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Dust Collector as a Central Vac?

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Forum topic by Phil_W posted 02-14-2008 07:50 AM 4987 views 1 time favorited 14 replies Add to Favorites Watch
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Phil_W

17 posts in 2507 days


02-14-2008 07:50 AM

I’m moving to a new house that’s been piped for a central vac but not fitted with one. My shop will be in the basement and I’d like to plumb in a dust collector. I’m wondering if I can kill two birds with one stone with a 1 1/2 Hp unit. Has anyone done this?

Phil


14 replies so far

View Suz's profile

Suz

51 posts in 2478 days


#1 posted 02-14-2008 01:34 PM

In my opinion it will not work to use a DC for a central vac unit. The dust collector works by moving a large volume of air which “carries” the residue with it and will not work with the small vacuum lines. As a test, just reduce down the 4” line from a DC and feel the difference in “suction”.

-- Jim

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cpt_hammer

133 posts in 2534 days


#2 posted 02-14-2008 04:40 PM

How about the other way around? I have a new house with a central vac installed. It is a big central vac also. It has a port on the side of the vacuum in the garage where my shop is located. I was thinking I could run PVC to the locations where my tools are stored and then hook it up with a toggle switch (to activate the vac when I’m using my tools). Any thoughts?

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8iowa

1489 posts in 2483 days


#3 posted 02-15-2008 01:16 AM

There are probably too many problems in trying to design a joint household/shop dust collection system. A dust collector operates at a lower suction pressure than a home vacuum. However the dust collector moves a greater volume of air, at a minimum of 3500 fpm in the piping, in order to suspend the dust particles in the air stream. This is why dust collectors are much larger and more powerful than the typical home vac.

There is also somewhat of a safety consideration. With collector hoses connected to our tools, we know that the only thing going through the pipe is sawdust. The vacuming in the house however, may introduce small pieces of metal, rocks, perhaps even some flamable substances. Wood dust can explode under certain circumstances, such as a spark generated by a hard object striking the fan or housing.

-- "Heaven is North of the Bridge"

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Partridge

296 posts in 2678 days


#4 posted 02-15-2008 01:52 AM

I like to add, Central vac have small collection container’s and filters will plug faster. so It will be cheaper and lease time consuming to just get a shop vac or a real DC

-- I get out in the shop when I can

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motthunter

2141 posts in 2521 days


#5 posted 02-15-2008 03:09 AM

You need both. You are comparing apples to oranges.. The function of both systems are for different things. The central vac filter will always be plugged with sawdust or the dust collector will not have the CFM needed for cleaning hte house at the farthest point from the collector.

-- making sawdust....

View Phil_W's profile

Phil_W

17 posts in 2507 days


#6 posted 02-15-2008 03:58 AM

You know that’s problem about spec’s. I read the operating specs on both the high end Beam unit and the 1 1/2 hp General Dust Collector and they are not that far apart in terms of CFM and operating vacuum.

Theory is always a great discussion point. However, the real benefit of a group like this is it’s experience. Has anyone actually done it?

Phil

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cpt_hammer

133 posts in 2534 days


#7 posted 02-15-2008 04:31 PM

After reading a few forums on dust collectors and the use of PVC pipe in those systems. I think I stick with my broom and dustpan and just keep my garage door open when I’m working. Potential problems include the following:

Wood dust is flammable AND can generate an electric charge in plastic piping.

Home Vacuums are not designed to stop generation of electrical sparks as they all say “Do NOT use with flammable materials”

PVC Piping can hold a high voltage charge. Ask those who have a PVC dust collection piping and are getting zapped all the time. Even with proper grounding, it is almost impossible to prevent charge build up as PVC piping is an insulator. Insulators are used to build capacitors. i.e. your PVC piping becomes a huge capacitor.

Repeated exposure to wood dust can cause chronic bronchitis, emphysema, “flu like” symptoms, and have more dangerous results decades after exposure such as cancer. Wood dust also frequently contains chemicals and fungi which can become airborne and lodged deeply in the lungs, causing illness and damage.

