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style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">Thanks Laren</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">The info on fan for thermo-siphon air collector control
and temperature is exactly what I was looking for.</FONT><SPAN
style="mso-spacerun: yes"><FONT style="FONT-SIZE: 16pt">
</FONT></SPAN></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt"></FONT></FONT></SPAN> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">Laren's comments:</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">Okay....So you may not be building a Solar air
heater.<SPAN style="mso-spacerun: yes"> </SPAN>What
will</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">you be using as your absorber?<SPAN
style="mso-spacerun: yes"> </SPAN>What kind of "plastic" will you
be</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">using?<SPAN style="mso-spacerun: yes">
</SPAN>Polyethylene is transparent to IR, so only has an Rvalue
of</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">around 0.83<SPAN style="mso-spacerun: yes">
</SPAN>TwinWall polycarbonate (also "plastic") can have</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">an Rvalue of R2.<SPAN style="mso-spacerun: yes">
</SPAN>With your partial sunny situation, that can</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">make the difference between heat and no
heat.</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt"></FONT></FONT></SPAN> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">My comments:</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">I do take pause per your input.<SPAN
style="mso-spacerun: yes"> </SPAN>I am proposing to use 6mil poly that we
purchased for a hoop house a few years ago.<SPAN
style="mso-spacerun: yes"> </SPAN>This is unused off the same roll.<SPAN
style="mso-spacerun: yes"> </SPAN>I called the supplier and learned it has
a solar transmittance of 92%.<SPAN style="mso-spacerun: yes"> </SPAN>I had
assumed all the insulating value was similar to a single layer of glass where I
thought all the insulating value was the air film on each side.<SPAN
style="mso-spacerun: yes"> </SPAN>Does solid glass material actually have
insulating value?<SPAN style="mso-spacerun: yes"> </SPAN>In any case, it
does trap and convert light to heat in the hoop house that I am sure is not very
tight.<SPAN style="mso-spacerun: yes"> </SPAN>My proposed installation
would be much tighter.<SPAN style="mso-spacerun: yes"> </SPAN>I have dark
wood siding that should absorb light to convert to heat.<SPAN
style="mso-spacerun: yes"> </SPAN>Behind siding is a 3/4" air space over
continuous 3" rigid insulation.<SPAN style="mso-spacerun: yes"> </SPAN>The
reason I thought it might produce a significant amount of heat is that I feel
the heat at my South facing windows.<SPAN style="mso-spacerun: yes">
</SPAN>The intention is to only circulate air during the productive times which
you advise to cut on fan circulating air into room at 90F and cut off at
80F.<SPAN style="mso-spacerun: yes"> </SPAN>At night it will get cold fast
with no thermal mass <SPAN style="mso-spacerun: yes"> </SPAN>and warm up
quickly when sun returns.<SPAN style="mso-spacerun: yes"> </SPAN>This
would be outside the thermal envelope and therefore not subtract heat from the
house.<SPAN style="mso-spacerun: yes"> </SPAN>This is the advantage over
passive windows are thermally weak areas in thermal envelope.<SPAN
style="mso-spacerun: yes"> </SPAN>The big unknown is how much do the tree
branches diminish the solar gains.</FONT><SPAN style="mso-spacerun: yes"><FONT
style="FONT-SIZE: 16pt"> </FONT></SPAN></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt"></FONT></FONT></SPAN> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt; LINE-HEIGHT: 13pt"><SPAN
style="FONT-FAMILY: ; LINE-HEIGHT: 18pt"><FONT face="Times New Roman"><FONT
style="FONT-SIZE: 16pt">Eli </FONT></FONT></SPAN></P>
<DIV><FONT face="Times New Roman"><B><FONT
style="FONT-SIZE: 12pt">LarenCorie</FONT></B><FONT style="FONT-SIZE: 12pt">
</FONT></FONT><FONT style="FONT-SIZE: 12pt"><A
title="[Greenbuilding] Power Vent for Solar Air Heater"
href="mailto:greenbuilding%40lists.bioenergylists.org?Subject=Re%3A%20%5BGreenbuilding%5D%20Power%20Vent%20for%20Solar%20Air%20Heater&In-Reply-To=%3C669B2AA3960E4DF8A12F1910EB5A3FC4%40LarenPC%3E"><FONT
face="Times New Roman">LarenCorie at axilar.net </FONT></A><BR></FONT><FONT
face="Times New Roman"><FONT style="FONT-SIZE: 12pt"><I>Thu Sep 19 13:33:29 MDT
2013</I> </FONT></FONT></DIV>
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<PRE><FONT style="FONT-SIZE: 12pt">Laren</FONT></PRE><PRE><FONT size=3>Thanks for info. This is exactly what I was looking for. I do take pause at the discussion about the effective R value and transmittance. I am </FONT></PRE><PRE><FONT style="FONT-SIZE: 12pt"></FONT> </PRE><PRE><FONT style="FONT-SIZE: 12pt">From: "conservation architect" <<A href="http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org">elitalking at rockbridge.net</A>>
><I> Can any on the list recommend a through the wall power vent to
</I>><I> achieve active flow in air heater. If not satisfied with the production,
</I>><I> I will remove and reuse the materials. I would like it to activate when
</I>><I> 80F is achieved that reduces the outward heat losses of increasing
</I>><I> to 90F before passive flaps can work. Motorized damper for
</I>><I> return air may also be useful.
