A furnace is often a background player at home, ensuring you're warm during the cold winter months. It often isn't noticed until something goes wrong.
One root cause might be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to learn the symptoms of a cracked heat exchanger and what you can do if you suspect that is the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger transfers heat from the combustion chamber inside your furnace to the air that circulates through the system. It typically accomplishes this via coils or tubes that heat up the air while acting as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from leaking out into your home.
Is a Cracked Heat Exchanger Dangerous?
Given its important role, it isn't surprising that a broken heat exchanger can be very dangerous. Cracks in the heat exchanger can enable dangerous gasses – such as carbon monoxide, which can be lethal – to circulate through your home.
For that reason, do NOT run your furnace if you suspect there's a crack in the heat exchanger, as doing so could make the whole family ill. Contact an HVAC professional immediately if you think your heater has a cracked heat exchanger that should be repaired.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace switches off: A cracked heat exchanger could cause your furnace to shut off.
- Strange Smells: If the air leaving your furnace has a powerful chemical smell, it could be evidence 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 goes off or you recognize symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm could go off or family members could experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel sick, exit the home immediately and then call for help.
- Soot: If you see black sooty accumulating around the exterior of your furnace, it’s another sign something could be seriously wrong.
What You Can Do if the Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, hire a professional well versed in furnace installation right away so they can take a look at your system and, if required, perform a furnace heat exchanger replacement. Costs will vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.
However, the good news is that heat exchangers are regularly protected by the warranty. You should confirm the warranty paperwork on your furnace, since while the warranty may not 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 easiest ways to avoid problems in your furnace overall is through regular furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Contacting a certified professional to inspect your furnace for broken-down parts, clogged filters and other common problems can help you avoid 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 changed every 90 days or sooner if they are dirty or grimy. While the filters aren't connected to the heat exchanger itself, the strain of pulling air through a clogged filter makes the entire furnace work more vigorously to do its job. And the harder your furnace works, the more strain components like the heat exchanger will experience.