Trane Heat Pump Thermostat Wiring Question.

About the Terminal Color Codes.

Connecting the Hunter 44428 Thermostat.

Trane Electric Heat Modification
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> Below is the result of your feedback form.  It was submitted by
>  () on Friday, November 2, 2001 at 17:41:22
> ---------------------------------------------------------------------------
> Brand: Trane
> type: heat-pump
> fuel: electricity
> location: basement
> Problem: temperature
> email address:

> S1: I have a Trane heat pump with auxiliary electric heat controlled by
> a Trane Weathertron thermostat.  I am attempting to upgrade the
> thermostat with a programmable Hunter model 44428.  I am having trouble
> verifying the correct wiring hookup for Hunter thermostat to the Trane
> unit.  So far, neither the local Trane rep. or the Hunter web site
> contact has been much help.  The current hookup for the Weathertron
> controller is:
> Terminal "F" (color-none) Purpose-Not used,
> Terminal "B" (color-Blue) purpose-24 volt common
> Terminal "X2" (color-Black) Purpose-Emergency heat?
> Terminal "W" (color-White) purpose-First stage Aux. Heat, Terminal "T"
> (color-Tan 0 purpose- Outdoor Thermistor, Terminal "G" (color-Green) purpose-
> Fan, Terminal "O" (color-Orange) purpose-Reversing valve, Terminal "Y"
> (color-yellow) purpose-First stage compressor, Terminal "R" (color-Red)
> purpose-24 volt hot
> The following are the referenced terminal connections in the Hunter 44428
> manual.
> Terminal "R" Function-24 VOLT HOT
> Terminal "Y" Function-FIRST STAGE COMPRESSOR
> Terminal "W" function-FIRST STAGE AUX. HEAT
> Terminal "W2" function-SECOND STAGE OF AUX. HEAT
> Terminal "G" function-FAN
> Terminal "E" funtion-EMERGENCY HEAT RELAY        (ALWAYS ON IN THE
> Terminal "0" funtion-REVERSING VALVE OPERATION
> Terminal "B" function-24 VOLT COMMON.
> ------------------------------------------------
> Based upon this I plan to make the following connections
> Trane "F" to no connection on the Hunter
> Trane "B" to Hunter "B" Warning: SEE Note BELOW!!!
> Trane "X2" to Hunter "E" SEE note below.
> Trane "W" to Hunter  "W"
> Trane "T" to no connection on the Hunter
> Trane "G" to Hunter "G"
> Trane "O" to Hunter "O"
> Trane "Y" to Hunter "Y"
> Trane "R" to Hunter "R"
> Trane ---no connection to the Hunter terminal "A"
> Can you verify that this is correct?  I am unsure about hooking the
> Hunter "E" terminal to the Weathertron "X2" terminal.  Also, I am
> assuming that the tan wire from the "T" terminal on the Weathertron will
> not be used by the Hunter unit and that there will be no connection made
> to the "A" terminal on the Hunter controller.
> Thanks for the help in advance.
> Mike

    The proceeding is an excellent question I wish every question I receive is like this. As I say in my other wiring page. It is more important to know what the colors and terminals do than to just match the colors with the letter of the terminal. In this case this person did just that (identify the function).

     Many manufacturers use the same terminal designation except for a few that change like "E" is emergency heat relay but it is not used on most units.
"B" is energize to heat (Rheem/Ruud) the opposite of "O" but here it is "Common" what would be "C" or "X" on Carrier or Bryant. I checked  a 3.5 ton Trane unit (General Electric is the same) and I found that "X2" is one set of auxiliary heat and "W" is the other. When the thermostat calls for auxiliary heat it energizes "W" when the outdoor unit calls for defrost it activates the "X2" line. If the unit has an outdoor thermostat (smaller units don't have one)  it will connect "W" and "X2" together. I recommend for proper operation of the Hunter thermostat to disconnect the outdoor thermostat (pull one wire loose and tape it) and let the Hunter do it's job. When the thermostat is placed in the Emergency heat mode it also connects the two together. The "W" terminal is connected to the "AUX. HEAT" lamp, the "X2" is not. Smaller units under 3 tons may not have this extra heat circuit. I recommend using "W" as the 1st stage of heat (W1) and "X2" as the second stage (W2).  If you are unsure leave it disconnected and if there are no problems leave it off while you decipher the wiring. It is better to have something not work than to fry the transformer or thermostat. Most GE/Trane units have a wiring diagram the inside cover of the outdoor unit control panel.

Notes: the older Hunter 44428 does not have a common terminal ("C") the newer ones do!

This part Written by Scott Meenen
 More to come...

November 2006:

Trane electric heat modification that will save you lots of $$$...

If you have a larger Trane heat pump with 2 sets of circuit breakers for the electric heat then consider making this minor modification that could save you lots of money. On the indoor unit there are 2 electric heat channels (inputs) W1 and W2. W1 is on the first circuit breaker with the fan and controls and W2 is on the second one and stands alone. Move the black wires (X2) to W1 and the white wires (W1) to W2 and power down that circuit breaker, remove any jumpers that may connect both inputs. This simple modification will give you emergency heat and defrost heat but allow the heat pump alone to heat the house without the benefit (or cost) of auxiliary heat.

    If the weather gets too cold for the system to keep up then you can close the second circuit breaker. This mod works on other brands of equipment with a similar configuration.

Related Pages:
    Other electronic thermostat stuff.
    Other Wiring page.
    Fan and Blower controls page.
    Identify which gas valve system you have.
    Heat pump service and repair page.
    Oil burner page.
    Millivolt electronic thermostat fix.
    Heat anticipator setting.
    Heat anticipator question.
    Electric Furnace repair.
    Wiring Scheme for a Wood Burning Furnace.

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Written By:  Scott Meenen N3SJH of:
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                 This text written by: Scott Meenen
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