On Fri, 31 Oct 2008 20:33:31 +0000, No-one
wrote:

I have replaced what I thought was a faulty water pump. However, it
does not run when the power is applied. The motorised valves are old
and I am sure the hot water one is dud but the central heating one
worked. If this one also had failed, would this stop the water pump
from switching on?

Quite possibly, the pump is often controlled via a microswitch on the
valve control motor so it only turns on when the valve is open and
turns off immediately it starts to close.

You should be able to open the valve by hand using the manual lever.