A furnace is often a background player for your home, keeping you warm across the cold winter months. It frequently won't be noticed until a malfunction appears.
One source could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to familiarize yourself with the evidence of a cracked heat exchanger and what you should do if you believe that is 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 throughout the ventilation. It usually accomplishes this with coils or tubes that heat up the air while functioning as a barrier to keep gas produced in the combustion chamber, called flue gasses, from getting out into your home.
Is a Cracked Heat Exchanger Dangerous?
Thanks to its important role, it shouldn't come as a surprise that a broken heat exchanger can be very dangerous. A crack in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to circulate across your home.
For that reason, do NOT run your heater if you think there's a crack in the heat exchanger, as letting it run could make the whole household ill. Reach out to an HVAC professional immediately if you believe your furnace has a cracked heat exchanger that needs repair.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace turns off: A crack in your heat exchanger may cause your furnace to shut off.
- Unusual Smells: If the air leaving your furnace has a strong chemical odor, it might be an indicator that gasses are seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a major warning sign.
- Carbon monoxide alarm is triggered or you recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or household members may struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel unwell, get out of the home as soon as you can and then call for help.
- Soot: If you spot black sooty collecting near the exterior of your furnace, it’s more evidence something may be seriously wrong.
What to Do if Your Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, hire a professional with extensive experience in furnace installation right away so they can examine your system and, if necessary, 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 regularly protected by the warranty. You’ll want to confirm 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 Avoid a Cracked Heat Exchanger in Your Home
One of the easiest ways to avoid problems in your furnace overall is through consistent furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Calling a skilled professional to examine your furnace for old parts, clogs in the air filters and other likely problems can help you avoid getting a big bill later on.
It’s also helpful to review your furnace filters every few months – it’s recommended some filters be swapped out 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 dragging air through a clogged filter makes the entire furnace work more vigorously to complete its job. And the harder your furnace works, the more wear and tear pieces like the heat exchanger will experience.