A furnace is almost always a background player in your home, ensuring you're 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 important to familiarize yourself with the symptoms of a cracked heat exchanger and what to do if you believe that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber in your furnace to the air that circulates inside the ventilation. It typically accomplishes this through coils or tubes that warm the air while functioning as a barrier to keep byproducts produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its central role, it isn't surprising that a broken heat exchanger can be hazardous. A crack in the heat exchanger can enable dangerous gasses – including carbon monoxide, which can be lethal – to be distributed across your home. 

For obvious reasons, do NOT run your heating if you believe you're dealing with a cracked heat exchanger, as this could make the whole family ill. Contact an HVAC professional immediately if you think your heating has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger may cause your furnace to switch off. 
  • Odd Smells: If the air escaping your furnace has a strong chemical odor, it may be evidence gasses are slipping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm initiates or you recognize symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide inside 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 an alarm goes off or you feel sick, get out of the home as soon as you can and then call for help. 
  • Soot: If you spot black sooty buildup on the exterior of your furnace, it’s more evidence something may be seriously wrong.

What You Can Do if a Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Manassas as soon as possible so they can inspect your system and, if needed, handle a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates often hover around $1,000 to $3,000. 

However, the good news is that heat exchangers are often covered by the warranty. You’ll want to review the warranty paperwork on your furnace, since while the warranty won't always cover the entire cost of repairs, it still may significantly shrink your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to prevent a problem in your furnace overall is through routine furnace maintenance. Furnaces work the best when they run efficiently. Contacting a trained professional to examine 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 helpful to take a look at your furnace filters every few months – it’s ideal some filters be replaced every 90 days or sooner if they are dirty or grimy. While the filters aren't connected to the heat exchanger itself, the strain of dragging air through a clogged filter makes the entire furnace work longer to do its job. And the harder your furnace works, the more wear and tear components like the heat exchanger will experience.