# overhead or keep them low?



## dat (Nov 11, 2010)

I'm thinking about expanding my shop vac and barrel/ dust lid to a regular dust collector, as far as the ducts, does it really matter I have room to run the by the wall, but overhead could be less cumbersom when moving around the machines. is it a matter of prefrerence how they are run or does it really make a difference anywhere?


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## joesbucketorust (Dec 13, 2011)

If you mean does one provide more suction than the other, then no it doesn't matter. I put mine up top of the wall because space is at a premium and I wanted to be able to push some of the tools against the wall and not trip over hose. There are a few pics in this forum of hoses snaked across the floor, so I guess either one works.


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## RetiredLE (Jan 20, 2011)

Overhead installations will add length (what goes up must come back down) and reduce velocity - but if your dust collector is up to the task then all is good.


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## joesbucketorust (Dec 13, 2011)

RetiredLE said:


> Overhead installations will add length (what goes up must come back down) and reduce velocity - but if your dust collector is up to the task then all is good.


Overhead does take more pipe or hose, yes. 
I've read that bit about velocity elsewhere, and not to argue, but it doesn't make sense to me, (Granted I went to school back with the "old" math, we hadn't invented zero yet.) In a closed system, same size pipe from end to end, airspeed is constant. The time it takes the dust to get from the machine into the bag is longer just because it has more feet to go, but I should be able to hook up 1/2 mile of 4" hose and run it from my collector to a tool in my neighbor's garage, turn it on and steal his sawdust. If air at the intaker impeller is moving by at a set speed, then at any point in the system the air is moving at that speed. It's not like electricity, there's no voltage drop due to resistance. I just have to wait an extra second or so after I turn off the tool before I turn off the collector. I do understand that if I change from 4" to 5" or 3" in the middle of a run that there will be changes, but that's a different math problem entirely.


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## rrbrown (Feb 15, 2009)

joesbucketorust said:


> Overhead does take more pipe or hose, yes.
> I've read that bit about velocity elsewhere, and not to argue, but it doesn't make sense to me, (Granted I went to school back with the "old" math, we hadn't invented zero yet.) In a closed system, same size pipe from end to end, airspeed is constant. The time it takes the dust to get from the machine into the bag is longer just because it has more feet to go, but I should be able to hook up 1/2 mile of 4" hose and run it from my collector to a tool in my neighbor's garage, turn it on and steal his sawdust. If air at the intaker impeller is moving by at a set speed, then at any point in the system the air is moving at that speed. It's not like electricity, there's no voltage drop due to resistance. I just have to wait an extra second or so after I turn off the tool before I turn off the collector. I do understand that if I change from 4" to 5" or 3" in the middle of a run that there will be changes, but that's a different math problem entirely.



I don't think it will slow down because you have the pipe high or low. It will slow down on longer lengths over shorter ones.


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## GeorgeC (Jul 30, 2008)

Ideally you will keep the runs as short as possible. Yes, more length does reduce capacity. 

That said, it is frequently more important to run the duct work out of the way than to be concerned about the reduced air flow.

George


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