Filters in all return vents?

Just inspected a townhouse the other day, and every return vent had a 16"x16"x1" air filter inside of it. The vents weren’t any kind of easy-access vent grille either…they were all screwed into the wall as usual. Anyone ever see this before? BTW, every one of them was caked/clogged with dust. I recommended that the client remove them all and just rely on the filter at the blower that’s easy to change. Am I missing something?

No good call and I agree … Roy

So there was a filter at the blower and filters in the returns also?

You got it

If the filter at the returns was the cheapo mesh, I wouldn’t have a problem with it as it’s acting as a pre-filter to keep the ducts themselves relatively clean.

They weren’t the cheapo ones, they were the paper type and completely clogged with a thick layer of dust.

I recommend filters at the return air vents especially if they are at floor level or the client has pets. They sure catch a lot of hair and debris. Much better to catch it there than have it gunk up the return air ducts. I just wouldn’t use really good filters. Get the cheap ones and leave a good filter at the furnace.

That’s what I do. I can easily change the filters at the return. My whole house filter is in the crawl.

Filters at the grilles always leaves the grille and the area around grille very dusty, unless homeowner has a contact for maintenance or is up too maintaining it themselves they should just keep a filter at unit. Just my opinion.

The manufacturer of the unit would determine whether it is OK to have the filters at the returns if there is already one at the blower. The more filters, the more air restrictions, the harder the blower works which can shorten the life expectancy of the unit.

I agree with William regarding restrictions and potential shortened life expectancy.

Apparently they were working.

I would recommend measuring the static pressure in the system to determine if these extra filters were impeding airflow (stresing the blower).