Venting Outside Question

[Andrew Kertesz]

So I'd like to vent my DC outside but it may be an issue. I'm in the basement and the floor joists run front to back of the house. Because of this I would need to run two 45* el's to be able to get up between the joists to vent outside. Or run a long (20') or more straight run to go out the back of the house. Will using these 45*'s decrease my flow to much to be efficient? They would be within 3' - 4' of the impeller, trying to make the exhaust run as short as possible. Any thoughts?

[eugene thomas]

I run mine through insulated 8" Heating duct got at menards. Wanted to run cheap as possible when first did but 2 years later still going strong. My run is 20 feet and it is around corners and all. I don't blow the wood outside though.

[Andrew Kertesz]

My intention is to hook up a Super Dust Deputy or cyclone on the front side and just exhaust the fines outside..

[William C Rogers]

Andy
i don't have a "engineering" answer but feel it would still be more effective than filter/bag based on my experience. I had a 3hp Jet twin bagger I converted with a eBay cyclone. The eBay cyclone had a 6" inlet and a 7" outlet. My Jet outlet (rectangular) area was just slightly more sq. inches bigger than 7" diameter. So I used 7" outlet pipe and have four 45's to get outside. I don't have any data, but Feel there is much better collection than going into a filter/bag. It stays totally constant. I don't have any problem with heat or make up air as it is in a pole barn with gable vents and the heat is radiant. You will need to determine if that would affect you. It was one of the best things I ever did regarding dust collection. The eBay cyclone works extremely well as I don't see any thing outside and I do run a drum sander.

[Dan Friedrichs]

Two 45 elbows won't have a noticeable impact on performance. As William said, it will still be much superior to bags/filters.

That said, since this is on the exhaust (pressurized) side, you have some other options, too. My exhaust is routed through some larger-diameter (10"?) flexible insulated HVAC ductwork. Lets me route it in gentle curves and it helps deaden the noise, just a bit.

[Erik Manchester]

Andrew,

How do you heat your house? If you are venting a DC from inside the house you will need to be cautious about creating a situation where your combustion appliances will not vent properly and carbon monoxide could become a hazard. Will you have a large exterior vent to draw in make up air while running the DC?

[Justin Ludwig]

So I'd like to vent my DC outside but it may be an issue. I'm in the basement and the floor joists run front to back of the house. Because of this I would need to run two 45* el's to be able to get up between the joists to vent outside. Or run a long (20') or more straight run to go out the back of the house. Will using these 45*'s decrease my flow to much to be efficient? They would be within 3' - 4' of the impeller, trying to make the exhaust run as short as possible. Any thoughts?

By venting outside, you gain a lot of SP and velocity by not having bags/filters. My 2hp shopfox can successfully pull my 4" TS and 4" RAS ports simultaneously. It struggled to do the TS when I had it hooked up to the double bag. My RAS is on a 12' run with 2 90*s and a 22*, while my TS is 38' with 2 45*s, 2 90*s, and 5' of flex hose. It sucks just fine. Don't ask me numbers cause I don't care about those - it removes dust and debris, period.

I've recently been playing with a 1hp grizzly DC to set up as a recirculating blower in a paint room. Upgrading the intake from 4" to 6" made a HUGE difference. So now I'm contemplating upgrading my 2hp shopfox main branch to 6" and upgrading the S&D pipe.

My main concern in your situation would be sucking all the hot air out of the house.

[John K Jordan]

Will using these 45*'s decrease my flow to much to be efficient?

I don't think the exhaust side is as critical as the intake side. If your exhaust is filtered you could even pump it through a relatively flat rectangular plywood duct as long as the cross-section area was sufficient. I exhaust through filters into a sealed closet and from there I built a return air duct to the shop. That return has a series of 90 deg angles and turns on purpose to baffle and reduce the sound coming through the duct. (I also sprayed rubberized coating on the inside.) I measured no difference in performance. Many people exhaust through the space between 2x4 studs in a wall.

But my exhaust and return air is well filtered. Is your the exhaust from a cyclone? Is that exhaust filtered? I am absolutely no expert on this but I would be concerned about a long exhaust run full of sawdust. It might be a real mess if a pressure drop, CFM reduction, or sharp bend would cause particulates to drop out of the airstream and clog up the duct.

JKJ

[Zac Lamas]

Hey All,

I wanted to jump on this thread because I have a similar question. I'm a beekeeper and make beekeeping equipment November through February lately in NC, but next year in New England. On most days the dust collector will stay on all day. Me and occasionally a hired hand will make one cut all day. So precut day, squaring day, dado day, fastenning day. Repeat (yawn, riveting, I know) I want to vent outside and prevent breathing in any fine particles, but in the course of the day that'll be a lot of air exchange. I have a crawlspace under the building, and was thinking of putting in moisture barrier and knee walls/insulate with foam and letting the air return under the building into a bay along the center joists. If the majority of the chips hit a closed in plywood catch before entering this bay, do y'all think that would take care of most issues brought up in this thread? I figured I would install a grate at the far return end to allow warm air back into the shop. I heat with a wood stove.

[Jebediah Eckert]

I'm in the same boat. I'm designing it to run the filter for the 3 months the wood stove is on, then vent outside the rest of the year. Oneida said if you have the proper square footage of makeup air it won't draw smoke from the wood stove. They are only giving $100 off not getting the HEPA filter with it so I figured I would be on the safe side. If I tried to vent outside and had smoke issues, to buy the filter then it is about $400 I think.