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

    Nov 3, 2011, 09:25 PM
    Terminal confusion. T90 general control thermostat replacement with new one.
    The T90 thermostat terminal is labeled G,F,C,H,V it is 4 wires in and jumper between G and F. The new one is a Honeywell RTH230B and has terminals marked Rh,R c,W,Y,G with a jumper between Rh and R c. Which wire do I connect to which terminal? I have a Lennox furnace and central air unit. There are 2 sets of 2 wires with 1 white and 1 black wire in each pair. G is a black wire, c is white, h is black, v is white. Jumper wire from g to f. Thanks.
    rfpaptorico3's Avatar
    rfpaptorico3 Posts: 1, Reputation: 1
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    #2

    Aug 2, 2012, 09:00 PM
    the T90 thermostat terminal is labeled G,F,C,H,V it is 4 wires in and jumper between G and F. The new one is a Honeywell RTH230B and has terminals marked Rh,R c,W,Y,G with a jumper between Rh and R c. Which wire do I connect to which terminal?

    I have a Lennox furnace and central air unit.

    Presently T90 wire layout G and F blue, C green, H white, V red

    please help with wire layout for RTH230B

    Rh and Rc =
    W =
    Y =
    G =
    samkhan79's Avatar
    samkhan79 Posts: 1, Reputation: 1
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    #3

    Oct 3, 2015, 02:28 PM
    Did anyone get this working? I am converting this to nest

    These setting worked for me but only for A/C, Nest support is sending me replacement of base board. If I swap the W with Y Heat works but in cooling mode.

    T90 Nest
    V Black RC RH
    H yellow W heat
    C red Y cooling
    F green G fan
    G green C Common
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