Strange issue with Thermostat on Carrier Heat Pump

Problems related to residential installations.

Strange issue with Thermostat on Carrier Heat Pump

Postby markinhsv » Wed Mar 14, 2012 10:45 pm

I have a Carrier single stage heat pump model 25HCB3/25HCC5 and it has an aftermarket Lux TX900TS thermostat wired as described at the bottom of page 11 in the manual.

*.*/images/I/712XuM1YTDS.pdf (images-amazon dot com)

I have no B connected but all of the others are connected as in the diagram, including the optional C.

The problem is the jumper between W and Y. It must be there in order for the compressor to come on for heating, otherwise only the heat strips work. It must not be there in order for the compressor to come on for cooling. I can't figure out how to wire it so that the compressor comes on for both heating and cooling.

Any ideas?

Thanks,
-Mark
markinhsv
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- Strange issue with Thermostat on Carrier Heat Pump

Postby markinhsv » Fri Mar 16, 2012 2:04 pm

The thermostat was an aftermarket one I had with my previous HVAC system. It was much nicer than the one that came with the new system so the installer asked if I'd like to just keep it. I did. I guess I should have not just assumed that he would not let me keep a thermostat that was not compatible with my system.
markinhsv
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