A furnace is often a background player for your home, ensuring you're warm in the cold winter months. It frequently isn't noticed until something goes wrong.
One root cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to learn the symptoms of a cracked heat exchanger and what to do if you believe 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 moves through the ventilation. It usually accomplishes this with coils or tubes that warm the air while functioning as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from getting out into your home.
Is a Cracked Heat Exchanger Dangerous?
Because of its central role, it’s no surprise that a broken heat exchanger can be very dangerous. A damaged 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 believe it has a cracked heat exchanger, as letting it run could make your entire household sick. Call an HVAC professional as soon as possible if you think your heater has a cracked heat exchanger that needs repair.
Four Signs of a Cracked Heat Exchanger:
- Furnace shuts off: A cracked heat exchanger could cause your furnace to shut off.
- Strange Smells: If the air coming out of your furnace has a strong chemical smell, it could be an indicator that gasses are leaking through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm initiates or you notice symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or family members could start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel sick, get out of the home as soon as you can and then call for help.
- Soot: If you spot black sooty buildup around the exterior of your furnace, it’s another sign something might be seriously wrong.
What You Should Do if a Furnace Heat Exchanger is Cracked
If you worry your furnace has a cracked heat exchanger, call a professional well versed in furnace installation as soon as possible so they can take a look at your system and, if necessary, handle a furnace heat exchanger replacement. Costs should vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.
Estimates aside, the good news is that heat exchangers are generally covered by the warranty. You should confirm the warranty paperwork on your furnace, as while the warranty won't always cover the entire cost of repairs, it can significantly lower your bill.
How to Prevent a Cracked Heat Exchanger in Your Home
One of the best ways to minimize the risk of problems in your furnace overall is with consistent furnace maintenance. Furnaces provide the best possible return on investment when they operate efficiently. Contacting a skilled professional to check your furnace for old parts, clogs in the air filters and other potential problems can keep you from getting a big bill later on.
It’s also helpful to review 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 are not part of the heat exchanger itself, the strain of dragging air through a clogged filter makes the entire furnace work harder to complete its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will sustain.