Help with confusing ventilation question

TwoLips

New Member
First of all im gonna say Hi 420 magazine!
Been following many journals for quite a while now, but only just registered. :D

Recently upgraded my veg box from a converted set of office draws, to a canvas cupboard frame wrapped with panda film.
Basically copied my tent layout but scaled down
Dimensions are 30inch x 30inch x 1.1m
I have a bathroom fan for the exhaust pushing 26L per second up in the back, right corner. This is on a fan controller so I can easily adjust the temps. This is also attached to ducting with 1 90 degree bend for light leaks.
My intake is a 80mm 12v PC fan (dont know the cfm) attached to a 'S' style light leak box. This is in the bottom left of the left wall. This is powered by a 12v transformer which I can turn down from 12v to 9v/6v ect.

My problem is I have positive pressure?! Both plants in there are pretty mature in their veg state so they do smell a bit.
Even when the exhaust is on full and the PC fan is down to 9v.
Also good to note when the pc fan is on 9v my temps rise to around 28.8c-29.2c mark

Surely a cheap fleabay pc fan cant be pushing more are in than 26L p/s?

Can someone please point me in the right direction?
Cheers :)
 
Thanks for your reply

That was my first setup, exactly how it is in my tent
The temps got to 31c before i had to add an active intake
 
Just a 200w dual spec cfl, doesnt even put out that much heat.
Tbh i thought i went overkill with the 4" bathroom fan, hence why i got the speed controller

I dont get positive pressure in my flower tent no.
Thats 0.8x0.8x1.8m with a 5" fan and filter. Thats got a speed controller too on about 3/4 speed.
Flower tent has a passive intake too
 
Not all fans work the same. Some can have the ability to run variable speed, while others it will just wear them out. I doubt many bathroom fans will have that. Kind of that same idea as "should I run it for 24/0 or should I give my hardware a break" It depends on the piece of equipment.

I doubt you will have heat problems with a 200fluro and that fan, unless your environment has heat problems of course. This is a veg area right? As long as temps dont get much over about 35°C your shouldn't have any problems there.
 
Ahh because its not really made for running at lower speeds. I understand
The high temps im getting at the moment is because where I live theres currently a heatwave :/
Was more bothered about the smell seeping throught the zip instead of going through the carbon felt scrubber

Had a thought. Gonna buy one of those dust filters, cut a peice and tape it over the intake to lower the cfm coming in.
 
I think adding the filter will be counterproductive. I think just removing the intake fan should do the trick if the tent is tight.
 
When i first built it, it had a passive intake. I had to put the intake fan on because temps got too high without it

The dust filter has sorted it. Got negative pressure and temps are level at 27.5c
:)
 
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