At 08:30 AM 2/2/2001, Doug Alcock wrote:
>Hi David --- maybe I'm completely missing the point here. I've been
>putting the
>black side up to the sun thinking that black absorbs the heat better. Should I
>have the clear side up??? Am I about to feel very foolish............?

Yup.  Light passes through water, absorbs in black plastic and warms it,
which in turn warms the water and sets up a convective current to pull down
the cold water to be warmed.  With the heating layer on top you get only
conductive and not convective mixing, takes way longer to warm the whole thing.

d

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"