Tutorial Ventilation 101

[FreezerBoy]

Hey man I got a question, I'm building a cab 10Lx5Wx6H Foot, I'll have 3 600w hps in there. What foot per hour or m3 per hour extractor fan should I have in there to have good temp control? And what intake should I have

Much respect

HGOz

Dude, it was right there on page one

 

[conehead]

Hey Red greenry top class thread!. maybe a bit above me but I'm trying to make sense of it all. I have a 12'' centrifugal can fan type it is 180watts I think it does about 350 liters per second, for an exhaust ( with carbon filter attached). Intake I have a 40 watt centrifugal bringing in fresh air from outside. I also have a scrubber with a small 4" duct fan 20watts & a very small stirring fan in the grow. My grow room is 9ft x 9ft x 9ft tall. Lighting used 1000w to 1800w. Does this set up sound O.K for the size room or is it overkill, or should I use passive intakes instead of the 40 watt centrifugal, this is where I am a bit confused!. Thanks Red for a great thread.

 

[mklod]

I had a pretty stable growing plan until reading further into ventilation (read: this whole thread) and heat so much that I am no longer sure what to do.

My plan is to grow 10 x auto hindu kush plants (Lowlife, seeds in hand). They aren't supposed to get any taller than 16". These would go into my closet, which is a closed/unventilated space, under a 400W CMH light. I was thinking of having two circulation fans for the space, directed on the plants, one on either side of the plants. Then I would also have two small fans mounted on the hood, directed on the CMH to cool the light. The ballast would be remote and outside of the closet space.

Now, I'm assuming that such a setup would still produce too much heat with the closet doors closed (I'm talking a 2-3' deep 8' long 8' tall closet) since there is air circulation but not ventilation. However, I would not like the closet doors open all the time and I would prefer the closet doors to not have vents put in them (this would not be stealthy). Are my assumptions correct?

So then I thought that I could cut through the wall of the right side of the closet and put in an exhaust fan, since that exhaust fan would exit directly to the outside of the house. This leaves the problem of intake. Any suggestions?

Finally, I plan on also having a cabinet (approx 4' tall 4' wide 2' deep) for mothers/clones/non-AF plants, with 4-6 x 42W CFLs. I can handle the intake/exhaust situation for the cabinet, so this is really just random fyi.


To sum it all up, I'm asking what the best setup would be for growing the 10 or so 14"-16" plants with the available space, with regards to ventilation. I'm open to doing a larger cabinet or more cabinets, and changing from my CMH plans to doing just CFLs. Would multiple smaller cabinets like the one I mentioned in the above paragraph be a better idea? I'm not partial to the idea of weaker yields with CFLs, but if that is the best option, so be it.

 

[InRainbows727]

I was wondering if somebody could aid me?
My box is a SOG style about 2x3x3 and I'm using a 130 CFM carbon scrubber w/Axial fan (exhaust). I am going to be using darkroom vents to eliminate all light leaks--my question is should I rather get 2-3 120 mm computer fans rated at about 36 CFM (passive intakes?) or should I go with a single 112 CFM Axial fan(easy because it's a single plug and merely one intake to whittle out of my box)?

 

[JackTheGrower]

Thanks for this thread.

I've sorta put off hooking up my cool tubes and I think it is because I don't know what is best to do in air flow...

Looks like that will change...

Jack

 

[SativaDreams]

Now that we have discussed fans, GREAT THREAD by the way i've learned alot about ventilation reading through the first two pages, can we discuss good sources online we use to find and purchase them?

I'm looking at some getting some smaller axial fans for the drawer to keep it stealth.

Anyone have good website ideas i could look at for ordering?

 

[petemoss]

I like the 12 volt computer case fans. Newegg.com usually has a good selection at very good prices. Scythe is one of the best brands.

 

[grasspass]

Used wall chargers can be obtained at Salvation Army stores. I bought about 6 of them of various voltages for 50 cents each for my guitar effects experiments. They could be used to power a dc fan. different voltages of dc will change the speed of a dc fan. Go to a second hand store for dirt cheap wall chargers.

 

[SpendThrift]

I'm sure this has been covered multiple times but I cant find anything about it. If I were to use a 8" to 6" ducting reducer does that have any significant effect on airflow or lower the cfm at all?

