I purchased a Honeywell RTH6400 Series programmable thermostat and having trouble with the wiring. I have a York Stellar Plus High Efficiency Heat Pump. Natural Gas blower in the attic. I labeled the wires of the old thermostat with the exact stickers provided, connected the new Honeywell best I could following the directions and the heat works, but switching to cool blows heat too. Someone mentioned I may have a 2 stage heap pump? I guess that is a multi-stage heat pump?
Page 11 reads is will not work with a multi-stage heap pump system or 120/240 volt system.
I don't have the old thermostat any more and can't remember if it have a aux/emerg switch. How can I tell? Wires are ''G'' ''O'' ''W1'' ''Y'' and a red one that was in RC/RH of the old one so I labelled it with both because it did not differentiate.
Hello You have only 5 wires? multi stage if so ,is run by something else.Check that RH/RC is jumped out on new stat.Also check that O is not on the B terminal.If there is an A/B select switch set it to O.Emergency heat button dont matter as there is no wire to run it with only 5 wires.
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Found old type. I did not throw away due to mercury. Just have that piece however. It is a HONEYWELL T874A-1036 NSFP T874A1036
THERMOSTAT 50-80 MULTISTAGE 24-30VAC.
So I assume Page 11 explains it perfectly. Will not work with. I guess I need to purchase another thermostat.
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