</I>
Hi Eli;
You do not want the fan to activate at 80F. When the fan starts
its will lower the collector temperature. You are better to have it start
at 90F (or more) and have the fan drop the collector temperature to
80F or so. Use a cooling snap switch. It will have an on temperature
that is higher than its off temperature, so that when the fan drops the
temperature, it will not turn it off until it truly can not supply useful
heat.
Use the fan on the lower end, so that it remains cool. If you can put
a passive backflow damper there too, fine. But, if you have to fit it
all within the depth of a wall, you might need to put the backflow
damper in the top vent. Depending on the collector size and the
capacity of the air mover, you might use a bathroom or kitchen
vent fan, that has a noise rating. Noise can be an important
aesthetic and customer satisfaction factor, for simple, through
the wall type, Solar air heater.
><I> I am putting plastic over the parts of the South wall that are
</I>><I> not windows. Because I live on a steep hill in a wooded site,
</I>><I> I am not sure about the reduction in solar available. However,
</I>><I> from my South windows, I know that I feel that warmth. I am
</I>><I> framing such that if it proves affective, I can replace plastic with
</I>><I> permanent glass when plastic wears out. If it proves not adequately
</I>><I> productive, I will dis-assemble materials to repurpose.
</I>
Okay....So you may not be building a Solar air heater. What will
you be using as your absorber? What kind of "plastic" will you be
using? Polyethylene is transparent to IR, so only has an Rvalue of
around 0.83 TwinWall polycarbonate (also "plastic") can have
an Rvalue of R2. With your partial sunny situation, that can
make the difference between heat and no heat.
-Laren Corie-
</FONT></PRE>
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<DIV style="BACKGROUND: #f5f5f5">
<DIV style="font-color: black"><B>From:</B> <A title=elitalking@rockbridge.net
href="mailto:elitalking@rockbridge.net">conservation architect</A> </DIV>
<DIV><B>Sent:</B> Wednesday, September 18, 2013 7:05 PM</DIV>
<DIV><B>To:</B> <A title=greenbuilding@lists.bioenergylists.org
href="mailto:greenbuilding@lists.bioenergylists.org">greenbuilding@lists.bioenergylists.org</A>
</DIV>
<DIV><B>Subject:</B> Power Vent for Solar Air Heater</DIV></DIV></DIV>
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<DIV><FONT size=4 face="Times New Roman">Can any on the list recommend a through
the wall power vent to achieve active flow in air heater. If
not satisfied with the production, I will remove and reuse the materials.
I would like it to activate when 80F is achieved that reduces the outward heat
losses of increasing to 90F before passive flaps can work. Motorized damper for
return air may also be useful. </FONT></DIV>
<DIV><FONT size=4 face="Times New Roman"></FONT> </DIV>
<DIV><FONT face="Times New Roman"><FONT style="FONT-SIZE: 13.6pt">I am putting
plastic over the parts of the South wall that are not windows. Because I
live on a steep hill in a wooded site, I am not sure about the reduction in
solar available. However, from my South windows, I know that I feel
that warmth. I am framing such that if it proves affective, I can replace
plastic with permanent glass when plastic wears out. If it proves not adequately
productive, I will dis-assemble materials to repurpose.
</FONT></FONT></DIV>
<DIV><FONT size=4 face="Times New Roman"></FONT> </DIV>
<DIV><FONT size=4 face="Times New Roman">Thanks Eli
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