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QUESTION:I have a Thermo Pride forced-air oil furnace. Is it normal for the
fan/limit switch to operate at the limit temperature?
Here is what is happening:
1. Thermostat calls for heat, and burner fires.
2. When the fan/limit switch hits 150 degrees, the circulating fan
starts.
3. The fan/limit switch hits 200 degrees, and the burner shuts off.
4. The fan/limit switch drops below 200 degrees and the burner fires.
5. Steps 3 and 4 repeat, as long as the thermostat calls for heat.
6. Thermostat stops calling for hear, and burner shuts off.
7. Circulating fan runs until fan/limit switch drops to 100 degrees.
By the way, 200 degrees is the manufacturer's spec for maximum output
air temperature. My question is: are steps 3-5 normal operation for
this type of furnace?
ANSWER: heat exchanger is getting too hot. check to ake sure blower is running,
not just blower motor,and check filters. ifunit has central air
evaperator coil could be clogged with dust. youv'e got to get the air
flowing. this assumes the limit switch is not defective and the temp
really does get up to 200 degrees. make a small hole and check withan
instant read meat thermmeter
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