What That Crack In Your Heat Exchanger Means

Posted On: March 03, 2013

A heat exchanger is the metal component in a furnace that allows for heat transfer. In essence, it separates the airstream from the fire. If it’s cracked, it may allow potentially lethal carbon monoxide (CO) and other combustion by-products into your home’s airstream. A cracked heat exchanger also likely will greatly reduce the efficiency of your furnace, or disable it entirely. When your furnace’s heat exchanger is cracked, you’ll likely have to decide between replacing the part, which can be very expensive, or replacing the entire furnace. It’s like finding out that the transmission in your 12-year-old car is shot; does it make more sense to put a lot of money into an old car, or just go out and buy one with much greater fuel economy?

Cracks in furnace heat exchangers may be caused by a variety of factors:

  • Stress and flexing of the metal; the heating and cooling cycle of the furnace naturally causes it to expand and contract, which applies stress can result in failure or cracking over time.
  • Improper airflow as a result of a dirty furnace filter, closed off vents or blocked vents may cause the system to work harder than it should, which may result in premature cracking.
  • Improper combustion of natural gas, propane or fuel oil causes your burners to run hotter than they should or at lower efficiency than they should. This eventually may cause cracking.
  • Improper displacement of condensation also causes cracking. This happens when a furnace has not been run for a long period. Condensation tends to accumulate in the exchanger and causes rusting, which can lead to cracking once you start using your furnace again.

The best way to find out if you have a crack in your heat exchanger is to call your trusted HVAC technician. He will turn on the furnace and conduct tests to see if your heat exchanger has cracks. If he finds a problem, he likely will “red-tag” your furnace, meaning it will remain disabled until you get it repaired or replaced.

For more expert advice on problems with your furnace, please contact us today at Ernst Heating & Cooling. We provide quality HVAC services to the Metro-East area.

Our goal is to help educate our customers in Hamel, Illinois and surrounding areas about energy and home comfort issues (specific to HVAC systems).  For more information about cracked heat exchangers and other HVAC topics, download our free Home Comfort Resource guide. 

Image courtesy of Shutterstock

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