Furnace vs Air Handler: What’s the Difference?

HVAC Logo IconBy Tom MoorJanuary 25, 2025

If you’re like many homeowners, you may not know much about how your HVAC system works or the key components that make it function. As long as it keeps you comfortable during extreme weather, that’s all that matters, right? Still, it’s a good idea to have a basic understanding of how your heating and cooling system operates, especially when issues arise.

One common area of confusion for some homeowners is the difference between an air handler vs furnace. Are they the same thing? How do they work? Do you need both? HVAC.com answers those questions and more to help you understand these crucial HVAC parts.

What Is an Air Handler?

Most HVAC systems – including air conditioners, furnaces, or heat pumps – require an air handler to push either cooled or heated air through your ductwork and distribute it into your home’s living areas to meet your home’s comfort needs.

The air handler is a large metal box typically found in the attic, basement, or utility closet. It can either be a standalone unit if you only use a heat pump for heating and cooling, or it can be integrated as part of the furnace system (we’ll discuss this in more detail in a bit).

An air handler works by circulating air throughout your home, using a blower fan to push conditioned air through your ducts. In heating mode, it operates with your furnace or heat pump to distribute warm air, while in cooling mode, it helps move cool air produced by the air conditioner. Key components, like the blower motor, evaporator coil, and air filter, all work together to ensure the air is properly conditioned and circulated for comfort.

What Is a Furnace?

furnace, meanwhile, is a central heating system that generates heat to provide your home with warmth. The heating process begins when the thermostat detects that the indoor temperature has dropped below your desired level.

The furnace starts by igniting its fuel source, and the heat produced is transferred to the air through the heat exchanger. From there, the air handler’s blower fan pushes the warmed air through the ducts to raise the temperature of your home.

Furnaces come in different types, like gas, electric, and oil, each coming with its own benefits depending on your home’s needs and energy sources. Gas furnaces are a popular choice because they’re cost-effective and heat your home quickly, making them ideal for colder climates. While electric and oil furnaces also get the job done, they tend to be more expensive to run than gas models.

Furnace vs Air Handler: How They Work Together

A furnace and air handler are often used together as part of a complete HVAC system. If you have a furnace, you don’t typically need a separate air handler because the furnace houses the blower and the components needed to circulate the air. However, if you have a heat pump that provides both heating and cooling, and you don’t use a furnace for backup heat, you’ll need a dedicated air handler to handle the air distribution.

When to Choose a Furnace or Air Handler

If you live in a milder climate, an air handler paired with a heat pump might be the best option. Heat pumps are energy efficient and can both heat and cool your home, making them an all-in-one solution for moderate temperatures year-round. They’re especially effective in areas where winters aren’t too harsh. Heat pumps generally don’t operate as efficiently once the temperature drops below freezing; however, new cold-climate heat pumps that can operate in temperatures as low as zero are being tested by leading manufacturers.

In colder climates, however, a furnace is usually necessary to provide reliable heat during the winter months. With a furnace, you can rely on consistent, efficient heating even in the coldest temperatures, with the air handler ensuring the warm air reaches every room.

To maximize efficiency, you might consider replacing your air conditioner with a heat pump. The heat pump will handle cooling your home and can heat your home up to a certain outdoor temperature in winter. When the heat pump becomes less efficient in colder temperatures, the furnace will take over to provide reliable warmth.