close up of a heat exchanger

A furnace is almost always a background player at home, ensuring you're warm across the cold winter months. It often doesn’t get noticed until a malfunction appears. 

One cause could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s critical to know the symptoms of a cracked heat exchanger and what to do if you are worried 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 moves inside the system. It generally handles this through coils or tubes that warm the air while functioning as a barrier to keep gas created in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given 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 enable dangerous gasses – like carbon monoxide, which can be lethal – to circulate through your home. 

For obvious reasons, don't ever use your heating if you suspect you're dealing with a cracked heat exchanger, as doing so could make the whole household ill. Reach out to an HVAC professional right away if you think your heater has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger may cause your furnace to switch off. 
  • Strange Smells: If the air leaving your furnace has a strong chemical scent, it could be evidence gas is seeping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you recognize health problems: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or family members could struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If an alarm goes off or you feel unwell, leave the home right away and then call for help. 
  • Soot: If you see black sooty buildup around the exterior of your furnace, it’s an indication something could be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, hire a professional well versed in furnace installation Sacramento as soon as possible so they can take a look at your system and, if necessary, start a furnace heat exchanger replacement. Costs will 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 often included in the warranty. You’ll want to check the warranty paperwork on your furnace, as while the warranty won't always cover the entire cost of repairs, it still may significantly lower your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the easiest ways to minimize the risk of problems in your furnace overall is with consistent furnace maintenance. Furnaces offer the most benefits when they run efficiently. Calling a certified professional to inspect your furnace for worn-out parts, clogged filters and other potential problems can keep you from getting a big bill later on.  

It’s also beneficial 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 pulling air through a clogged filter makes the entire furnace work longer to do its job. And the harder your furnace works, the more strain pieces like the heat exchanger will sustain.