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Wiring Trane/Honeywell TH8320U

I currently have a Trane 3AAT80B1A1 thermostat that I'm replacing with a Trane/Honeywell TH8320U.

My current thermostat has R (red), T (tan), O (orange), G (green), Y (yellow), X2 (black), B (blue), W (white), and U (which looks like a metal wire coming out.

The NEW thermostat (Trane TH8320U) has SEVERAL different Inputs. On the left outside input it has Y2, F, X2, W1, S1, S2.

On the left inside input it has Y2, blank, blank, W2, S1, S2.

On the right inside input it has RC, R, W1, Y, G, B

On the right outside input it has RC, R, O, Y, G, B

Any experts out there have any ideas on how to wire my old thermostat to my new one? Thanks!!!!!

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  • chaus21 Jul 27, 2009

    Ok, so just so I'm clear. I live in Florida and have an AC unit and a Heat Pump. For sake of easyness, let's call it 4 columns, starting from left to right.

    1st column (outside left)Y2, F, X2, W1, S1, S2
    2nd column (inside left) Y2, blank, blank, W2, S1, S2
    3rd column (inside right) RC w/jumper to R, R, W1, Y, G, B
    4th colun (outside right) RC, R, O, Y, G, B

    I understand connection the colored wires to the appropriate letter on the new thermostat. However, which column should they all go into, since I have several duplicates?

    In addition, coming out of the wall, I have a T (tan) wire that you said to put into Y2. Which Y2? Column 1 or 2? Also, I have a W coming out of the wall - Would that go into W1 or W2 and also, I have W1 in column 1 and W1 in column 3.

    Does this make sense or am I just making things more confusing?

    Regarding the U wire, it is a metal wire that is screwed down to the U label. Where will I put this one on my new thermostat?

    THANK YOU for your advice. GREATLY appreciated!



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Use the outside designations for heat pump, and inside for standard, I would assume a heat pump since you have more than five wires attached to it now. Use the colors of the wire to match to the designations, use tan for y2, black for w2 rc and rh should already have a factory jumper. I would have to trace out the "U" and see where it terminates, I have not seen a bare wire on a stat in 27 years of doing this. before powering, verify the tan and black at the indoor unit circuit board and see if they are landed on the terminals designated at the stat. hope this helps

Posted on Jul 27, 2009


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