The furnace is one of the most important parts of your home, and when the temperatures drop in the Birmingham area, they can go from a source of comfort to a literal lifesaver in a hurry. That’s why understanding important furnace components is so helpful—it allows you pinpoint any potential problems and help the service technician get on with his repairs quickly.

For instance, what is a heat exchanger and why is it so important?

What Is a Heat Exchanger?

Heat exchangers are essentially long tubes of metal with openings at either end. They facilitate the transfer of heat from gas in the burners (which produces toxic byproducts when it burns) to the air that can then blow into your home.

Heat exchangers are not “coils.” They are typically made from steel sheet metal and facilitate the gas-to-air exchange.

The burning gas passes through the heat exchanger so the toxic byproducts can safely vent out of the system. A fan then passes the air in your home over the heated metal, and that hot air is blown through the ducts of your system, where it can be safely passed throughout all the corners of your home.

If you have a boiler, the hot-water radiators receive their heat from hot gas jets, but first the water has to absorb the heat energy from the gas. The heat exchanger allows the heat energy to pas from the gas to the water safely. If we were to try to heat water directly from the gas, the flames would be extinguished by the water. The general principle of the heat exchanger is that it allows heat to be transferred without transferring the fluid (liquid or gas) that carries the heat.

Why Is a Working Heat Exchanger So Important? 

Generally speaking, heat exchangers don’t require repair. They have no moving parts and they are designed to last a long time. Unfortunately, that means that when a problem does occur, it’s a big deal. Heat exchangers can crack over time or become damaged by outside circumstances, such as freezing conditions.

If you have a cracked heat exchanger, dangerous combustion gases can leak into your living spaces. One of the main dangers of a cracked or improperly designed or installed heat exchanger is CO poisoning.

When combustion gases are not properly vented, carbon monoxide can leak into your home.

Heat exchangers should last at least ten years, but when they go, they can’t be easily replaced. Heat exchangers need to be serviced by a trained and licensed HVAC professional.

How to Tell If You Have a Cracked Heat Exchanger 

Black Soot – If you notice soot around your furnace, that is a clear sign that your gas is not burning cleanly. Unhealthy and incomplete combustion can lead to dirty soot around the furnace. This is usually the result of a damaged heat exchanger or a problem with your burner/furnace flame.

Old System – If you are experiencing other aging problems with your furnace, such as wear and tear, loud noises, and other signs of aging, it’s a good idea to have a professional diagnose the entire system.

Strange Smells – Although some gases, such as carbon monoxide are odorless, if you smell anything strange or unpleasant near your furnace or air ducts, contact a professional HVAC company right away. Cracked heat exchangers can leak combustion gases into your home that can cause a clear and present odor. If you smell something similar to sulfur or formaldehyde, turn your heating system off immediately and wait for a professional to diagnose the situation.

Water Near the Furnace – If you notice water on the floor near your furnace, you may have a problem with your heat exchanger. Whether it is condensation or a cracked heat exchanger, contact an HVAC professional right away to determine the cause.

Gas Leak Signs and Symptoms – Headaches, nausea, dizziness, and flu-like symptoms are indications that there is a CO or other combustion gas leak (sulfur dioxide or nitrous dioxide) in the home. Test all of your CO detectors to make sure they are working. If the CO detector goes off, turn your heating system off, evacuate the building, and wait until the fire department, utility company, or professional HVAC technician has deemed it safe for you to reenter.

Heat Exchanger Safety and Maintenance Tips

If you suspect a problem with your heat exchanger, turn your heating system off and contact a professional right away. Do NOT continue to run your furnace as dangerous gases will continue to leak into the home.

Keep all vents and registers open in your home. This keeps the air flowing and prevents excess air pressure within your HVAC system.
Check your air filter every 30 days and wait no longer than 90 days to replace it. Dirty air filters decrease airflow and cause dirt to accumulate in the system.
Install CO detectors on every level of the home and outside of every sleeping area. Check the batteries every 30 days and replace all CO detectors every 10 years or according to the manufacturer recommendations.
Schedule annual furnace tune-ups every fall before the heating system begins. Your HVAC technician will be able to check your furnace for safety issues such as cracks in your heat exchanger. The system will be cleaned and ready to go for winter.

Cracked heat exchangers NEED to be replaced by a professional. Learn about the dangers of DIY furnace repair. If your furnace is over 10 years old and you need a new heat exchanger, consider a full replacement. Learn if it is time to replace your furnace.

Understanding important furnace components like the heat exchanger will help you understand what happens with things go wrong.

If you haven’t scheduled your furnace tune-up this year, schedule one as soon as possible. For all other furnace service in the Birmingham area, contact OnTime Service for fast and reliable furnace troubleshooting and repair. Schedule service online or call us at 205-942-1405.


Give OnTime Service a call to schedule your annual heating inspection at (205) 942-1405.

Our experienced team of technicians is fully trained to handle any heating system. As always, we will troubleshoot your home and give you straightforward pricing options.

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