A furnace is almost always a background player at home, keeping you warm across the cold winter months. It regularly won't be noticed until something goes wrong. 

One source may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to learn the symptoms of a cracked heat exchanger and what you should do if you suspect that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber of your furnace to the air that flows throughout the ventilation. It usually accomplishes this with coils or tubes that heat the air while functioning as a barrier to keep byproducts 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’s no surprise that a broken heat exchanger can pose a risk. A damaged heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to circulate through your home. 

For obvious reasons, never run your heating if you suspect there's a crack in the heat exchanger, as this could make the entire family sick. Reach out to an HVAC professional as soon as possible if you think your heater has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A cracked heat exchanger may cause your furnace to switch off. 
  • Unusual Smells: If the air leaving your furnace has a powerful chemical scent, it could be an indicator that gas is seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm is triggered or you feel health problems: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm could go off or family members might experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel unusually tired, get out of the home right away and then call for help. 
  • Soot: If you see black sooty collecting near the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Should Do if a Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a professional with extensive experience in furnace installation Branchville right away so they can take a look at your system and, if required, perform 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 often included in the warranty. You’ll want to review the warranty paperwork on your furnace, since while the warranty might not cover the entire cost of repairs, it can significantly shrink your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to prevent a problem in your furnace overall is through consistent furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Contacting a skilled professional to inspect your furnace for old parts, clogs in the air filters and other likely problems can help you avoid getting a big bill later on.  

It’s also a good idea to inspect your furnace filters every few months – it’s encouraged 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 drawing air through a clogged filter makes the entire furnace work longer to accomplish its job. And the harder your furnace works, the more strain parts like the heat exchanger will sustain.