Home heating question. Furnace cycles often.

[Riverrojo]

I bought my newly renovated 1300sq ft brick ranch last year. The man who did the renovations (at closing) showed me his business card (owns heating/cooling business). He put in a new Goodman 93% efficiency furnace and new ac. Told me that if this was his house, he would insulate above the poured walls in the basement and put more insulation in the attic. Put two layers of r13 insulation
above the poured basement walls and increased my attic insulation from r13 to above r60. My furnace still constantly turns on and off. The thermostat is a one year old digital/programmable honeywell. Windows are double paned about 10yrs old. Walls were insulated when the house was built in 1973. Doing online research, I keep getting the answer that possibly my heat anticipator could be incorrect. Do programmable thermostats have these? The thermostat is in a central location, not near any windows/direct sunlight/heat registers. So, now I have been resorting to turning the heat on manually when I am home, and just turning it off when I'm away. The house loses heat very slowly when the heat is off (2-3*F overnight w/ freezing temps outside) Any clues as to why the furnace turns on every 10 minutes or so, runs for 10 minutes or so and repeats constantly? Thank you for your help.

 

[Innov8tive1]

Mine has started doing this ever since I installed a digital thermostat prior to this heating season. My only answer to this is that the digital t-stat is more tightly regulating the temperature in the house. My old analog one would let it get quite cool before kicking on and it would keep running long after it had reached a comfortable temperature. I found it frustrating trying to find a comfortable setting. I am not sure how this will be reflected in our gas bill, I am guessing that more cycling will use more gas as you have to heat up the heat exchanger and duct work all over again.
Our house was built in 1977 and has lots of extra insulation in the attic (haven't measured but I think over 16" of cellulose) and 2" of rigid foam board on the outside. It is very comfortable and easy to heat and doesn't seem to lose heat very fast although I haven't done any measurement.

 

[RobertMo1988]

where is your stat located? it could be in a colder spot in the house and could just never be satisfied or get to the temp you want in that one spot.

 

[Innov8tive1]

If it's shutting off it's satisfied. But why is it not satisfied so quickly I think is the question.

 

[Innov8tive1]

I wonder if it is possible to change the range of temperature which will satisfy the call for heat. In other words when the temp drops half a degree it doesn't kick on it wait's until it has dropped a whole degree or two. Perhaps this is what a heat anticipator does. I know how a furnace works and the principal behind a thermostat but I do not think all digital t-stats are created equal.

 

[danski0224]

Some digital thermostats have an adjustable "cycles per hour", which mimics the function of a heat anticipator if it is set properly.

Not all digital thermostats are created equally.

Is the wall opening behind the thermostat sealed?

 

[lilredex]

Whenever I move to a new house, one of the first things I do is widen the differential setting (distance in degrees between demand and satisfied) and set the fan to run on "continuous". This will stop the burner from that constant cycling. Most installations are set with a tight differential because people complain. Never had a digital version, so cannot help you there, a mechanical version has a very simple adjustment...........>longer cycle.

 

[Innov8tive1]

I guess it boils down to preference, do you want your house to be as close to the set temp as possible or can you tolerate a degree or two higher or lower.
Still don't know if you can adjust the differential setting with a digital t-stat.......probably depends on the t-stat.

 

[Sureshot]

What about blocking any direct airflow past the thermostat. Say if you have a duct or something close. Try covering it partially or blocking the air. Hang a spaghetti strainer over it and see what happens.

 

[theoldwizard1]

If it's shutting off it's satisfied.

Not necessarily !

It is unusual, but I have this problem. If there is too much restriction in the output plenum (like a horizontal furnace in a crawl space) and the heat demand is high (outside temperature well below zero) the heat exchange may over temp.

The furnace will shut down until the heat exchanger cools, but because the thermostat was not satisfied, it will cycle back on. This can happen a dozen or more times in an hour.

The only solution is a stronger blower or possibly a less powerful burner (which would run longer).

