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Tutorial Ventilation 101

Cruzin831

Member
Ok so I just want to make sure I have this correct before I do some handy work to my closet.
If I have a 4'' exhaust pvc pipe with a PC fan attached, then I need a passive intake of about 6-8'' for air to travel in without the need of a fan. is that correct?
 

Bloom

Member
Any pictures around here where it shows a few different methods of running ventilation inside of a grow room? I have a 1k cool hood 6" with a 6" fan, and I have a 8"scrubber with a 8" fan, Im just confused.. help me please, My house smells like a fruitloop/orange skunk big time
 

Granger2

Active member
Veteran
I'm unsure about how to handle my lamp heat problem. I have 3 600w lamps cooled by a 6" Vortex. Two 6" intakes from floor going to a collector box, 3 4" ducts, each one going to a lamp. Three 4" lamp exhaust ducts going to a collector box w/ a 6" duct going to the Vortex which takes it out of the room.

I wish I had gotten an 8" Vortex, but I'm stuck with what I've got. The problem is that even with good air flow thru the three 3x3 stalls, the stalls go into the 90'sF if closed up except in cool/cold weather. I'm leaving the first stall door open so it catches direct AC air as a work around. This is at least inconvenient.

I don't really want to spend the money on an 8" fan which would cause me a lot of work and expense with changing duct, cutting round holes, etc. I will be insulating the reflectors with Prodex w/airspace http://www.insulation4less.com/

I was considering getting 3 4" inline duct booster fans to help the 6" Vortex move the air thru faster.
http://westcoastgrowers.com/ventilation.htm

I don't know about the pros and cons of doing this since they each have a lower cfm rating [65 cfm x3=195cfm, Vortex 449 cfm] and are less powerful against static pressure. I know the Vortex is not moving 449 cfm thru the system.

Would 3 of these help much to cool the lamps better. Where is the best place in the run to put these fans. I was thinking about putting them either on the exhaust outlet on the reflector or where the duct leaves the stall. Ideas will be appreciated. Thanks. -granger
 
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oneshot

Active member
I have a can-fan max 6" fan hooked up to a Can33 filter in a Lighthouse Hydro 3'x2'x5' tent. I am currently using the fan on speed 1 which is stated at 201 CFM.
Speed 2 is rated at 264CFM, Speed 3 is 334.

I am using speed 1 because A) It's already creating so much negative pressure in my tent, I think any higher would cause MORE interference. The tent is actually touching the light B) Noise

The filter states this on the specs:
Max Recirculating (Scrubbing) CFM: 400 cfm / 700 m³h
Max Exhaust CFM: 200 cfm / 350 m³h
@ 0.1 sec contact time
Recommended Min Airflow: 100 cfm / 175 m³h

My question is, why does it say Max Exhaust CFM 200cfm but Max Recirculating (Scrubbing) CFM: 400cfm? Does this mean I need to run it at 400cfm to get odor control?

I also want to know if I would be able to speed control an already speed controlled fan? Any good ones people recommend? What CFM should I actually be running it at to make sure it will remove the smell? I am awful at math :/ I would ideally want to move the filter outside of the tent but I am worried about smell. I haven't started flowering yet but the filter is so obnoxious.

I am also worried about the negative pressure hitting my light. It's mainly due to the filter being in the tent with how large it is. Any suggestions would be great.

You can get an idea of how large it is and is interfering with the light hangers :/ I just don't want to risk security by putting it outside the tent. I also want to make sure I am putting accurate CFM's through it or if I can even LOWER the speed of the fan to ease up the pressure. I know this is a long post but I really would appreciate the help.
 
3x2x8 grow closet

3x2x8 grow closet

so i have a 3x2x8 grow closet with a 150w hps light in there and i really couldnt figure that chart looks like i only need about 100 cfm for my space a duct booster fan would be good. but if i run a carbon filter do i need more power. like an inline fan. wat should i use for my sized closet?
 

Granger2

Active member
Veteran
matt,
You'll need a centrifugal fan for sure. The duct booster isn't strong enough. Good luck. -granger
 
C

Cptn

My question is, why does it say Max Exhaust CFM 200cfm but Max Recirculating (Scrubbing) CFM: 400cfm? Does this mean I need to run it at 400cfm to get odor control?


The faster you move the air through the carbon, the less "scrubbing it does.
If you have the filter attached to a recirculation fan in a room "scrubbing" the air and recirculating it IN TH ROOM, then you don't need to get all the smell in one pass, so volume of airflow can be increased to help with environmental issues (recirc fan + scrubber function.)
Most people don't do it that way, but I can imagine a scenario when separating scrubbing function from the exhaust function would be a good thing.

If you have the filter attached to an EXHAUST fan, then the air leaving the grow space must be thoroughly cleaned (it only has one pass to do it.)
Lower airflow means more time spent in the carbon, means better scrubbing before the air finally leaves the tent.

The benefit of separating the scrub from the exhaust function is it allows you to use a lower powered fan for exhaust with a lower noise signature.

I have not tried this but it is something I have considered.

Hope that helps
cptn
 

evanb

New member
Hi all. A simple question I hope. Should I get my fresh air intake directly from out side of the house? I live in an area that gets really cold in the winter and can get damn hot & humid in the summer. I am thinking the fresh outdoor air is the best but I would think a "dust shroom" cap needs to be on the intake so no pests, molds or other funk gets into the room.

Thank you in advance.
 

St3ve

Member
Lots of good info on airflow.

