Re: [APD] Building a new hood

["Wise, Nicholas" <Nicholas_Wise at eon-us.com>]

> Putting one fan blowing in and one blowing out is the 
> equivalent of stacking one fan on the other in terms of 
> airflow. Stacking fans like that does increase the 
> airflow--it's like stacking two water pumps in series; the 
> flow doesn't increase. You would be better off having two 
> fans blowing in or two fans blowing out (parallel) -- that 
> will double the airflow provided there is adequate sized 
> intake and exhaust ports. 

  
> Fans are stacked on personal computer cases sometimes for one 
> of two reasons:  1) to ensure a particular direction of 
> airflow (for example, to ensure that the airflows past the 
> the cpu fan) and 2) to market to overclockers that think more 
> or something is always better.

This is exactly what I was thinking.  When I built a custom MH hood
(much hotter), I wanted directional airflow like in a computer.  I
wanted the air to flow over the bulb and out the other side.  And you
are out of touch with computer modding, since air-cooling is what newbs
use ;).  The newest thing is water cooling with radiators and pumps.
  
> As Nicholas points out, there's no point trying to move air 
> one way at one end unless you have an opening for the 
> opposite air flow at the other.
  
> I've found that vented hoods, along the design of those that 
> AHsupply.com sells do as well passively, by convection, as 
> enclosed hoods with a single fan. I'd try a vented hood 
> first, and add a fan if mere convection proves inadequate in 
> your situation. Passively cooled hoods are much quieter ;-)

Two fans blowing in across the lights w/ vents routed in the top would
be quite efficient for something like PCFs.

-Nick

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