smell from hot air furnace
- Thread starter raaizin
- Start date
Have the heating elements checked. They could be starting to burn in two from being 25 years old.
dnewton3
Staff member
Your statements are confusing ...
Is this a gas furnace, and you're saying the odor isn't gas?
Or is the not a gas furnace, and it smells like electrical buring?
Probably blower motor bearing
Quick question, if it is the heating elements could this be done in a month if they cannot get it done by Tuesday. We were scheduled to be away for the month of February. The house will be empty concerned furnace will quit and pipes freezing or fire possibly.
If it is a natural gas furnace, please verify your Carbon Monoxide detectors are functioning properly. A hairline crack in the heat exchanger is not uncommon in a 25 year old furnace. While CO is undetectable to the human senses, trace amounts of combustible gasses could be leaking through a compromised heat exchanger into the ductwork. Combustible gasses can have a unique odor that is not unlike burnt electrical, metallic/ozone compounds.
My thoughts exactly, every home with fossil fuels should have a CO detector.
They work!!! Don’t ask how I know but my family and I survived when the thing went off and the siren sounded while we were sleeping one winters night decades ago.
It could have turned out very bad.
Do you have a humidifier on your furnace? When I forget to change the pads in ours sometimes it smells like damp cardboard. I second the carbon monoxide detector to be safe.
It is possible to get an ionized air odor from a failing start switch on the blower motor. Good luck tracking this odor.
I think I may have found the issue. I checked my sump pump and the wire was hot. I unplugged it and noticed the water was so hot I could see water vapors rising from the well. Not sure why the fuse didnt blow it is a new panel with new fuses. I will make another post to ask that question. Hopefully this was the issue!
dnewton3
Staff member
This is a misunderstood issue that is not a significant risk.
Small cracks in the HX are an overblown risk; it is very typical for the primary HX to have cracks, in every brand. Modern furnaces run under a slight negative pressure inside the combustion system; the draft inducer draws the air through and keeps the heat exchangers in a slight vacuum. There's no reasonable way the CO would escape to a higher pressure area (into the main air flowing to ducts). Low pressure areas don't force their way into a higher pressure area.
Should the draft inducer motor fail, the pressure switch should drop out and shut down the furnace.
A major void in the primary HX could allow cumbustion gases to escape, but then it would be highly improbable that the draft inducer could hold the pressure switch closed should that condition occur, and so again, the furnace would not run.
I had a weird electrical burning smell from my 33 year old oil furnace and it turned out to be the nozzle. It was quite dirty and was preventing complete combustion and it would puff out of the barometric damper and cause an electrical burny smell.
