October 2, 2014
Cracked Heat Exchanger

So what is a heat exchanger even for? It’s for transferring heat from the furnace to the air inside your home.

A heat exchanger is metal tubing that contains the heat energy from the gas combustion of a furnace. Here’s how it works: The flame in a furnace powers on and fills the heat exchanger with heat. Then the furnace fan motor pulls air from the home, and forces it through the heat exchanger. The air absorbs heat energy from the hot metal tubing, and is then delivered back into the home via ducting.

Why Have a Heat Exchanger?

The reason you need a heat exchanger is because gas furnace combustion has bad things in it like carbon dioxide, carbon monoxide, pure carbon and nitrogen oxides. These can cause death to humans at high levels. So a heat exchanger encases them while still allowing heat energy to be absorbed by the air. The pollution is then vented outside.

The picture at the top shows a cracked heat exchanger, and is compliments of Steffens Plumbing and Heating. Heat exchangers are designed to last the life of a furnace, but sometimes they can wear out prematurely and crack. This obviously presents a very dangerous situation for your home, because gases would be pumped into every room, and that of course is fatal.

What Causes a Cracked Heat Exchanger?

As mentioned above, they should last the life of your furnace. So what causes them to have problems prematurely? A few things:

  • Not changing your furnace filter can cause a heat exchanger to eventually crack. The reason is because a furnace overheats with restricted air flow.
  • Ducting issues can also cause restricted airflow problems and overheating.
  • Constant cycling: When a furnace turns on and off, the heat exchanger must heat up and cool down. Illian Heating likens it to bending a paperclip. We all know what happens if you bend a paperclip back and forth a lot. Constant cycling can be the result of a wrongly sized furnace.

So make sure your HVAC contractor checks out your heat exchanger for cracks, and be careful of shiesty HVAC companies as they will often say your heat exchanger is cracked simply to sell you a new furnace.

Some furnace manufacturers offer long warranties on heat exchangers, so look into those details before buying new equipment. And most of all, make sure your system is sized, installed and maintained correctly as this is the ultimate way to stay efficient and keep your family safe.

Happy heating as we approach another winter season. Thanks for reading the Find an HVAC Dealer blog!




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