Derek Broughton wrote:

Harry Chickpea wrote:

(Nick Pine) wrote:


We might build a 12'x16' equilateral A-frame with a 4'x12' shallow pond
at the top (view above, in a fixed font) and 2 poly film water ducts
along the north and south edges to avoid wind sliding and overturning...
20 psf makes 208 lb and 1082 ft-lb on each 1' EW slice of the greenhouse,
so we need 12W = 1082 ie W = 90 pounds of water in each foot of duct, eg
1.44 ft^3 of water in a 16" duct.
snip

This might also be a standalone structure in a yard, with the filter pump
that comes with the pool.


Gotta laugh. Note the concept of putting water near the peak of a
triangular prism to absorb and store heat. This wonderous idea is
presented by the same Nickie that pooh-poohed the idea of
inexpensively preheating water for a domestic water heater via the
simple expedient of placing a 4" pipe underneath and along the
ridgeline of a roof. IIRC, his comments were along the lines of what
if it leaks, what if it freezes? Yet, he has no comment or solution
for the same questions about his own Nickie special design.

And your problem is??? In a stand-alone greenhouse, you don't have a
serious problem if it springs a leak. If it's in your house, you sure do.

It isn't my problem. As I pointed out to Nick at the time, a 4" pipe
contains enough thermal mass, and the location is inherently warmer
than the rest of the attic, to preclude freezing in all but the most
extreme climates, and allowing a small cushion of air at the top for
expansion would resolve the issue even if it did freeze. The pipe
would be no more or less likely to spring a leak than any other pipe.
I suggest that you and Nick might want to remember that people have
plumbing and even gasp! bathtubs on the second floors of their
homes, and condos and apartments and office buildings have plumbing
that reaches to the sky. Somehow, they survive.

Compare the likelihood of standard pipe leaking in a properly designed
and protected tempering tank system to the potential for catastrophic
leaks in "a 4'x12' shallow pond at the top and 2 poly film water ducts
along the north and south edges to avoid wind sliding and
overturning.." contained in a minimally protected A frame covered in
plastic. Can you say "BB gun?" Can you say "mouse nibble?" Mice
would find such a structure a nice winter home. Poly film - pipe.
Poly film - pipe. Hmmm.

Nope. I don't have a problem.