Aside from occasionally adjusting your thermostat, replacing air filters and annual furnace tune-ups from professional HVAC technicians, modern furnaces require very little attention. Your heating system provides warmth throughout the coldest months and most brutal winter storms. For most homeowners, your furnace exists in the background of their life. That is until catastrophe strikes and your furnace breaks down.

When a furnace malfunctions or stops running completely, there is a reasonable sense of fright. Without a gas furnace to warm air, icy outdoor temperatures quickly fill your home. The health of your family and the security of your home is in jeopardy. Gas furnaces can pose a secondary risk when a heat exchanger malfunctions. Carbon monoxide poisoning is a very serious possibility when a cracked heat exchanger is not quickly detected. Knowing the warning signs of when your furnace heat exchanger has gone bad should be a primary focus of every homeowner.

What is a Heat Exchanger?

A heat exchanger transfers heat from natural gas or propane to the indoor air. Burners ignite gases entering the heat exchanger. As the heated gas moves through coils air absorbs the heat through thermal conduction. The heat exchanger exhausts flue gas to the outside of your home.

Heat Exchanger Cracks

Cracks may occur in any area within the heat exchanger. There are many causes for heat exchangers to develop cracks, but they are most commonly caused by improper maintenance. Strained systems often result in a cracked heat exchanger. Clogged filters, dirty coils, moisture, and malfunctioning burners are common culprits. Potential risks are numerous and serious. Generally, the most immediate concern is carbon monoxide which poses a serious health risk.

Signs of Heat Exchanger Problems

Cracked heat exchanger symptoms vary from moderate warnings that can be treated to severe problems. As a basic rule, any changes in the normal operations of your furnace should be inspected by a certified HVAC technician. Heat exchanger cracking should only be diagnosed by a trained professional.

Unpleasant Odor

Unpleasant odors from natural gas and propane furnaces are immediate signs to take action. Shut down the furnace, turn off gas lines and immediately contact professionals. A damaged heat exchanger may leak foul-smelling odors throughout your home.

Soot Build Up

Build up of soot inside the furnace indicates improperly adjusted burners. Carbon should not build up within furnace housing. If you observe any soot or black carbon spots within the furnace, contact a professional HVAC contractor. Proper service will clean and evaluate the condition of the furnace.


Even small cracks in a heat exchanger often generate noise. Rattling and banging within your furnace is a warning to shut down the furnace and call on service professionals.


Corrosion in heat exchangers is monitored during maintenance. Properly adjusted burners prevent corrosion caused by vibration, temperature and water. Spotting corrosion and acting quickly before a heat exchanger cracks is wise.


Heat exchanger cracks are cause for immediate concern. Any damage to a heat exchanger can seriously risk the health of your family, the safety of your property, and obviously, the function of your furnace.

Reducing Risks

There are some very economical ways to reduce the risks of damaged heat exchangers and other furnace repairs. When you contact HVAC professional to schedule maintenance you can ask about the carbon monoxide detector and how to replace the air filter on your heating system.

Furnace Maintenance

Annual inspections by a professional HVAC technician prevents the most dangerous risks to family and home. Cleaning all components, testing the system and calibrating the furnace during the fall greatly reduces the risk of a cracked heat exchanger endangering your family. A complete tune-up of your furnace each year also protects other components from failing, improves energy efficiency, and improves the life of the equipment.

Carbon Monoxide Detector

Installing carbon monoxide detectors throughout your home will alert you to leaks quickly. If a carbon monoxide detector alarm sounds you should shut down all systems, vacate your property and contact professional services to diagnose and repair the issue.

Replacing Air Filter

Clogged air filter issues create many issues within HVAC systems. Checking the air filter monthly, cleaning around the furnace, and replacing the air filter throughout the year are easy tasks any homeowner can perform. Adding a reminder to your calendar to replace your air filter may avoid expensive repairs.

Call Poston Brothers for Furnace Maintenance and Repairs

If you’re concerned that your furnace’s heat exchanger is cracked, call Poston Brothers right away. We can inspect your furnace and talk to you about installing a new unit if needed. Contact Poston Brothers to make an appointment.