Furnace Short Cycles Off and On
I have a Suburban SF30fq furnace that cycles the heater flame off and on about every three minutes while the coach is reaching the thermostat setting (technically called short cycling on the limit swi...
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It would appear that the heat exchange isn't keeping up with the burner. I think you've already covered most of the reasons why this would reasonably happen, at least the reasons I know of as a moderately handy guy who isn't at all a furnace specialist.
Have you verified that the limit switch is indeed what is shutting the flame down (and not something else in the control system)? I can envision that something like a poor connection or bad solder joint on the control board could act similarly to the limit switch cycling under the right (wrong?) conditions.
I'd also check that the baffles etc. in the "house" part of the furnace are all properly in place, and that the combustion chamber area is clean.
Have you verified that the limit switch is indeed what is shutting the flame down (and not something else in the control system)? I can envision that something like a poor connection or bad solder joint on the control board could act similarly to the limit switch cycling under the right (wrong?) conditions.
I'd also check that the baffles etc. in the "house" part of the furnace are all properly in place, and that the combustion chamber area is clean.
