I have just been reading the heating controls Wiki page (http://
http://www.diyfaq.org.uk/plumbing/co.../controls.html) and it seems quite
dismissive of the W-plan system. However, if my understanding of
weather compensation in many modern boilers is correct is the W-plan
not perfect given that it prevents simultaneous CH and HW operation
thus allowing completely independent control of the CH and HW
temperatures? The Y-plan, which the Wiki seems to imply is
preferential, would surely negate weather compensated benefits for
those times when both CH and HW are being demanded.

The reason I am interested is that I am considering purchasing a new
boiler, with weather compensation, and will be moving away from my S-
plan system given the potential requirement for pump overrun and
desire for optimum efficiencies. I am thus looking at Y-plan and W-
plan and am viewing the benefits of the W-plan as being somewhat
simpler (less complicated valve, no microswitches/electronics to fail)
and facilitating independent temperature control for CH and HW
operation. The general feeling of the Wiki is putting me off though!

Any comments?

Mathew