 

[z28toz06]

No one has asked the question "is the boiler sized correctly". It sounds like its oversized for the task at hand. If its too big it will come on often and shut off pretty quick. Its bad for the boiler and will kill it prematurely. Check boiler size with load requirements/heat loss and insulation(sounds like that's already squared away)

 

[Dodge]

I have a Goodman furnace in my house. After it was about 3 years old, it started cycling the burners on and off. It was the flame sensor. Just remove it and clean with a piece of emery cloth or fine sand paper. Mine is right in the front of the furnace, below the burners. One small screw removes it. Simple. I have had to do it another time a few years later. Hope it is your problem. Another thing that can cause cycling is not enough cold air returns.

 

[RobertMo1988]

If it's shutting off it's satisfied. But why is it not satisfied so quickly I think is the question.

I was thinking in normal circumstances it would shut off if it is satisfied but with in a couple minutes what if its not? what if its in a breeze way or something for it to alter the desired temperature. I see it as maybe its not satisfied it is turning back on.

Is the stat by a Door? in lower part of the house? by any registers?


As far as Digital Thermostats I have one, and its the Carrier Edge Programmable Stat, Pretty good size lcd screen, Customizable colors, programmable, only down side is the price, and that goes with everything. I have absolutely no problems with it.

 

[stevefasano]

removed due to

 

[Dragster Racer]

I didn't read anything about a boiler...but I would say that the furnace is larger than what is appropriate. If the swing is adjustable on the tstat, widen it out as much as it will go and start there.
We have a White Rogers tstat with all the bells and whistles at work, and I can't find where to adjust the swing on that thing. It has a bunch of menus. I can't find the directions. If anyone knows, it would help me.

 

[Sidekick]

Ok, let me chime in. Back in the day furnaces would discharge air at 150 degrees to the registers, not any more. Furnaces today do not allow much heat energy to be lost up the chimney. Digital stats are as different from each other as cars, some allow for temperature differentials and most do not. I would not worry about the cycling of the furnace at all. Above 90% efficient furnaces are supposed to run almost continuously if they are sized right. that is where the lab boys say they run to design perimeters.

New furnaces squeeze as mush heat out of the gas as possible yet only discharge 95 to 125 degrees to the registers so they WILL run longer. Gone are the days you could come in out of the cold and warm your hands quickly at a floor register.

 

[Sureshot]

Ok, let me chime in. Back in the day furnaces would discharge air at 150 degrees to the registers, not any more. Furnaces today do not allow much heat energy to be lost up the chimney. Digital stats are as different from each other as cars, some allow for temperature differentials and most do not. I would not worry about the cycling of the furnace at all. Above 90% efficient furnaces are supposed to run almost continuously if they are sized right. that is where the lab boys say they run to design perimeters.

New furnaces squeeze as mush heat out of the gas as possible yet only discharge 95 to 125 degrees to the registers so they WILL run longer. Gone are the days you could come in out of the cold and warm your hands quickly at a floor register.

If I understand the problem it is not the total amount of time running rather the frquent on/off periods.

When we went to a central boiler to heat the house and shop we simply installed a heat exchanger(radiator) in the furnace duct work. The oil burner was left in tact and used in spring and fall when only a morning warmup was required. Our furnace cycled far less frquently on the boiler than the oil heat. I think it was due to the "less warm" air taking longer to warm things thus the objects in the house were warmed. Then the thermal mass kept the place feeling warmer longer. So instead of 10 on 10 off we now get 60 on 60 off.

I think the floor heat in the shop has the same effect. People talk of a unit heater for quick recovery and I was prepared to go this way but found it totally unnecessary. My doors are 12x14 and we were bringing in 35k pound trucks that were -30. And I do have the unit heater and never installed it.

 

[jimp]

Just a thought,

Do you have a two stage furnace and thermostat? If so it is made to "short cycle" on the lower range. It only kicks in the full capacity once it gets cold outside and its not able to keep up with the lower capacity.

Mine is a two stage and it cycles quit often, but only on the lower range. It keeps the house very stable and is very quite on the lower range.

