A furnace is often a background player in your home, keeping you warm across the cold winter months. It often doesn’t get noticed until something breaks down.
One source could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to learn the signs of a cracked heat exchanger and what you can do if you believe that may be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps move heat from the combustion chamber of your furnace to the air that flows inside the system. It typically does this through coils or tubes that heat the air while acting 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?
Because of its key role, it isn't surprising that a broken heat exchanger can be hazardous. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow through your home.
For that reason, do NOT run your furnace if you suspect you're dealing with a cracked heat exchanger, as doing so could make your entire household ill. Call an HVAC professional right away if you think your furnace has a cracked heat exchanger that should be repaired.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace turns off: A crack in your heat exchanger may cause your furnace to turn off.
- Strange Smells: If the air escaping your furnace has a strong chemical scent, it may be evidence gasses are seeping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a major warning sign.
- Carbon monoxide alarm initiates or you notice symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm should go off or household members might struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If an alarm goes off or you feel unusually tired, exit the home as soon as you can and then call for help.
- Soot: If you find black sooty accumulating near the exterior of your furnace, it’s another sign something could be seriously wrong.
What to Do if the Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, contact a professional with extensive experience in furnace installation right away so they can take a look at your system and, if necessary, perform a furnace heat exchanger replacement. Costs will 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. It's a good idea to confirm the warranty paperwork on your furnace, because while the warranty might 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 most convenient ways to minimize the risk of problems in your furnace overall is through consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a skilled professional to check your furnace for old parts, clogged filters and other common problems can help you avoid getting a big bill later on.
It’s also a good idea 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 are not part of the heat exchanger itself, the strain of dragging air through a clogged filter makes your entire furnace work longer to do its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will experience.