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KarlS

5 posts in 2475 days


#8 posted 02-15-2008 07:27 PM

Regarding using a central vac as a dust collector. I went into a central vac store and inquired about that exact same thing. The comment was that while they would love to make a sale, they wouldn’t recommend the use to the point that they would refuse the sale. I dont remember all their reasoning, but it made sense at the time (Soory, it was about 1.5 years ago.)

I started with a shop vac and added one of those 5 gallon bucket lids. I had to empty the bucket a lot, and was ready to cut the bootom off one bucket, mount it on a trash can, and go that route when I came across a deal on a full sized collector. The shop vac works, but be ready to empty it a lot.

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Phil_W

17 posts in 2507 days


#9 posted 02-15-2008 07:53 PM

Karl, I’m using a trash can cyclone with a shop vac at my current shop. While it works reasonably well, but I have to clean the filter on my shop vac ( the small 5Hp Ridgid Model) daily to maintain any kind of CFM. The fine dust seems to clog it very effectively. Better it than my lungs I guess.

I know a central vac (ie a Beam) counldn’t do the job because it just doesn’t have the filter area and relies on higher pressure. But I figured that with all wood floors in the house, I don’t need to suck Persian cat hair out of 2” shag carpet. As bachelor, I don’t keep that clean a house anyway.

Phil

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KarlS

5 posts in 2475 days


#10 posted 02-15-2008 09:25 PM

Phil,

One thing I did with my shop vac was to put a pleated filter AND a bag filter on it. I then changed the bag when needed, but found that if I kept the bucket fairly empty, the bag didn’t fill too quickly. I emptied the bucket almost daily. The bag/pleated filter arrangement helped keep the CFM up.

What you will find is that the bucket or trash can will only fill so full and then the suckings just go ito the vac. I have a small shop vac brand that you pick up or slide, and has what they call a 5 hp motor (Let’s not start that discussion) It is blue, which means it was made for the blue giant retailer and came with off-sized hoses. I replaced the hoses so I could more easily get attachments. The good people at Shop Vac’s customer service said it would not be a prblem.

I still use the shop vac to clean the floors and saws and also use it with the compund miter and sanders, but no longer use the separator as the bag doesn’t fill quickly now. Having a big dust collector and the right hookups really helped!

Also, I use one of the plug units that starts the shop vac when the saw or sander starts. I highly recommend them.

Karl

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tpastore

105 posts in 2538 days


#11 posted 02-16-2008 08:17 AM

One other thing to consider is the path of the air through the blower. It may just be the DC I have, but the path of the dust is through the hose, into what I will call the paddle chamber, and pushed out into the bag. Vacuums typically the air goes through the hose, into the bag, the air is pulled through the air and then into the blower/paddle chamber. I figured this out once when I grabbed the end of the hose attached to my DC and started using it to vacuum my floor that had screws, bits of wood chunks, etc in it. As soon as those large pieces hit the paddles WHAM it was like batting practice inside my dust collector. In your house you will be sure to suck up a penny or something hard that may just be shot right through the dust bag. Using a vacuum as a DC does not create projectiles but it does not perform the way you would want. Ask anyone that upgraded from using their shop vac from tool to tool to a dedicated DC. It is all about capturing more dust and not needing to clean filters all the time.

View Phil_W's profile

Phil_W

17 posts in 2507 days


#12 posted 02-16-2008 09:55 AM

Good Point! Had not thought about that. May be I would have to leave my cyclone inline before the DC to eliminate damage to the fan.

Phil

View chuckk's profile

chuckk

1 post in 2110 days


#13 posted 02-14-2009 02:22 PM

I have twice used my cv to collect sawdust, aaaand have both times clogged the system so I am assumming it is the dust that is caussing the clogg. Can some one please confirm this for me.

thanks Chuckk

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Phil_W

17 posts in 2507 days


#14 posted 02-14-2009 09:47 PM

Chuck, I did plumb in my CV for dust collecting in the shop. I put the cyclone inline which cuts down on the efficiency on the CV. It works reasonably well on small tools with good closed capture ie my router table or my palm sander. It doesn’t work with big tools like my table saw or the jointer. I think this is because it lacks the air volume required for these tools. When I use the big stuff for more a quick cut; I open doors, use box fans and sweep up after. Hope that helps

Phil

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