Cracked Heat Exchanger: When Is It A Problem?

A furnace heat exchanger is a metal compartment that serves as a barrier between the warming flame and the fumes it generates and the air in your home.

The heat exchanger is heated by the flame, which in turn warms the air that enters your home. This system keeps combustion fumes contained, directing them to the flue to be carried away safely through the chimney.

A cracked heat exchanger can allow dangerous fumes to leak, such as carbon monoxide, and can create other hazards, such as poor combustion, soot buildup and flame roll out.

What causes a cracked heat exchanger?

Metal expands and contracts during temperature changes, so the repetitive cycle of heating and cooling stresses the heat exchanger, eventually causing deterioration. In a properly installed and well-maintained furnace, the heat exchanger should last approximately 15 to 20 years. However, insufficient airflow, due to dirty filters, poor maintenance or improperly sized ductwork can cause excessive heat in the furnace, leading to stress cracks in the heat exchanger, or moisture problems can promote rust, causing premature failure.

Diagnosing a dangerous heat exchanger

Your heat exchanger should be inspected for damage by a reputable HVAC professional at least once a year. Many heat exchangers develop hairline cracks that aren’t necessarily dangerous, but will require monitoring. If cracks are severe enough that you can see light shining through upon evaluation, they definitely need immediate attention.

Your heat exchanger should be inspected for damage by a reputable HVAC professional at least once a year. Typically, a crack will cause problems with furnace operation, making burner flames dance or roll out of the combustion chamber.

If you’ve been informed that your furnace needs replacement due to a cracked heat exchanger, feel free to contact us for a second opinion. Family owned and operated, Apollo Home Heating, Cooling and Plumbing has been a trusted source in home mechanical repair in the greater Cincinnati area since 1910.

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- Cassandra B.
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- Randy B.
"We scheduled an estimate AND a tune-up. We knew something was wrong with our furnace, but hoped we could make it through the rest of the season. Upon telling Bill what our furnace was doing, he warned us immediately what the possible outcome was going to be; a cracked heat exchanger. He watched the flames roll backward, tested carbon monoxide levels, which were so high they meter’s last reading was 5,600 before saying “high”. He immediately shut it down, tagged it, and explained that with levels that high and children in our home he wanted off right away. He continued his inspection and showed us via a camera that not only was it cracked in multiple places, but had holes all over it. He gave us a few options for repairing it; his knowledge as well as genuine concern was beneficial and refreshing. Luckily we also scheduled an estimator, Micah, to come too and we were able to get costs between repairing and replacing (with several options). We decided to replace with a much higher efficiency furnace and one sized properly to our home. Hands down, not only did they both provide us great service and knowledge, but without sounding dramatic, they may have saved our lives. This was our first time calling Apollo, but it won’t be our last."
- Sarah B.
"Apollo is an excellent company. I always receive great service. Alex A. was professional and friendly. He kept me informed during the process of checking my furnace and heat pump to make sure they were working properly. The company makes sure you are notified who is coming and when they are on the way. All my interactions with the company have been wonderful."
- Beverly S.
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