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roadbiker255 07-20-2012 08:01 AM

Trane Thermostat Replacement
I currently have a Trane heat pump system (model number will be posted as soon as I get home) at my residence. I want to upgrade my thermostat to a new touchscreen. I just purchased a new Pro1 IAQ T905 programmable thermostat to take the place of the older trane. When looking over the diagram I really do not know which wires from the trane will be the correct ones to connect to the new thermostat and I do not want to break anything. Heres what is on the Trane: I will state the letter abbreviation that is on the thermostat and the color of the wire hooked into the screw.

B (has a blue wire hooked in)
G (has a green wire hooked in)
0 (has an orange wire hooked in)
x2 (has 2 white wires hooked in- ONE OF THESE JUMPS TO THE W SCREW)
Y (has a yellow wire hooked in)
T (has a brown wire hooked in)
R (has a red wire hooked in)
W (has the white wire jumped from x2)

This is how the trane is currently hooked up. The new Pro1 IAQ has different colors to hook iwres into and I am not sure which ones to hook up and where. Heres the description of the new thermostat wire blocks:


Any help on how to connect this new thermostat would be great. Thanks!

Houston204 07-23-2012 09:55 PM

Your new stat will not support your multistage heat pump.

turnermech 07-23-2012 10:17 PM

RH jumper from factory with RC connect red wire
G green
Y yrellow
C blue
O orange
B not used (should be one terminal O/B would be configured in configuration mode to reversing valve energized in cooling)
W white

Make sure you turn power off to the inside unit before changing wires or you could damage the low voltage transformer.
Make sure your new tstat is for heat pump with electric backup heat. By your list of terminal I cant be sure. Usually would have more terminals on heat pump tstat such a E.

Houston204 07-23-2012 11:45 PM

beenthere 07-24-2012 05:13 AM

That thermostat doesn't energize the Y terminal on a heat call. It requires a jumper from W to Y to run the compressor. Which is why it can't be used on a heat pump with aux heat. Since there is no way to bring on the aux heat.

roadbiker255 07-24-2012 07:02 AM

Well I guess this thermostat will not work. Thanks for the input. So I need to look for one that will run a heat pump with aux heat? Do you guys have any recommendations of a thermostat that will work that is similar to the one I bought?

scottmcd9999 07-24-2012 08:45 AM

This one will:

I don't know anything about these thermostats, so cannot comment on whether it's the right one for your SYSTEM - but it will control a multistage heat pump.

turnermech 07-24-2012 01:29 PM

Buy a Honeywell 5000 for non programable or a 6000 for programable. Box will say if it works for heat pump with Aux heat.

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