What fan to vent a 40 ft3 box - 250W hps

Bawzer

Active Member
Hello everyone!

So, I have a question about which fan I should use to vent my cabinet. The cabinet itself is 2.5ft * 2.5ft * 6.5ft. The reason it's so tall is because it's basically an old closet I slightly modified. Anyhow, inside is a cool-tubed 250W HPS and with the current setup, the temperature in the grow box is around 84 fahrenheit, - a bit too warm for my liking. The room the cabinet is in has no windows, so I thought about venting the hot air outside the house - but to do that, the air would have to run through 20 feet of ducting with around 5 bends, as well as a carbon scrubber, as I don't want any smell escaping the house. The fan would be pulling air out of the cabinet, then pushing it through the rest of the ducting outside the house.

Now I'm wondering - what type of fan should I use, and just how strong should it be? If need be, I could use a booster fan somewhere in the ducting run, as I can get them quite cheap. Below, I've attached a poorly (not to scale) made diagram of my cabinet and the whole ducting run. I've thought about the duct run a lot and it is pretty much as short as it can get. I can't get rid of any of the bends, nor can I make it any shorter.

So, if anyone could advise as to how strong of a fan I should get (200 CFM inline, or even more?) or if such a run is even viable without dishing out a couple of hundred bucks, the help would be greatly appreciated! Thank you all in advance :).diagram.png
 

Bawzer

Active Member
Hey, thanks for the response! That looks like a good deal, but unfortunately, I can't get the one you linked shipped over here (not from the States - I'm in Europe). On that note, I found a similar fan from a different brand but without a speed controller - is it possible to add a speed controller to any fan, or do they have to be designed that way in the first place? (Not much of an electrician myself) :p

EDIT: I also just found a 325 CFM fan with a speed controller at a local shop for roughly 75 USD. Since everything I would order from ebay or amazon would cost a fortune to ship, I'm actually leaning in this direction right now, but am a bit sceptic if 325CFM is enough for what I'm trying to do? Opinions? :)
 
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