A furnace is often a background player in your home, helping keep you warm across the cold winter months. It regularly isn't noticed until a malfunction appears.
One cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to learn the signs of a cracked heat exchanger and what you can do if you believe that may be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps move heat from the combustion chamber of your furnace to the air that flows through the air ducts. It generally does this via coils or tubes that warm the air while serving as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from leaking out into your home.
Is a Cracked Heat Exchanger Dangerous?
Thanks to its central role, it’s no surprise that a cracked heat exchanger can pose a risk. A crack in the heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to flow throughout your home.
For obvious reasons, never turn on your heater if you believe there's a crack in the heat exchanger, as this could make the entire household sick. Reach out to an HVAC professional immediately if you think your heating has a cracked heat exchanger that should be repaired.
Four Symptoms of a Cracked Heat Exchanger:
- Furnace switches off: A crack in your heat exchanger may cause your furnace to switch off.
- Unusual Smells: If the air coming out of your furnace has an intense chemical odor, it could be a sign gas is seeping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm initiates or you feel poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm may go off or family members might struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel unusually tired, leave the home as soon as you can and then call for help.
- Soot: If you spot black sooty accumulating around the exterior of your furnace, it’s more evidence something may be seriously wrong.
What You Can Do if Your Furnace Heat Exchanger is Cracked
If you worry your furnace has a cracked heat exchanger, call a professional experienced in furnace installation right away so they can take a look at your system and, if needed, perform a furnace heat exchanger replacement. Costs should vary depending on the situation, but estimates often hover around $1,000 to $3,000.
Estimates aside, the good news is that heat exchangers are regularly included in the warranty. You should review the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it still may 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 with regular furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Hiring a certified professional to examine your furnace for broken-down parts, dirty filters and other common problems can help you avoid getting a big bill later on.
It’s also beneficial to review your furnace filters every few months – it’s ideal 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 drawing air through a clogged filter makes the entire furnace work more vigorously to complete its job. And the harder your furnace has to work, the more strain components like the heat exchanger will sustain.