correct multi chamber cab ventilation ????

[bdomina]

I think i have my cab ventilation ran wrong. right now i have 3 chambers that ALL have intakes from the outside. and passive "through" vents in between chambers that go to the main chamber with the exhaust fan in it. it looks like this:




I am thinking that this is inefficient and ineffective. i think that the fan is pulling the most air from the intakes in it's own chamber, and minimal if any from the other 2 chambers. I am thinking that i have this all wrong and need to run them more like this:





where all the intakes from the outside come in on one chamber and sort of "daisy chained" together using passive through vents on each adjoining wall, into the last one where the exhaust fan sits. no external intakes in ALL chambers (instead in chamber with inputs and 1 with outputs ) = better air suction throughout the entire cab? and providing that the through vents are of the correct size in comparison to the exhaust , my fans should be more efficient. Am i in the ballpark here? something tells me i am. with a 500CFM fan would you think that i could expect my temps to drop a little bit ? the chamber that has the exhaust fan in it now stays a lil hot due to ambient temps but really still in the 70-85* window. surprisingly the other 2 contain the "cooler" cfls but get hot.....so wha cha think?

thanks,
BD

I PM'ed a respected user here on this issue and I think he pointed me in the right direction. I sent him another to recomfirm what i was thinking. if you are reading this you know who you are, and thanks a ton!

 

[bdomina]

I have heard back from the man. and this assumption is correct. as far as airflow goes . now my question is do you think it would be better to have the exhaust fan / filter in the bigger flower chamber or to have the intakes for the entire cab in the flower chamber.....

 

[HeD333]

BDomina-
I have a 3 chamber (actually 4)
My passive intakes are in the bottom of my flowering chamber.
...
A pictures worth 1000 words.
I just jotted this up, let me know if it's not clear enough

The sketch certainly isn't to scale, but you get the general idea. Also, the 4th chamber was just for ease of light proofing. You could just as easy make a diy light trap, I'm lazy so this was simpler.

 

[bobblehead]

I asked a similar question the other day. So do you have any fans blowing air from pod 1 to 2, or 2 to 3? Or is it all passive, with just an in and an out?

 

[HeD333]

In my box it's all passive, with 2 6" ports anywhere air is exchanged, and 1 6" vortex setup like:
diy bug Filter->blower->cooltube->wall for flower chamber->diy scrubber. Some smaller fans would help... especially in the upper part of the "veg side". I do have wall mount (clip) fans in both areas, and that helps, but you could get more directional air flow will some active air circulation between partitions.

 

[bobblehead]

I'm talking about 3 boxes. 3 4x4x8 pods... but now I'm considering a 3k watt stadium... I can do it. Still, the input would be appreciated.

 

[bobblehead]

I should add I'm used to growing in a room. It was real easy to vent, one intake hole in the ceiling, and one exhaust into the ceiling...

 

[HeD333]

Well, my entire cab is only 6x6x4.. so I'm not really sure what I'd do with three 8x4x4's. I would probably build them to be independent... If you really want to cool them cumulatively, I would run seperate fans for lighting and scrubbing, which means you have to have cooltubes or air tight hoods. It seems like it would be more practical to just vent them individually.

 

[bobblehead]

That's where I was headed with it... And then I figured hey, why not just do a stadium again... It's simple and effective. Thanks for confirming this.

 

[bdomina]

bobble head

essentially the "correct" way of venting multi chambers on 1 run or with 1 fan would be to have all your passive intakes ( air coming in from outside ) in 1 chamber. passive vents from 1 chamber to the next and then the fan sucking the air and exhausting out of the cab in your last chamber.


the only place to have intakes from the outside is in 1 chamber at the "beginning" of the run. that is where i made my mistake.

"If you have a three chamber run, with the fan pulling all the air from the last chamber, in theory you need to increase the holes just slightly for every chamber it passes through, as you will loose a little bit of flow from the resistance each chamber can add.
This would really show itself if you have many chamber to pass through, but with one or two you can stick with the 10% over at each wall."
- from a little help from a friend

click on this pic i added some general measurements.

 

[Quazi]

You're correct that a single passive intake will be what you want.

Make sure you light trap between the chambers to prevent different scheduled lighting patterns from interfering with eachother, especially between flower/veg.

The other advantage of the single intake and single exhaust is that it can be easily carbon-filtered. Slap a carbon filter in there so that you're pulling through it as the air is on it's way out and you'll be able to control smell much better.

-Q