You notice a strange smell coming from your furnace – could it be a cracked heat exchanger? Upon further inspection you see the outside has rust. You wonder: Is this something I need to call an HVAC company about?
The answer: Yes, immediately.
Both of those signs point to a cracked heat exchanger, which, if not handled soon, poses a safety and health risk to your family.
The heat exchanger is the largest component of your home’s heating system, and over the course of its lifespan cracks. Your furnace may not completely combust fuel. This leads to unacceptable levels of carbon monoxide entering your home.
What Does a Heat Exchanger Do?
Made up of metal shells and tubes, the heat exchanger is the part of the furnace responsible for generating hot air. How? When your furnace burns natural gas or propane, its exhaust byproducts enter and travel through the heat exchanger.
This heats the metal as it passes through to the furnace’s exhaust outlet. At the same time, the hot metal heats air as it blows across the heat exchanger. Then it distributes the warmed air throughout your home through ducts.
What Causes a Cracked Heat Exchanger?
The air inside the furnace and around its heat exchanger gets extremely hot, causing the metal inside the exchanger to expand and contract. Well-maintained heat exchangers and on the front end of their working life withstand this heat.
Over the course of several years, however, it’s fairly common for the metal expansion and contraction to cause cracks to the heat exchanger.
Heat exchangers typically last between 10 to 20 years. So, if yours is within that age range, it’s likely the cracks are from normal wear and tear. If your heat exchanger is less than a decade old, other factors may be to blame, including:
- Limited airflow to your furnace. Too much pressure may build up inside the furnace if you have several blocked registers. An overly clogged or dirty furnace filter or obstructed air ducts also cause heat exchanger cracks.
- When a furnace is too large for a home. An improperly-sized furnace may turn on and off frequently. This is known as “short cycling.” It causes the heat exchanger to expand and contract more than necessary. This overuse may eventually lead to premature cracks.
Why Is a Cracked Heat Exchanger a Problem?
If you suspect your furnace has a cracked heat exchanger, it’s important to call an HVAC technician to diagnose the issue immediately. A cracked heat exchanger poses serious health risks for a couple reasons:
- Carbon monoxide leaks. The heat exchanger contains and burns off carbon monoxide, sulfur dioxide, and nitrous oxide. A leak means they could escape into your home’s air ducts. This is known to cause illness or, in extreme cases, death.
- Flame-outs. When an incorrect mixture of gas and air mix and combust in the heat exchanger, uncombusted gas builds up until it reaches a high enough volume to be explosive.
Then it combusts and forces flames and air pressure out of any accessible hole, such as a cracked heat exchanger. According to the National Fire Protection Association (NFPA), furnace fires occur about 2,600 times per year.
What Do You Do If You Have a Cracked Heat Exchanger?
You may be unaware unless your carbon monoxide detector beeps. You may notice the signs mentioned above. Unfortunately, you can’t really know for sure you have a cracked heat exchanger without an HVAC technician’s inspection.
Our service technicians identify a cracked heat exchanger using specialty tools and video inspection systems to examine it closely.
If you have a cracked heat exchanger, in most cases it should be replaced. Because they’re more likely to crack late in your furnace’s life, consider a system upgrade or replacement.
Schedule a Furnace Check-up Today; Avoid a Cracked Heat Exchanger
One of the best things you can do if you suspect a cracked heat exchanger is to call in a pro for help. Even if your heat exchanger is new, we can still perform routine maintenance to make sure your furnace is safe to operate this winter. Call KS Services to set up a heating tune-up today!