A furnace is usually a background player in your home, helping keep you warm during the cold winter months. It frequently doesn’t get noticed until something goes wrong.
One root cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to familiarize yourself with the signs of a cracked heat exchanger and what to do if you suspect that is the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger transfers heat from the combustion chamber in your furnace to the air that flows throughout the system. It usually accomplishes this via coils or tubes that warm the air while acting as a barrier to keep the gasses formed in the combustion chamber, called flue gasses, from getting out into your home.
Is a Cracked Heat Exchanger Dangerous?
Because of its key role, it shouldn't come as a surprise that a cracked heat exchanger can be very dangerous. A crack in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow throughout your home.
For obvious reasons, never turn on your heater if you think there's a crack in the heat exchanger, as doing so could make your entire family ill. Call an HVAC professional immediately if you think your heating has a cracked heat exchanger that should be repaired.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace shuts off: A crack in your heat exchanger can cause your furnace to shut off.
- Unusual Smells: If the air leaving your furnace has an intense chemical scent, it could be a sign gas is seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a major warning sign.
- Carbon monoxide alarm initiates or you feel health problems: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm may go off or household members might struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unusually tired, exit the home right away and then call for help.
- Soot: If you notice black sooty collecting on the exterior of your furnace, it’s another sign something might be seriously wrong.
What You Should Do if Your 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, start 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 generally protected by the warranty. You should check the warranty paperwork on your furnace, because while the warranty won't always 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 most convenient ways to prevent a problem in your furnace overall is with consistent furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Hiring a trained professional to examine your furnace for broken-down parts, dirty filters and other common problems can help you avoid getting a big bill later on.
It’s also helpful to take a look at 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 harder to accomplish its job. And the harder your furnace has to work, the more deterioration components like the heat exchanger will experience.