A furnace is almost always a background player in your home, keeping you warm across the cold winter months. It often won't be noticed until something goes wrong.
One cause could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to familiarize yourself with the symptoms of a cracked heat exchanger and what you should do if you suspect that may be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger transfers heat from the combustion chamber of your furnace to the air that flows inside the air ducts. It generally does this through coils or tubes that heat the air while acting as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from getting out into your home.
Is a Cracked Heat Exchanger Dangerous?
Because of its important role, it’s no surprise that a cracked heat exchanger can pose a risk. A crack in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to circulate across your home.
For this reason, don't ever run your heater if you suspect you're dealing with a cracked heat exchanger, as doing so could make the whole family ill. Contact an HVAC professional immediately if you are worried your heater has a cracked heat exchanger that needs repair.
Four Signs of a Cracked Heat Exchanger:
- Furnace turns off: A cracked heat exchanger can cause your furnace to turn off.
- Odd Smells: If the air coming out of your furnace has an intense chemical scent, it may be a sign gasses are seeping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a major warning sign.
- Carbon monoxide alarm is triggered or you notice health problems: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm may go off or family members may struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel unwell, leave the home as soon as you can and then call for help.
- Soot: If you see black sooty collecting on the exterior of your furnace, it’s an indication something could be seriously wrong.
What You Should Do if a Furnace Heat Exchanger is Cracked
If you believe your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation right away so they can take a look at your system and, if required, perform a furnace heat exchanger replacement. Costs should vary depending on the situation, but estimates can roughly suggest $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are often protected by the warranty. It's a good idea to review the warranty paperwork on your furnace, since while the warranty won't always cover the entire cost of repairs, it could significantly lower your bill.
How to Avoid a Cracked Heat Exchanger in Your Home
One of the best ways to minimize the risk of problems in your furnace overall is via routine furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Hiring a skilled professional to inspect your furnace for old parts, clogs in the air filters and other common problems can keep you from getting a big bill later on.
It’s also a good idea to review your furnace filters every few months – it’s recommended some filters be replaced 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 dragging air through a clogged filter makes your entire furnace work more vigorously to do its job. And the harder your furnace has to work, the more strain pieces like the heat exchanger will endure.