A furnace is usually a background player at home, helping keep you warm across the cold winter months. It often won't be noticed until something breaks down.
One cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to know the signs of a cracked heat exchanger and what you should do if you are worried that might be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps transition heat from the combustion chamber inside your furnace to the air that moves inside the system. It generally accomplishes this using coils or tubes that heat the air while serving as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from escaping out into your home.
Is a Cracked Heat Exchanger Dangerous?
Given its key role, it shouldn't come as a surprise that a cracked heat exchanger can be very dangerous. A crack in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to circulate throughout your home.
For this reason, never run your heating if you suspect there's a crack in the heat exchanger, as doing so could make the entire household ill. Reach out to an HVAC professional as soon as possible if you are worried your heater has a cracked heat exchanger that should be repaired.
Four Symptoms of a Cracked Heat Exchanger:
- Furnace turns off: A crack in your heat exchanger may cause your furnace to turn off.
- Strange Smells: If the air escaping your furnace has a strong chemical odor, it could be an indicator that gas is slipping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm goes off or you feel symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide into your home, your carbon monoxide alarm could go off or family members could experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel sick, exit the home as soon as you can and then call for help.
- Soot: If you see black sooty buildup around the exterior of your furnace, it’s more evidence something could be seriously wrong.
What You Should Do if Your Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, call a pro with extensive experience in furnace installation right away so they can take a look at your system and, if necessary, start a furnace heat exchanger replacement. Costs often fluctuate depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are regularly protected by the warranty. It's a good idea to check the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it still may significantly reduce your bill.
How to Avoid a Cracked Heat Exchanger in Your Home
One of the easiest ways to avoid problems in your furnace overall is via regular furnace maintenance. Furnaces work the best when they work efficiently. Hiring a certified professional to check your furnace for broken-down parts, clogged filters and other likely problems can help you avoid getting a big bill later on.
It’s also helpful to review your furnace filters every few months – it’s encouraged some filters be changed every 90 days or sooner if they are dirty or grimy. While the filters aren't a part of the heat exchanger itself, the strain of drawing air through a clogged filter makes the entire furnace work harder to accomplish its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will sustain.