A furnace is usually a background player at home, helping keep you warm during the cold winter months. It regularly won't be noticed until a malfunction appears.
One root cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to learn the signs 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 helps move heat from the combustion chamber inside your furnace to the air that circulates inside the system. It typically handles this through coils or tubes that warm the air while serving as a barrier to keep byproducts created in the combustion chamber, called flue gasses, from getting out into your home.
Is a Cracked Heat Exchanger Dangerous?
Because of its key role, it shouldn't come as a surprise that a broken heat exchanger can be hazardous. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow through your home.
For this reason, do NOT use your heater if you think there's a crack in the heat exchanger, as doing so could make your entire household ill. Reach out to an HVAC professional as soon as possible if you are worried your furnace has a cracked heat exchanger that needs to be repaired.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace switches off: A crack in your heat exchanger can cause your furnace to switch off.
- Odd Smells: If the air leaving your furnace has a powerful chemical scent, it could be evidence gas is seeping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a significant warning sign.
- Carbon monoxide alarm initiates or you notice poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide inside your home, your carbon monoxide alarm should go off or family members may 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 unusually tired, get out of the home right away and then call for help.
- Soot: If you notice black sooty collecting on the exterior of your furnace, it’s another sign something might be seriously wrong.
What to Do if the Furnace Heat Exchanger is Cracked
If you believe your furnace has a cracked heat exchanger, call a professional with extensive experience in furnace installation right away so they can take a look at your system and, if required, handle a furnace heat exchanger replacement. Costs should differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are regularly protected by the warranty. You should review the warranty paperwork on your furnace, since while the warranty won't always cover the entire cost of repairs, it can significantly shrink your bill.
How to Prevent a Cracked Heat Exchanger in Your Home
One of the most convenient ways to avoid problems in your furnace overall is through regular furnace maintenance. Furnaces work the best when they run efficiently. Contacting a certified professional to check your furnace for old parts, dirty filters and other likely problems can keep you from getting a big bill later on.
It’s also beneficial 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 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 needs to run, the more wear and tear parts like the heat exchanger will endure.