On Mon, 26 Mar 2007 11:42:11 GMT someone who may be "Alan"
wrote this:-

I plan to install a new twin-coil solar HW cylinder soon, and plan to
convert the CH system from gravity-fed to fully pumped at the same time.
(Solar coil to be utilized at a later date) [snip]

I plan to utilise the original pipework where possible but move the CH pump
to upstairs and install a motorized valve to divert flow between CH and HW.
I'll also fit a cylinder stat.

It is often simpler to add a pump to the former gravity circuit and
leave the central heating pump where it was. These pumps can then be
controlled by a thermostat and time clock as appropriate.

The only major thing to watch is that the gravity circuit was often
used as an expansion pipe and this must not be interfered with.

I *could* also use a motorized valve to create upstairs & downstairs zones
if worthwhile.

Depending on the arrangement of the building it can be better to
have north/south zones rather than top/bottom. However, this very
much depends on how rooms are arranged in the house.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54