Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
Interesting stuff, Paul.  The "geo-thermal" heat pump HVAC system is very popular here in North Central Arkansas.  Here the typical approach is to drill a 300' well with a water well type of rig.  Then they install a PVC or PEX "U", then back fill the hole.  This has the advantage of getting to the water table, so the bottom part of the "U" is immersed in wet back fill.  By about 5' below the surface the temperature of the earth stays at about 50F year around.  This means that heat pumps can work well in the winter as well as in the summer.

I am interested in how your system works out.  It could help me decide what to do for us.  My existing heat pump is at least 20 yrs old and will surely die in another few years.  I am considering about 1 KW of solar panels on the roof of my shop bldg. which faces south and has about a 30 degree slope.  That could protect us against future increases in cost.

How much do your thermal solar bags weigh when they are being used?  How much water do they hold?  That would determine whether my roof structure is adequate.

Looking forward to reports on future progress.

"It is not necessary to have hope in order to persevere."

by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Mon Jun 30th, 2008 at 11:45:35 PM EST
it seems to me. Clumsy, but easily handled. Water might add 7 kg. They are about 1 meter wide by 4 m long, so the weight is spread out to the point where the psi is almost nil.

As far as hold-downs, you use c-clamps on the upper interconnecting pipes, screwed into the roof. Then you screw small eyes between the pads at about the 1/3 and 2/3 points of their lengths and run a rope or strap through the eyes, tied off at the ends. Idea is that the pads expand and contract according to temperature conditions, so you give them some freedom to compensate.

Definitely go water-to-air, when you replace your heat pump. Via well, or trench - or solar water-heating pad - the "ground source" system is the most efficient method.

paul spencer

by paul spencer (paulgspencer@gmail.com) on Tue Jul 1st, 2008 at 11:11:23 AM EST
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