intake hole size

[chuckyoufarley]

how big should i cut the hole for a cab that is 18 x37w 48 h the exaust hole
is about 4x4" thats what the fan exaust is anywaytrying to rearange my grow cab to fit a 400 watt hps .have been using 2x150 hps and a 100 watt mh to
get my 400watts. im wondering if it will be cooler cuz im only gonna be using 1 bulb instead of 3 smaller ones so i neeed to know how big to make the hole so i get the right airflow thanx
peace chucky

 

[Guest]

A 4 inch intake should be fine but may need more if temps get to high. Hard to tell without seeing exactly what your working with. Good Luck Jubei

 

[sunnyside]

4" should be fine...you could also make 2 or 3 smaller holes if you like. I'd say the bigger the better...you dont want to choke your exaust fan out!!

 

[Einsteinguy]

Hey chuckyoufarley

I have a cab similiar size. I have a 4" exhast I have 2 3" inch intakes. I used drain pipe (White outside/Black inside) with 2 90degree turns to prevent light leaks. (Both Directions)
Air should come into bottom of cab and exhast top preferably opposite sides.
I like to use my fans to guide wind from intake to exhast. Ive seen fans blowing hot air down inside cabs, I think fans should blow the cold air up.

These are somethings that have worked for me.

Good Luck
Einstein

 

[chuckyoufarley]

thanx for the replys guys i got it done might have to put a piece of glass in the hood
peace chucky

 

[valk]

What is the cfm of your fan? I have a 6 inch exhaust with a 420cfm inline fan. With 7, 2 inch passive intakes I still have negative pressure in the box at around 75F.

 

[chuckyoufarley]

the fan is a 185 cfm active intake
peace chucky