A furnace is usually a background player for your home, helping keep you warm in the cold winter months. It often isn't noticed until a malfunction appears. 

One cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to know the evidence 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 inside your furnace to the air that circulates inside the ventilation. It typically does this using coils or tubes that warm the air while functioning as a barrier to keep gas formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its important role, it’s no surprise that a damaged heat exchanger can pose a risk. Cracks in the heat exchanger can permit dangerous gasses – such as carbon monoxide, which can be lethal – to flow across your home. 

For that reason, never run your heating if you suspect it has a cracked heat exchanger, as this could make the whole household sick. Reach out to an HVAC professional right away if you believe your heating has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: Cracks in the heat exchanger may cause your furnace to switch off. 
  • Odd Smells: If the air escaping your furnace has a strong chemical scent, it might be an indicator that gasses are slipping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you recognize poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm could go off or household members could experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel sick, exit the home as soon as you can and then call for help. 
  • Soot: If you notice black sooty buildup on the exterior of your furnace, it’s another sign something might be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, hire a professional well versed in furnace installation Lafayette right away so they can examine your system and, if required, handle 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 regularly covered by the warranty. You should confirm the warranty paperwork on your furnace, because while the warranty may not cover the entire cost of repairs, it can significantly reduce your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the best ways to prevent a problem in your furnace overall is with regular furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Hiring a skilled professional to inspect your furnace for broken-down parts, clogged filters and other common problems can keep you from getting a big bill later on.  

It’s also a good idea 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 aren't a part of the heat exchanger itself, the strain of pulling air through a clogged filter makes your entire furnace work more vigorously to complete its job. And the harder your furnace works, the more strain pieces like the heat exchanger will experience.