Gas Furnace

By Anne Fonda

According to the United States Census Bureau, gas furnaces are the most common heating appliances in the country, especially in northern states.

Natural gas furnaces burn fuel to heat your home. As it enters the burner assembly, the gas ignites, creating combustion which produces heat. The heat is then transferred into metal chambers called heat exchangers. 

When a furnace burns natural gas, its exhaust/combustion by-products enter and travel through the primary heat exchanger. The hot flue gas heats the metal as the gas makes its way to the exhaust outlet of the furnace. As this occurs, the hot metal heats the air circulating over the exterior of the heat exchanger.

If your furnace has a secondary heat exchanger, the combustion exhaust that leaves the primary heat exchanger will enter into the secondary heat exchanger.  In the secondary heat exchanger, additional heat is released from the flue gas and water vapor begins to form. This change of state from water as a vapor to a liquid releases latent heat in the secondary heat exchanger, bringing the furnace to an even higher level of efficiency. 

The furnace blower fan then distributes the heated air throughout your home via the ductwork.

Gas furnaces have a lot going for them, including:

Regular gas furnace maintenance includes changing your furnace filters regularly (usually every 30-90 days) and scheduling an annual furnace tuneup. By having an HVAC professional inspect, clean, and maintain your furnace, you can prolong the life of the unit. Check out our gas furnace maintenance tips for more information.

At the yearly furnace tune-up, the HVAC technician may spot issues that can be fixed on the spot. In other cases, the top signs that you may need furnace repair are:

Check out our furnace troubleshooting tips to see if you can resolve the problem yourself before scheduling furnace repair near you.

Refer to our Repair or Replace Guide for complete information on deciding to replace your gas furnace. But in general, if the furnace is approaching the end of its expected lifespan, furnace repairs are becoming more expensive, or if you want to upgrade to a more efficient system, you’ll want to consider furnace replacement.

The best way to choose the right furnace for your home is to work with an experienced HVAC professional. Some factors to consider when selecting a gas furnace include:

Considering replacing your old gas furnace? Contact your local American Standard dealer for product recommendations and a furnace installation quote.

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need. 

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by John Kim, Senior Product Manager, Furnaces