Indicator
Active Member
Alright you ventilation pros... please check my figures prior to my ripping into my sheetrock for passive intake.
Scenario 150 cu. ft. closet, 600w hps, 300 cfm exhaust. According to a chart running around, a 300 cfm fan requires @ 12" diameter passive intake. A 12" diameter intake has a surface area of @ 113 sq. inches. So, my vent choices are (1) 12.75" x 6.75" for a surface area of 86 sq. inches, or (2) 14.75" x 6.75", for a surface area of 99 sq. inches.
I realize both are on the shy side of the suggested intake size. But, as it has to look semi-inconspicuous, option number two, which is designated as a 16" x 8" register is the biggest I am willing to go.
I am thinking I might be able to get away with option one as there are always constrictions with ducting in small closets and the fan more than likely will be running a bit less than 300 cfm, especially if I add an inline carbon filter (undecided at this time). Option two would be fine... just seems like a big opening... will be drawing from air conditioned house and fresh air from a nearby window at times. Venting through dryer duct.
So, any guidance on this one is appreciated... prior to making swiss cheese out of my house!
Mods... please remove this post... I reposted in proper area. Thank you!
Scenario 150 cu. ft. closet, 600w hps, 300 cfm exhaust. According to a chart running around, a 300 cfm fan requires @ 12" diameter passive intake. A 12" diameter intake has a surface area of @ 113 sq. inches. So, my vent choices are (1) 12.75" x 6.75" for a surface area of 86 sq. inches, or (2) 14.75" x 6.75", for a surface area of 99 sq. inches.
I realize both are on the shy side of the suggested intake size. But, as it has to look semi-inconspicuous, option number two, which is designated as a 16" x 8" register is the biggest I am willing to go.
I am thinking I might be able to get away with option one as there are always constrictions with ducting in small closets and the fan more than likely will be running a bit less than 300 cfm, especially if I add an inline carbon filter (undecided at this time). Option two would be fine... just seems like a big opening... will be drawing from air conditioned house and fresh air from a nearby window at times. Venting through dryer duct.
So, any guidance on this one is appreciated... prior to making swiss cheese out of my house!
Mods... please remove this post... I reposted in proper area. Thank you!