 

[eglider]

Reducing from 8" to 6" will increase air speed which will increase turbulence that translates to higher static pressure (resistance). By how much I cant help you with because thats above my paygrade. You'll need Red to nuts and bolts that one for volume, speed and all that smart guy stuff. My guess would be that unless your fan is a little booster home depot job you would probably be okay.

 

[eglider]

BTW Red , Great thread. Thanks for the effort, it's well appreciated. For a lot of us the science of air movement is limited to lifting a cheek a bit....

I also like your idea about using a cheap melamine garage cabinet. The perfect stealth grow unit in a pantry or a garage. Clean white interior, adj. shelves, hide intake in the toekick. Add a couple of elbow catches on one door, top and bottom and drill a 7/8" hole for an inconspicuous cabinet lock ("keep the kids out of the bugkiller granma") Put your random cardboard box on top to diguise the ventpipe or can filter.

As Martha would say ... "It's a good thing"

 

[ft100]

ok i have a ventilation ? for the gurus. i have a 4 x 8 tent setup. i have 2 canfan complete setups including fan and filter. I run 2 600 watt hoods in there. what is the best way to do this using my equipment. right now i have 1 fan and filter hooked up to each light. I was thinking of maybe putting one filter and fan on the lights alone and one filter and fan on the top of the inside of the cab? any ideas? thanks guys. peace and smoke.

 

[Dank Sinatra]

so which 6" centrifugal would i want to use,

the PV-150x which is rated 468 cfm and had way better sp than the comprable can fan http://www.solerpalaucanada.com/pdfs/Brochures/PV%20Power%20Vent%20Series.pdf

or the elicents 150B whose performance can be found here

I can't tell whether the power vent would beat the elicent. I have heard elicents are the way to go, but powervent destroyed can fan for SP on the 6" models. On the 8" models not so much.

I was planning on using one to air cool 2 days star ac reflectors with 1000w each, r-6 insulated ducting and cool night time air. What do you think?

Thanks

 

[lysol]

I now use one of those duct boosters to keep my 400w + 150w lights cool in a tube. And it is quite enough to do that job. Two won't help much in that situation because there is very little pressure to deal with, and two wouldn't help matters in that situation.
(hope it makes sense why...red has explained it technically)

IMO, leave the boosters to boosting and doing what they are capable of doing. Get a decent inline fan to use with the scrubber.

Thanks for this post, I had one of those duct boosters a guy sold me for like $30, I was wondering if it would be enough to cool my 600w in a cool tube, if it cools 550 whats another 50w eh?

I also use the scythe 120mm fans in my PC and in rubbermaid "veg" box

 

[hoosierdaddy]

If you are just pulling air through the tube, then it should do the job. Those fans will not overcome much resistance at all, so you don't want lots of ducting and twists and turns. Make it as straight of shot as possible and the duct booster should be fine. Add a carbon filter, and the booster is a no-go.

THose 6" Suncourt boosters sell for like $27 at HomedePot.

 

[micro gro]

Nice thread & information.

 

[lysol]

Thanks. I will probably pick up a couple more of the boosters, I will put 2 in series to increase [the amount of negative] static pressure and hedge my luck against a failing ductbooster ruining my crop. I think I'll keep the one I have with the 6" ducting pulling from my rubbermade and attach a little 8" duct on the intake to lightproof it, ventillation has been confusing / taking up my time but your explanation I found very terse and intuitive ( for those not understanding it, try smoking MORE and reading it a 2nd time, always works for me ;-) ). Either that or just "caveman" it and spend $100s on fans that wake up your neighbors and get you caught :-(

 

[lysol]

Wow I just had a sleight bend in my duct and I straightened it out, you really do underestimate how that affects the back pressure, the pitch of the fan changed dramatically indicating a huge difference in air-speed, just from removing a sleight bend.

 

[lysol]

You want to be careful of cutting your intake too large, sometimes a higher CFM thru a smaller opening is more beneficial. specifically if your lights are near the bottom of the container. This is because the air will take the shortest path, the larger your intake relative to the amount of air being pulled, the slower the air needs to move since there is more of it, this could negatively impact cooling if you are relying on air movement inside the cabinent generated from the vacum effect of the exhaust.



If you found you cut it too large you can just use duct tape to fine tune the shape of the opening. Having a fan near the intake blowing towards the lights helps but your fan may not generate the same air speed you could by designing the intake properly.

 

[Dank Sinatra]

what the hell does cave man it mean
hahahhaha