"Harry Chickpea" wrote in message
news:42e53afa.13651974@localhost...

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,

Say a 20 foot length of this 4" plastic pipe running under the roof apex in
the attic. Say, 20C in the attic and water inside, coming in from the water
mains at 5C, who long to raise the mass of water to 20C?

How much are you going to gain from solar heat? It may take a while to
payback the cost of the pipe and fitting.

Just out of interest.