IMM wrote:

"Ed Sirett" wrote in message
...

If you decide to go the 3 port way - be strongly advised that the
diveter valve variant (either but not both CH and HW) - has been found
wanting by many.

This new to me. A 3 port diverter is as simple as a two port. They use the
same heads.


I don't mean to imply that there was a reliability issue. As you say the
heads are the same as a two port unit. What I mean is that people are
unhappy with a system that cannot simutaneously run the heating and the
water!
More than once I have been asked to 'fix' a system with a diverter valve
that the owners perceived as broken, and as you know, the customer is
always right.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html