Is a High-Efficiency Furnace Worth the Cost?
Summary: If you live in an area with especially cold winters, a high-efficiency furnace can save you money on your fuel bills. Learn what a high-efficiency furnace is and how they work to achieve greater efficiency.
By Anne Fonda
So, you’ve decided it’s time for furnace replacement, and you’re doing your research. Smart move. If you’ve never purchased a new furnace or you haven’t bought a new one in 15+ years, a lot has changed.
Today’s high-efficiency furnaces leverage advanced technology and greater fuel efficiency to provide you with enhanced comfort while saving energy. Ready to learn more? Let’s get started.
What is a high-efficiency furnace?
In the simplest terms, a high-efficiency gas furnace is a furnace with an Annual Fuel Utilization Efficiency (AFUE)at or above 90. This means at least 90% of the natural gas the furnace burns goes into heating your home rather than being vented out of your home as flue gas.
How does a high-efficiency furnace work?
High-efficiency furnaces are also called condensing furnaces. They achieve higher efficiency with two heat exchangers. Conventional furnaces have one heat exchanger. 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.
Secondary heat exchanger
A high-efficiency gas furnace has a secondary heat exchanger. When the combustion exhaust gases leave the primary heat exchanger, instead of exhausting immediately to the outside, they enter the secondary heat exchanger.
In the secondary heat exchanger, the flue gas releases additional heat, 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.
What’s the difference between a variable speed furnace, a modulating furnace, a two-stage furnace, and a single-stage furnace?
High-efficiency condensing furnaces can become even more efficient with additional heating stages and/or a modulating gas valve. A single-stage furnace is either off or running at 100% capacity. A two-stage furnace has both high and low speeds, which can result in more even and efficient heating.
A modulating furnace means it has a modulating gas valve. This means it can operate between 40% and 100% depending on your specific heating needs, providing for ultimate comfort and greater efficiency. Meanwhile, a variable-speed furnace is compatible with a variable-speed heat pump or air conditioner and can offer precise temperature control year-round, running longer at lower speeds.
How much more efficient is a 97 AFUE two-stage furnace vs an 80 AFUE two-stage furnace?
A standard-efficiency furnace with an AFUE of 80% returns 80 cents to the dollar you put into it as heat. 20 cents goes up the chimney as flue gas. A high-efficiency model with a 97% AFUE returns 97 cents as money spent on heat. So, you get 17 cents more heat for every dollar you spend. That can really add up.
If you live somewhere where you run your furnace from mid-October through March, that savings can really add up.
When is a high-efficiency furnace most appropriate?
“A high-efficiency furnace makes sense in regions with colder climates and higher utility costs. These furnaces use less gas to produce the same amount of heat, which translates to lower energy bills for homeowners.”
-Amy Gulas, Senior Furnace Product Manager
In addition to the cost savings, a high-efficiency furnace has other benefits, including:
- More even heating for greater comfort
- Better indoor air quality (IAQ)
- You lower your carbon footprint by burning gas more efficiently and wasting less
What furnace is most appropriate in a dual-fuel system?
The answer to this question will be different for every homeowner. A dual-fuel system, or hybrid heating system, is one that combines an electric heat pump for cooling in the summer and heating in the fall, winter, and early spring with a gas furnace.
The heat pump heats for the majority of the time, and the furnace kicks in when the heat pump’s efficiency starts to drop. Many of our heat pumps are designed with a heating capacity ratio to provide 100% of your heating down to 27-32°F.
Our newest cold climate heat pumps (CCHP), which will be available in late 2025, are designed to operate efficiently even in below-freezing temperatures.
Work with your local Trane dealer to choose the best furnace to pair with your new heat pump.
The bottom line
Only you can decide if a high-efficiency furnace is worth the higher purchase price compared to a less efficient furnace. Since a furnace can last 15+ years, the higher efficiency will save you money on natural gas bills for years to come.
You’ll need to weigh your heating needs vs future savings. Be aware that HVAC financing can help you spread the cost of a new furnace or hybrid heating system out over several years.
Learn about your options
If you’re in the market for a new gas furnace, turn to your local Trane dealer for assistance. Whether you’re upgrading to a dual-fuel system, want the most efficient furnace, or want to find the most affordable option, Trane has options.
Anne Fonda, Content Writer
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 Amy Gulas, Senior Product Manager, Furnaces
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