Should I cover a smallish tear/hole at the lower part of my furnace casing with aluminum tape, or is it not a concern?

Pataskala, OH

Furnace works OK and was checked in April in an energy audit. Furnace is 13 years old.


David Willson

Answered by David Willson

Sebastopol, CA

Advanced Home Performance

October 21, 2011


I'm not sure where the tear/hole is in the furnace casing, nor what kind of furnace you have. I'll assume it's a standard forced air furnace with ducts coming out of the top or bottom.

If the tear/hole is somewhere on the outer painted metal box of the furnace, made of sheet metal,

  • it should be fine to cover it with aluminum tape since it doesn't get too hot there and
  • I often use aluminum tape on the seams of the outer boxes of furnaces to make them more airtight.

If the tear/hole is inside your furnace or in a part of your furnace that is directly connected in any way to the flames or that gets way too hot to touch, STOP.

  • Do not run your furnace until it is looked at by a professional.
  • If it is the 'heat exchanger' part that is cracked or holed, then it is likely putting Carbon Monoxide (CO) into the air around your furnace and that is dangerous.

This is not to make you fearful, but hopefully cautious: CO is odorless and, in high enough concentrations can kill. In lower concentrations, it gives one a headache and/or feeling sluggish and foggy. The government says CO is the most common poisoning in the US, so a cracked heat exchanger is not to be taken lightly.

Please have your furnace looked at unless you are sure the tear/hole is external and safe.

Tagged In: heating cooling

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