0calli white widow sprouted may 22

[QUOTE=Flo Grow;5496965][B][COLOR=darkgreen]Ventilation is a serious concern for us growers.[/COLOR][/B]
[B][COLOR=#006400]Lots of ppl have questions about :[/COLOR][/B]

[B][COLOR=#006400]Passive intake[/COLOR][/B]
[B][COLOR=#006400]Active intake[/COLOR][/B]
[B][COLOR=#006400]Active exhaust [/COLOR][/B]
[B][COLOR=#006400]F[/COLOR][/B][B][COLOR=#006400]an size[/COLOR][/B]
[B][COLOR=#006400]Passive intake hole size(s)[/COLOR][/B]
[B][COLOR=#006400]How much CFM's for a light of a certain size[/COLOR][/B]
[B][COLOR=#006400]How close can I get my lights to my plants[/COLOR][/B]

[B][COLOR=#006400]And so on.[/COLOR][/B]

[B][COLOR=#006400]Hopefully the info below will help clear most of the confusion.[/COLOR][/B]




[IMG]http://www.rollitup.org/attachments/grow-room-design-setup/1511644d1239905695-more-passive-intake-should-i-ventilation-chart_01.jpg[/IMG]




[COLOR=black][FONT=Verdana][B]---------------------------Calculating the passive intake.-------------------------[/B][/FONT][/COLOR]

[FONT=Verdana][COLOR=black][B]The Home Ventilating Institute recommends one square foot of open air inlet per 300 CFM of ventilation fan capacity.[/B][/COLOR][/FONT]

[FONT=Verdana][COLOR=black]If you were going to use 256 CFM, you’d want 256/300 square feet of intake area, which is 122.88 square inches. [/COLOR][/FONT]

[FONT=Verdana][COLOR=black]Here are some options for the [B]intake area[/B] for a 256 CFM ventilation fan:[/COLOR][/FONT]

[FONT=Verdana][COLOR=black]1 hole - 12.5 inches in diameter.[/COLOR][/FONT]
[FONT=Verdana][COLOR=black]2 holes – 8.84 inches in diameter.[/COLOR][/FONT]
[FONT=Verdana][COLOR=black]3 holes – 7.22 inches in diameter.[/COLOR][/FONT]
[FONT=Verdana][COLOR=black]4 holes – 6.25 inches in diameter.[/COLOR][/FONT]
[FONT=Verdana][COLOR=black]5 holes – 5.59 inches in diameter.[/COLOR][/FONT]
[FONT=Verdana][COLOR=black]6 holes – 5.11 inches in diameter.[/COLOR][/FONT]


[FONT=Verdana][COLOR=black]Here is how to calculate the hole sizes:[/COLOR][/FONT]

[FONT=Verdana][COLOR=black]1. Take the total area in square inches needed, in this case 122.88 square inches, and divide by the number of holes you want. [/COLOR][/FONT]
[FONT=Verdana][COLOR=black]2. Then divide by Pi (3.14). [/COLOR][/FONT]
[FONT=Verdana][COLOR=black]3. Take the square root of that value. [/COLOR][/FONT]
[FONT=Verdana][COLOR=black]4. Then multiply by 2.[/COLOR][/FONT]

[FONT=Verdana][COLOR=black]The answer is the diameter that each hole would need to be to make up the total area needed for intake.[/COLOR][/FONT]

[FONT=Verdana][COLOR=black]A large number of small holes will create more backpressure than one large hole of equivalent area. This would be negligible unless you’re using a huge number of holes or you’re using ducting to supply the air to each intake hole. If you’re just cutting them in a wall you should be fine using 8 or less holes without having to take into account the extra backpressure.[/COLOR][/FONT][/QUOTE]