Exhausting Grow Room

[Chris628]

Hi, I been searching for a while to determine what size exhaust fan I need for my grow area.
My room is 5'x5'x7'. Inside I have a 24"x12"24" grow box I'm using for vegging. Also I have a 3'x2'x5' grow tent I'm using for flowering. I want to exhaust air from the tent and run it through a carbon air scrubber and run the exhaust through a dryer vent.

Will I be able to run a small osselating fan in my tent and run it with passive intake? I am unsure what cfm fan to get to run the entire room and through a carbon filter. Sq footage of the room is (LxWxH) 175 so should I multiply that by 3 times and find something around 400-500cfm? I also been reading that 3 times is over kill.

Anyone point me in the right direction?

Thanks
Chris

 

[oldman60]

I would go with at least a 6 inch inline fan. 4 or 5 hundred cfm is good. Don't waste your money on one of those duct booster fans.
You can use the dryer vent but I believe it is smaller so it will restrict the flow some. Even more reason to get a high output fan.

 

[Chris628]

Thanks for the reply...

I just want to make sure 400-500cfm wouldn't be too much and completely deflate the tent.
I don't have to run to the dryer vent, was just a option to remove the old air. I could always just run through the filter and back into the room.

 

[JJ Bones]

I would get around 300-400 CFM, something like this.

I always recommend a fan-speed controller as it's just a great feature to have and puts you more in control. If that is too expensive here is another option.

 

[GreatLife4All]

I just want to make sure 400-500cfm wouldn't be too much and completely deflate the tent.
I don't have to run to the dryer vent, was just a option to remove the old air. I could always just run through the filter and back into the room.

400 to 500 CFM with a speed controller will be perfect for your tent.

Running the vented air directly back into the room is a bad idea for two reasons.

1. Heat - By running the exhausted air back into the (enclosed) room, you will raise the temperature of the room. This will depend on a lot of factors, but when I vented to a different room - my grow room temps dropped by 4 degrees F.

2. Humidity - The most humid air in your environment is that which comes out of the hot tent. Hot air retains more moisture than cold air. If you dump this hot, moist air back into your room - you will be raising the humidity levels. This will put an extra burden on a dehumidifier - or could cause mold if you don't use one.
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For these two primary reasons, it is always a good idea, IMO, to vent the exhaust (preferably) outside or (minimally) to another room in the house.

 

[Autolabor1]

Hi guy's,

Hey I saw this thread and wanted to ask. Do I have to exhaust my grow room? I mean if lights are controlled heat wise in the room and I get enough fresh air from the house environment. Then I should be ok right? Or am I missing something I may need.

My room is 16' x 10' x 8'. Two 600Watt HPS/MH lights. Ceiling fan and 16inch wall fan. Thank you in advance.