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Solar Thermal

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Posted by j on February 14, 2012, 1:15 pm
   Anyone doing solar thermal here? Perhaps Morris?

   I've just reworked my Kreamer style pass through collector. 25' * 8'
of south facing collector (+ another 16" on top). Black felt for the
pass through, SunTuf glazing with a layer of mylar underneath for double
insulation. I'm drawing the air out and ducting it into a collector box
and then distributing that into the heating vents. I'm getting about
~16,000 BTUs/hr (20F delta at ~650 CFM) when the sun shines, but I
suspect some unfound leaks.

   I've got the collector divided in half so I can throttle down half
when it falls in shade. The collector sits slightly to the west of due
south and solar gain starts about 3 hours after sun up.

If anyone is working on something similar, I'll post up some pics and
data. There is a lot unknown to me at this point.

One of the other projects has been the solar cabana, which has the roof
(formed of 3/4" 10' irrigation PVC, ie thin wall) glazed in corrugated
polycarbonate with vinyl under. The sides are all single wall vinyl (~8
* 10' footprint). That heats up nicely, well into the 80's on a blustery
40F day, but of course loses heat rapidly at sun down. But during the
day a delight to pour a glass of scotch and image myself in the tropics.


Posted by Morris Dovey on February 14, 2012, 5:48 pm
On 2/14/12 7:15 AM, j wrote:

I'm taking a break from solar thermal to see if I can incorporate a LENR
heat source into one of my solar designs. See bottom of

    http://www.iedu.com/Solar/Electricity/  and

Good. Seal your leaks and work to minimize the delta-T. A large delta-T
means high (re)radiation losses and airflow resistance.

Welcome to the club. Pix and data would be welcome!

You might be very pleasantly surprised by the performance of twinwall
polycarbonate glazing. If you orient the channels vertically, it may
even extend the collection day. :-)

Morris Dovey

Posted by Jim Wilkins on February 14, 2012, 6:32 pm
Do you know how it compares as collector glazing to Suntuf polycarbonate
panels from Lowe's or Home Depot?

I have roofs of Palram Suntuf over cheaper clear PVC that have held up well
to sun, weather and falling branches for several years. Although the
corrugation shapes don't match the pitch is the same and together they will
support at least two feet of snow.

I'm long-term testing what I think is the most economical durable glazing,
after being quoted ~$0 per 4'x8' sheet for the twinwall. PVC alone becomes
quite brittle from UV but one layer of Suntuf seems to protect it.

My house windows have two layers of clear Mylar film on wood frames for
extra insulation, installed in 1981 and still doing fine.


Posted by j on February 14, 2012, 6:58 pm
 On 2/14/2012 1:32 PM, Jim Wilkins wrote:

The Lowes corrugated definitely does *not* have a UV shield.

SunTuf claims something in excess of 99% UV blocking.

Wow, that's pretty good. I have some mylar interior storms that have
been up 3 years and they seem fine.


Ordinary glass is partially transparent to UVA but is opaque to shorter
wavelengths, whereas silica or quartz glass, depending on quality, can
be transparent even to vacuum UV wavelengths. Ordinary window glass
passes about 90% of the light above 350 nm, but blocks over 90% of the
light below 300 nm.[7][8][9]

Thanks for the mylar storm info.


Posted by Jim Wilkins on February 14, 2012, 7:23 pm

It's on only the label side of Suntuf, both on Suntuf UV2:
See Panel Orientation on page 5.


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