What size passive intake hole?

[967]

yeah i googled it, but i plan on growing in a bedroom without sectioning it off. Would like to keep negative pressure so odor doesn't escape. I have a 296cfm centrifugal fan which i'll attach to carbon filter and vent to the ceiling. Intake will be an open window, covered with panda plastic and a length of duct (or two, three?) bent to keep light proof

Room is a bit over 500 cubic feet. Have a grow going in a 4x4 box i made. Going to take carbon filter out of that box and exhaust with no filter into main room (bedroom), then exhaust main room with carbon filter into ceiling. When current box grow is finished i'll probably do away with the box and run two 600W vert setups

Can anyone give me advice on how to sort ventilation?

 

[967]

Or..... is it a stupid idea to use only two 600W lights in such a large area? I like the idea as it cuts down on setup costs, and would make moving around and tending to plants in a vert setup sooooo much easier

 

[St3ve]

the rule that HVAC contractors use is 12x12 passive intake (or 144sq") for every 300cfm.

Nothing wrong with 2x600's, you should be able to get close to 2# once you get things dialed.(assuming good genes)

 

[967]

I do have what i consider good genes, and think 1 lb each 600W is easily doable, provided right environment. But not sure a corner grow of a large room is the right environment..

Is the 12x12 passive hole the same rule for a 4x4x6 box as it is for an 8x8x8 bedroom?

I think i'll just give the corner grow a go and see how it goes. Half the reason i want to do it like that is to keep costs down (also want to try vert). Whether it works well or not, i'll still harvest weed, weed is money, then i can look at upgrading/building something to suit

Best harvest so far is 14oz from 600W horizontal. I'd be surprised if i can't match this with 600W vert. 8 plants, 2oz each is 1lb...

 

[Bok Choy]

Go to the ventilation 101 thread stickied
in the growroom designs and equipment section of this site. Generally you want your passive intake hole approximately 3.times the size of your outtake hole for proper passive intake and negative pressure. Go there though and learn all about passive intake. Good luck.

 

[St3ve]

967, the passive hole rule is based on the actual amount of air being pulled through the hole. The size of the room doesn't matter, and the size of the outtake hole doesn't matter. (sorry Bok but you have fairly generic anecdotal information). 144sq or 12x12 for every 300 CFM being extracted out of the room.

There is nothing wrong with growing in the corner. In fact, in some ways its better because you can get to the plants easier for maintenance as well as better air flowing around the plants. The only negative really is less wall area to reflect light back to the plants. However, if you were really wanting to get the most out of the light and reflect from all sides, you can make reflector stands to stand on the ground or hang from the ceiling.

Good luck!

 

[Green_science]

I would usually use 2x10" passive for every 12" extraction, sure that sounds a bit small, but I always use over powered extraction, there is a few great things about doing it like this, the negative pressure you get is of a great value, the 2 10" passives can be of varying lengths, and pressure counteracts resistance, meaning they both output similar amounts of air, lastly you can turn you're extraction way down and still have a good negative pressure