A furnace is almost always a background player at home, keeping you warm in the cold winter months. It frequently won't be noticed until something goes wrong.
One cause might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to know the signs of a cracked heat exchanger and what you should do if you suspect that might be 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 moves inside the system. It generally handles this through 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?
Given its central role, it shouldn't come as a surprise that a broken heat exchanger can be very dangerous. Cracks in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to be distributed across your home.
For this reason, don't ever turn on your heater if you think you're dealing with a cracked heat exchanger, as letting it run could make the whole household ill. Call an HVAC professional immediately if you are worried your furnace has a cracked heat exchanger that needs repair.
Four Symptoms 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 could be a sign gas is leaking through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm is triggered or you notice symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm should go off or family members might start experiencing signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel unwell, get out of the home immediately and then call for help.
- Soot: If you find black sooty buildup on the exterior of your furnace, it’s more evidence something might be seriously wrong.
What to Do if a Furnace Heat Exchanger is Cracked
If you worry your furnace has a cracked heat exchanger, contact a pro experienced in furnace installation right away so they can inspect your system and, if required, handle a furnace heat exchanger replacement. Costs will fluctuate depending on the situation, but estimates often hover around $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are regularly covered by the warranty. It's a good idea to check 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 most convenient ways to minimize the risk of problems in your furnace overall is through routine furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Contacting a trained professional to check your furnace for broken-down parts, clogs in the air filters and other common 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 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 drawing air through a clogged filter makes your entire furnace work more vigorously to do its job. And the harder your furnace works, the more deterioration components like the heat exchanger will sustain.