Where is the air filter slot in this house?
HVAC air filters in new or unfamiliar homes are often hidden away or missing from the return grates entirely, leaving homeowners scouring the house with no obvious place to install one. This makes it impossible to figure out the correct setup or even know if a filter is missing altogether.
What the numbers show
Counted from the threads quoted below. How we count
- This comes up 22.5× more often in r/hvacadvice than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1leaving the unit without a filterDid this help you?
- 2making custom filters to sit on top of the coilsDid this help you?
- 3Searching near the blower unit for alternative filter placementsDid this help you?
- 4Measuring the existing washable filter to replace it with a standard disposable oneDid this help you?
- 5Searching ceilings or walls for large return vents that hinge openDid this help you?
- 6Getting a cheap HVAC inspection done to have professionals point out filter locationsDid this help you?
- 7Checking both the wall return vents and the air handler unit to locate the filter slot.Did this help you?
- 8Searching different potential compartments on the air handlerDid this help you?
- 9Measuring the filter slot manually with a tape measureDid this help you?
- 10Checking for separate return air grill filter locationsDid this help you?
- 11Checking underneath the duct tape area on the right side of the furnaceDid this help you?
- 12Trying to remove different panels like the lower vented door or top cover to search for the filter compartmentDid this help you?
- 13Tipping or fitting the filter awkwardly into the designated space based on community adviceDid this help you?
- 14Guessing the filter size and thickness from markings on the unitDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“for the life of me I can't seem to find where the hell the air filter should be.”source ↗
“I have scoured the house for a spot that seems like it would house the filter to no avail.”source ↗
“What I Don’t understand is they gave me a 16 x 20 filter and it doesn’t seem to fit on either side . Both vents have 16 width but not 20.”source ↗
“I can’t figure out where or how the air filter goes on this thing.”source ↗
“I recently bought my Grandma’s house and noticed there’s no filter on the return grate in the house.”source ↗
“Is this possibly the only filter location, or could it be designed to run with 2 filters in line?”source ↗
“Hi! First time homeowner here. I went into my attic today to replace my hvac filter but I have no clue where it is.”source ↗
“I have this furnace. There’s a filter underneath where the black duct tape on the right side of the furnace is. Is there another one somewhere? Where?”source ↗
“Really don’t want to have to call someone. I tried taking off the lower door, the one with the vents. It shifts up easily but I could not take it off.”source ↗
“I did. There’s nothing there”source ↗
“I have a new house that I’ve built and I got my HVAC installed about three months ago I just noticed that he never put in a filter because this fuse box is pretty dusty.”source ↗
“I tried to take the screws off, but it’s pretty tight on there. Anything you suggest I do? Obv put in a filter .”source ↗
“I do know there is suppose to be a filter some where here and I can’t find one or a place for one.”source ↗
“The spot on the wall is just open into the top of the furnace. Would just putting a filter there be acceptable?”source ↗