Two Separate Pumps

[Johntheo5]

The UPS3 is a very powerful pump, it will circulate up to 13LPM at a head of 4.2M even on its (yours) lowest speed setting, its head will then start falling at increased flowrates but will still circulate almost 22LPM at a 3.0M head. Its unlikely that the head is lower than this when you have both CH&HW on together so I would suggest as a start that you change the pump mode to CP1 (constant pressure) which gives a constant 3.0M head up to 48LPM and see does the HW only noise decrease/go away. There is another mode that can be tried as well, based on the info you can post, its called PP (proportional pressure), would suggest PP2 which might work very well.
Having said all that, you shouldn't really be getting any noise really at the 4.2M head but that can be looked at later.
The attached will show how to change pump modes, if you require any help!.

Is your system a S, with two motorized valves?.
Has your system got a ABV (automatic bypass valve)?
What make/model (gas/oil?) boiler?.
How may rads?.

 

[Munroast]

@Johntheo5 - thanks for that
Yes, I think it is an "S" System, and it def has 2 motorised valves
No ABV
Gas Boiler - Ideal Mexico Super 3
4 x 3' double
8 x 2' double
4 x 2' single
(most are controlled by thermo valves on radiators - but overall controoled by wall thermostat)

As for - should we be getting any noise; To explain, we are on a small little estate and there are 3 houses exactly like mine, plumbing exactly the same - the other 2 houses have never made any noise, and 25 years ago beofre I fell out with that plumber, that seemed to be his defense - "the other 2 houses don't make that noise" like it was my fault or something - LOL
In fairness he did try a few things non of which worked, one was to put a crossover pipe between feed and the return pipe (it didn't help much

I have just set the pump to Proportional 1 - (I won't really know until tomorrow morning (when the house is quiet)

 

[Johntheo5]

PP1 is very very weak and while it will give the lowest noise level it probably will heat the cylinder with extended time, it will be utterly useless IMO with CH on, you can certainly leave it at PP1 to see if the noise ceases on HW only, (you can throw your hat at it if it doesn't because the pump head will then only be ~ 1.2/1.5M), I would then change it to PP2 which will/should be a pretty good compromise. (Finally, if PP2 still a bit weak then try CP1).

 

[Munroast]

set at PP1 it was beautifully silent this morning (had to go and see if it was actually running), and since we won't have the heating on until possibly October, that is how I will leave it for now
what I need is for it to switch to CP1 when CH comes on and then PP1 when only HW is on

saying all that I don't know how well it heated the water this morning with PP1 - will find out tonight

 

[Johntheo5]

Maybe just switch it to PP2 now which still probably/may give relatively silent running on HW only and will almost certainly IMO prove sufficient on CH only as well but possibly a bit weak if both CH&HW on together which, in any event, you may rarely require.

You might also check the direction of flow through the HW motorized valve via a arrow on the side of the valve body, the motorized valve is almost allways installed on the flow (hot) top pipe going to the cylinder coil. the arrow should be pointing towards the cylinder.