<font><font face="verdana,sans-serif">Well, thanks for the note regarding your experience, Corwyn. <br><br>There are always missing details aren't there? Re the shed reaching ambient outdoor temperature, my shed has a small space heater in it to keep it from freezing. Necessary for the tankless.<br>
<br>Re passive vs active solar, yes you're correct. I apologize for my lack of precision. Was thinking of the difference between PV and panels on the roof. Below is the wiki take on passive. I note pumping glycol obviously isn't part of such a system. How about a drain-down system? I suspect this might fit in the def. of passive. Rhetorical of course but not a bad application for my situation. Pumping the water back up would scotch the passive deal though.<br>
<br>Thanks, Sacie<br>
<br></font></font><p><i>Passive solar technologies include direct and indirect <a href="http://en.wikipedia.org/wiki/Solar_gain" title="Solar gain" target="_blank">solar gain</a> for space heating, <a href="http://en.wikipedia.org/wiki/Solar_hot_water" title="Solar hot water" target="_blank">solar water heating</a> systems based on the <a href="http://en.wikipedia.org/wiki/Thermosiphon" title="Thermosiphon" target="_blank">thermosiphon</a> or <a rel="nofollow" href="http://www.sunnovations.com/content/how-sunnovations-system-works" target="_blank">geyser pump</a>, use of <a href="http://en.wikipedia.org/wiki/Thermal_mass" title="Thermal mass" target="_blank">thermal mass</a> and <a href="http://en.wikipedia.org/wiki/Phase_Change_Material" title="Phase Change Material" target="_blank">phase-change materials</a> for slowing indoor air temperature swings, <a href="http://en.wikipedia.org/wiki/Solar_cooker" title="Solar cooker" target="_blank">solar cookers</a>, the <a href="http://en.wikipedia.org/wiki/Solar_chimney" title="Solar chimney" target="_blank">solar chimney</a> for enhancing natural ventilation, and <a href="http://en.wikipedia.org/wiki/Earth_sheltering" title="Earth sheltering" target="_blank">earth sheltering</a>.</i></p>
<p><i>More widely, passive solar technologies include the <a href="http://en.wikipedia.org/wiki/Solar_furnace" title="Solar furnace" target="_blank">solar furnace</a> and <a href="http://en.wikipedia.org/w/index.php?title=Solar_forge&action=edit&redlink=1" title="Solar forge (page does not exist)" target="_blank">solar forge</a>,
but these typically require some external energy for aligning their
concentrating mirrors or receivers, and historically have not proven to
be practical or cost effective for widespread use. 'Low-grade' energy
needs, such as space and water heating, have proven, over time, to be
better applications for passive use of solar energy.</i></p><br><br><br>