How many cfm to cool 8 lights? - Growroom Lighting - International Cannagraphic Magazine Forums

goalie · 07-18-2006, 08:23 PM

Hello,

I have 8 Bell Lighting shades with air in/out vents. Was wondering what kind of fan i would need for intake and out.

What I would like to do is one fan blowing the air and the other fan pulling the air out. Any suggestions welcome. If someones got a pic of this setup i'd love to see it.

thanks!

MTF-Sandman · 07-18-2006, 09:36 PM

The rule of thumb is 200cfm per 1K. You'll need to build a plenum that's connected to your exhaust fan(s) to prevent excessive pressure buildup on any one chunk of ducting.

What size are the ducts on the hoods?

gsxxer · 07-19-2006, 12:09 AM

^^ whats a plenum?
why would you need a intake and outake fan? if your just using it to cool lights that are attached together you should only need 1 fan.

or if your using the fan to ventilate fresh air and cool the lights you just need a passive intake...

maybe you can have an 8" inline fan just attached for the vented hoods and pull cold air from an inside a/c so the cool air passes through the lights...

then have another 8" inside the box thats attached to a carbon scrubber thats the exhaust and use a passive intake...

but it all depends on what temps you have in the first place without the lights, im not sure that would be enough

what watt lights are you talikng about anyway? is it an enlosed grow box with co2?

goalie · 07-19-2006, 02:55 AM

eight 1000 watters. The ducting size is 4" on the shades i was thinking of using an 8" main duct that has Y for each light going down to the shade

MTF-Sandman · 07-19-2006, 05:40 AM

A plenum is basically a distribution or collection point...for outgoing or returning air. Here's a couple of pics to better show them...

There's going to be a fairly high amount of static pressure with 4" ducting, so you'll want to use 2 lights at most per run of ducting.

A 10" inline connected on the plenum with 4 runs of 4" ducting coming off of it should do the trick though. If you're using a sealed room, I wouldn't use a push/pull configuration though since it'll have a tendency to leak air at the hoods...which will create positive pressure in the room and possibly defeat your odor removal.

gsxxer · 07-20-2006, 02:37 PM

^ yeah im gonna have the same problem...i got some 8" vented hoods that are going to be recirculating through each other, and the new XL 8" sun hoods dont have a rubber seal...i have to chauk the hell out of it

as long as i chauk the inside real well and outside of the hood it should seal up pretty tight right?

any ideas how to test each individual hood to make sure it is seal up tightly? I was thinking have a big ballon on one end...put a fan to fill the balloon up and see if the balloon stays the same size?

Stealthy · 12-27-2007, 02:40 AM

Quote:

Originally Posted by gsxxer

^ yeah im gonna have the same problem...i got some 8" vented hoods that are going to be recirculating through each other, and the new XL 8" sun hoods dont have a rubber seal...i have to chauk the hell out of it

as long as i chauk the inside real well and outside of the hood it should seal up pretty tight right?

any ideas how to test each individual hood to make sure it is seal up tightly? I was thinking have a big ballon on one end...put a fan to fill the balloon up and see if the balloon stays the same size?

I always suck air through my hoods rather than blow air through...after setup I usually light an incense and allow the smoke to move around all the sections that may leak. If smoke is "sucked" towards any one area then you know your not full sealed. That's how I do it.

07-18-2006, 08:23 PM	#1
goalie Member Join Date: Jun 2006 Posts: 78	How many cfm to cool 8 lights? Hello, I have 8 Bell Lighting shades with air in/out vents. Was wondering what kind of fan i would need for intake and out. What I would like to do is one fan blowing the air and the other fan pulling the air out. Any suggestions welcome. If someones got a pic of this setup i'd love to see it. thanks!
	Quote

07-18-2006, 09:36 PM	#2
MTF-Sandman OG Refugee Join Date: Jul 2005 Location: Over yonder... Posts: 2,001	The rule of thumb is 200cfm per 1K. You'll need to build a plenum that's connected to your exhaust fan(s) to prevent excessive pressure buildup on any one chunk of ducting. What size are the ducts on the hoods?
	Quote

07-19-2006, 12:09 AM	#3
gsxxer Member Join Date: Oct 2005 Posts: 50	^^ whats a plenum? why would you need a intake and outake fan? if your just using it to cool lights that are attached together you should only need 1 fan. or if your using the fan to ventilate fresh air and cool the lights you just need a passive intake... maybe you can have an 8" inline fan just attached for the vented hoods and pull cold air from an inside a/c so the cool air passes through the lights... then have another 8" inside the box thats attached to a carbon scrubber thats the exhaust and use a passive intake... but it all depends on what temps you have in the first place without the lights, im not sure that would be enough what watt lights are you talikng about anyway? is it an enlosed grow box with co2?
	Quote

07-19-2006, 02:55 AM	#4
goalie Member Join Date: Jun 2006 Posts: 78	eight 1000 watters. The ducting size is 4" on the shades i was thinking of using an 8" main duct that has Y for each light going down to the shade
	Quote

07-19-2006, 05:40 AM	#5
MTF-Sandman OG Refugee Join Date: Jul 2005 Location: Over yonder... Posts: 2,001	A plenum is basically a distribution or collection point...for outgoing or returning air. Here's a couple of pics to better show them... There's going to be a fairly high amount of static pressure with 4" ducting, so you'll want to use 2 lights at most per run of ducting. A 10" inline connected on the plenum with 4 runs of 4" ducting coming off of it should do the trick though. If you're using a sealed room, I wouldn't use a push/pull configuration though since it'll have a tendency to leak air at the hoods...which will create positive pressure in the room and possibly defeat your odor removal.
	Quote

07-20-2006, 02:37 PM	#6
gsxxer Member Join Date: Oct 2005 Posts: 50	^ yeah im gonna have the same problem...i got some 8" vented hoods that are going to be recirculating through each other, and the new XL 8" sun hoods dont have a rubber seal...i have to chauk the hell out of it as long as i chauk the inside real well and outside of the hood it should seal up pretty tight right? any ideas how to test each individual hood to make sure it is seal up tightly? I was thinking have a big ballon on one end...put a fan to fill the balloon up and see if the balloon stays the same size?
	Quote