A furnace is usually a background player for your home, helping keep you warm across the cold winter months. It regularly isn't noticed until something breaks down.
One source may be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s critical to learn the signs of a cracked heat exchanger and what you can do if you are worried that might be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps transition heat from the combustion chamber of your furnace to the air that flows inside the system. It typically does this with coils or tubes that heat the air while acting as a barrier to keep gas formed in the combustion chamber, called flue gasses, from escaping 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 pose a risk. Cracks in the heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to flow across your home.
For this reason, never use your heater if you suspect it has a cracked heat exchanger, as letting it run could make the whole household ill. Contact an HVAC professional right away if you are worried your heating has a cracked heat exchanger that needs repair.
Four Signs of a Cracked Heat Exchanger:
- Furnace switches off: A cracked heat exchanger may cause your furnace to shut off.
- Strange Smells: If the air escaping your furnace has a powerful chemical odor, it may be an indicator that gas is leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a significant warning sign.
- Carbon monoxide alarm is triggered or you feel poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm should go off or household members might start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel unwell, exit the home right away and then call for help.
- Soot: If you notice black sooty accumulating on the exterior of your furnace, it’s another sign 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, hire a professional with extensive experience in furnace installation right away so they can inspect your system and, if needed, perform a furnace heat exchanger replacement. Costs often fluctuate depending on the situation, but estimates can roughly suggest $1,000 to $3,000.
However, the good news is that heat exchangers are generally protected by the warranty. You’ll want to check the warranty paperwork on your furnace, because while the warranty may not 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 easiest ways to minimize the risk of problems in your furnace overall is through routine furnace maintenance. Furnaces work the best when they work efficiently. Contacting a skilled professional to examine your furnace for old parts, clogged filters and other common problems can keep you from getting a big bill later on.
It’s also helpful to inspect your furnace filters every few months – it’s encouraged some filters be swapped out 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 the entire furnace work more vigorously to do its job. And the harder your furnace has to work, the more strain components like the heat exchanger will sustain.