Is the fan big enough?

Pureblood89

Well-Known Member
Is a 440 CFM Inline fan enough to cool a single 1000w hps (connected via cool tube/hood) in a 160 cubic foot space? I've heard you want to vacate all the air in your grow space at least once per minute, this will vacate all the air 2.75 times per minute or once every 22 seconds. Is it enough?
 

Pureblood89

Well-Known Member
Is the fan mounted directly to hood? How long is the ducting attached?
From the ground to the ceiling is only 95" and I'll run in a few feet through the crawl space and connect it directly to bathroom fan vent. I'm guessing no more than 16' of total ducting.
 

DDub

Well-Known Member
From the ground to the ceiling is only 95" and I'll run in a few feet through the crawl space and connect it directly to bathroom fan vent. I'm guessing no more than 16' of total ducting.
That stretch of ducting is a decent amount, had you said 5-6' I would've said it could be enough. But my mind tells me 440 isn't enough in this case. It's always better to have more CFM than less and use a variable speed controller if necessary. If it were me I'd go with 600-700 CFM at a minimum. I'm guessing you're just running the hood open ended on one side? What do you have for an intake?

This math won't directly apply because of the air cooled hood but the general CFM math can give you an idea of requirements on passive Intake size and Exhaust CFM. It's old and from 09' but still good info.

https://www.rollitup.org/t/ventilation-101.154722/#post-1997937
 
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