Inline blower flow - Air direction

[Randyb]

Is there any difference in end output if you're using an inline fan to pull air, (vacuum) instead of pushing the air (Blower) when you using closed hoods.

I was told by a shop owner that the output is severely reduced when pulling the air through hoods but he couldn't explain it convincingly enough to me exactly why.

Do to space restrictions I've always pulled the air from outside, through ducting, my hoods, then fan and blew it outside through a very short run of ducting, out another vent in the opposite side of my room. Seems to work well. Whats your thoughts.

 

[Jsän]

Hey Randy, i am far from an expert but i think i have your answer.

It is more efficient to Pull (vacuum). Less load on your fan, easier on your ducts etc.
it has to do with fluid dynamics and the path of least resistance.
By blowing through your ducts you create turbulence. in a sense, you end up blowing against yourself.

Now having said that the "vacuum" is more efficient, the air spends LESS time on/around the bulb. Which means that it may actually COOL better to Push air across the bulb. Which is what i think your hydro guy was meaning. The turbulence that we dont want in the duct works in our favor in the hood.. BUT, just after the hood, heat exchange will be gimped again by "back pressure"

in the end, id say it is best to have your In-line pull through your rig... and a duct booster on the hoods intake..blowing on the bulb. :)

 

[Randyb]

thanks Jsän

I thought the same thing. The hydro guy analogy for his idea was using a supercharger on a race car, forcing the air through the hoods. I know a little about engines and supercharger setups and although our goal is to force air, it 's through some stainless tubing with almost 0 restrictions on a very short run with the fin head spinning around 70,000 RPM's. Two very different animals. I'll keep doing what i've been doing. Thanks:)

 

[hiboy]

I like the idea of using an inline fan and a regular vortex fan, one at each end. I can actually see the lining of the xxl magnums moving from such force.
hiboy