A furnace is almost always a background player in your home, helping keep you warm during the cold winter months. It frequently won't be noticed until a malfunction appears.
One root cause could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to familiarize yourself with the signs of a cracked heat exchanger and what you can do if you are worried that is 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 throughout the ventilation. It usually does 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 escaping out into your home.
Is a Cracked Heat Exchanger Dangerous?
Given its central role, it isn't surprising that a cracked heat exchanger can be very dangerous. Cracks in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to circulate across your home.
For this reason, do NOT use your heating if you believe it has a cracked heat exchanger, as doing so could make the whole household sick. Contact an HVAC professional right away if you believe your heater has a cracked heat exchanger that needs repair.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace shuts off: A crack in your heat exchanger can cause your furnace to shut off.
- Strange Smells: If the air coming out of your furnace has an intense chemical smell, it might be a sign gas is leaking through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm is triggered or you notice symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm may go off or household members may start experiencing signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel sick, get out of the home right away and then call for help.
- Soot: If you see black sooty collecting near the exterior of your furnace, it’s more evidence something may be seriously wrong.
What to 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 as soon as possible so they can inspect your system and, if necessary, perform a furnace heat exchanger replacement. Costs will vary depending on the situation, but estimates often hover around $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are generally covered by the warranty. You’ll want to check the warranty paperwork on your furnace, because 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 prevent a problem in your furnace overall is through routine furnace maintenance. Furnaces work the best when they work efficiently. Calling a certified professional to inspect your furnace for broken-down parts, clogged filters and other potential problems can keep you from getting a big bill later on.
It’s also helpful to take a look at 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 your entire furnace work more vigorously to accomplish its job. And the harder your furnace works, the more strain parts like the heat exchanger will endure.