Thread: Shop vac washable filters worth it?

Bearing in mind that nearly all vacuum cleaners generate more fine dust than they capture, how the filters are cleaned may not matter that much.

Assuming the filter is doing something, even though it's a bastard of a job I reckon it's better to just shake out most filters rather than washing them. While new or washed filters allow the vacuum cleaner to collect more air hence dust, but the filter will also allow even more fine dust to escape. When filters are close to being blocked they are releasing the least amount of dust, but unfortunately they are not collecting as much to begin with.

So their optimum filtration and capture is when they are partially blocked.

Originally Posted by BobL

Bearing in mind that nearly all vacuum cleaners generate more fine dust than they capture, how the filters are cleaned may not matter that much.

Assuming the filter is doing something, even though it's a bastard of a job I reckon it's better to just shake out most filters rather than washing them. While new or washed filters allow the vacuum cleaner to collect more air hence dust, but the filter will also allow even more fine dust to escape. When filters are close to being blocked they are releasing the least amount of dust, but unfortunately they are not collecting as much to begin with.

So their optimum filtration and capture is when they are partially blocked.

John,

After I noticed a build up of very fine dust from my very excellent superfine dust producing machine (the shop vac), Bob advised me to put my shop vac outside, to duct it into my shed with 50 mm PVC pipe, and to ditch the filters (he aslo advised me to check that removing the filters did not result in drawing too much power and overheating the motor - it did not, thankfully).

It worked like a charm. If you are interested, details are here ... https://www.woodworkforums.com/showth...amuel+shop+vac

Cheerio!

John

Originally Posted by John Samuel

After I noticed a build up of very fine dust from my very excellent superfine dust producing machine (the shop vac), Bob advised me to put my shop vac outside, to duct it into my shed with 50 mm PVC pipe, and to ditch the filters.

Yeah, I read that thread. I did think about removing the filters, but didn't like the idea of the dust blowing through the motor, plus the dust blowing into the yard. Also not sure about venting via tubing, since the whole point of the vac is its on wheels so you can move it around.

I get your point that even a fancy vacuum might not stop the fine dust. I wonder if pro mini-units like clearvue or dust deputy also miss the ultra fine dust. Do people use those with filters? I've recently upgraded the design of my cyclone, but it's still homemade.

Originally Posted by John G

Yeah, I read that thread. I did think about removing the filters, but didn't like the idea of the dust blowing through the motor, plus the dust blowing into the yard. Also not sure about venting via tubing, since the whole point of the vac is its on wheels so you can move it around.

You don't have to remove the filters but once you have set the vacuum cleaners (VC) up outside then you can always give it a go and see what it looks like.
If you put the VC outside with the filters removed and put a non air tight enclosure around it, the flow rate from VCs is so low most of the visible residual dust is likely to fall out inside that enclosure and won't spread all ove rthe back yard.

Most VCs use a separate cooling loop for the motor but a heap of dust already goes through through this cooling motor and comes out as more even finer particles than it went. This is yet another reason to vent these things outside.

It depends on the size of your shed and the power of the vacuum cleaner but most vacuum cleaners can easily handle ~5m of hose without any problem and this will cover a wide area.
If you need to cover a wider area, plumb the externally located VC via 50 mm ducting to a couple of key points around the walls or ceiling of the shed and then attach the 5m of hose to these points.
As well as the dust this removes the clutter and the noise from the VC, it's well worth the effort.

I get your point that even a fancy vacuum might not stop the fine dust. I wonder if pro mini-units like clearvue or dust deputy also miss the ultra fine dust. Do people use those with filters? I've recently upgraded the design of my cyclone, but it's still homemade.

They all output some fine dust and some output more than others which is why it's a good idea to vent all DCs outside. The real reason to vent dust extractors outside is due to dust collector bag and filter leaks. Cyclones like the Clearvue have their collection bags on the negative pressure side of the impeller so those leaks are not a problem. The Clearvue is very efficient so they output only a small amount of invisible dust so they can be vented externally without any filters. If they are vented internally then filters are available that are very effective. These filters cannot be used on regular DCs because the filters would be exposed to too great a dust load and would clog up very quickly.

John,

Its a matter of personal priorities. My priority was eliminating as much fine dust from the shop as possible. That meant getting the vac outside.

Originally Posted by BobL

You don't have to remove the filters but once you have set the vacuum cleaners (VC) up outside then you can always give it a go and see what it looks like.
If you put the VC outside with the filters removed and put a non air tight enclosure around it, the flow rate from VCs is so low most of the visible residual dust is likely to fall out inside that enclosure and won't spread all ove rthe back yard.

Most VCs use a separate cooling loop for the motor but a heap of dust already goes through through this cooling motor and comes out as more even finer particles than it went. This is yet another reason to vent these things outside.

