Original message
| mikef
 |  "thermostat help"
, posted Thu 26 Oct 10:39:  
I need assistance changing from an old Honeywell thermostat T874R/Q674L to a Honeywell digital model RTH7400. The old base had 7 wires connected on the following terminals blue on B, orange on O, yellow on Y, black on X, green on G, red on R and a white wire on W2, which was strapped to E.
Per the installation manual I have red on R, orange on O, yellow on Y, green on G, blue on C, black on E and white on Aux, also RC and R are jumpered.
No smoke is coming out but the inside unit freezes up when running. When I rewire the old thermostat, it works great, any suggestion would be appreciated.
[this message was edited by mikef on Thu 26 Oct 11:00] |
| Replies:
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| Zzz
| "Re(1):thermostat help" , posted Sat 25 Nov 10:09
I am thinking you are hooking this t-stat up to a lennox heat pump with electric back up. X is normally common on newer models. I notice you have a separate B and O written these are the reversing valve and in the set up it asks which way you want them to oporate, lennox reverses for cooling. Y on older models runs the fan where on newer ones it runs the compressor.
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| Freezone12
| "Re(1):thermostat help" , posted Sat 28 Oct 09:30
first, you need to look in your condensing unit at the wiring diagram and compare notes with your thermostat wiring diagram.
if/after all is well there you may need to configure the thermostat itself. look in the installation manual for the procedure and options available to you. if you no longer have the booklet, go to honeywell.com and sniff around for your particular stat. all the data is available there.
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If it don't fit
force it.
If it breaks
it needed to be replaced anyways.
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