Trane Heat Pump Thermostat Wiring Question.
About the Terminal Color Codes.
Connecting the Hunter 44428 Thermostat.
Trane Electric Heat Modification
> 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: email@example.com
> 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
> purpose-24 volt hot
> The following are the referenced terminal connections
in the Hunter 44428
> 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
> EMERGENCY MODE, OFF IN NORMAL MODE)
> Terminal "A" funtion-NORMAL COMPRESSOR OPERATION
> 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
> Trane "X2" to Hunter "E" SEE note
> 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.
(Weathertron is a Brand name of General Electric)
GE/Trane thermostats use an outdoor anticipator similar
to the one described here.
The new electronic Hunter Stat will not need an out door
stat ("T" lead) but some units do have them.
The only purpose of the common lead on most stats is to operate
the lamps unless it needs the 24 volt transformer to power the electronics.
See Note below.
The Hunter 44428 has the advantage of not using the electric
heat unless necessary and when it does it will bring the room to the
set point and shut the system off instead of running the heat pump forever.
It has 2 W terminals that allows the electric heat to be broken into 2
There is a reversing valve switch. It should be set to "RO"
in most cases, "RB" if Rheem/Ruud.
See Note below.
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!
On GE/American Standard/Trane and York "B" is common, please
do not confuse with Rheem/Ruud that use "B" to energize the reversing valve
with the system switch set to heat. If you connect "Common" to the reversing
valve "B" (or "O") you will blow out the transformer and possibly smoke
"X" can be common on some systems, or the indicator lamp.
On Trane/American Standard/GE "X2" is the second stage of electric heat
connect it to "W2".
If you have a Lennox system that uses terminals like:
F, V, R , P, L and H ect. triple check the function of each wire before
you connect a new thermostat!!!
I have amended my wiring
page and I will add it here too. I want to urge any one changing a
thermostat, especially one this expensive in the strongest terms to check
the function of each wire BEFORE you blow up your $80+ thermostat
and the control transformer. Obtain a set of clip leads (available from
Radio Shack) and a 1 amp fuse and test each function by connecting from
"R" to each of the wires that needs to be connected to make the system
work. If the fuse blows instantly then you most likely found the common
wire or a defective component.
An assistant is useful for verifying
each function on the outdoor unit, the reversing valve and contactor. The
electric heat functions should turn on the indoor blower.
I also insist that you never replace a thermostat or any
other components as a diagnostic or on a system that is not working correctly.
Isolate the problem first.
This part Written by Scott Meenen
More to come...
Trane electric heat modification that will save you lots
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.
electronic thermostat stuff.
and Blower controls page.
which gas valve system you have.
pump service and repair page.
electronic thermostat fix.
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Written By: Scott Meenen
G&S MECHANICAL SERVICES.
Specializing in Mechanical, Controls
and Electrical Modifications Of
Heating, Air conditioning, Refrigeration,
Ice Production and Food preservation.
Anything having to do with Heat
Serving Maryland, DC, and Northern
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This text written by: Scott Meenen
can be seen at the G&S Mechanical Framed home page