Passive intake.....

[norkali]

If my closet is 44 cubic feet, with a 270 CFM fan pulling dirty air from the top through a 4'' duct, up to a carbon scrubber... (Bodom's DIY) How big should my passive intake be? I have 1 2'' 90 degree PVC at the bottom so far....

Pictures (http://boards.cannabis.com/closet-cabinet-growing/121325-came-closet.html)

[norkali]

So, I added another 2'' intake, everything runs well, but not well enough. Temps. in closet stay, consistently, 22 degrees higher than whatever the temp outside of the room is. 80 degrees in the closet? my a/c'd room needs to be at 58. BAH!

The electrical cost to maintain this is out of the question, especially considering were about to be in July in about a week. Any suggestions? Bigger exhaust fan? More passive intake? Anything?

[rhizome]

-Lose the 4" reducers on your fan. I'll bet those alone are bringing you under 150 cfm.
- Much bigger intake- like maybe 8" to match your 6" fan. 4 two-inch intakes do not equal one eight inch intake- you want a total of twice the surface area in intake that you have for exhaust. Maybe a little more if you want to put in 90's to contain light. Each 90' bend in ductwork reduces flow by about 20%.

You have plenty of fan, just too much drag. Upsizing the fan won't help that much.

[norkali]

thanks. I'll be refitting to 6'' soon, a/c is directed at intake so temps are stable for now....

[TheMetal1]

Great info about the reduced air flow, due to 90 degree bends and reducers for scrubbers Rhizome. One of those things I know... but didn't really think about. :thumbsup:

Norkali, are you dealing with odor at the moment? If so, how well is your scrubber working? I ask because now that you are changing some intake/exhaust dimensions, I wonder how will that effect the efficiency of your carbon scrubber? I've read that you need to make sure you have adequate time for the exhausted air to pass through the carbon to work well. Rhizome, any info on maximizing the efficiency of your exhaust fan/carbon scrubber relationship? I'm guessing that since his intake and exhaust capabilities will be increased, it will cause the air to pass through the carbon faster. Hope this isn't considered a jack... thought it might help Norkali if he does experience problems when refitting. Keep :jointsmile: