Furnace can't keep up

I have a Bryant 80 furnace and a 3,000 sq foot house. Right now it is in the low single digits in Chicago with a windchill below zero.

I felt like my furnace was constantly on but never spent much time worrying aboit it. I have a wifi thermostat and recently found a program the tracks usage.

For example last night we had it set to 69 degrees. It would take about 20-30 minutes to drop a degree and cause a call for heat. The first 20 minutes running it would actually drop another half a degree. Overall it took about 50 minutes from the initial call to get back to 69.

Just to give a little more data from midnight to 530 am the furnace was running for a total of 4 hours just to maintain 69 overnight.

I have a clean filter installed. So I know it isn't that. I am not sure if this is normal because of the extreme cold or my house is just one big leak. Half the windows are new and I had new siding installed.

 

you may have a 2 stage furnace which in such case your furnace is likely properly sized. A properly sized furnace will run non stop on the coldest day it was designed for.

 

I believe it is a single stage furnace but I am not 100% sure. Does that change your answer?

Seems odd that the furnace has to run almost an hour to change the temp by 1 degree.

 

I'd start by taking the cover off the furnace and checking to see if the burners are staying lit whenever the thermostat is calling for heat.

In very cold temperatures, the furnace SHOULD stay lit much or all the time to keep the house properly heated.

But IF the thermostat is calling for heat AND the burners are shutting off, you have a problem someplace that deserves for investigation.

Also, you post the model number of the furnacfe which will be found on the rating plate in the burner compartment of the furnace.