Furnace keeps running almost non-stop?

[Jdeere562]

Seems like it almost never shuts off! Had it serviced less than a month ago. Cleaned, tested and new filter.

Worked great until a few days ago. Now that it got below zero, when i need it most, it keeps running!
-2F now and falling to predicted low of -20F tonight by 7 PM. Should I be concerned?

 

[proveitwithdata]

Seems like it almost never shuts off! Had it serviced less than a month ago. Cleaned, tested and new filter.

Worked great until a few days ago. Now that it got below zero, when i need it most, it keeps running!
-2F now and falling to predicted low of -20F tonight by 7 PM. Should I be concerned?

Digital thermostat have double a batteries that need to be replaced from time to time. If the batteries go out, the furnance might not turn off according to the interwebs.

 

[hrv]

Is it maintaining the set temperature or does it feel like it is getting warmer in the room???? If so look at the thermostat...may need a new one...

 

[hrv]

Digital thermostat have double a batteries that need to be replaced from time to time. If the batteries go out, the furnance might not turn off according to the interwebs.

Yup I had that happen to me once...was a almost dead battery in the thermostat....It took 2 AA batteries and they were both just about dead.

 

[MasterSolenoid]

How efficient is the furnace ?
Could be anywhere fron 80% thru 96%

The less efficient, the more it will run.

 

[MasterSolenoid]

Yup I had that happen to me once...was a almost dead battery in the thermostat....It took 2 AA batteries and they were both just about dead.

I always thought the batteries were for maintaining the 'set' temperatures.
And that the thermostat got power from the furnace.
But I could be wrong.

At least changing the batteries is inexpensive (and may eliminate one possibility).

 

[Oil Changer]

As long as it's maintaining set temperature, let it run. I purposely set my fan to "run" 24/7. Constant airflow and filtration makes the home more comfortable. Doesn't hurt anything but a few pennies on the electric bill. Google it, you will find it is an accepted practice.

 

[tbm5690]

If it is properly sized, it will be running near constantly at the coldest temperatures that you see in your region. If it was -20F and it was cycling on and off constantly that would be uncomfortable and a sign that it is oversized. So, not at all unusual that in extreme cold it's running frequently, although if it's older it would have lost some efficiency as well so that very well may be a contributing factor.

 

[hemioiler]

I always thought the batteries were for maintaining the 'set' temperatures.
And that the thermostat got power from the furnace.
But I could be wrong.

At least changing the batteries is inexpensive (and may eliminate one possibility).

Depends on the furnace setup. Mine is just two wires running to the thermostat (or rather one circuit that is open/closed accordingly). It used to have an old skool mercury thermostat, all physical with nothing electrical inside. When the thermostat calls for power the mercury blob falls to the right side (gravity) and closes the circuit and the furnance turns on.

I replaced it with a battery system couple years ago, the batteries are there just to power the LCD display and run the date/time + temperature sensor. The same simple wire remains on the furnance itself. If the batteries go out, I just get no heat.

 

[2010Civic]

How efficient is the furnace ?
Could be anywhere fron 80% thru 96%

The less efficient, the more it will run.

Would a lower efficiency furnace run more or just burn more gas? If the 80% and 96% have the same btu rating they should have the same runtime.

 

[LazyDog]

If the furnace is size properly for a temperature level, when it gets to that temp it would run almost none stop.

I some times help my furnace when we gets those -20F and below by lowering the set temperature by 2-3 degrees.

Do check the mention batteries.

 

[tcp71]

Had our 44 year old furnace replaced last June. The new one is 96% efficient (lowest allowed here and bought to remove further complexity from the 99% ones) It has a control beside the furnace and a "smart", learning thermostat that just communicates and gets power through the old two wire interface from the original furnace. It has a two stage burner and infinitely variable motor control. I have the blower set to run and circulates air (at 10% motor speed) all the time and ramps the fan up as necessary while controlling the two stage burner. It has been a game changer dealing with cold/warm areas of the house with little difference between upstairs and downstairs in our 4 level split.

It really depends on the furnace and the logic it uses to maintain the temperature you are requesting. If it can, it will run at a reduced level continuously to maintain the temperature and that might be what you are experiencing, ramping up or down as necessary to deal with temperature change requests from the thermostat (if you have multiple day settings). A steady low burn is thought to be the most efficient energy mode on a newer furnace.

This is today:

 

[oil pan 4]

Sounds like you need a small indoor propane heater.

 

[JohnnyG]

Not enough information to make an educated guess.

 

[ATex7239]

If it is a multi-stage heat pump system as long as the aux heat isn’t on all the time it is fine. The system will use less energy to maintain warmth than it will to make it warm. Also cycling on/off cause more stress mechanically than running continuously.

 

[tbm5690]

If it is a multi-stage heat pump system as long as the aux heat isn’t on all the time it is fine. The system will use less energy to maintain warmth than it will to make it warm. Also cycling on/off cause more stress mechanically than running continuously.

Doubt he has a heat pump living in IA.

 

[97prizm]

Seems like it almost never shuts off! Had it serviced less than a month ago. Cleaned, tested and new filter.

Worked great until a few days ago. Now that it got below zero, when i need it most, it keeps running!
-2F now and falling to predicted low of -20F tonight by 7 PM. Should I be concerned?

I worked apartment maintenance for a while. First off the batteries may be low and not display low but will cause really odd behavior like this. Second I used to run two furnace filters on my old furnace but my new high efficiency furnace had Similar symptoms of constantly running with two filters.

 

[Jetronic]

Would a lower efficiency furnace run more or just burn more gas? If the 80% and 96% have the same btu rating they should have the same runtime.

Uses more fuel for the same output

 

[Hermann]

As long as it's maintaining set temperature, let it run. I purposely set my fan to "run" 24/7. Constant airflow and filtration makes the home more comfortable. Doesn't hurt anything but a few pennies on the electric bill. Google it, you will find it is an accepted practice.

I do that also, it balances my upstairs and downstairs temps. I like it better than the ceiling fan which creates drafts.

 

[eljefino]

How efficient is the furnace ?
Could be anywhere fron 80% thru 96%

The less efficient, the more it will run.

That's not how it works. Efficiency is how much fuel input is needed for a given heat output.

OP should actually set the thermostat a few degrees HIGHER, so the heat gets into the furthest corners of the house and helps keep pipes from freezing etc. And the house will have a running start for the next cold night.

Adding electric space heaters will probably overload the electrical grid if everyone's going through the same thing. Of course if he's on Natural Gas, same thing.