"Andy Dingley" wrote in message
...
On 13 Oct, 05:16, Matty F wrote:

OK, so I'll look out for two containers, and use that expanding foam
stuff between them.

Expanding foam isn't a good insulator - different mechanical structure
to the factory-foamed stuff, much lower performance.

And difficult to get into a restricted space.

My solution to this (solar thermal store) is to switch from a round to
a rectangular plastic tank, then use a constructed box of yellow foam
PIR boards on the sides of it.

A solution suggested to me by someone high up in such things is to build the
box round it and fill it with expanded polystyrene beads. It wouldn't be
perfect but it would be cheap and easy to do.

Nothing's perfect :-)

Mary