I have a question though.. as far as whats good for the plants, how did you (the op) come up with exchanging the air once per 5 min? It doesn't seem logical that fresh air could be bad. I mean.. I'm not talking about temp, RH, VPD or air directly blowing excessively on the plants. Just fresh co2 and o2 turning over in the room. I mean if the plants were outside.. they would get fresh air turning over constantly. I'm just curious where the 5 minutes came from.
 

wattsonfat

New member
Hi, is it possible for scrubber to be too big? I have 350m/h fan and about the same size scrubber, but it isnt doing its job anymore so well. So i have one about 1000m/h scrubber in storage and im thinking is it too big? Can somebody enlighten me of what would happen if i put a 350m/h fan sucking air through 1000m/h scrubber?
 

St3ve

Member
Hi, is it possible for scrubber to be too big? I have 350m/h fan and about the same size scrubber, but it isnt doing its job anymore so well. So i have one about 1000m/h scrubber in storage and im thinking is it too big? Can somebody enlighten me of what would happen if i put a 350m/h fan sucking air through 1000m/h scrubber?


I just asked the same question and the consensus was it will be fine. Since you already have it, you have nothing to lose to try it out.

That said, I'll rep you hard if you try it and post your results. :):peacock:
 
C

Cptn

Larger surface area means that the air will (potentially) travel at a lower velocity across the surface increasing time in contact with the carbon and cleaning better.

The fan will tend to pull through the media closest to it until it hits resistance.
As the filter becomes dirty, the fan will start pulling through media further away from it where there is less resistance.

There is no problem running a filter "too big" for the application. If you notice a problem or it bothers you too much, you can always block a portion of the surface of the new large filter to force the air to only flow through a portion of the filter.

Hope this helps,
cptn
 

1ManGrow

Active member
Let me know if there is anything else I can do to lower Temps in my Rubermaids and if my Ventilation is good..

I don't think I have the ventilation dialed in right ....

Here are the sketches I made of everything..I hope it is understandable..


Closet Space ( 7'L x 5'W x 8'H ) Ambient Temp In Closet Lights On Or Off -" 77F / RH 33 - 44% "

picture.php



I have the 4" Duct running from the Home A/C into the closet for fresh and cool air

I have the 72 CFM fan above the rubbermaid ( Pulling ) Air out of closet

I have a Oscillating Fan blowing at the intake area of the top rubbermaid box

- I figure this will give me fresh and cold A/C air in the close to help keep rubbermaid temps down while constanly pumping the closet air out and pumping A/C air in .. ( Not Sure if this is good or not worth the effort / extra electricity ...)))



Now Onto the Scrubber - Plastic Shoebox Tote On Top Of Medium Tote..

picture.php


The 4" Duct going from the scrubber to the top half of the rubbermaid is in a slight "U" Bend and length is 20" on the left and 17" on the right..

Top Half Of Rubbermaid

picture.php


Bottom Half Of Rubbermaid

picture.php


Tempatures with the Grow Lights on ( 4x 43w and 2x 26w CFL)

House Ambient Temp - 76F

Closet Ambient Temp - 77 - 78F

Rubbermaid Ambient Temp 86 - 91F - Lights On -

Light Chamber Exuast Temp - 91F only had it in the duct for an hour..Will going longer and edit temp if needed..

--Closet Dimensions - 7'L x 5'W x 8'H
--RubberMaid Dimensions (Top)-- 31"L x 19"H x 17"D
--RubberMaid Dimensions (Bottom)-- 31"L x 19"H x 17"D

If I am missing anymore info that could possible help.Then let me know and I will get it for you...

Also is having the 2 scrubber fans pulling side by side pulling a bad thing or overkill??Should I go back to 1 fan Pulling?

I will take pictures of it later as I am doing a time lapse of my plant on my phone..



Thanks for the help !!!!!
 
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Lots of good info on airflow.

I have a question though.. as far as whats good for the plants, how did you (the op) come up with exchanging the air once per 5 min? It doesn't seem logical that fresh air could be bad. I mean.. I'm not talking about temp, RH, VPD or air directly blowing excessively on the plants. Just fresh co2 and o2 turning over in the room. I mean if the plants were outside.. they would get fresh air turning over constantly. I'm just curious where the 5 minutes came from.

Steve, from what I can gather, the OP mainly focused this article on what he grows in, micro cabs. He states that any airflow more than this will stress out the plants............which may be the case if you're growing in a rubbermaid and there's a vortex going on inside.

I don't really think that's applicable for larger apps, as you can exhaust your air much more quickly (I can go up to 1X per minute in my 1200 CF grow room) without my plants even knowing anything's going on :)

He talks about it in the first post (although it's from more than two years ago).
 

Prea

New member
I'm gonna suggest, air-cooled hood/filter/fan------>outside

It'll keep your glass cleaner thus allowing more lumens to get to your plants. Scrubbers, bought or homemade always leave fine particles on your hoods glass.

Are there any drawbacks to this setup? I've been reading up trying to figure out the best way to setup an air-cooled hood and filter, and most people seem to suggest filter before the hood. But the setup you listed seems like it would make the most sense. Only problem I could see is that you'd be pulling hot air through your carbon? (and some places say that at high temps the absorption capacity of carbon decreases, but it doesn't say at what temps, and I would think if your fan is working well enough it would keep both the light and carbon cool)
 

wattsonfat

New member
I just asked the same question and the consensus was it will be fine. Since you already have it, you have nothing to lose to try it out.

That said, I'll rep you hard if you try it and post your results. :):peacock:
It works more than well, go for it
 
M

Mtn Dew

Noob needing some help

DIGITAL 600w HPS

I got a tent: 5ft (W) x 6ft (H) x 24in (D) house sits bout 70-74.F

I got a 4in 175CFM Vortex pulling air out "top right corner roof"

2x 4in passive intake's "bottom left corners left wall"

Should I be set

No carbon filters nothing
 

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