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What is a Furnace?

A furnace is a home heating product that delivers warm air throughout a home. In a central heating system, the warm air is delivered via a connected system of ductwork.

How does a furnace work?

In a gas furnace, (the most common type of furnace used in homes) natural gas is ignited in the burner and the flames heat up the heat exchanger. The heat exchanger warms up the incoming air and a blower or air handler sends the warm air throughout the home. Watch this video on how HVAC systems work to learn more details on heating and cooling systems, a furnace’s role in the process, and how you can achieve optimal comfort in your home.

Energy saving features

When shopping for a new furnace, energy efficiency is one of the most important factors to consider. For a furnace, there are a few important features to keep in mind.

  • AFUE – this is similar to the SEER rating in an air conditioner. AFUE is a standard industry measurement of a furnace’s efficiency. The higher the AFUE, the more energy efficient the unit.
  • Heating stages – Furnaces with multiple heating stages are more energy efficient than single stage furnaces. Single stage furnaces have to run at full power to reach a desired temperature while variable speed systems or two-stage systems can maintain a desired temperature while using less energy.
  • ENERGY STAR QUALIFIED – ENERGY STAR is a government backed symbol and standard for energy efficiency. This designation is applied to multiple consumer products including HVAC systems like furnaces, heat pumps and air conditioners. Look for the ENERGY STAR logo to see if a furnace qualifies.

Types of furnaces

There are two main types of residential home furnaces: gas and oil. Most homes today have gas furnaces, but some continue to use oil furnaces. While both will heat your home, there are some differences to consider.

Gas furnace

PRO: Better energy efficiency. Gas furnaces can have an AFUE rating of 89 to 98 percent. Oil furnaces usually have an AFUE rating of 80 to 90 percent.

CON: Initial cost. Gas furnaces are normally more expensive upfront than an oil furnace.

Oil furnace

PRO: Your initial cost will be lower compared to a gas furnace.

CON: Oil furnaces are not as efficient as gas furnaces. Heating oil is also more expensive than natural gas.

Furnace maintenance

A furnace is a complicated machine but when properly installed and maintained, it will run smoothly for years. Here’s a few tips to keep in mind to get the most out of your furnace. For a full list of maintenance tips and service schedule, visit our furnace maintenance page.

  • Have your furnace installed by a trained and trusted HVAC technician. Most maintenance problems are caused by installation error, not mechanical failure.
  • Service your furnace before the heating season.
  • Change your filter regularly.

Read more about furnace maintenance

Repair or replace? How do you know?

How long a furnace will last depends on a lot of things including how it was installed and how it’s used and maintained. However, here’s a few things to keep in mind to help you decide whether to repair your furnace or replace it. Check out our interactive repair or replace tool to get an instant recommendation on your system.
You should consider replacing your furnace if

  • A furnace is over 10 years old
  • A furnace is 80% AFUE or lower
  • A furnace is breaking down often
  • Energy bills are increasing without changing energy usage

How much does a new furnace cost?

Unlike our HVAC competitors, Trane believes in making the purchasing process as simple as possible. That includes being upfront about the cost of our furnaces. You can find average furnace prices on our pricing guide and local prices on our furnace page. Please note, the price of a furnace depends on several factors including where you live, the unit you select, the size of your home and the difficulty of the installation process. That’s why we recommend talking to a Trane Comfort Specialist™ to get a custom quote for your home.

Browse Trane furnaces

Contact a local dealer

Dealers can answer questions, help you find the right products for your home, and repair your system.

We’re here to help

Connect with our Customer Care team about your products, warranties, and dealer concerns.

Available Monday – Friday from 7am to 5pm CST


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