What Is the Difference Between Downdraft and Updraft in a Furnace?

Heating

• Both downdraft and updraft units pull the outside air into the system, heat it, and pump it back into the home. The return ducts draw in the air, which is heated by natural gas combustion or electric coils, and blows it back into the home.

Cooling

• Cooling requires a coil to be mounted on top of the furnace and also involves an outdoor compressor unit. The coil cools with a refrigerant. The warm air inside the home comes in the same way it does for heating and cools when blown through the coil. This cooler air distributes itself through the house to create a central cooling system.

Updraft Units

• An updraft unit pulls air in through the bottom and pushes it out through the top. Updraft units most commonly are installed in basements or crawl spaces under a house. The ducts are attached to the unit and blow the warm air up into the living quarters.

Downdraft Units

• A downdraft unit pulls air in from the top, heats or cools it, and forces it downward. These units are the preferred method of heating or cooling if installation is on the ground floor or in an attic. Vents can be on both the floor or ceiling, depending on how the coils are arranged through the home.

Efficiency

• Updraft units are more efficient than downdraft units for heating. Warm air naturally rises, which reduces the work the furnace needs to do, heats the home faster and saves on energy costs. Updraft units are the preferred method for homes, but downdraft furnaces are still available for mobile homes or those without a basement or adequate crawl space to install the furnace.