D.C. Venting

[Kenneth Reidy]

Hi Everyone,

Question: I will be moving to a new shop that I am presently designing. I have a Oneida 5hp Gorilla DC and the new room does not have access to an outside wall for venting. The only way I can think of venting the room, 6'x6', is through the roof. Oneida could not supply me with any guidelines for sizing the vent. Any thoughts?

Many thanks,
Ken
Corrales, NM

[Jim Becker]

Hi Everyone,

Question: I will be moving to a new shop that I am presently designing. I have a Oneida 5hp Gorilla DC and the new room does not have access to an outside wall for venting. The only way I can think of venting the room, 6'x6', is through the roof. Oneida could not supply me with any guidelines for sizing the vent. Any thoughts?

Many thanks,
Ken
Corrales, NM

Generally speaking, if you are direct venting, if you employ duct that is just a little larger than the outlet of your blower you should be fine as long as there are not a lot of bends and a really long distance. Air doesn't weigh anything, so it's all about not having any backpressure...free flow, in other words. So if the outlet is 8", a 9" or 10" direct vent should likely work just fine.

Just remember, if you overfill the bin or get a leak in the same, you're going to be pushing noticeable debris out that vent. A roof top situation is going to make that "very" visible in some cases!

[Andy D Jones]

Like Jim, I'd be concerned about sawdust collecting visibly on the roof, but over time, even if the bin never overflows. Especially from when the roof is wet.

Is the roof easily accessible to clean up once in a while?

-- Andy - Arlington TX

[james manutes]

Why vent outside in this situation , if the roof is your best option ? Plus , lose all that AC in New Mexico ! What is the filter situation on the DC , Oneida should have matched one w/ the unit .

[glenn bradley]

I love Jim's use of bold (Generally speaking) in his response. He just knows some smarty-pants will post something like this:

"At 0 °C and normal sea level pressure a mole of gas occupies 22.4 liters, so a cubic meter of air has a mass of: 1000/22.4 × 0.02896 = 1.293 kg."

:D:D:D

[Jim Becker]

That was massively interesting, Glenn... :) :D

BTW, I tend to avoid math for some reason. ;)

[Matt Day]

I’d buy filters if I were you. Pumping conditioned air that you paid for outside doesn’t seem like a good idea.

[Darcy Warner]

Venting outside has never crossed my mind.
My new system will sit outside and then be vented back inside to 4 bag houses.

[Eric Arnsdorff]

Are you thinking of venting directly through the roof or dropping a vent through the eaves?
I would be concerned with the aesthetics of the dust collecting on the roof. Granted a good rain would likely take care of that but it could build up over time and be a pain to clean.
Through the eave seems easier to keep clean.
I would consider using a large post filter and vent back into the shop.
I've set mine up so I can direct vent out a window when the weather is nice and switch over to a large post filter when the weather gets hot or cold. The good thing about living in Knoxville, TN is we do get a lot of good weather so venting outside brings in a nice flow of air during nice weather. Either way though I still have the need for the post filter which may be the better option in your case all around.
BTW - I did utilize a Thien baffle design on a metal trash can that works well so it becomes a 2 stage dust collector with the post filter from a Grizzly DC.