A furnace is often a background player in your home, helping keep you warm in the cold winter months. It often won't be noticed until something goes wrong. 

One cause might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s worthwhile to know the symptoms of a cracked heat exchanger and what to do if you are worried that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber in your furnace to the air that moves through the air ducts. It usually handles this via coils or tubes that heat up the air while functioning as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its important role, it shouldn't come as a surprise that a cracked heat exchanger can be hazardous. A damaged heat exchanger can allow dangerous gasses – like carbon monoxide, which can be lethal – to circulate through your home. 

For that reason, never turn on your heater if you think you're dealing with a cracked heat exchanger, as doing so could make the whole family sick. Reach out to an HVAC professional as soon as possible if you believe your furnace has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A crack in your heat exchanger can cause your furnace to turn off. 
  • Strange Smells: If the air leaving your furnace has a strong chemical scent, it may be a sign gas is slipping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm initiates or you recognize health problems: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm may go off or family members could start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel sick, leave the home right away and then call for help. 
  • Soot: If you find black sooty buildup near the exterior of your furnace, it’s an indication something could be seriously wrong.

What You Can Do if a Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, hire a pro experienced in furnace installation Frederick right away so they can examine your system and, if needed, start a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Estimates aside, 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 may not cover the entire cost of repairs, it still may significantly reduce your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the best ways to minimize the risk of problems in your furnace overall is with regular furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Calling a trained professional to check your furnace for worn-out parts, clogged filters and other common problems can help you avoid getting a big bill later on.  

It’s also beneficial to inspect your furnace filters every few months – it’s recommended some filters be replaced 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 more vigorously to accomplish its job. And the harder your furnace works, the more strain components like the heat exchanger will endure.