HeatingWhat is a Downflow vs Upflow Furnace?


There are a lot of different factors to weigh when you are picking a new furnace to install. What’s size is right for your home? What kind of fuel does it use? Should you stick with combustion or try an electric unit? What’s the AFUE rating? One important question that most overlook, however, is whether a furnace should be an upflow furnace or a downflow furnace. Read on for a description of each, and which would best fit your needs.

Downflow Furnace

The primary difference between an upflow and a downflow furnace which direction they take in and expel air. A downflow furnace takes in cold air at the top of the unit and expels air at the bottom. By doing this, the downflow furnace directs heat downwards towards the area that requires it. This makes downflow furnaces naturally suited to being installed in attics. They can also be installed in the upper floors of a house if you don’t have an attic.

This makes them very versatile, able to be installed in almost any type of home. The downside is that a downflow furnace is less efficient than an upflow furnace. Heat naturally rises, so the downflow furnace must constantly fight against the natural tendency of the air it’s circulating.


An upflow furnace takes in cold air at the bottom of the unit and expels warm air upwards. This makes them more efficient than downflow furnaces because they are working with the natural tendency of heat to rise upwards. Upflow furnaces tend to heat spaces more comfortably since heat moves from the floor of a room upwards. This keeps the actual living area of each room more comfortable than a downflow system, which wastes heat on areas like ceilings.

The downside is that upflow furnaces have more strict installation requirements. Oftentimes you’ll need a basement to get the most out of an upflow furnace. This precludes a lot of homes in areas like the west coast.

If you are having trouble picking the best furnace for your home, call G&S Heating, Cooling & Electrical, Inc. We install and maintain heating systems throughout the Puget Sound Area. Schedule an appointment with us today!


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