A furnace is usually a background player in your home, keeping you warm in the cold winter months. It often isn't noticed until something breaks down. 

One source could be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to learn the signs of a cracked heat exchanger and what you can do if you are worried 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 circulates through the air ducts. It generally accomplishes this with coils or tubes that heat the air while acting 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? 

Because of its important role, it’s no surprise that a broken heat exchanger can be hazardous. A damaged heat exchanger can enable dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home. 

For obvious reasons, never use your furnace if you think you're dealing with a cracked heat exchanger, as this could make your entire family sick. Call an HVAC professional as soon as possible if you are worried your heater has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: Cracks in the heat exchanger can cause your furnace to shut off. 
  • Unusual Smells: If the air coming out of your furnace has a strong chemical odor, it might be a sign gasses are slipping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you feel health problems: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm may go off or household members could struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel unwell, leave the home as soon as you can and then call for help. 
  • Soot: If you spot black sooty collecting near the exterior of your furnace, it’s more evidence something may be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, hire a pro with extensive experience in furnace installation Los Angeles as soon as possible so they can examine your system and, if necessary, handle a furnace heat exchanger replacement. Costs should vary depending on the situation, but estimates often hover around $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are generally covered by the warranty. You’ll want to confirm the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it can significantly lower your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to minimize the risk of problems in your furnace overall is through consistent furnace maintenance. Furnaces work the best when they work efficiently. Contacting a certified professional to examine 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 helpful to take a look at your furnace filters every few months – it’s ideal some filters be changed 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 drawing air through a clogged filter makes the entire furnace work more vigorously to accomplish its job. And the harder your furnace needs to run, the more deterioration pieces like the heat exchanger will sustain.