A furnace is almost always a background player for your home, keeping you warm in the cold winter months. It regularly won't be noticed until a malfunction appears. 

One source may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to learn the evidence of a cracked heat exchanger and what you can 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 through the ventilation. It usually accomplishes this through coils or tubes that heat up the air while acting as a barrier to keep gas formed in the combustion chamber, called flue gasses, from leaking 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 pose a risk. A damaged heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to flow throughout your home. 

For that reason, never turn on your heater if you believe there's a crack in the heat exchanger, as letting it run could make the whole family sick. Call an HVAC professional as soon as possible if you are worried your heater has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A crack in your heat exchanger may cause your furnace to switch off. 
  • Unusual Smells: If the air leaving your furnace has a strong chemical smell, it could be evidence gas is leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you recognize health problems: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm could go off or family members might struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel sick, 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 another sign something might be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Reinholds right away so they can examine your system and, if needed, handle a furnace heat exchanger replacement. Costs should vary 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 check the warranty paperwork on your furnace, as 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 avoid problems in your furnace overall is with consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a certified professional to check your furnace for old parts, clogged filters and other potential 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 encouraged 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 pulling air through a clogged filter makes the entire furnace work longer to complete its job. And the harder your furnace works, the more strain components like the heat exchanger will experience.