Growbox ventilation q's

[iogrow]

Hey people, me got couple q's
I'm building a 120cm x 60cm x 60cm (4ft x 2ft x 2ft) growbox/growcloset

I've got 7 PC fans - 12 cm diameter , 55m³/h , 24V 0.46A

Q's

1. What's the rule? More air in, less out or the other way around? I want to split my fans 4/3 (in/out), and I don't know how many should I use for the outtake.

2. Sucking air is more efficient than blowing, right?

3. I've tried the fans with 12V and they are pretty loud, so I will run them at 9V. Is there a way to find out how many m³/h they will pump running at 9V?

4. Running at 9V instead of the rated 24V they will still consume 0.46A?

5. How thick should the scrubber be? I want to construct something like this

taken from this thread http://www.icmag.com/ic/showthread.php?t=21035 ,

but smaller, to match the 12cm fans.


.... hmm, I thought I had more questions, hmmm, I forgot

 

[Jnugg]

1. If you're going to use the PC fans then I would put two at the top of the grow box and two at the bottom...mount them to the box so that the two at the top are sucking air out and the two at the bottom are sucking air in....my suggestion would be to get a 4" or 6" Inline centrifugal exhuast fan and use passive intake for a negative pressure environment.

2. Yes,sucking the air into the cab is more efficient in my opinion as opposed to blowing.

3. Not my area.

4. Not my area.

 

[iogrow]

....my suggestion would be to get a 4" or 6" Inline centrifugal exhuast fan and use passive intake for a negative pressure environment.

I might get one of them exhaust fans later, at this time I have to use what I've got. Maybe I should just use the 7 PC fans on the outtake, then I will get a negative pressure environment, or?

Can someone write the formula or how to calculate how much air should be blown out in an hour out of a growbox etc...? In my case the volume of the growbox is approximately .440 cubic meters or 15 cubic feet.

 

[evertking]

i had a box close to that size with a 250 hps... got hot using computer fans!!!..... make passive intakes and use your fans for exhaust.

 

[iogrow]

I'm gonna set up six 55watt Dulux L CFl's, so 330 watts in total. I'm thinking of installing 2 timers, one will be hooked up to a thermostat. In case that the fans will reach their maximum and the temp will rise above 30 C, the thermostat will switch off 3 of the lamps, then back on once the temp will lower.

 

[Jnugg]

Rule of thumb is to have an exhuast fan that can exhuast and replenish your grow space's air 3-4 times in one minute...so....

your grow space = 15ft^3 so you'll want to use about 60cfm and to keep the lights cool you'll want to add a little so maybe 90-120cfm.If you add a carbon/charcoal scrubber your going to want to add more fan power to your exhuast and I'll tell you right now that pc fans don't do well with static pressure.Save your money and buy atleast a 4" inline centrifugal if not a 6" on a solid state speed reducer.