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Cracked Heat Exchanger: What That Means and What to Do Next

September 20, 2022

A furnace is often a background player in your home, ensuring you're warm in the cold winter months. It regularly isn't noticed until something goes wrong.

One source might be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s critical to know the signs of a cracked heat exchanger and what you can do if you suspect 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 circulates inside the air ducts. It usually handles this with coils or tubes that warm the air while functioning as a barrier to keep the gasses formed in the combustion chamber, called flue gasses, from leaking out into your home.

Is a Cracked Heat Exchanger Dangerous?

Given its central role, it isn't surprising that a cracked heat exchanger can be hazardous. A crack in the heat exchanger can permit dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home.

For this reason, do NOT turn on your heater if you think it has a cracked heat exchanger, as this could make the entire household sick. Reach out to an HVAC professional immediately if you believe your heating has a cracked heat exchanger that needs to be repaired.

Four Signs of a Cracked Heat Exchanger:

  • Furnace switches off: A cracked heat exchanger can cause your furnace to shut off.
  • Strange Smells: If the air escaping your furnace has a powerful chemical scent, it may be an indicator that gas is slipping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a significant warning sign.
  • Carbon monoxide alarm goes off or you feel symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide in your home, your carbon monoxide alarm should go off or household members might start experiencing signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unwell, leave the home right away and then call for help.
  • Soot: If you notice black sooty collecting on the exterior of your furnace, it’s more evidence something may be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked

If you worry your furnace has a cracked heat exchanger, call a professional with extensive experience in furnace installation the Bay Area as soon as possible so they can inspect your system and, if required, start a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates often hover around $1,000 to $3,000.

Fortunately, the good news is that heat exchangers are generally included in the warranty. You should review the warranty paperwork on your furnace, since while the warranty won't always 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 prevent a problem in your furnace overall is through routine furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a trained professional to inspect your furnace for worn-out parts, dirty filters and other potential 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 are not part of the heat exchanger itself, the strain of dragging air through a clogged filter makes your entire furnace work harder to do its job. And the harder your furnace works, the more wear and tear components like the heat exchanger will experience.