Do I need a surface fan?

I've read through the old posts, so I would just like some opinions on my idea. I'm getting a 16" split-tube dob soon (have 12.5 split now), and I'm curious about surface fans and which way the fans should point (I agree with Floyd's onto the back setup).

Currently I use three standard, 80mm DC fans at the rear, and will do the same on the 16". Is it worth it to install a small 1.5" fan to blow in across the mirror? Or is it better to have it blow out? Lastly, should it be mounted on the top of the scope, since that's where the heat will go?

I'm confused, some people have fans which blow out the back, most blow in....which is better?

Here is my thought on how I will setup: one 1.5" fan on the left blowing across the mirror to a 1.5" on the right sucking it out, and three 80mm fans blowing onto the mirror from the rear. The cool air hitting the mirror will go up and get caught by the side blowing fans and go out. Just my guess.

Any help would be greatly appreciated.

Clear Skies,

Guy

This post was modified on 7/17/2006 8:48 AM



Thread:

Hi Guy,
With a solid tube, split-tube or not, I would suggest that the fans be mounted to a plate that closes the end of the tube and that they blow inward. This forces the air past the mirror and sets up a great scrubbing vortex on the front side. With 3 fans you should have a very good cooling flow and front vortex. Seal the plate as much as possible, just leaving opennings for the collimation screws if necessary.

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