"Lurch" wrote in message
...
One more question, would one expect a symphonic flow if there was a
complete
pump failure but the ports on the above valve had opened IYSWIM ?

Is that making music with water?

Not sure what you mean by that, but if you mean making steam, hammer blow
type sounds, and forcing water up into the feed / expansion tank, YES :~(

One pipe form the boiler is VERY hot (can't touch it for more than a second
or two) and the other is not more than warm. This morning there was not heat
in any radiator and the HW hasn't been re heated....