Ventilation; supply and exhaust

N

NEmedgrower

Active Member
Hi everyone, maybe one or some of my fellow horticulturalist can help me. I've been searching all over with some luck but not exactly the knowledge I'm looking for. I'm finishing up my new indoor garden. The dimensions are 4'x6' with 8' ceiling, I framed out all the walls, insulated the walls and ceiling, installed a
Dri-core floor and hung 1/2" plywood on the walls and ceiling. I finished off the walls with a layer of 1/4" insulation board that has a metallic mylar type film on the front and back sides. I'm not overly concerned with temperature as I'm using HLG and Growmau5 LED's. I have a portable AC unit in the room and a fan forced heater to keep the temps in check. I'm not running a sealed room as I'm not using any alternative CO2 sources. I have a 6" ACinfinity T6 fan with a Vivosun carbon filter exhausting the air in the room. The fan comes with a humidity and temperature speed controller. As for my fresh air intake, that is where I could use some assistance.

Here's where you all come in

Intake:

- I want to filter the air coming in.

- What size air intake should I make?

- Can a filtered air intake be passive? (this would be ideal)

- What size fan would be needed if an active intake is required?

Exhaust:

- Should I allow the fan to be controlled via the included Humidity/Temp controller?

or

- Should I have the exhaust constantly run or run it off a timer on a schedule?


Thanks for all the help, I appreciate and respect it all.
NEMG:bigjoint:​
 
Your grow room exhaust, with carbon filtering, should be run 24 / 7, and the rate of speed to use for your exhaust fan should be 15% less than whatever the flow rate is for your carbon filter. I use that "15% less" because the environments humidity even at 55% RH will lessen the overall filtering effectiveness of a carbon filter, so running your exhaust fan at 15% less than your carbon filters effective flow rate will help it trap more contaminants because the air being pulled through the carbon filter will move at a 15% slower rate thus giving the carbon filter more time to trap more contaminants. And as for your intake, if you are not running Co2, then a passive intake is the way to go, but make sure you have at least one fan near the passive intake that can push some of that incoming air to the opposite side of your grow room because if you don't do that you will create stagnant air spaces in your grow room because any air that is pulled in through the passive intake will take the path of the least resistance to the carbon filter / exhaust fan, that has created, and is always maintaining that passive intake. Also I think your ACinfinity fan is only rated for something like 350CFM(s), so I would run it always on high because you want to at least exchange the air in your grow room (2) times a minute, which a 6" ACinfinity fan really can't do for your size space (4 x 6 x 8 = 192 x 2 = 384CFM), but its rating is pretty close, (350CFM), so I would still use it. Also the carbon filter for your size area, should have a rating of at least 400CFM! < Why? Because a 400 CFM rated carbon filter minus the 15% to compensate for humidity effectiveness would match your exhaust fan perfectly ( 400CFM carbon filter - 15% = 340CFM filter flow rate) which would be right in the range of what your ACinfinity fan supports (350CFM)!
 
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piratebug said:
Your grow room exhaust, with carbon filtering, should be run 24 / 7, and the rate of speed to use for your exhaust fan should be 15% less than whatever the flow rate is for your carbon filter. I use that "15% less" because the environments humidity even at 55% RH will lessen the overall filtering effectiveness of a carbon filter, so running your exhaust fan at 15% less than your carbon filters effective flow rate will help it trap more contaminants because the air being pulled through the carbon filter will move at a 15% slower rate thus giving the carbon filter more time to trap more contaminants. And as for your intake, if you are not running Co2, then a passive intake is the way to go, but make sure you have at least one fan near the passive intake that can push some of that incoming air to the opposite side of your grow room because if you don't do that you will create stagnant air spaces in your grow room because any air that is pulled in through the passive intake will take the path of the least resistance to the carbon filter / exhaust fan, that has created, and is always maintaining that passive intake. Also I think your ACinfinity fan is only rated for something like 350CFM(s), so I would run it always on high because you want to at least exchange the air in your grow room (2) times a minute, which a 6" ACinfinity fan really can't do for your size space (4 x 6 x 8 = 192 x 2 = 384CFM), but its rating is pretty close, (350CFM), so I would still use it. Also the carbon filter for your size area, should have a rating of at least 400CFM! < Why? Because a 400 CFM rated carbon filter minus the 15% to compensate for humidity effectiveness would match your exhaust fan perfectly ( 400CFM carbon filter - 15% = 340CFM filter flow rate) which would be right in the range of what your ACinfinity fan supports (350CFM)!
Click to expand...

Piratebug thank you so much, very informative and easy to follow. As far as the passive intake goes with keeping the negative air pressure I know the rule of thumb is the intake should be twice as large as the exhaust but do you think two 4” passive intake vents would be enough to match the one 6” exhaust?

Also

Would filtering the passive incoming air through some basic HVAC filters be adequate?

Thanks again!
 
I went with 3 times the sq/inches,so 6" is radius sq x 3.14 about 28 sq inches.So say 75.I made 3 openings all in different spots that add up to 75 sq".Works for me, my room is pretty sealed up to control smell.
Air filter can be anything,car or hvac.Make them easy to remove for cleaning.
Filters restrict air so thats why I went with 3x.With no filters on the passive openings you could probably go with 2x .

edit to add my room is constructed the same way,pretty air tight.
 
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myke said:
I went with 3 times the sq/inches,so 6" is radius sq x 3.14 about 28 sq inches.So say 75.I made 3 openings all in different spots that add up to 75 sq".Works for me, my room is pretty sealed up to control smell.
Air filter can be anything,car or hvac.Make them easy to remove for cleaning.
Filters restrict air so thats why I went with 3x.With no filters on the passive openings you could probably go with 2x .

edit to add my room is constructed the same way,pretty air tight.
Click to expand...

Myke.

What type of filters do you use on your intake?

and

You have 3 - 6" passive intake openings?

Thanks :bigjoint:
 
Furnace filters over my passive intakes. I have a 5”x5” sq hole at the top one about waist high. Then another on the floor. There just framed in squares of various sizes. The room is so tight that when I close the door. The filters get pushed into the holes. I use an air cleaner from my truck for my outside air return
 
You can run scrubbers in the room to control odor when a ventilation system needs to stop. Can't have it run 24/7 if it's -20 outside.

Might look at dust shrooms to filter the intake.
 
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