# DC ducts vs. shop obstructions



## buzzhazzard (Mar 10, 2013)

Hi

I'm brand new to the forum, but I thought I'd join and get some insight. I'm just finishing my shop. electric, plumbing, etc is all done and limited drywall next week. I am having difficulty with the dust collection design. My DC will be in an insulated closet under the stairs (for noise). I'll have a vent above the door for airflow. 

Right in the middle of the shop, I have two steel beams running parallel to the joists above and all the HVAC duct work is between those beams. Every space between the joists has something in it--plumbing, HVAC, cold air returns. I thought I might have enough room, but when I tried to run a piece of 4" PVC pipe, it was just too tight. I am going to have to explore other options.



I can reduce to 3". This branch will lead to my table saw which has a 2-1/2" port anyway, so I could reduce to 2-1/2" right above the saw. If I do this, is there any advantage to transitioning back to 4" once I have cleared the obstructions and before I get to the area of the saw?
I can use 4" DC hose as it will probably fit
I could use another route for 4" PVC, but it will be a longer route and contain more 45s and/or 90s
That's the general issue. I'd love any suggestions. The duct work I have to run probably spans about 12' or so.


Thanks


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## Fastback (Sep 2, 2012)

You don't say what size DC you have (how many CFM's) Most of the DC literature that comes with the machine will tell you what size ducts you can get away with. I would try to stay away from 90's as much as possible. Ask me how I know. You may also want figure in some clean outs. Like a tee-y with a cap so if necessary you can easily access. Don't forget grounding. I ran mine inside, but that tends to catch on large chips. When you do your layout it is suggested that you place the machines with the most chips (like a planer) closest to the DC. I used 4-inch light weight drain pipe for my system. It is much cheaper than standard 4 inch pvc sewer pipe. I did not glue my joints so removal was possible with out cutting. My DC is a JDS 1,200 cfm with low decibels. 

Oh, I made my own blast gates and wired them 24 volts and micro switches so the DC would start as soon as the valve was opened. 

Hope this helps.


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## woodnthings (Jan 24, 2009)

*4" is the "minimum" size...*

... larger is better. Do not drop to 3", but find a way to run the 4".
I've run some right on the floor under my saws and then use a short length of flex hose to the separator and then the DC which is on caster in my shop. 
A central tool island is often done to minimize long runs of DC pipe. Sometimes the DC is built into the center island as well.
Can't find the You Tube of that one, but here's one:


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## buzzhazzard (Mar 10, 2013)

Thanks Fastback and Woodnthings. My DC is a Grizzly G1029 2HP unit rated at 1182 CFM. There is a 5" inlet which has a y-fitting to two 4" ports. I like the idea in the video where the motor is mounted to a wall. I may do that in my DC closet, which for my setup will allow me to minimize some connections in the closet. I think I figured out a solution to my original problem. I have one almost empty joist bay, but I do have an HVAC branch and a drain pipe at one end (as previously discussed). I tried to get the 4: S&D pipe through there. It's close but just too tight. But a few minutes ago, I tried a 4" DC hose (which has a smaller diameter of course) and it just fits. So I am thinking of using just enough hose, maybe 2-3 feet to get through the congestion and connect each end to the S&D pipe. I would keep the ground continuous by jumping the short section of hose.

Does that sound like a reasonable plan? I should be able to stay at 4" throughout the shop until very close to each machine.


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## woodnthings (Jan 24, 2009)

*Don't use flex hose*

If possible just squish the metal or heat the plastic PVC to get it it there and keep a smooth wall pipe through out. Flex hose is not your friend except at the very extremes to connect up tools. 

http://www.thewoodnerd.com/articles/dustExplosion.html

Grounding is not really necessary, in a home shop system. Mostly a wives tale about dust explosions. We have researched here extensively and while it can't hurt, except for clogs... it's not necessary. I used to get static shock just by brushing against my DC until I conned the motor to the dust inlet with a copper wire. The amount of airborne dust necessary for an explosion is way higher than a in home shop environment and other conditions have to be just right as well.


*Static in Dust Collectors*
*What to do and not do in building a dust collector system. *


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## buzzhazzard (Mar 10, 2013)

woodnthings said:


> If possible just squish the metal or heat the plastic PVC to get it it there and keep a smooth wall pipe through out. Flex hose is not your friend except at the very extremes to connect up tools.
> 
> http://www.thewoodnerd.com/articles/dustExplosion.html
> 
> ...


Thanks for the links. So what should I use to heat the Schedule 20 with? A slight oval distortion may do the trick for me.


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## woodnthings (Jan 24, 2009)

*heat guns, hot plate, electric stove...*



buzzhazzard said:


> Thanks for the links. So what should I use to heat the Schedule 20 with? A slight oval distortion may do the trick for me.


No flame heat source, otherwise you will distort the pipe. there are methods on You Tube and other sources; http://www.ehow.com/facts_7646833_can-abs-pipe-heated-bend.html

http://www.instructables.com/id/Bending-PVC-pipe-Just-because-you-can/


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