A furnace is usually a background player in your home, ensuring you're warm across the cold winter months. It regularly isn't noticed until something breaks down.
One root cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to know the evidence of a cracked heat exchanger and what you should do if you suspect that is the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps transition heat from the combustion chamber in your furnace to the air that moves throughout the system. It typically handles this with coils or tubes that heat up the air while serving as a barrier to keep byproducts produced in the combustion chamber, called flue gasses, from escaping out into your home.
Is a Cracked Heat Exchanger Dangerous?
Because of its important role, it shouldn't come as a surprise that a cracked heat exchanger can be hazardous. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to circulate throughout your home.
For obvious reasons, don't ever use your heating if you suspect there's a crack in the heat exchanger, as this could make your entire household sick. Reach out to an HVAC professional right away if you are worried your furnace has a cracked heat exchanger that needs repair.
Four Signs of a Cracked Heat Exchanger:
- Furnace turns off: A crack in your heat exchanger could cause your furnace to shut off.
- Unusual Smells: If the air escaping your furnace has a strong chemical odor, it may be a sign gas is slipping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign.
- Carbon monoxide alarm initiates or you feel health problems: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm should go off or household members might start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel sick, get out of the home right away and then call for help.
- Soot: If you find black sooty collecting on the exterior of your furnace, it’s more evidence something could 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 pro well versed in furnace installation as soon as possible so they can examine your system and, if needed, start a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates often hover around $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, because while the warranty might not cover the entire cost of repairs, it could significantly reduce your bill.
How to Prevent a Cracked Heat Exchanger in Your Home
One of the easiest ways to prevent a problem in your furnace overall is with regular furnace maintenance. Furnaces work the best when they work efficiently. Calling a trained professional to examine your furnace for broken-down parts, clogs in the air filters and other common problems can help you avoid getting a big bill later on.
It’s also helpful to inspect 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 connected to the heat exchanger itself, the strain of dragging air through a clogged filter makes your entire furnace work harder to complete its job. And the harder your furnace has to work, the more wear and tear components like the heat exchanger will sustain.