Passive intake

[Dion]

Please can someone help me.

I've got a room 2.4m x 2m active growing area is 1.17m x 2m

Running 4 x 600watt lights and the room is hitting 30c now I've got a 12" RVK 1,300M3/HR Fan running in there but I've got a 6" passive intake coming from the loft with ducting from the hole going down the side of the soffit vent.

I think the heat is due to not enough fresh air coming in.

How many passive intakes do i need I don't want positive pressure I was thinking another 6" hole in the door of the grow room?

Any thought?

 

[HigherTheHigh]

What is the temp of the room the tent is sat in?

 

[Dion]

What is the temp of the room the tent is sat in?

Hello, It's a whole room no tent walls are lined with panda film etc.

 

[Dion]

What is the temp of the room the tent is sat in?

Temps outside the room ie in the house is about 19c at the moment, This is why I think there is not enough air getting in.

 

[HigherTheHigh]

Got yeah,

I have sometimes seen people cut whole in doors one at the top to remove hot air and one at the base to let cool air in, if you can't supply a feed of fresh cool air in have you thought about using Co2?

 

[Dion]

Got yeah,

I have sometimes seen people cut whole in doors one at the top to remove hot air and one at the base to let cool air in, if you can't supply a feed of fresh cool air in have you thought about using Co2?

I've got a 12" hole in the celling for outake just not sure on the intake if 6" hole in the door would be enough for such a big fan.

I would need to run a sealed room to run the Co2, I would love to but I've got 4 months left at this place before i move into my new place.

 

[SmokeLake]

You need your passive intakes to be that passive which Ive found means at minimum triple the area or more. My tent just for example with ex fan using 4” still pulls a negative pressure on med speed with 3x4” passive intakes. You may consider getting an inlet booster fan to cycle the air in your room quicker and of coarse observe the laws of thermal convection pipe cool air to the floor and draw off the top. Hope this makes sense.
Grow Hard!!

 

[Bush Doctor 77]

Welcome. 2400W is a bunch of heat. A 6" inlet should help a lot, but I am no expert. Have you got speed control for your 12".

 

[Dion]

You need your passive intakes to be that passive which Ive found means at minimum triple the area or more. My tent just for example with ex fan using 4” still pulls a negative pressure on med speed with 3x4” passive intakes. You may consider getting an inlet booster fan to cycle the air in your room quicker and of coarse observe the laws of thermal convection pipe cool air to the floor and draw off the top. Hope this makes sense.
Grow Hard!!

I've got my fan running full power a lot of air movment. Do you think a 6" fan 420m3/hr will help on the inlet.

I've got 1 16" floor fan running to mix the air about.

 

[Dion]

Welcome. 2400W is a bunch of heat. A 6" inlet should help a lot, but I am no expert. Have you got speed control for your 12".

Yes got one online, I need 1,100M3/HR to refresh the room every min but now I've got it runnig the full 1,300m3/hr and it's pulling mad but I think i need to have another inlet of fresh air as the neg pressure is making it hard to close the door ha ha

 

[Dion]

So here is my outake going into the celling.

 

[Dion]

Carbon filter is on the floor at the moment, Will try and hang it in the middle of the room once I've got a pair of hands to help.

 

[TurboBucket]

As noted your passive intake needs to be two to three times as large as your exhaust. You are looking for 1200-1800 cm sq. Larger is quieter.

 

[Dion]

I've got a Iso max 6" fan that I'm going to run for the intake. Will keep the neg pressure i want to keep the smell in

 

[John Wick]

So here is my outake going into the celling.

good morning, being that your exhaust is going into your attic, have you considered a potential mold problem that could be started up there?

 

[SmokeLake]

I've got my fan running full power a lot of air movment. Do you think a 6" fan 420m3/hr will help on the inlet.

I've got 1 16" floor fan running to mix the air about.

If you force air in a slightly lower volume than the exhaust that’s removing the air than you can maintain a negative pressure on the room. Get your filter up off the floor no amount of mixing from a fan will fix the fact your drawing out the cooler air in the room. Circulation is a must but get your inlet low and outlet above the lights that way you draw air up around the lights and remove the hottest air in the room. You should have happy temps and good odour control. Venting into an attic is not a good idea for many reasons depending where you live ect get that exhaust air outside if its not already.

 

[Dion]

If you force air in a slightly lower volume than the exhaust that’s removing the air than you can maintain a negative pressure on the room. Get your filter up off the floor no amount of mixing from a fan will fix the fact your drawing out the cooler air in the room. Circulation is a must but get your inlet low and outlet above the lights that way you draw air up around the lights and remove the hottest air in the room. You should have happy temps and good odour control. Venting into an attic is not a good idea for many reasons depending where you live ect get that exhaust air outside if its not already.

I've going to try and vent out side into a brick vent in the attic. I've got a header tank up there to so was wondering if I direct the hot air into that will be stop moisture from forming in the attic,

 

[SmokeLake]

That should work fine as Im assuming there’s ventilation for the header tank your real issue comes from the grow rooms warm air hitting cold air in the attic and condensation forming.

 

[Weaselcracker]

I used run two 600’s in flowering, with a 12” vent fan. I used to have a 6” passive intake.
I switched it up to a 12x12 square passive intake vent, in an attempt to reduce the fan noise. It helped hugely.
Cooling was ok, but the fan was on a lot and I’d noticed that, as you mentioned, the door was hard to open when the fan was going, and the fan noise level went way up with it closed.

I put a 90°bend in the intake venting, painted black inside against light leaks. On the end inside the room it has a small door or hinged flap with a spring to keep it closed and seal against light and smell.