On Fri, 18 Sep 2009 05:44:26 -0700, NT wrote:

Would 1 or 2 central heating pumps be sufficient for this? They do
seem to have good life expectancy.

They would but they'd corrode badly in fresh water. Grundfos do one
designed for hot-water boosting, which contains a flowswitch too, to
switch the pump on when water starts flowing (under gravity - so there's
got to be enough un-boosted flow to kick it in). Or an ordinary
double-ended shower pump can be used single ended. Either way the OP
would need to ensure that the little header tank of the cylinder doesn't
empty when the pump is running. Replacing the standard filling valve with
an equilibrium valve (e.g. "Torbeck") may help, as would adding a second
filling valve to further increase the flow.



--
John Stumbles -- http://yaph.co.uk

Thesaurus: extinct reptile noted for its wide vocabulary.