Dust from hvac..

there are filters that can be placed in the registers themselves or you could likely make your own using the filter material that you trim yourself

where do i find them/ or the filter material?

they can be purchased at Home Depot or on Amazon. Google air vent filters and several options pop up

Most any variety store or home improvement store usually has the filters you can cut to size! But plan on cleaning them other otherwise they will get dirty and block your heat from coming up thru your vent! It doesn’t take much blockage to loose your heat circulation thru your vents! I have tried this myself and ended up throwing my homem filters away. Best thing is to keep your furnace filters clean, I have put a large filter, same material I used to cut own for vents only don’t cut it and put the large piece over the top of the furnace where the furnace sucks the air down to your vents as a extra dust filter that seems to work best for our heat pump furnace. Our furnace is in a closet size room with a door that has a large hole cut out of the top of the door with a grill over the large cut out hole. I also installed this same filter material in the door behind the grill that also catches a lot of dust before it ever gets to my furnace to blow thru my system! Better to keep the dust from getting in the furnace then it is trying to catch the dust after it’s coming thru your vents from my experiences!

You had all those gaps and openings in the ducts. They were sucking dust/ dirt all the time and a lot settled in the ducts. Now that the ducts are sealed all the dust is migrating out the registers. It may happen for a while or longer to get all dust out of the ducts. I would start with a pleated filter at the furnace. Or you can have the ducts cleaned to remove the accumulated dust. Installing filters at the registers will just cause the dust to load up the filters quickly and restrict air flow. This can make your furnace work harder and put a strain on it.

Send a person that you can trust to check to see if the ducts are secured. The handler is pulling dirt from register runs. Have the ducts cleaned if no leaks are found. Change filter every month see if those mentioned answers above solve your problem..