"FrancisJK" wrote in message
...


I'm now puzzled.

Is it a choice between

Standard pump AND automativ by-pass

against

Alpha Pump AND no by-pass


No. I have a conventional boiler, Alpha pump and an automatic bypass. Plus
4 zones valves run from room thermostats and only a couple of TRVs. This
gives lots of degrees of freedom in setting up the system to operate
efficiently - or in getting it wrong if you don't set it up well.