Venting a DC to the outdoors

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Forum topic by Bob posted 04-04-2012 07:42 PM 1155 views 0 times favorited 8 replies Add to Favorites Watch
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19 posts in 2537 days

04-04-2012 07:42 PM

Topic tags/keywords: dc dust collection

If you have an efficient dust separator that is capturing all but the finest dust, why not vent the remaining finest dust out the window instead of to a filter? I would think it would be carried off by the breeze. No worries about capturing fractional microns of dust, expensive filters, and the adverse impact they have on CFM. Bill Pentz talks about how hobbyists get more exposure than industrial workers because the later’s DC is outside of the building. It seems that the only thing you really need outside the building are the small nasty dust particles that you don’t want in your lungs. I must be overlooking something, this seems too easy.

8 replies so far

View Lifesaver2000's profile


556 posts in 3382 days

#1 posted 04-04-2012 07:56 PM

The main reason this is not done is because it pushes heated or cooled air from inside the shop to the outside, meaning that you then have cold or hot air coming in to your shop. Of course, if you only use “natural” air conditioning (also known as open doors and windows) in your shop like I do, then it wouldn’t be a problem.

Also, if you have any gas operated appliances in the same air space, there can be problems with actually pulling combustion gasses into the room as make up air.

View bondogaposis's profile


5218 posts in 2621 days

#2 posted 04-04-2012 08:04 PM

Yeah, Lifesaver’s got it right. If you heat your shop you will be sucking the heated air outside. At today’s fuel prices not many can afford that. But if you live in a climate where you don’t need to heat or cool then there is no reason not to.

-- Bondo Gaposis

View Fred Hargis's profile

Fred Hargis

5308 posts in 2764 days

#3 posted 04-04-2012 08:05 PM

Like they said…it’s a great way to do it, if you don’t have conditioned air to worry about (and pilot lights and such) I keep trying to figure a way to vent outdoors in the summer, and then convert it back to the filter in the winter (easily, that is)

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

View Bob's profile


19 posts in 2537 days

#4 posted 04-04-2012 08:10 PM

My shop is in my garage so the only heating and cooling is “natural”. And my house is 100% electric so no issue with gas. All I need is a 6” dryer vent attached to some plywood at the bottom of the window opening. Am I correct in thinking that without the resistance of a filter, that my CFM is going to improve significantly?

View BlankMan's profile


1490 posts in 3623 days

#5 posted 04-04-2012 08:11 PM

Yeah I agree it the makeup air issue. I thought of it too but here in our Wisconsin winters heating the makeup air could be costly. I thought of using a heat exchanger to capture the heat of the outgoing air but don’t know if they could do anything because of the high air volume. Well at least one of reasonable size. Although I heat my basement workshop with a efficient wood stove I don’t know how it would fair with 5°F or lower makeup air.

-- -Curt, Milwaukee, WI

View Lifesaver2000's profile


556 posts in 3382 days

#6 posted 04-04-2012 09:05 PM

Bob, I don’t see any reason it wouldn’t work for you if you don’t have to worry about heating or cooling. I actually plan to do this myself at some point. I can’t point to any figures to support it, but I would expect that not having to overcome the resistance of a filter should improve the air flow of your DC, and it would also result in a more consistent flow since a filter’s resistance will increase as it gets dirtier.

About the only other thing I can think of would be to make sure you don’t have any ignition sources near where the vent exits the building, and to keep a close eye on that area to make sure you don’t get any sawdust build up. You might (like me) forget to check your separator at times and wind up with more than just the fine dust going though the DC.

You don’t mention what separator you plan to use, but I use a Thien separator with a top-hat design, and get next to nothing in the large shop vac I am currently using for dust collection duty.

View longgone's profile


5688 posts in 3579 days

#7 posted 04-04-2012 09:16 PM

I have been thinking of how I could have it both ways by installing a large “Y” connector on the exhaust end with one leg going to the filter and the other vented straight outside. By using a balst gate on both legs it would be possible to have it directed outside during good weather days and directing it just inside on days when I do not want the inside shop heating/cooling lost. My exhaust end of the cyclone is 8” diameter and would just be a matter of finding a 8” Y connector and 8” blast gates.

View Bob's profile


19 posts in 2537 days

#8 posted 04-04-2012 11:35 PM

Lifesaver, I was planning on building a Thien separator. I will check out the top-hat design. Found a youtube video here. I also plan to buy or build a dust level sensor/alarm to avoid shooting chips out the window.

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