It depends on the size of your shed and the power of the vacuum cleaner but most vacuum cleaners can easily handle ~5m of hose without any problem and this will cover a wide area.

This was my experience. My vac is a 2 HP machine, and it came with 9 M of hose. Putting it outside under a hood and ducting it inside was a piece of cake because it was already a wall mounted unit and was not moved around the shop. I bought a wall mounted unit so that the vac did not occupy floor space or cupboard space.

As Bob indicated, even with the filters out, it does not spread dust far and wide. Nearly all the dust falls on the ground under the hood. Every month or two I hose this area and that dust disappears.

Originally Posted by BobL

As well as the dust this removes the clutter and the noise from the VC, it's well worth the effort.

Amen! The vac was noisier than the cyclone when it was inside. Now I can barely hear it. This itself can be a small problem. Once I left it running for about 20 minutes because I did not realise it was on ... but it is a nice problem to have.

But we have strayed from the original question ... about washing filters. My experience is that a washable filter makes 5/8 of 4/5 of bugger all difference because in a woodwork shop we generate a lot of fine dust, especially when we use the vac to pick up dust from hand machines such as orbital/belt sanders and biscuit cutters. In my shop, very soon after washing a filter it is full of very fine dust and/or over-spray again, so I have achieved zip by washing it. But that is in my shop. Yours may be different.

Every shop is different, and we have differing priorities. What works for you, works for you. QED.

Cheerio!

John

Originally Posted by John Samuel

My experience is that a washable filter makes 5/8 of 4/5 of bugger all difference... In my shop, very soon after washing a filter it is full of very fine dust and/or over-spray again, so I have achieved zip by washing it. But that is in my shop. Yours may be different.

Ok, I've gone off the idea of washable filters. I can see myself needing to wash and swap them too often. I re-read your thread and am warming to the ducted idea. My VC is a blower shop vac, so I can duct the exhaust as well as the inlet. Need to check if it can run without filters though.

Will also take a bit of planning - my shed is on the property boundary, so there is no convenient "outside" to place it. So it will need to stay in the shed, either under a dust shroud, or I make a hole in the wall and vent the exhaust into the rear lane. Also need to work out where best to place it so it out of they way, but the ducting is not too long.

Originally Posted by John G

Ok, I've gone off the idea of washable filters. I can see myself needing to wash and swap them too often. I re-read your thread and am warming to the ducted idea. My VC is a blower shop vac, so I can duct the exhaust as well as the inlet. Need to check if it can run without filters though.

Just about every blower Vac uses a separate motor cooling loop.

Will also take a bit of planning - my shed is on the property boundary, so there is no convenient "outside" to place it. So it will need to stay in the shed, either under a dust shroud, or I make a hole in the wall and vent the exhaust into the rear lane. Also need to work out where best to place it so it out of they way, but the ducting is not too long.

Unfortunately it's not that simple.

If you put the VC inside a box in the shed (see LHS side of pic below) and just run the VC dust exhaust outside that will mean the motor cooling loop will keep reusing the same air inside the box and overheat the air inside the box and it may damage the motor.
It does not even have to be air tight to overheat.
The best solution is outside with the motor cooling loop having plenty of access to cooling air as shown on the RHS


A possibility would be to keep the sealed box inside the shed and don't vent the VC outlet to outside but into the box and then the contents of the box outside via a vent in the wall - see LHS of pic below.
This will continually remove some warm air generated by the motor.
This would at least keep the motor cooler than LHS above but totally contaminate the motor cooling loop as well as over pressuring the box with dusty air and if the box leaked it would let dust back inside the shed.
It could also damage the motor

If you absolutely have to have the VC inside the shed a workable solution is a well sealed box with a fan in the side of the box (a 12V computer fan would be OK) that pulls cool air into the box from the shed and then pushes the air from the box outside the shed a separate outlet. Since shed air is dirty even better would be to outdraw the motor cooling air from outside the shed. If I had a brand new VC that is what I would do. For an old VC is already probably contaminated beyond redemption.

Originally Posted by John G

Also need to work out where best to place it so it out of they way, but the ducting is not too long.

I found that the length of the ducting was the least of my problems. It seems that the losses in suction incurred by the ducting were offset by removing the filters. I can't detect any difference with about 6 m of 50 mm PVC duct, which surprised me, and it certainly does a good job.

Just read BobL's post and was reminded why I am at this forum. The brains trust here is outstanding.

Wow, I never considered the motor cooling fan chopping up stuff into finer particles! I replaced my ryobi shop vac with a shopvac shopvac recently as my plan was to attach a second hose to the blower outlet to vent all the waste outside. As my ryobi wasnt a blower capable model there was no easy way to ducts its outlet (and the enclosure I made for it was a bit pain to roll around!). Looks like building an inside enclosure and running a more central piece of ducting would have been a better option!

