Supply Vent Question

Every once in a while I inspect a house that has what looks like air freshener sheets, or a filter like material behind the supply vent registers. Someone told me they are to help control air flow? Could someone identify these things and tell me what they do? I should have taken the thing out for the picture. I think you will get the idea. Thanks in advance.


My feeling is they are not needed and just restrict the flow from the furnace,
The furnace manufacture designed the furnace and One good filter is all that is needed.
Some also add a filter in the floor vent not good.
People would be better of changing their furnace filter more ofen and use a good one each time.
The cheap filters catch some of the animal hair but not much dust,
… Cookie

If those are about 5inches square they might be one of the scented air freshner sheets that are sold at the box stores. I have seen them before. Vanilla, “outdoor freshness”, apple. All sorts of different scents.

Personally, I would not have removed the register grille. If you had damaged the ceiling finish, register, or anything in the room, you are responsible for repairing or replacing it. Best to follow the SOPs and limit what you have to dismantle.

I alway hate the house where the little old lady has her collection of tea cups and saucers on little stands attached to the walls. They’re there just waiting for someone to bump into them.