What size duct fan should I use?

Hey RIU, I'm starting my first closet grow soon and I need advice on what size of duct fan I should get. A 4" or 6"?


My closet is about 78Lx42Wx85H.
I'm planning on using the fan to exhaust air from above my plants to the door of the closet and out into my room. I'll probably be using about 8-10 feet of ducting.

The 4" does 80 cfm and the 6" does 160 cfm.
There's not much different in price but the 6" is WAY louder than the 4" so I'd much rather have the 4", but not if it isn't going to be effective.
So what do you think?

, GTS

Based on the CFM that you are listing these sound like booster fans and I don't think that either of them is going to do what you want them to.

ow.douglas said:

Based on the CFM that you are listing these sound like booster fans and I don't think that either of them is going to do what you want them to.

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What would you recommend?
I don't feel like paying $80+ for a fan that's gonna be doing so little. Air cooling isn't an issue here I only have a 250w HPS and I'm only gonna have about 8 feet of ducting and the booster fan has dual crimped ends so it would be in the middle of the ducting.

If you want to look at the fan here you go.

, GTS

Grow, do you have the light? Turn it on for a few hours with a thermo in there. What kind of temps are you getting? Don't measure on the floor, go up a few feet where the plant tops will be.

I think this fan can work, you don't need a vortex to exaust hot air of a closet. If you can handle the 160cfm then get this one, more air flow is better than not enough.

I on my 1st setup used a bathroom fan to exaust hot air and everything was fine!

ow.douglas said:

Grow, do you have the light? Turn it on for a few hours with a thermo in there. What kind of temps are you getting? Don't measure on the floor, go up a few feet where the plant tops will be.

Click to expand...

I don't have the light right now but I think I'm gonna be battleing with low temps more than high. It rarely get's into the 50's where I live right now(outside of course), and my closet it always the coldest part of the house. I'm gonna go with that booster fan for now because it's just a little over $20 bucks so if I NEED to upgrade it wont be too big of a deal.

Xan2 said:

I think this fan can work, you don't need a vortex to exaust hot air of a closet. If you can handle the 160cfm then get this one, more air flow is better than not enough.

I on my 1st setup used a bathroom fan to exaust hot air and everything was fine!

Click to expand...

Nice! That's good to hear I just want to keep it relatively simple and a $80+ dollar FAN is anything but that IMO.

Thanks for the reply and happy growing!