View Full Version : How long is a "short cycle"?
01-30-2006, 12:59 PM
Furnace short cycling is frequently mentioned in this forum as not being energy efficient. I have a Honeywell thermostat that can be set to 3 or 6 cycles per hour. (Currently set at 3 cycles). Are either of these considered short cycles?
Maybe I should have asked if a 10 minute run time is considered a short cycle.
[Edited by whitedog on 01-30-2006 at 05:49 PM]
01-30-2006, 01:07 PM
3 cycles is ideal set point.
Depends on how cold it is outside, the furnace run time may vary.
On an avg, I seen about 20 min run time on 3 cph, and about 10 to 15 min down time.
01-30-2006, 03:36 PM
3 per hour would be 10 min on 10 min off right? That's how I count them...maybe I'm wrong...a Cycle to me is "time on + time off" 6 would be 5 on 5 off . Correct me.
01-30-2006, 04:24 PM
I'm also interested if 2 stage unit is supposed to run on first stage during these cycles or needs to be partially on 2 stages while maintaining temperature (no change). What's preffered?
01-30-2006, 06:25 PM
Anywhere between a smidgen and just shy of a long cycle... Sorry.
01-30-2006, 07:02 PM
3 cycles per hour is a good setting. A short cycle would be less than 5 minutes during minimum demand IMO. During extreme outdoor temperatures(depending on design temp), the furance should run nearly constantly. A 2 stage system runs normally on 1st stage, but when extra heat is needed for it to maintain the temp setting, the tstat will bring on the 2nd stage. 2nd stage should only run during peak demand. A normal cycle should consist of a long run on 1st stage.
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