Grow Room Ventilation Question

[redclayguerilla]

Hey guys,

Quick question. I plan on growing stadium style (Northern Farmer-style) and will be hanging (2) 1000w HPS bulbs vertically in a 5' wide, 5' long, 7.5 tall room (187.5 cu/ft) and I will need roughly 370cfm. I plan on using an 8" Hyper Fan with an appropriate sized Phresh filter which should be more than enough air movement.

My question is this:

What size of intake hole should I have? I would like to use an HVAC-Style return grill (like you see in most households; 20"x20"), and within the grill, I would like to use a 3M filter that will catch mold spores, pollen, etc. What do you guys think? Should I use just one grill or maybe 2 grills? Any thoughts would be greatly appreciated!!

 

[EastCoast710]

trial and error was my best friend. with the help of a few dudes.. but EVERYTHING U JUST ASKED. is here. in the ventilation 101 thread.. read . and try.

goodluck

 

[redclayguerilla]

Here's what I've came up with

Here's what I've came up with

After doing more reading, and more designing, here's what I have:






Considering the above, I'm thinking I need over 800cfm to pull this off; however, I am still trying to decide what size of intake. I know the ventilation thread says twice the diameter of the exhaust duct; however, this means only 100 square inches of intake. I will be using a 3m filter so I am sure this will slow things down, thus I propose to use a 20x20 intake, which is 4x the suggested intake amount (again, due to the 3M filter).

Thoughts?

Also, does the exhaust ducting have to be insulated? Noise is a concern.

Thanks a lot!!!

 

[Phaeton]

I do it in reverse with forced air intakes and passive exhaust. Bug screens on the intakes and a positive pressure room keeps the plants pest free.

The bud room is ten by ten and eight feet high (800 cubic feet) running 2500 watts.
It currently uses 5000 CFM (free air rating) of intake air to maintain 12 degrees above ambient with a 500 square inch exhaust vent. The two intakes are 300 square inches each pressurized by 20" fans rated at 2500 CFM.
Opening the exhaust to more than 2000 square inches (15 square feet) will keep the room within 4 degrees of ambient.

Ambient comes from a twelve by fourteen lung room, and this being Alaska the cooling is provided by a blend door on the window (hence the bug filter). Inverted lighting for a month every year during solstice is the only labor intensive time.

Isolating the fans and insulating the ducting cuts the noise by 90% but does not translate into any efficiency upgrade. Minimal ducting for airflow leaves a noise level in the next room competing strongly with a television.
In the bud room I cannot hear the phone ring, in addition to the two large intake fans there are another four circulation fans and two ceiling fans. The lung room is not much quieter.

The happy medium between hot still air and leaf damage from fluttering must be maintained throughout all plants in the bud room.
With the same wattage and one quarter the cubic feet (200 versus 800) I do not envy your task.

Keeping the air moving through instead of around the plants is difficult, much depends on intake/exhaust locations.
A pump bottle with a misting head set on fine spray squirted around the room/plants shows the direction and speed of the air. Distilled water hurts nothing and can be used right in the canopies.
Nothing is perfect but large hot spots can be found easily.

 

[stoned-trout]

as big as you want as long as its 2xor more....yeehaw,,I run fans on both on speed controls..passive never worked as good for me...duct silencers ,oversized fans ,insulated ducting ,ect all make it quieter..it doesn't have to be that loud...

 

[redclayguerilla]

trial and error was my best friend. with the help of a few dudes.. but EVERYTHING U JUST ASKED. is here. in the ventilation 101 thread.. read . and try.

goodluck

Thanks eastcoast. It will be trial and error. I'll be sure to post my findings later.

 

[redclayguerilla]

I do it in reverse with forced air intakes and passive exhaust. Bug screens on the intakes and a positive pressure room keeps the plants pest free.

The bud room is ten by ten and eight feet high (800 cubic feet) running 2500 watts.
It currently uses 5000 CFM (free air rating) of intake air to maintain 12 degrees above ambient with a 500 square inch exhaust vent. The two intakes are 300 square inches each pressurized by 20" fans rated at 2500 CFM.
Opening the exhaust to more than 2000 square inches (15 square feet) will keep the room within 4 degrees of ambient.

Ambient comes from a twelve by fourteen lung room, and this being Alaska the cooling is provided by a blend door on the window (hence the bug filter). Inverted lighting for a month every year during solstice is the only labor intensive time.

Isolating the fans and insulating the ducting cuts the noise by 90% but does not translate into any efficiency upgrade. Minimal ducting for airflow leaves a noise level in the next room competing strongly with a television.
In the bud room I cannot hear the phone ring, in addition to the two large intake fans there are another four circulation fans and two ceiling fans. The lung room is not much quieter.

The happy medium between hot still air and leaf damage from fluttering must be maintained throughout all plants in the bud room.
With the same wattage and one quarter the cubic feet (200 versus 800) I do not envy your task.

Keeping the air moving through instead of around the plants is difficult, much depends on intake/exhaust locations.
A pump bottle with a misting head set on fine spray squirted around the room/plants shows the direction and speed of the air. Distilled water hurts nothing and can be used right in the canopies.
Nothing is perfect but large hot spots can be found easily.

Thanks Phaeton. I think I'll do an 8" exhaust with 1 20x20 intake first with a 3M filter in the intake.

 

[redclayguerilla]

as big as you want as long as its 2xor more....yeehaw,,I run fans on both on speed controls..passive never worked as good for me...duct silencers ,oversized fans ,insulated ducting ,ect all make it quieter..it doesn't have to be that loud...

Stoned-trout,
The biggest size insulated ducting I can run to the attic will be 8" so I hope that suffices. I'll only be running (1) T5 light and (2) HPS bulbs so I'm thinking I'll be good. I plan on using a hyper fan giving that a rheostat comes with it. It'll be trial and error I suppose. I'll be sure to report back what works.