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My head is spinning over ventilation issues

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weedlover_89

Member
Hello to everyone, i have a 10x10x10 grow room dedicated to growing and plenty of inline fans to play with! I have:

2x200 CFM fans
3x450 CFM fans
1x1100 CFM fan

I have carbon filters only for the 3x450 CFM fans and the 2x200 CFM fans. I don't have a carbon filter for the 1100 CFM fan and i can't say i am very willing to spend 300 bucks on getting one....

I have one window in this room and i want to use it for intake and exhaust at the same time. There is a door with blinds on the window, a rolling one if you get me. Because winter is coming, obviously, i want to use the lower part of the window for intake and the higher for exhaust.

I want to use 4000 watts in this room (6x600w bare bulbs and 1x400w bare bulb).

I was thinking this:

The 1100 cfm fan will be dimmed to about 600 CFM with a variac and will be used for intake since i don't want to use it with a carbon filter.

So that leaves me with 3x450 CFM fans and 2x250 CFM fans for exhaust (after duct losses and losses to carbon filter, i estimate the exhaust power to about 1200 CFM).

Assuming intake temps of 50-60 temps, do you think this could be done to keep temps at 75-80 F? I know i spit many numbers and much data, i really appreciate any answer you can give me. Thank you in advance.
 
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weedlover_89

Member
And in case i finally decide to give the fking 300 dollars and get a 1100 CFM carbon filter, how would i setup a passive intake? It would have to be massive i think with so many inline fans for exhaust! Experience has taught me that in bigger places a fan for intake can be used and see a difference for sure. Anyone who has gone with passive intakes for such big space?

And how do you light trap it? I know the trick with the ducts in a "s" shape, but i would have to use a hell lot of ducts to do that. And putting dust filters on the ducts, more than i can think of!

Any answer to anything valuable!
 
O

Oti$

You want to exchange the air 2xs/min, and you want your passive intake twice the size as the hole you will be exhausting.
 
O

Oti$

I use, I think, four 8" holes for the passive intake on a couple of my rooms in which I'm exhausting with 12" can fans. To find the area of a circle, I think its radius x pi(2.14). You want the intake twice as big as the exhaust to maintain negative pressure in the room keeping the odors in. If you are using more than one exhaust fan to get the air exchange you require, just figure the total area for all the exhaust holes, then multiply that number by 2 to get the area you need for intake. My 4 8" holes are not exactly double my exhaust, but close enough. I couldn't source two 12" elbows, so I used the 8" ones. Paint the insides of the s shaped ducts to help keep light out
 
Warped1

Warped1

I'm a victim of fast women and slow horses
Veteran
I've only been a micro grower, but I have to agree that a passive intake is the way to go. I've not grown in the past couple of years, but when I get back at it I'll definitely go with a passive intake.
 
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weedlover_89

Member
Thanks a lot for your answers!! :) So much help already, that's impressive!

So, having a 10x10x10 room, going for 2x air exchanges per minute, i estimate it at 2000 CFM! Wow, that's a pretty big number!


The only way i can see exchanging the air at 2000 CFM, is to use all the fans i have available (wtf!!)

And adding all the exhaust holes and then multiplying them by 2, i calculate 72" for intake!! Wtf, the whole window should be an intake in that case!!


Wouldn't active intake be better in that case? Imagine a 72" hole for intake!

Thanks a lot for the useful formulas you posted here! They helped, but at the same time i am dissapointed a bit :(. I don't see it possible and seems i will have to downsize it :(. Everything leads me there if i don't want to spend more and more and more money.
 
Warped1

Warped1

I'm a victim of fast women and slow horses
Veteran
Well like I stated, I've only grown in a really small cab..I'm going to go bigger as soon as I get my own spot, so I may be in for a rude awakening. Let me look around a bit and maybe I can find something else for you, before someone smarter than I does so lol.
 
O

Oti$

Would it be possible to do several smaller intake holes. If you have any DIY skills what so ever, you could make some square holes around the room near the basebordz and cover those openings with ac/heat vents. You can fix those holes in the future with drywall. Two times a minute is ideal, but if the temps stay in line with 1xs a minute you should be good and when you pull a harvest you can invest in a 12" can fan, j think they are about 1800cfm. That's what I use for my 10x10 rooms. Iz your 1100cfm a 10 inch fan? I think sin e winter is coming, you should be able to get away with 1xmin.
 
