Where Is the Furnace Air Filter Located? | Easy Guide by System Type

VentMaven diagram illustrating Where Is the Furnace Filter Located? (By System Type), showing upflow, horizontal, and downflow furnaces in brand green colors, with arrows highlighting the filter positioned in the return duct near the blower for each configuration.

We’ve pulled filters from systems where the homeowner didn’t even know a filter existed—let alone where it was hiding. On our service calls, we’ve found filters wedged behind return vents, buried inside blower compartments, and tucked into filter racks that were never labeled during installation. The location changes depending on your system type—horizontal, upflow, downflow, … Read more