Upflow, Downflow, and Horizontal. What do they mean?

Decoding Upflow Downflow And Horizontal - Upflow, downflow, and horizontal are very important factors when purchasing your HVAC equipment, however you might be wondering what these terms actually mean. These terms are used to explain the direction of airflow through your system and how your furnace is installed.

So why do you need to know which direction the air is flowing through your system? Furnaces and evaporator coils are designed and built to be used in certain configurations and you need to be sure that you are purchasing the correct configuration when ordering your replacement units. Below we have an example of each configuration to help you decide which type of system you have.


Airflow comes in from the bottom of the air handler or furnace and flows out the top of the unit. This type of system is most common in basement installations. Upflow Configuration


Airflow comes in at the top of the air handler or furnace and flows out the bottom of the unit. This type of unit is most common when the unit is installed in a closet. Downflow Configuration


The unit seems to be laying on its side and the airflow flows in from one side and out the other side. This type of system is most common in attics and craw spaces.Horizontal Configuration

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