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re: concrete solar collector feasibility in pnw?
28 may 1998
wrote:
>...many pools do not have a flat bottom... in order to rest on the
>bottom of some pools, your masonry cover would have to... articulate...
it may not fit every pool. i'd be happy to see something that fits a
round pool with a flat bottom, for starters. something made with 4x4
or 4x8' foamboard panels, thin concrete over fiberglass mesh, 4x8'
winterizing pillows, inner tubes, crazy glue, velcro, etc.
>second, crud gets into pools. it will get under your semi-permanent cover.
you might think of this as "our" cover, harry. a cooperative design
experience. seems like the filter and skimmer would still remove the
mobile crud...
>does the pool owner go water spelunking every week when they
>clean the pool?
sounds rather anal. do you sweep the floor under your wall to wall
carpet every week?
>third, how do you propose to protect the edges of the pool from abrasion
>from such a cover, roller bearings?
something softer. i'm thinking the "solar cover" might form a skirt
that's a bit wider than the solid part of the cover, so it would lightly
center the solid part, and reduce evaporation and heat loss around the
perimeter. or the edge might be an inflated pillow ring.
>over time, abraded vinyl will tear...
daily solar collection means slowly moving the cover an inch or three
twice a day, say 500 times a year, so abrasion might be minimal. perhaps
the part that touches the liner walls shouldn't slide at all, just flex,
on a day with no swimming.
>fourth, kids. kids do the darndest things, like dive under pool
>covers for the challenge, walk on covers just to see if it can be
>done, and forget about safety ropes or precautions.
canadians too :-) this might meet the astm spec for safety covers, or
it might be designed as a kid trap, some sort of eugenic experiment.
>the only practical thing your floating concrete covers do is increase
>the amount of insulation available to the top of the pool when solar
>gain is not sufficient to maintain the water temp.
no, they would also collect solar energy, when the masonry's touching
the water, with a little dithering, perhaps, a very small up and down
motion to pump some water between the foamboard and the masonry.
>there are better ways of doing that.
perhaps you can suggest a few better ways.
>if you insist on concrete covers...
no, i don't. i'd be happy to see any sort of practical cover that can
collect sun during the day, and really insulate at night, but it seems
useful to focus on this system for now.
another possibility is a large rigid foamboard cover hinged along the
edge of a rectangular pool, some sort of giant flap with a reflective
underside that opens during the day and closes at night. (aaoogah...)
it might be twice as wide as the pool, and articulate into a parabola
during the day. wind, winches, counterweights, lots of iron...
another possibility is a ring of pvc pipe with a layer of greenhouse
poly film on each side to make a large pillow that's filled with air
during the day and tiny bubbles at night, and sinks to the bottom for
swimming. tiny cold bubbles work as well as fiberglass insulation.
that system seems more elegant, with a lot less material, but it's
also more difficult to design, and we couldn't walk on it.
another possibility is some sort of inflated plastic film floating
greenhouse with a hard floor, like an inflatable tennis court cover,
or the commercially available pool cover domes which have a skirt
attached to the coping and an underwater wet seal. sticking up higher,
that could collect more winter sun, and it would shed snow, and
it might be used for bridge parties, with an airlock door, but
how would you swim in the pool?
thanks for your thoughts,
nick
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