big shop vac for central vac

I looked at that a few years back. For a central vac you want fairly good suction (100-130 inches of water), decent air flow, and reliability. Shop vacs are ok on the first 2, just don't have it for long term built in use.

I also looked at using the cheaper schedule 40 PVC or ABS pipe instead of the expensive vac fittings. Found that nothing matches up in terms of fittings size. Also, the suppied fittings have a tighter radius that is usefull for the wall outlets.

But d> Anyone ever use a big shop vac as a central vac. How does the suction of a

About 35 years ago I had a large central vacuum system (made by BVC) installed in the Rank Xerox UK photocopier refurbishment facility when I worked there. Installation was expensive - both the cost of the central unit and the piping. It was ultra-reliable and liked by the workers, apart from when someone broke a stink bomb at one of the inlets and the people near the central suction unit got rather cross about it. 8-)

I can't see an ordinary shop vac doing the same job.

Leon

Don't the shop vacs usually say, "not for household dirt" or something like that? I think their filters are set up for sawdust and such. I know mine tends to spout a cloud of dust when I turn it on. I think the filter would clog up pretty fast or just past dust through. That sounds like the kind of problem you wouldn't want in a whole house cleaner.

Regards, LB

Having personally installed a commercial central vacuum system, I'd have to suggest that at best, a shop vac is a joke. The best one I've seen doesn't come close to the level of performance the purpose built units have. I was going to do exactly as you suggest, but checking into the commercial units changed my mind, in spite of the fact it was expensive. A poorly performing unit would serve no real purpose. That made making the right decision easy.

You can avoid using a built in with a filter by selecting the right manufacturer. Some are equipped with a cyclonic separator and discharge outside. I highly recommend going that direction. Filters limit the ability of the best units and are but one more thing to maintain. By discharging outside instead of inside, you remove troublesome dust instead of placing it back in circulation, along with the smell of dead tissue, which you find in all habitats.

Harold

I've found that doing the reverse of this is quite nice.

I've scrounged a couple of true "whole house vac" units and use them to clean chips off machines in my shop here at work, and also at home.

(the one at work was in the warehouse here, free for the taking, and the one at home was snagged during one of the local trash pickup days. It didn't work because it was clogged with dust and hair)

Those things develop a huge pressure differential and will suck the chrome off the proverbial trailer hitch. The only thing I haven't done yet is to discharge the one at home to outside, and find some spot on the wall to hang it.

Jim

I did use the proper piping and fittings with an adapter on the

BTDT ~ about a dozen years ago when Sears made some fairly decent Vacs. I use a big 15 Gallon Vac and I plumbed the whole shop making an outlet at each device, I.E., table saw, planer, vise, radial saw, grinder, 9x20 lathe, mill/drill, etc. I used 2" class 125 PVC water pipe with short sweep elbows and DWV plumbing sanitary tees for the connections. A 2" is cap slipped over the ends of the pipes for terminal points. The hoses use ONE 2" coupling turned to accept the Vac hose, and The whole shebang is plumbed into an enclosed cabinet to keep it quiet. There isn't much chrome left in my shop either.... the shop vac has PLENTY of suction.

Bill P. PhxAz.

Yes.

Some may complain about the relative reliability of a shop vac vs. a high-end central unit -- fooey! At $800+ for a good central, and less than $99 on sale for a _good_ shop vac, you can wear out one every year and a half, and still be ahead.

I built our system around a Sears $99 heavy-duty vac. The vacuum 'head' lasted six years of thrice-daily in-house use, plus double-duty in my shop, because I plumbed my workshop with overhead gates and floor scuppers.

The problem of standard PVC pipe not mating up to, say, ManorVac fittings is trivial. Hey, guys... this is a metalworking forum. Just use one of your eighteen lathes to bore standard PVC couplings out the few thou necessary to match up with the commercial wall plates.

All this, I did. I built up a low-voltage relay system from an old filament transformer and a 12vac relay.

The rest was six years of trouble-free, wonderful performance for a _total_ expense of about $300 for both the house and workshop.

(don't forget to use long sweeps for turns, rather than ells, or those socks and cats WILL get caught at the corners )

LLoyd

Discharging outside seems the best for removing dirt. However I wonder how much heated air it removes from the house? Is it significant?

Similar question. I have a baldor 10 inch grinder with dust collecter which discharges into a big cloth bag. I considered discharging outside but at 500cfm, but I figure I would be loosing LOTS of heated air.

I would also like to plumb this dust collector to remove the dirt from my small rockwell toolmakers grinder. The tool makers grinder might run for 30-60 minutes for big jobs. Blowing 500cfm outside for an hour seems like a lot of heated air. I figure a multistage dust filter makes more sense.

chuck

Hm, discharging metalworking related dust outside... That's bound to create rust spots on everything where that dust settles...

i

Yep, losing heated air is the down side. Not a problem during warm seasons. Lots of problems with filters if you use your system in the shop, though, one of which is starting fires when grinding. It's not very difficult to ignite the contents of a vacuum if you pick up sparks, makes no difference if you filter, or not.

Harold

You must match the tools to the job. If your floor brush is gluing down, you have the wrong brush. Vacuum cleaners work ONLY when there's air movement, so a good brush will provide a large volume of air movement without attaching to the floor. If you achieve the same results by slowing down the process of air movement, you also slow down the process of cleaning, lowering the quality of the job. Think of it this way. Your brush will move over the floor effortlessly if you don't turn on the system. That's the direction you're headed when you run with a plugged filter. What's the point? I use my system to get clean, not push things around. Go to a commercial janitorial supply house and check out good floor brushes. You'll be amazed that they actually work.. even without plugged filters.

One other thing. If you think your vacuum emulates a large industrial built in unit, you're sadly mistaken. I've seen some of the largest of shop vacs and they don't come close to the level of performance----not even close.

Harold

On carpet you can lift the carpet off the

You could calculate this pretty easily by Googling for some numbers. Based on a quick search (and no time spent on reality checks or detailed analysis) it looks like you'd be losing about 13k Btu/hr. That's assuming

500 SCFM at 0.075 lb/SCF and 6 Btu/lb air. At 6$/MM Btu, it will cost you about 8 cents per hour.

Maybe someone that does this for a living can double check those results.