Air filters have arrows printed on the sides of them that show you which way they are supposed to be installed. These arrows should be pointing in the direction that air flows through your system, which is away from the supply ducts and (typically) toward the blower.
Which way are air filters supposed to face?
On the new filter, find the arrow indicating the proper airflow direction. The arrow must face toward the furnace and away from the return duct that pulls the air in need of heating or cooling. It’s smart to draw the airflow direction arrow with a permanent marker on the furnace or ductwork.
What happens if I put my air filter in backwards?
When a furnace filter is placed backwards, the fibers can’t do their job properly. This means your furnace has to work harder to generate the same air flow, resulting in increased energy costs. Particles are also allowed to build up irregularly, making the furnace working even harder to draw air.
What is the direction of air flow?
Air always flows from the high pressure region to the low pressure region. A warmer place is usually a low pressure region while a colder place is a high pressure region. Thus the direction of air is from warmer to colder region. Forward.
Why do air filters have a direction?
This allows the filter to effectively trap airborne particles while also minimizing the slowdown of airflow through your system. By installing your filter backwards, air will have a harder time flowing through the filter and your air handler will have to work harder to make up for the loss of airflow.
