A furnace is almost always a background player in your home, helping keep you warm in the cold winter months. It often doesn’t get 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 worthwhile to learn the evidence of a cracked heat exchanger and what you can do if you believe that might 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 circulates throughout the ventilation. It typically accomplishes this with coils or tubes that heat the air while functioning as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its central role, it shouldn't come as a surprise that a damaged heat exchanger can pose a risk. Cracks in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to be distributed through your home. 

For this reason, don't ever run your heating if you believe you're dealing with a cracked heat exchanger, as letting it run could make the whole household ill. Call an HVAC professional as soon as possible if you believe your heating has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: Cracks in the heat exchanger could cause your furnace to switch off. 
  • Unusual Smells: If the air escaping your furnace has a powerful chemical smell, it may be an indicator that gas is leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm initiates or you feel poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide inside your home, your carbon monoxide alarm should go off or family members might start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If an 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 accumulating on the exterior of your furnace, it’s more evidence something might be seriously wrong.

What You Should Do if a Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, call a professional well versed in furnace installation Wisconsin Rapids as soon as possible so they can examine your system and, if needed, perform a furnace heat exchanger replacement. Costs should 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 often covered by the warranty. You’ll want to confirm the warranty paperwork on your furnace, as while the warranty won't always 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 easiest ways to minimize the risk of problems in your furnace overall is with regular furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Contacting a trained professional to inspect your furnace for worn-out parts, dirty filters and other potential problems can keep you from getting a big bill later on.  

It’s also a good idea to take a look at 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 connected to 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 needs to run, the more wear and tear pieces like the heat exchanger will sustain.