If you want or have to keep the VC inside the shed and already have a DC that vents outside, then the following are a couple of options.

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The disadvantage of both methods is that that you have to run the DC at the same time as the VC, so more power is used.

"A" requires a blower vac so the blower hose can be placed inside a duct to the DC. Don't seal up the DC duct around the VC hose but place it near the motor cooling loop outlet. It works surprisingly well because the volume of air removed by a DC is mach larger that what passes through the VC motor cooling loop. Of course this method does not remove the noise from the shed. The reason that this method cannot be used easily on a non blower vac is because the filtered air outlets are often spread around the VC and this makes it difficult for the the DC air bubble being captured to grab the fine dust coming out of the VC. On the odd occasion I uses a VC this is what I do.

If you want to reduce the VC noise and/or have a non blower VC then method B is one way to go. The volume of air drawn by the DC is so great that relatively little fine dust coming out of the VC will pass through the motor cooing loop.

So why would you bother running a VC if you have a vented CD - the mean reason would be to hook up VCs to power tools.

Originally Posted by BobL

If you put the VC inside a box in the shed (see LHS side of pic below) and just run the VC dust exhaust outside that will mean the motor cooling loop will keep reusing the same air inside the box and overheat the air inside the box and it may damage the motor.
The best solution is outside with the motor cooling loop having plenty of access to cooling air as shown on the RHS

Thanks for all the pictures (hope you didn't draw them just for me!) but I don't think I explained myself. I never intended to seal the VC in a box. I assume you are doing that purely for the noise. IF I vent the blower directly outside, then I wouldn't have anything around the VC. In that case it would look like your RHS except with the inside and outside reversed. Or are you doing that so the cooling loop doesn't generate more dust?

If I don't fancy boring a 50mm hole through my brick wall, then the VC will need to vent inside. In that case, I meant to vent into a dead air space under some sort of dc shroud, kind of like how other John did with his wall mounted vac. I have a mini cyclone before the VC, so it is only ultra fine dust I am venting. I would rather it settle in one spot rather than all around the shed. Not sure if this is even possible, but I thought I read it in one of your responses.

Originally Posted by John G

Thanks for all the pictures (hope you didn't draw them just for me!)

The pics I draw I often also use in talks/presentations I give on dust.

[QUOTE]but I don't think I explained myself. I never intended to seal the VC in a box. I assume you are doing that purely for the noise.[QUOTE]
Nope it's to control where the dust goes - noise is a secondary consideration

[QUOTE] IF I vent the blower directly outside, then I wouldn't have anything around the VC. In that case it would look like your RHS except with the inside and outside reversed. Or are you doing that so the cooling loop doesn't generate more dust?[QUOTE] Yhe issue of the cooling loop generating more fine dust doesn't matter if you vent outside.

If I don't fancy boring a 50mm hole through my brick wall, then the VC will need to vent inside.. In that case, I meant to vent into a dead air space under some sort of dc shroud, kind of like how other John did with his wall mounted vac. I have a mini cyclone before the VC, so it is only ultra fine dust I am venting. I would rather it settle in one spot rather than all around the shed. Not sure if this is even possible, but I thought I read it in one of your responses.

Unfortunately it won't work. The very fine (most unhealthy) dust won't settle in one place (even under shroud) but will waft all over the shed. The dust that settles out around John's VC is some of the visible dust that is coming through his system as he doesn't have filters. His finest dust is invisible and he can't see where it's going.

Unfortunately there's no way to vent inside the shed and not prevent the shed filling up with fine dust every time you use the VC.

So I've been contemplating this motor cooling air issue and was thinking what about teeing off the main suction line (I have a small cyclone connected to the vac with 50mm pvc so would do that in there) and putting a couple of small hoses to the cooling outlets, so the vacuum effectively sucks in its own motor cooling air once it has gone through. Totally silly idea? Enclosing the vac in a box or putting it outside is a little tricky with my current shed but ducting the blower outlet outside is a piece of cake.

Originally Posted by wobbz

So I've been contemplating this motor cooling air issue and was thinking what about teeing off the main suction line (I have a small cyclone connected to the vac with 50mm pvc so would do that in there) and putting a couple of small hoses to the cooling outlets, so the vacuum effectively sucks in its own motor cooling air once it has gone through. Totally silly idea? Enclosing the vac in a box or putting it outside is a little tricky with my current shed but ducting the blower outlet outside is a piece of cake.

I assume you mean like this?



If so this will work, but there will be reduced suction at the end of the uptake hose?
Not much air flow from the box into the VC would be needed to keep the motor cool so maybe a some sort of gate valve could be used on the intake to the box so that most of the sic could be diverted to the intake hose.
I would test this with an air flow meter or you could just use a thermometer that reads the air temp inside the box.

definitely worth a try