 

[thooks]

Honeywell thermostats are garbage. About 2002, they started making them where they automatically fired the furnace 6 times per hour if they were in heating mode, whether or not the thermostat was calling for heat or not.

No, I'm not joking. I had a system put in my addition at the time and the contractor put a Honeywell Tstat in that fired the furnace 6 times per hour...as I said, whether it needed it or not, while on "Heat".

I had him take it out and put in a Robertshaw.

 

[rickairmedic]

Thats odd I swear by honeywell Tstats and actualy my favorite " current" T stat is the Honeywell 8000 . Granted there will never be another great Tstat like the good old T87 but I like the 8000 and can actually go in and program many things including number of cycles per hour in it .

Rick

 

[AmickRacing]

I wouldn't be surprised if that was true of the consumer grade honeywell's, but the contractor grade one's (aka, not home depot one's) won't cycle the heat if it's not needed.

I'd agree with everyone that's saying widen the deadband out so it won't cycle as much. Also there should be a setting in there where you can adjust the cycles per hour, lower this. This won't make it cycle if it's not calling, it will just help keep it from cycling as much.

Also, make sure you have a clean filter in the unit. I doubt it's going off on high limit, but you never know. A dirty filter could be restricting the air enough to now allow the house to warm up like the duct was (hopefully) designed for.

If none of that solves it, I'd say call a good company to come out and give your furnace a good tune up, it'd be money well spent. Heck, it really wouldn't be a bad idea to do that anyway... equipment loves maintenance.

 

[Jay41]

We use Honeywell t-stats exclusively, never had a problem.
On the 5,000 and 6,000 series stats, 5 cycles per hour is default setting for 90% eff. furnaces. Go to installer set-up, when you get to option #5, lower it to 3 cycles per hour and see if that helps you.

 

[thooks]

Someone please explain to me why the furnace should cycle X times per hour, whether or not there is a call for heat?

Please. If the space is 74°F and the setpoint is 68°F and the Tstat is set to "Heat"....Please explain to me what ***** at Honeywell said "we need to kick the heat on, anyway. It does not matter what the space temp is."


Yes. In 2002 when this piece of **** was installed and I discovered what was going on and verified that the factory programming for this Tstat was indeed to fire the furnace 6 times per hour....I called Honeywell to inquire why....

They didn't have an answer, only that it was indeed true that these were supposed to do that.

FWIW, these were the square, white thermostats with the digital readout, an up and down button along with Heat-Off-Cool and Auto-On.

There will never be another Honeywell product in my house. Nor will I ever spec one.

You can't fix stupidity.

 

[tk03]

Honeywell or anyone else has ever produced a thermostat to cycle when there was no call for heat. That is a misunderstanding somehow. If you had a thermostat over shooting there was another issue as to why. In 33 years and probably thousands of thermostats, all Honeywell, I have never seen that. I have customers with no a/c in the house and they do not turn off the thermostat. That would mean the thermostat would cycle all summer. Why would they have temperature settings if it had to run x number of times an hour even it it did not need heat.

 

[thooks]

I'm sorry, TK, but you are wrong.

You obviously have not read this thread completely. There's other posts that state that the default, factory settings for some Tstats are to fire the furnace X number of times per hour, whether there is a call for heat based on the space temp and setpoint or not.

This only occurs when the selector button is at "Heat"....not "Cool".

There is or were some idiots loose at Honeywell. When I called them in 2002, NOT A SOUL there could explain why their controller was setup this way.

 

[thooks]

Here's some info

http://hvac-talk.com/vbb/archive/index.php/t-69744.html

There's a lot more out there concerning "Cycles per hour" and "Honeywell".

I want the furnace to fire when there is a call for heat. I want it to stay off when there isn't.

It's not that complicated.

 

[Gary S]

Check to see if your thermostat has adjustable hysteresis.
http://en.wikipedia.org/wiki/Thermostat

It is the hysteresis that determines the rate it will cycle.