In an earlier contribution to this discussion,
mike ring wrote:

"Set Square" wrote in
:


I've considered the Grundfos Pump Plan - seems very advantageously
priced at plumbworld ATM, and came up with this doc

UPP_Pump_Plan_05_03.pdf

but I don't know where from.

It contains a wiring diagram.

A URL would be *awfully* useful!

http://www.centralheating.co.uk/inde...ewFile&id=6551

I hope it works, took ages to find again,


I can't find any reference to prevention of flow if only one service
is required - if the CH is on ISTM that the pump will pull water
through the boiler, but also tend to pull it back through the HW
circuit.

Otherwise I'm very rempted, the price isn't too outrageous against
one pump and a 3port or two two port valves, and it seems more direct.

I realise 2 pumps in one casing means quite a lot of replacement for
one failure, but I haven't found grundfos pumps bad

mike

Thanks for the link. Looks interesting! May not be too easy for diy-ers to
diagnose if the integrated logic goes wrong.

As far as I can see, you still have two water circuits with a common feed
from the boiler. I can't see any reason why either pump should induce any
flow in the other circuit. However, there is nothing to stop gravity
circulation if either circuit decides to do its own thing.
--
Cheers,
Set Square
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