"Malcolm Reeves" wrote in message
...

"FrancisJK" wrote in message
...

Has anyone any opinions (silly me, of course you have) about alpha
pumps?

With an alpha, as TRVs close the flow falls but the head does not rise
as in normal pumps. With a normal pump you need a bypass. So normal
pump+bypass gives constant-ish flow rate and return temperature rises
as TRVs close. Alpha gives reducing flow and a lower return
temperature.

Hence Alpha's are a good idea if you have a condensing boiler since
those are more efficient with lower return temperature. But normal +
bypass is probably better for a standard boiler since they do NOT want
a lower return temperature due to the risk of condensing causing
boiler corrosion.


--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
, or ).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and
Power
electronics. More details plus freeware, Win95/98 DUN and Pspice tips,
see:

http://www.fullcircuit.com or http://www.fullcircuit.co.uk

NEW - Desktop ToDo/Reminder program (free)


Hi Malcom,

Great site. I have not heard BESPOKE since that TV show "Never mind the
quality, feel the width". I'll have a look in detail later.

We have a back boiler unit at the moment, which is coming to the end of its
life.

I have an automatic by-pass valve in the circuit, but I'm not sure how to
set it. Any guidance on this appreciated.


Francis