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solardan1959

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Reply with quote  #11 
 Dutch,
   Have you read through the screen section?  You seem to have a pretty good handle on it but maybe you'll pick up some ideas/designs there.
 

Scott Davis

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Reply with quote  #12 
Hi Dutch,

The shorter answer is that yes, I blow basement air through a screen collector similar to the downspout, but on a larger scale.  We have not done any direct, side by side tests of screen to downspout, but the screen appears to be at least as good, probably better, cheaper, easier, quicker and lighter.

Since this is the empty black box thread, if you have questions on the double layer screen, please continue on the thread Dan referenced.

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solarusmc

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Reply with quote  #13 
getting back to the black box design..

I have 4 black box designed collectors installed at my house all kicking butt like we the people.

The ones displayed on builditsolar have the input / out put supply/return holes 'behind' the aluminum soffit material which means hot air absorbed by the aluminum soffit must be pulled out of the box via the backside of the aluminum soffit material.

I'm not sure but could that be a performance issue?

I built my black boxes using aluminum swimming pool material for the absorber, inserted baffles to route/slow down the air flow... and my supply/return holes are visable thru the polycarbonate and mine work beautiful.

In other words I did not cover my supply/return holes with the aluminum absorber.

I suppose I could have added aluminum screen inside before closing them up but honestly I get super air flow and temps over 100 degrees on days that are only 13 degrees ambient outside temps.

I'm using 6 inch diameter (commercial) fans at: 250 cfm.

If anyone would like to see a powerpoint presentation of my latest designed 4 ft x 6 ft dual panels hanging on the side of my house feel free to write me anytime via email ok? web401 @ cox DOT net

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Pat B. Warwick, Rhode Island Rest Assured! Comments and/or suggestions I make here at the forums on 'your' projects as well as my own have all been carefully and scientifically calculated by the 'seat of my pants'
Scott Davis

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Reply with quote  #14 
Actually, your design is a variation on the black box that Gary and I tested (and found to perform significantly worse than other alternatives).  Our black box tests were literally that - black boxes with no absorber at all.  You've added a metal absorber and it would be interesting to compare that to the double layer screen reference standard.  I do believe adding screen would make your collectors perform even better, but the proof is in the testing!
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solarusmc

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Reply with quote  #15 
Hi Scott,

Yes, I think the metal I added for absorber plate makes the big difference.

On my other collectors I built I used regular 'flashing aluminum' from Lowe's... comes on a 50 ft roll... real thin stuff..

but on the latest ones I built I used the smimming pool aluminum side material which was much thicker then the aluminum flashing.

The fact that it's much thicker aluminum may be why I am getting higher temps out of these latest 2 collectors..

Not 100% sure.. but thinking that could be the reason.

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Pat B. Warwick, Rhode Island Rest Assured! Comments and/or suggestions I make here at the forums on 'your' projects as well as my own have all been carefully and scientifically calculated by the 'seat of my pants'
Marino

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Reply with quote  #16 
If one is building a 3'X8 box that is already installed against an existing living room wall, where would you drill out your intake and exhaust flows? Would it be on the bottom with air intake into the box and the exhaust of hot air at the top opposite side back into the living room? And would you need fans to move the air?
solardan1959

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Reply with quote  #17 
Marino,
  As with everything, everybody has different ideas and opinions.  I would keep it simple and do like you said, but probably just have one 4-6" vent in the middle at the top and bottom. I would lean towards a 3"  X 12" vent so that you get pretty good even flow rather than just a round hole in the center but that again is personal preference and plenty of people use a round vent with good results.  The bigger the vent the less you need a fan but a fan will allow you to extract more of the heat.  Long narrow vents most of the width will work pretty well passively with no fan but as the vents get smaller a fan becomes more useful.  Since most people can't have or do not want to cut such large hole the fans come more into play.
  Offsetting the vents to the corners could be used if that's what your build required but does not really do much for performance unless you are going to also use a back and forth channel design and that probably would not help much with a 3 foot wide collector.
 Do not forget to design some kind up back flow protection using a flap or something so the air does not flow the opposite way at night and cool the room down.
  I tend to go with the normal heat rising flow with my designs again so that a fan is optional.

Welcome to the site and good luck.
Dan
Marino

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Reply with quote  #18 
thanks so much Dan. I had just looked at rectangular 3"X12" floor vents at the hardware store. I though that they might be a good way to go, perhaps putting two of them spaced in third and 2/3 positions both top and bottom and using them without a fan at first to see how they work. Including a flap which maybe a can be controlled with a thermostat and snap switch would be great, since I have electricity inside the box.  Your suggestions are all very good and I will take them seriously.


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solardan1959

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Reply with quote  #19 

Marino,

Quote:

perhaps putting two of them spaced in third and 2/3 positions both top and bottom


Sorry, must be late, I have no idea what you mean by that.
I was thinking one on each end, two on each end if you really want the flow.

Dan

Garage_Hermit

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Reply with quote  #20 
Reckon that's what he meant Dan: two at the top & two at the bottom, spaced equally across the width of the box...

G_H

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