I have a Rheem ROBF-067LBEA949 oil furnace as part of a forced-air Rheem UPNL-036JAZ heat-pump heating-and-cooling system, controlled by a Honeywell TH5220D1029 thermostat in its 2H1C w/ AUX configuration. We've only been in this house through one winter, so I don't know what's "normal", but the oil furnace seems to come on, run for 5-10 minutes, shut off, wait for 5 minutes, then come back on. I know in a compressor A/C system, this would be called "short cycling", and would be bad for the compressor. I'm concerned that this might be bad for the furnace over a long period.

Got any advice?

  • A wiring diagram would help if you can find one on the furnace. It could be a high temp cutoff, or a bad or dirty flame sensor, or something else.
    – Tyson
    Feb 5 '18 at 0:08

Yes I would call 5 to 10-minutes with a heat pump is a short cycle. You or someone needs to trouble-shoot to see what is interrupting the signal to the compressor contactor. If it is coming from the thermostat it could be programmed wrong. If you want a non-programmable Heat Pump stat try Honeywell #RTH3100C. Many companies make this though. Google non-programmable heat pump thermostat.

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