Oh ventilation, is it ever enough. is anyone ever right?

So i'm nearing the end of my 1st grow DUBBED: the experiment, and about to start the second. I still havne't gotten this squared away. I have done tons of research and have done non stop reading and all i can come up with is no one is right when it comes to ventilation. Its nothing but argueing over whos math is better...

I understand the cfm's and how that all works, Im just still a little confused on some things.

SO i just recently went into a 4x4 tent. Im using a carbon filter and a 4" inline fan 165 cfm. I have a 400w hps inside on its own, not cooling. I guess my question is do i leave my fan running 24hrs? WHen its on and the lights are on it stays a constant 74 F with humidity at like 40%.At night it's 67 F. SO should i hook my fan up to a thermastat and have it only run when temps reach above say 75? or constantly since when the lights are off i wouldnt get any fresh air in?

I also want to pull fresh air in from a window i have a bracket for my intake ducting to sit in the window. I guess my question is, is my fan strong enough to be pulling this air or do i need a small intake fan? NOTE: The intake ducts are approx. 4-6ft from tent to window.

Any positive comments would be greatly appreciated! Be easy I am still new...

Ya man, go to home depot or any home improvement store and just pick up a little booster inline fan to put in your window. Your temps are primo as is and your RH is spot on aswell. I would leave your fan running 24/7, I always like to have constant fresh air running through the grow room.

by letting ur fan run 24-7 , how long do u think it will last? I;m just wondering...

mines a 6inch 465cfm and runs all the time... I'm just wondering if i should turn it off at lights off so that it might last a bit longer...

nickman said:

by letting ur fan run 24-7 , how long do u think it will last? I;m just wondering...

mines a 6inch 465cfm and runs all the time... I'm just wondering if i should turn it off at lights off so that it might last a bit longer...

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Nearly all centrifugal fans are designed to run 24/7, 365.



OP this article should help you out.

http://urbangardenmagazine.com/2010/07/planning-your-grow/




J

iPACKEDthisBOWL4TWO said:

Ya man, go to home depot or any home improvement store and just pick up a little booster inline fan to put in your window. Your temps are primo as is and your RH is spot on aswell. I would leave your fan running 24/7, I always like to have constant fresh air running through the grow room.

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Thanks for the reply, yea i was lookin at those but Unfortunatly im not educated in electrical work, what do i wire it up too? there's the green and black wire.

And I believe my fan says it runs for 20,000 hours which is like 833 days.

iPACKEDthisBOWL4TWO said:

Ya man, go to home depot or any home improvement store and just pick up a little booster inline fan to put in your window. Your temps are primo as is and your RH is spot on aswell. I would leave your fan running 24/7, I always like to have constant fresh air running through the grow room.

Click to expand...

I do the same thing. I have a clip fan on 24\7 , but then my intake and hood cooling fan are on timers with my light. The more fresh air the better!

Well the booster fan claims 250cfm isn't that bad to have 250 going in and only 165 comming out?

You would want the stronger fans pulling out more air and the smaller fans for circulating the air in and around grow area imo.

htroff420 said:

Well the booster fan claims 250cfm isn't that bad to have 250 going in and only 165 comming out?

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Not if you want your whole house to stink.

In the article it explains everything you need to do.

Booster fans are ok for intakes only.


I personally use a speed controlled 6inch 400CFM fan on my 600w aircooled light. It has a cool air intake and NO grow room air passes through this lighting rig then it exhausts away. Then i have a 5inch 200CFM fan with CARBON FILTER scrubbing the grow room air and exhausting away. I also have 1x5inch passive intake and a 5inch 140CFM PC fan as a powered intake.


400CFM fan runs with lights 12/12
200CFM fan with filter runs 24/7
140CFM PC fan runs with lights 12/12


This allows me precision on temps so that i can hold canopy temps at anything from 18C/65F to 30C/86F. I intake air from within my home .




J

jondamon said:

Not if you want your whole house to stink.

In the article it explains everything you need to do.

Booster fans are ok for intakes only.


I personally use a speed controlled 6inch 400CFM fan on my 600w aircooled light. It has a cool air intake and NO grow room air passes through this lighting rig then it exhausts away. Then i have a 5inch 200CFM fan with CARBON FILTER scrubbing the grow room air and exhausting away. I also have 1x5inch passive intake and a 5inch 140CFM PC fan as a powered intake.


400CFM fan runs with lights 12/12
200CFM fan with filter runs 24/7
140CFM PC fan runs with lights 12/12


This allows me precision on temps so that i can hold canopy temps at anything from 18C/65F to 30C/86F. I intake air from within my home .




J

Click to expand...

THanks man great info! one question If my tent is in it's own room with a window open and an oscilating fan up their moving it around the room do i really need active intake? I exhaust across the house so all air in that room is essentially from outside. I was going to hook up ventilation to the window but im thinking this is overkill. i may just leave it open and blowin around the room...

if you are exhausting into the room that your tent is located in, then you are just recirculating old Co2 depleted air around.

a few simple things to remember .
1. exhaust ALL old air away from grow area.
2. bring in new Co2 enriched air.



This is how my system runs.

GROW LOCATION - spare bedroom closet
EXHAUST LOCATION - chimney stack
COLD AIR INTAKE LOCATION (LIGHTS) - just under my roof line , ducted from above the closet in attic space
AIR INTAKE LOCATION - passive and powered mounted into closet door pulling ambient house air into the closet

So with it setup like this i can choose to slow down or speed up my 400CFM fan to tune temps or increase/decrease the ambient temp of my home .




J

If your temps are 74/67, why are you concerned with a bigger fan? If anything you need a fan speed controller to slow it down and raise temps about 5%.
That tent could handle a 1000W lamp. Only then should you think about bigger fans.
Your idea about bringing in fresh air from the window is sound. More CO2 enriched air will definitely increase growth rates. Just leaving the window open should be enough, though in August there may be some cooling issues.
If you opt for the 1000W you'll probably need to consider two fan circuits. One to cool the lights and one for fresh air exchanges. Your existing fan would be enough for the latter and a 6in Vortex should handle the light.
Jondamon offers some solid advice here. Ideally you would want a fan controller that would slow the fan way down in the dark cycle. This would keep fresh air circulating and eliminate any smell issues.
Fred

fred flintstoned said:

If your temps are 74/67, why are you concerned with a bigger fan? If anything you need a fan speed controller to slow it down and raise temps about 5%.
That tent could handle a 1000W lamp. Only then should you think about bigger fans.
Your idea about bringing in fresh air from the window is sound. More CO2 enriched air will definitely increase growth rates. Just leaving the window open should be enough, though in August there may be some cooling issues.
If you opt for the 1000W you'll probably need to consider two fan circuits. One to cool the lights and one for fresh air exchanges. Your existing fan would be enough for the latter and a 6in Vortex should handle the light.
Jondamon offers some solid advice here. Ideally you would want a fan controller that would slow the fan way down in the dark cycle. This would keep fresh air circulating and eliminate any smell issues.
Fred

Click to expand...

Hey man thanks, Yea after a few days of setup i've realized a few things and i have just purchased a speed controller just for slowing down at night. my light is about 8in above canapy and it stays a steady 74/75 when on so im def not complaining about that!