A Cracked Heat Exchanger: What Does It Mean for Your Furnace? – Sobieski Services | DE, NJ, PA, MD

A Cracked Heat Exchanger: What Does It Mean for Your Furnace?

Pile of Red StickersA cracked heat exchanger is a serious failure in your gas-fired furnace. The heat exchanger absorbs energy from the burner flame and transfers it to airflow in the furnace plenum. This separates dangerous combustion gases produced by the burner from the heated air that circulates through your home. The result of heat exchanger cracks is usually non-negotiable. For the sake of your family, an HVAC technician is required to “red tag” —shut down and render inoperative—any furnace with a cracked heat exchanger.


The age of the furnace and the overall cumulative operating hours are often the main factors in a cracked heat exchanger. Made of thin metal to ensure efficient heat transfer, an exchanger expands and contracts each time it’s heated and cooled. This may ultimately result in cracking. A burner that cycles on and off frequently may crack a heat exchanger earlier in the furnace’s service life.


Cracks in a heat exchanger may allow poisonous carbon monoxide (CO) gas to enter living spaces. The danger is especially severe where any obstruction or restriction exists in the furnace vent. Positive pressure building in the combustion chamber may cause CO gas to infiltrate household air through small cracks in the heat exchanger.


Cracks in a heat exchanger can be revealed by an HVAC technician using a number of methods. Visual inspection with strong lights may reveal larger cracks. Smoke infused into the combustion chamber under pressure may pinpoint smaller leaks, as well as detectors that sample furnace airflow for the presence of CO gas.

Contact Sobieski Services for more information about the hazards of a cracked heat exchanger.

Our goal is to help educate our customers in Wilmington, Delaware and surrounding areas about energy and home comfort issues (specific to HVAC & plumbing systems).

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