Posted by Bill Kreamer on October 11, 2007, 4:50 pm
Jeff, here is some info on Acrylic, polymethylmethacrylate ("plexiglas,"
used on storm doors). It has excellent UV resistance. Mechanically, it
should stand up well in a vertical air collector. Allow for .050" per foot
expansion. I have also used PETG-UV (Vivak VU)(tougher and more expensive
than acrylic, but less than polycarbonate).
From Altuglas International (Plexiglas® brand):
The allowable continuous service temperature ranges for Plexiglas® G sheet
(180°F to 200°F) and Plexiglas® MC sheet (170°F to 190°F) are sufficiently
high for exterior applications and fluorescent lighting.
Gary, quick question - what was the trade name of the PVC sheet; maybe
-best regards, Bill Kreamer
Posted by Jeff on October 12, 2007, 3:48 am
Bill Kreamer wrote:
Nice to see you around.
I've got 190 SF of double fiberglass screen collector on the south
wall. I used the screen because I wanted to look out the window that I'm
using for the air return. This is fed from a plenum on the bottom that
has 1" holes on the glazing side of the absorber every 6".
But now I'm thinking of going with black felt and simply framing
around the window. Can I go with the cheap synthetic felt or should I
opt for the real stuff? I imagine my collector efficiency will go way up!
I'll look into the plex. Not sure why there is so much PVC out there
except that it must be cheap to make. I used to have a great plastic
shop downtown but they seem to have moved to the hinterlands... At the
bigbox stores they distribute Palruf as PVC (I thought it was acrylic)
from the same people that sell SunTuf.
Posted by Bill Kreamer on October 13, 2007, 4:35 am
"Clothing" or dressmaker's felt is made from polyester fibers, and you can
probably find that easily. Polyester felt will do the job. Perhaps you
could try supporting the felt on a layer of screen, with a dab of silicone
every foot or so, and seal around the edges.
Posted by Jeff on October 13, 2007, 5:34 am
Bill Kreamer wrote:
Will do, and thanks. Hope you are doing well. We need more guys like you!
Posted by gary on October 16, 2007, 1:42 am
Hi Jeff, Bill,
If you make the changeover to black felt, it would be interesting to
actually measure both the flow and temperature rise and see which
arrangement is most efficient and by how much. Blower size and blower
power to maintain enough flow for a modest temperature rise would also
be good to know, but probably hard to measure.
I used 1/8 inch acrylic on my garage door collectors, and it has
worked out fine in that application. The best source I could find was
about twice as expensive per square foot as the SunTuf corrugated
This is just my 2 cents, but if you don't mind working with the
corrugations, I think its hard to beat SunTuf. It has a good UV
treatment and is guaranteed for "life", and also has the 270F
temperature capability, also tough and easy to work with -- all for $
per sqft. My barn collector is going on its fourth season, and it
looks just like it did the day it went up -- no signs of deterioration
of any kind.
If you are willing to get up into the $ per sqft area, dual wall
polycarbonate with a UV treatment would also be a candidate. It gives
more R value, good light transmission, requires less support and looks
very nice. It has become my favorite glazing material.
Bill -- I'm not sure about the brand of the PVC glazing -- I'll check
next time I'm at the place I got it.