In-line fans vs. Squirrel cage blowers vs. Inline duct style fans

Ok, so I'm trying to decide on the right exhaust fan for my setup (2.5' x 5' x 7').. I was wondering if any vets had some advice to give me on which type of fan I should buy.. until recently I was just going by cfm ratings, but those can be misleading.. I'm going to have the exhaust be linear to reduce any air restrictions, and ideally, have 8" duct tubing going to a wall mounted register.. here's what I'm looking at now

8 In. 110VAC 500FM In-Line Duct Fan - 3012 at The Home Depot

..but for some reason, it doesn't seem like this could do the job that a can-fan of the same size and lower cfm rating could do... squirrel cage alike.. are cfm ratings always what they seem?? what should i do?
also, there will be a scrubber the air needs to pass through as well, and it will be connected to a cool tube as well

PS Im broke..
thanks

That looks like it would do the job - especially in the winter.

You'll be fine, and I'd advise the inline. You can hook the carbon scrubber to one end to kill the smell, hook the other end to your light to keep it cool. I'm only using a 350 CFM inline with 6" exhaust and it keeps the temps on my 1000w HPS down just fine

I use all in-line in both chambers 4" and 6" and they work well. They pull hard enough to bring the fresh air through about 4ft of duct.

nice, so you guys use inline fans similar to the one in that link? or do you use those "can-fans".. i think can is a company name, but the style is totally differn.. not exclusively for ducts i think... but you think this thing'll work?

I have a fan like the one you are looking at, only the 250cfm but, it pulls the air good when nothing is connceted to it. I mean once you add a scrubber, it does not pull the air. If you decide to get one like this, you see what i mean, once you put restriction on the fan it slows down, and does not give you the full cfm. I have dayton 105cfm that pulls just as hard when hooked to the scrubber as the 250. I Hope this helps

Also, the distance it has to push or pull and the number of bends in ducting decreases CFM.

It looks like a Suncourt fan. I have a 6" hooked up to my 600W. No filters - I like the smell of fresh weed in the morning.

I have one; I can't remember the cfm but it does the job and it's not real huge. Mine is mounted directly on top with a 4" flange and vents outside. The fan is about 12' or so from the grow cabinet and about 8 more feet to the outside.

it's pretty easy to figure it out. you multiply the cube feet of your grow area by three and that will give you the approximate CFM rating so you can exhaust your grow area three times a minute.

So for you it would be: 2.5 x 5 x 7 = 87.5, 87.5 x 3 = 262.5
So a fan with CFM rating around 265 would do the trick for you nicely.

As far as the different styles go, my understanding it the vortex style may be most efficient but i would surmise it might be the noisiest.

Bottom line - any fan that does the job is the right fan.

I should add that a properly rated fan in a properly sealed room will easily create a vacuum in your grow area so remember to put some passive intake holes (with a properly rated fan there is no need to use an intake fan).

email468 said:

I should add that a properly rated fan in a properly sealed room will easily create a vacuum in your grow area so remember to put some passive intake holes (with a properly rated fan there is no need to use an intake fan).

Click to expand...

right on, thats what i plan on doing.. thanks

yeah those loose power real quick once things are hooked to them, i would suggest saving up for a decent inline fan such as a fantech, a 4 inch one would overpower one of those any day of the week once you hook some duct to it

I have that same fan it works fine pulling air through my carbon filter