I live in NC.  I have a double and single car garage that I use.  The single is relegated to my wife's car.  I had my car in the double but its looking more and more like my nice Lexus is going to stay outside most of the time, but I digress...

When it gets warm I get all kinds of bugs and dragon flies and every other thing trying to get in while I am working.  This year I bought one of those screen set ups that attaches to the garage door frame with sticky tape.  Surprisingly it does an adequate job.  I may have to replace it every other year or so but for $50, thats not bad to me.

I also bought a Wen 3410 air filter.  Its their smaller one and I have been using it for a month or so.  I may get another one or their larger version.

My question, if I run this air cleaner with the garage door open, I assume I am maybe doing it for nothing? 

The two are going to move air through the shop in very different ways.

The open door is passive and depends on air movement caused by whatever breeze is present at the time and is continuously variable and also beyond your control. You are at the mercy of Mother Nature.

The air cleaner however makes its own wind so to speak. It stirs the air in the space and depending on where and how it is mounted may cause air movement in spaces the breeze of an open door would never reach.

You mentioned this is a smaller size air cleaner. If it is undersize (machine CFM vice shop volume) it may not be effective at all. It might take so long to remove dust from the air that nothing is gained by operating the air cleaner.

How well a combination of the two would work I don't know.

My gunsmith has a really large roll-up door on his shop, and inside that steel door, there's another roll-up screen.  That combined with some floor-stand fans keeps his shop air quality quite decent.  True, it's not sawdust, but he does use some pretty stinky chemicals in his practice.  And he gets very few bugs in the shop. 

The best with air cleaners is to let them run overnight or during the lunch break so they filter out the micro-dust that tends to stick around in the air. The bigger dust particles tend to fall to ground themselves and are not that dangerous to begin.

Another thing is, in a city/town/near road setting, a good air cleaner output can easily have less dust particles than are present in the outside air ...
I remember someone testing a Festool CT 26 with a particle filter meter and what was coming in was dirtier than what was coming out ... it was literally working as an air purifier, despite having sawdust in the bag.

Upgrade to the Oneida Supercell, if that’s in your budget.

I just switched from the Mini Gorilla to the Supercell and my car in the garage is totally dust free.
I have a 3 car garage and use the single 12x20 side as the woodshop.
After planing or using the CMS I used to have big chunks on the floor and fine dust I noticed on the clean car.
Now, I can see that super sucker getting just about every last drop and there’s really nothing to clean up. And I don’t taste walnut wood in the air.  Lol

Anyway, my point is catch the dust at the source and you will be miles ahead of what you can do after it’s floating in the air.
Kinda like seeing my neighbors sanding in their garage with no dust collection. Makes me appreciate how wonderful it is to use the CT.

My cleaner is a furnace squirrel fan fitted with MERV11 filters or so, next by the table saw.

After edge-ripping oak intensely last week with the cleaner on all the time as well as with under-the-table and above-the-table dust extraction working, I found that the intake filter was full of fine dust. The outtake filter looked ok. But my car was also full of fine dust on the windshield and hood. Not some, but lots of it all over the car. Dust on my N95 mask, too.

This shows me that for my 200+ sq ft shop, the air filtration system helps very very little. Don't rely on it unless the dust generation is minimal. I always wear an N95 mask when the table saw is used in a prolonged session.

Thanks Chuck.  Every day is a new situation (what to turn on, what to do differently), but like you said, the first thing I am doing is keeping my dusk mask on much more than I used to.

I purchased a Jet AFS 1000 air cleaner and rather than mounting it on the ceiling, I made a simple cart from aluminum angle and move the machine to whatever area that I'm working in. It comes with a remote control and it's a 3-speed machine so simple to turn on & off as needed.

That way you're addressing the dust issue at the source.

If it were me working with the doors open I would still run my filter near my work area to directly suck the dust up. That is what I do anyhow with a Powermatic PM1250. Super quiet on low to medium. As suggested above running the timer for hours after departing helps.

Filter set similar to this, but I use an X-table as it takes up a small foot print and I already own it. I suppose I could weld up a stand for it, but often it just hangs from brackets mounted to the rafters. 


Another thing I do, especially with welding fumes, is to run one or two box fans pushing air out the garage door. Sometimes one is pushing and one pulling.