Connecting 2 DC systems

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Forum topic by CecilD posted 11-04-2013 04:33 PM 906 views 0 times favorited 8 replies Add to Favorites Watch
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53 posts in 3424 days

11-04-2013 04:33 PM

Has anyone connected 2 DC unit to the same system? I have 2, 1 1/2 hp units now but only one is connected to my DC system. It works OK but when the edge and/or drum sanders are on I need more flow. I was thinking that if I hooked the other unit to my system then when I needed additional flow I could turn on the additional unit. I have around 80 ft of 4 inch pipe rounding in the shop. Not up on airflow or vacuum for shop air.

8 replies so far

View a1Jim's profile


117091 posts in 3574 days

#1 posted 11-04-2013 04:47 PM

There have been other post about this idea and what I remember the the pros that install DC units for a living saying is that both units have to start exactly the same time which can be hard to do.

-- wood crafting & woodworking classes

View bigblockyeti's profile


5112 posts in 1718 days

#2 posted 11-04-2013 04:56 PM

Shouldn’t be too hard, to remove the need to start both at the same time, you would need a check valve of some sort to keep the first one started from sucking the dust backwards out of the one that’s not yet running. If you only need it occasionally another option would be to turn on the second before connecting it to one of the drops from a tool not being used at the time. 4” is on the small size for getting good flow and you’d need a dust collector(s) that would pull a good bit of suction to keep the air velocity high enough to keep the dust in suspension to avoid quickly clogging the line.

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Fred Hargis

4985 posts in 2490 days

#3 posted 11-04-2013 05:40 PM

Stumpy did that, check his video for tips. The biggest caution (that I remember) is that the one feeding the other may overload it burning the motor out (maybe it was the first one you have to worry about). So watching the amps on each motor becomes important. In his case he was using HF blowers and didn’t have a problem.

-- Our village hasn't lost it's idiot, he was elected to congress.

View crank49's profile


4030 posts in 2968 days

#4 posted 11-04-2013 06:25 PM

One basic potential flaw in the concept of connecting two systems is the ductwork design.
A duct properly sized for one collector will be totally wrong for two collectors.
A duct properly sized for two collectors will be wrong for one collector.
A duct sized half way in between will be half bad for both or either.

And I might add I been designing this stuff for 40 years and I’ve never seen this work properly, other than maybe two collectors connected to different parts of the same machine; each with their own duct system.

Or, one collector with two or more fans where all the fans have to be identical and all have to be run together.

View CecilD's profile


53 posts in 3424 days

#5 posted 11-05-2013 02:41 AM

Thank every one, I think that I will increase the main duct to 6” and bypass the filter by going thru the wall to vent the fine dust. I have a inline container to catch the large material. The main problem I think I might have is the intake side of my fan is 4”. If I run 6” to the intake and then reduce it will that be a problem?

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18269 posts in 3673 days

#6 posted 11-05-2013 06:31 AM

Why not just cut it in half and have 2 systems? Neither will have to suck that far.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View crank49's profile


4030 posts in 2968 days

#7 posted 11-05-2013 05:09 PM

You have a container for large stuff?
Why not double the inlets and outlets.
Block off the pair you are not using when you shut down one collector.

View CecilD's profile


53 posts in 3424 days

#8 posted 11-05-2013 06:31 PM

Starting to refit. the system with 6 inch. Going thru wall with exhaust . If that does not work will do as Topmax suggested and divide it into 2 systems.

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