on the heneywell where this goes. The only terminals left open are the Rc and the L
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #2

    Aug 24, 2008, 01:19 PM
    Quote Originally Posted by rfl4
    I just purchased a Honeywellrth7400 thermostat. I have connected this except for one wire. I have a T wire but cannot figure out on the heneywell where this goes. The only terminals left open are the Rc and the L


    Old thermostat model number and brand?
    Did you write down where the wire was rempved from the old thermostat?
    Color of wire?

    See T Outdoor anticipator reset

    This doc
    rfl4's Avatar
    rfl4 Posts: 2, Reputation: 1
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    #3

    Aug 24, 2008, 01:39 PM
    The old thermostat is a trane weathertron. The wiring on it was O, B, Y, R, G, X2,W and T
    The installation instructions do not show where the T wire would go. I tried leaving it off and the thermostat does not work.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #4

    Aug 24, 2008, 03:19 PM
    Quote Originally Posted by rfl4
    The old thermostat is a trane weathertron. The wiring on it was O, B, Y, R, G, X2,W and T
    The installation instructions do not show where the T wire would go. I tried leaving it off and the thermostat does not work.

    Read this one

    It says to tape off (T). Are you sure you do not have another problem. I never new a unit that required the (T) to be hooked up except for the original units the thermostat was made for. Do you still have the old Trane/GE units.
    Attached Images
  1. File Type: pdf heat pump wiring.pdf (13.3 KB, 572 views)
    2. hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #5

    Aug 24, 2008, 03:25 PM
    Question?

    Did you have separate wires for RH and RC on the old thermostat?
    If you did did you remove the jumper?
    If you did no did you leave the jumper in?

    Did you follow EXACTLY the diagram on page 12


    http://customer.honeywell.com/techli.../69-1900EF.pdf
    T-Top's Avatar
    T-Top Posts: 1,871, Reputation: 100
    Ultra Member
    		  
    #6

    Aug 24, 2008, 03:30 PM
    You need a jumper wire from R to RC, X2 and W will go to the same place, T is not used cap off.
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