Furnace Filter Airflow Arrow: Which Way Should It Point?
Key Takeaways Point the furnace filter’s airflow arrow toward the furnace blower or air handler, in the direction air travels after passing through the filter. At a wall or ceiling return grille, the arrow points away from the room and into the duct; at an equipment-side slot, it points into the unit. If there is no arrow, compare the old filter and consult the filter instructions and HVAC equipment manual rather than guessing. Turn off the HVAC system before replacing the filter, then confirm the replacement is seated in the compartment with the arrow following airflow. Table of Contents What does the furnace filter airflow arrow mean? How do you find the airflow direction at the filter slot? How should you replace a furnace filter without reversing it? What if the furnace filter has no arrow—or has confusing markings? How can you check the filter after installing it? What happens if you install a furnace filter backward? Which direction should you choose in different furnac...