Shop vac blowing dust out back? It’s the filter.

Is your shop vac blowing dust out the back? Mine always do after a while. Fortunately it’s an easy fix, and you don’t need to replace the unit. If yours just started doing it, stop what you’re doing right away and give the unit a checkup. You may save yourself 20 bucks.

A shop vac-type vacuum blowing dust out the back is always a filter problem: either your filter is clogged, missing, loose, or the dust is too fine. But once you clean or replace the filter, the problem goes away.

Checking out your filter

To check out your filter, remove the top. Usually there are two clips holding it on. In my case, I found the remnants of my filter inside the vacuum. It was just two rubber parts with a bit of fiber on the edges. My filter had clogged to the point where it disintegrated. And then my vacuum started blowing dust, and just moving my mess from one side of the room to the other. That’s not what I want, and probably not what you want.

shop vac blowing dust out back
My shop vac was blowing dust out the back because there’s supposed to be a filter on that plastic frame. The remnants of the filter are in the bin.

My vacuum takes a VF4000 filter. Yours may vary, but a lot of shop-type vacuums use them. In my case, the replacement filter names were printed right on the vacuum. Knockoff VF4000s are available on Ebay, and they cost about half as much as the ones in retail stores. But I couldn’t wait that long so I sourced one from the home center down the street.

Cleaning or replacing your filter

The filter snaps on and off the plastic frame in the middle. In the picture above, I’d already snapped off the little bit of the filter that was hanging on. If your filter hasn’t disintegrated, you can shake the dust off it, rinse it off with a hose, and let it dry overnight and put it back to use.

If you’re going for replacement, snap the old filter off. It will fight you a bit, as there’s a very tight hole in the filter that engages a knob on the frame. The tightness holds the filter in place while the vacuum moves torrential winds around. Once you remove the old filter, slide the new filter onto the frame.

shop vac blowing dust out back? Replace the filter.
The replacement filter just slides right onto the frame.

There’s a little knob on the end that locks the filter into place. Snap the center of the filter down onto the knob. It takes a bit of force to snap a new one in.

Shop vac blowing dust out the back? Make sure the filter is secure.
Snap the filter into place to keep the problem from happening again.

A new filter made my 10-year-old vacuum run like new again. The filters aren’t super cheap, but they are a lot less expensive than replacing the unit. And if you buy the filters online, you can save quite a bit.

Upgrading your filter

If your filter is in good condition but your shop vac is still blowing dust, the dust is too fine for the filter you’re using. For finer dust or debris like cement dust or fine powders, upgrade to a VF5000 or higher filter. For most debris you’re able to see, a VF5000 will be sufficient. If you’re concerned about pet dander or pollen, you’re probably using a household vacuum. But if not, the VF6000 is the appropriate filter for that kind of debris.

You can use the heavier-duty filters for typical shop-type dust like sawdust and tracked-in dirt. They just cost more.

Preventing future recurrences of your shop vac blowing dust

To keep your shop vac from blowing dust out the back in the future, I recommend shaking off the dust from the filter each time you empty the bin. That will help to keep the filter from clogging up on you. I’m not great about remembering to do this myself. But if you keep the filter clean, it can last years, and your vac will run better too.

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