O

Oti$

Just remember you need to figure the area. For the holes you are working with...google the formulas for the areas of square, rectangle and circles and then make the openings you need.
 
W

weedlover_89

Member
Thank you dude, your help has been precious! Yeah, the 1100 CFM fan is 10". You buy the carbon filters for your 10" and 12" fans or you have made some on your own? I would love to make my own and save some bucks.

Will check the formulas. I was thinking that i could put the 2x250 CFM fans for intake+passive intake holes. I believe that in this way there would be less holes to make. Will check the formulas, thank you very much for your input!

Oh, another issue i have, because of the blinds in my window, if connect the ducts straight to the blinds, there is this "whoosing" sound that can be heard outside. Anything i could do to fix this? I was wondering if there is some soundproofing material that is "breathable" and would not cut airflow to the outside. By that way, i could put it to the window blinds, between the blinds and my exhausts. Don't know if i am comprehensive, sorry.

Winter is coming, temps will be average between 50-60F. Mild winter here...

Here is the only thread i have found, which presents a carbon fillter that is suitable for more CFM. The rest i have seen analyze carbon filters for up to 6" fans.....:


https://www.icmag.com/ic/showthread.php?t=39506
 
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noyd666

THESE ARE GREAT 280 BUCKS IN OZ. SOFTWARE CONTROLLED WITH MOTION FLOW IT AUTO SCANS AND ADJUSTS FLOW OF FANS TO WHAT IS NEEDED, COME IN OF A MORNING AND THERE JUST TURNING OVER,ALSO WORKS THROUGH THE NIGHT FOR HUMIDTY SPIKES. THIS IS IN 5X5 BY ABOUT 8'6'' HIGH, WHEN I USED FAN ON INTAKE ON ITS OWN I USED TIMER 15 ON ETC AND SPREAD OUT OVER N/TIME TO KEEP HEAT IN. THIS ONE IS ON A PHRESH FAN 8'' NEW TYPE, AND 6'' CAN AND INTAKE FILTER = $75 using passive in another room but in summer I have to supplement with 8'' intake fan.
 
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noyd666

should have said my exhaust is running through phresh filter and back into room, scrubbed air back in, no ducting to poke outside.
 
O

Oti$

I made a filter for a six inch fan, and when it was all done I wished I would have just bought a cheap one...gku can find them on the internet for cheap....you get what you pay for though. I just pi ked up a Maximum yield magazine that had an article about building a sound dampener for exhaust fans. I'm sure you could find instructions online as well
 
O

Oti$

Also its best to have your exhaust and intake on opposite sides of the room so the fresh air isn't sucked right out. You can achieve this by either putting your fan/filter on one side and running the exhaust duct across the ceiling to your window or by running ducting from the intake ports to the opposite side of the room so th fresh air coming jn has to travel to the other side of the room before being exhausted. Good luck!
 
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weedlover_89

Member
Hey bro, i have already done those two steps! Exhaust fans are at the opposite side of my intake!

I have also used sound dampeners for all my fans! The results are impressive! I live in a very quiet neighborhood, right now, i have the 3x450 CFM fans running on full blast and i can't hear a thing when i am standing outside 4' away from my window blind!

I made them in this way:

Bought rigid aluminum tube(the lighweight type) 2" bigger than the diameter of the 6" fans. So, it was 8".

Then i bought soundproofing material like this (copopren):

imgres


I rolled it and put it inside the aluminum tube. I taped it with packing tape to sit well. Optionally you can buy a sound barrier material and tape it all around the outside of the aluminum tube too. If you do it this way you will be far more impressed than you would be if you had bought insulated ducting!

I buy only a little bit of insulated ducting to put it on the front and the back side of the exhaust fan (about 1' for each side) because it fits better than the flexible aluminum tube with the copopren inside. From there on, it continues with the rigid tube which has the soundproofing material in it.

I did the same with my 10" fan, only that i could not find rigid tube bigger than 10". I improvised a bit and still the result is very good.

Don't know if i am making sense. Noise is a crucial issue to me since i live in such a quiet neighborhood.

The only thing that troubles me now is whether i should go with passive intake or active intake and how to lighproof it. What do you use in this case? Passive intakes?

If i use active intake, its supposed to be half CFMs of my exhaust?

:tiphat:
 
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