furnace ignoring thermostat set point - http://www.hvacmechanic.com/ Forums
Original message
| amyhughes
 |  "furnace ignoring thermostat set point"
, posted Sun 2 Mar 19:17  
[posted this to HVAC, this seems like a better place, sorry for the duplicate]
I've had the following problem for 15 years and finally bought a new thermostat, and it didn't solve the problem.
Frequently (multiple times per day) I'll feel hot, so I'll go to the thermostat and find that the setpoint is 72, the current temperature is 78, and the furnace is turning *on*. So I'll reduce the set point 2 degrees and eventually the furnace will stop, and an hour later I'll feel cold. I'll check the thermostat and find that the current temperature is 65, the set point is 70, and the furnace is off. So, I'll increase the set point two degrees, the furnace will turn on, and the cycle will repeat.
The new thermostat is a basic honeywell digital model. I use it in "run mode"--no timer, just a constant temperature. The old one is a late-80's vintage analog Trane. The furnace is a late-80's vintage Trane gas model, apartment size.
Any clue why this furnace does this?
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Replies:
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| Freon
| "Re(1):furnace ignoring thermostat set point" , posted Mon 3 Mar 11:37
On your old thermostat, assuming your problem was the thermostat, the heat anticipator may have been messed up. However your new Honeywell should have a cycles per hour setting that will regulate how many times per hour your furnace runs. Be sure the cycles per hour (cph) and the type of heating system are correctly set in the thermostat setup program.
If the problem persists, come back here and we'll try some further tests.
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| justsomeguy
| "Re(1):furnace ignoring thermostat set point" , posted Sun 2 Mar 20:46
I'm curious as to why you waited 15 years to do something about it. You're trolling this group right?
BillyBob
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