A furnace is almost always a background player at home, keeping you warm across the cold winter months. It regularly doesn’t get noticed until something breaks down.
One root cause may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to learn the symptoms of a cracked heat exchanger and what you should do if you are worried that might be 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 throughout the air ducts. It typically does this using coils or tubes that heat the air while serving as a barrier to keep gas formed in the combustion chamber, called flue gasses, from leaking out into your home.
Is a Cracked Heat Exchanger Dangerous?
Given its key role, it’s no surprise that a broken heat exchanger can be very dangerous. Cracks in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to circulate across your home.
For this reason, do NOT use your heater if you think you're dealing with a cracked heat exchanger, as letting it run could make the whole family ill. Reach out to an HVAC professional immediately if you are worried your heater has a cracked heat exchanger that should be repaired.
Four Signs of a Cracked Heat Exchanger:
- Furnace turns off: A crack in your heat exchanger may cause your furnace to shut off.
- Strange Smells: If the air escaping your furnace has an intense chemical odor, it may be evidence gasses are leaking 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 symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm should go off or household members may experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel unusually tired, get out of the home immediately and then call for help.
- Soot: If you find black sooty buildup near the exterior of your furnace, it’s more evidence something might be seriously wrong.
What You Should Do if Your Furnace Heat Exchanger is Cracked
If you believe your furnace has a cracked heat exchanger, call a professional well versed in furnace installation as soon as possible so they can examine your system and, if required, start a furnace heat exchanger replacement. Costs often fluctuate depending on the situation, but estimates often hover around $1,000 to $3,000.
However, the good news is that heat exchangers are generally included in the warranty. You should review the warranty paperwork on your furnace, because while the warranty may not cover the entire cost of repairs, it still may significantly shrink 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 via regular furnace maintenance. Furnaces provide the best possible return on investment when they operate efficiently. Contacting a certified professional to check your furnace for broken-down parts, dirty filters and other likely problems can keep you from getting a big bill later on.
It’s also a good idea to take a look at 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 are not part of the heat exchanger itself, the strain of pulling air through a clogged filter makes your entire furnace work longer to do its job. And the harder your furnace needs to run, the more strain components like the heat exchanger will sustain.