I have a thermostat/furnace combination that results in a hyper system --
sometimes the furnace turns on for a minute or less, turns off for a minute
or less, etc. This gets annoying.
I would like to reduce the frequency of switching on and off. In other
words, if it turns on, stay on longer. When it turns off, stay off longer.
This may results in more temperature fluctuation, which is ok.
So, is there a thermostat that allows me to control either: minimum on/off
duration or the on-temperature and off-temperature independently?
My temporary hack is to cover the thermostat with a box. This delays the
temperature change at the thermostat and lengthens the on/off cycle
duration. But I'd rather not have a box on the thermostat.
The current thermostat is a honeywell low voltage system, bought some 10
It might be defective. They shouldn't short-cycle like that.
But there is one thing you can check -- is there solid wall and
insulation behind the thermostat on which it is mounted? If not, plug
up any holes (as the installation instructions, if you still have them,
tell you to do).
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It could be a defective or misadjusted thermostat. Some mechanical
thermostats have a heat anticipation feature which must be set once for
the current going through the thermostat. If it's not set properly, the
thermostat may show the symptoms you described. Some modern thermostats
have electronics that avoid short cycles.
It should function much better than that. You can tinker with the
anticipator if it can be adjusted, but you may do as well just replacing it
with a new one with other features you may want, such as programmability.
Does it short cycle if you were to turn the thermostat up say, four or more
degrees? Or only when near the setting you have?
It is also possible there is a problem with the limit switches in the
heater. It may cut out on the high limit well before it should. The only
way to know is to watch a full cycle to see what is happening. The burner
should be coming on, then once a certain temperature is reached, the blower
should come on and stay on as long as the thermostat calls for heat.
I am surprised that nobody "has got it right" so far.
Many Honeywell thermostats cycle the furnace this way to "ease" the
temp up to the set point. The idea is to provide greater comfort
while not "overshooting" the temperature setting on the t-stat. My
"fancy pants" Honeywell VisionPro has a setting where you can choose
how many cycles per hour (max), to avoid really short cycles. I think
the current setting is 5 per hour. Yours won't have that option,
I believe that the "work around" is to set the switches on the back
(If you have them) to "gravity hot water" which should defeat the
cycling completely. The trade off is that the t-stat might shut off
early, before it hits the set point, or it might overshoot the temp.
To me, I would rather lose a little comfort to keep the furnace from
cycling 50 times a day.
A little more research yields this:
Electric warm air systems - 9 cph (cycles per hour)
Gas / OIl warm air systems - 6 cph
Gravity (or steam) systems - 1 cph
More often would indicate another issue.
Do you still have the instructions. If so it should tell you how to
adjust it. It may be called an anticipator. Of course also check for
those open holes and possible malfunction or a bad location, like just above
I believe most manufacturers consider it an adjustment, not a feature,
so the only place you will find it is in the owner's manual.
If you check the owner's manual for your current stat, you might find it
is there. I have no experience with two stage units so my comments may not
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