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Signs Your Furnace Heat Exchanger May be Cracked

Dec 21, 2015

Furnace Heating & Cooling

A damaged heat exchanger in a gas furnace is not an issue that should be ignored. Leaking and broken heat exchangers expose homeowners to toxic gases, which can be very dangerous to you and your family. It can be hard to know if your heat exchanger is cracked by merely looking at it. If you notice any of these signs, it’s best to call a furnace service company to check your furnace’s heat exchanger.

Strange smells

A malfunctioning heat exchanger will often create an unpleasant and strong odor that smells similar to formaldehyde. This smell can cause headaches, as well as other physical symptoms in humans. If you smell an odor that resembles formaldehyde, contact a furnace technician immediately to get things checked out.


The presence of soot (a black carbon buildup) on the internal side of the furnace is a sign that your system isn’t burning cleanly. An increase in soot is usually due to incomplete combustion, which is caused by improperly adjusted burners or a cracked heat exchanger.

Corrosion & Cracks in other furnace components

When exterior furnace components start to show signs of minor or significant wear and tear, it’s likely that the internal components are beginning to wear. Stress cracks are a common occurrence and can happen due to the expansion and contraction of the components during heating and cooling. Additionally, components can become corroded due to exposure to fumes that emit chloride or moisture from other sources.

Change in appearance of flame

A gas furnace that is functioning will have a stable blue flame. If you notice your burner has a yellow flame that moves, it means that either your burner is dirty or that the heat exchanger is cracked. Note: Flames that flicker or bend more when you turn on the fan are a good indicator of a cracked heat exchanger.

Other physical signs

Combustion gases leaking from a cracked heat exchanger can be responsible for headaches as well as flu-like symptoms. Other combustion pollutants like sulfur dioxide, nitrogen dioxide, and carbon monoxide can cause nose and eye irritation, nausea, sleepiness, and disorientation. If you notice these symptoms in you or a family member, take note whether the symptoms disappear when you leave your home. If so, it’s essential to get the air quality of your home checked immediately.

If you suspect your furnace is suffering from a cracked heat exchanger, give the experts at Romaniuk Heating & Air Conditioning a call. Our technicians offer full-service furnace repair for Edmonton and surrounding areas, and are available 24/7!