A furnace is almost always a background player in your home, helping keep you warm in the cold winter months. It regularly doesn’t get noticed until something breaks down. 

One cause might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to learn the signs of a cracked heat exchanger and what you should do if you are worried that is 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 flows through the air ducts. It usually handles this with coils or tubes that heat up the air while functioning as a barrier to keep the gasses formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

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

For that reason, don't ever run your heater if you suspect it has a cracked heat exchanger, as this could make the entire household ill. Reach out to an HVAC professional immediately if you believe your furnace has a cracked heat exchanger that needs to be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: Cracks in the heat exchanger could cause your furnace to turn off. 
  • Unusual Smells: If the air coming out of your furnace has an intense chemical odor, it could be a sign 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 is triggered or you notice health problems: If a cracked heat exchanger is relieving carbon monoxide in your home, your carbon monoxide alarm may go off or household members might experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel sick, get out of the home immediately and then call for help. 
  • Soot: If you see black sooty buildup on the exterior of your furnace, it’s more evidence something could be seriously wrong.

What You Should Do if the Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Port Clinton as soon as possible so they can examine your system and, if required, start a furnace heat exchanger replacement. Costs often 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 generally covered by the warranty. You’ll want to check the warranty paperwork on your furnace, because while the warranty might not cover the entire cost of repairs, it could significantly reduce 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 through routine furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Calling a skilled professional to inspect your furnace for broken-down parts, dirty filters and other likely problems can keep you from getting a big bill later on.  

It’s also a good idea to review your furnace filters every few months – it’s recommended some filters be changed 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 has to work, the more wear and tear parts like the heat exchanger will sustain.