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    On 3/13/2012 8:42 PM, Clarke Olsen wrote:
    <blockquote
      cite="mid:%3CAB777798-D048-4512-8ECA-D0033CFD6DA7@fairpoint.net%3E"
      type="cite">If drain-back occurs within a closed system, somewhere
      in there is a void equal to the volume of the collectors...
      <div>Doesn't sound efficient.<br>
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                <div>Clarke Olsen</div>
                <div>373 route 203</div>
                <div>Spencertown, NY 12165 </div>
                <div>USA</div>
                <div>518-392-4640</div>
                <div><a moz-do-not-send="true"
                    href="mailto:colsen@fairpoint.net">colsen@fairpoint.net</a></div>
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    </blockquote>
    <br>
    The diagram on their website shows how it works: <a
      href="http://old.wagner-solar.com/wagnerUS/SW/04/09secusol.php">http://old.wagner-solar.com/wagnerUS/SW/04/09secusol.php</a><br>
    Part of the heat exchanger runs with a mix of air and water in it,
    but there is still hot collector water running through that part of
    the exchanger, so maybe the efficiency penalty is not that great?<br>
    Its unusual for a drain back system to use a serpentine collector --
    I wonder if that's how they get the collector volume low enough to
    make the part empty heat exchanger to work?<br>
    <br>
    Seems to me where it misses the boat is that like most of the
    commercial systems it costs about $8000.   I don't think that a
    significant number of people are ever going to want to pay $8000 up
    front to save$300 a year?<br>
    <br>
    I like my $1000 system better, and it also does not have a separate
    drain back tank :)<br>
    <a
      href="http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm">http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm</a><br>
    <br>
    I think the Fafco deserves some credit for innovation on their pool
    heating collector based domestic solar water heater -- it at least
    tackles the cost of system issue.<br>
    <br>
    Gary<br>
    <br>
    <br>
    <br>
    <br>
    <br>
    <br>
    <blockquote
      cite="mid:%3CAB777798-D048-4512-8ECA-D0033CFD6DA7@fairpoint.net%3E"
      type="cite">
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          <blockquote type="cite">
            <br>
            <div class="gmail_quote">On Tue, Mar 13, 2012 at 1:06 PM,
              Sacie Lambertson <span dir="ltr"><<a
                  moz-do-not-send="true"
                  href="mailto:sacie.lambertson@gmail.com">sacie.lambertson@gmail.com</a>></span>
              wrote:<br>
              <blockquote class="gmail_quote" style="margin:0 0 0
                .8ex;border-left:1px #ccc solid;padding-left:1ex">
                <font><font face="verdana,sans-serif">This sounds very
                    good to me:<br>
                    <br>
                    <a moz-do-not-send="true"
href="http://www.buildinggreen.com/live/index.cfm/2012/3/13/German-Innovation-in-Solar-Water-Heating"
                      target="_blank">http://www.buildinggreen.com/live/index.cfm/2012/3/13/German-Innovation-in-Solar-Water-Heating</a></font></font><br>
              </blockquote>
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