The traditional 3 speed fixed settings which are/were used for 50/60 years worked very well as you get effectively 3 pumps for the price of one, the circulation flow through any system depends on the number of rads, the size of the pipework etc and flowrate is proportional to the (sq.root) pump head or pressure so the pump's three (speed) settings might give 4M,5M & 6M (or even 7M) and if your system only required 4M then running it at 7M takes more energy and cost but it should not really cause a noisy pump, pumps installed on the boiler flow and pumping downwards can be prone to noisier operation for one reason or the other.
Variable speed (smart) pumps were introduced to further increase energy savings, for example my Wilo circ pump only requires well less than half the power of my original fixed speed pump.
Proportional Speed or PP operation further increases energy savings as the pump pressure or head is reduced automatically with reducing flow requirements ie TRVs closing in or Zone valves closing. Some pumps also have different constant pressure (CP) modes which also give bigger savings but are generally used for UFH applications.
UPS's choice of PP setting's unfortunately was and still is to some extent very poor as they were too low, the UPS2 (your one) was/is particularly poor and UPS didn't actually push the advantages of PP control with this model, some arn't even aware that it has PP control.
The UPS 3 was a fairly good step up in PP settings and also includes CP settings, unfortunately your plumber, no doubt in good faith, thought that it was too powerful, probably based on the 3 fixed speed settings, but it was/is more suitable to you than the UPS2 as you can get a slightly higher flowrate on one of its PP settings (or the CP settings) which may have proved to be more suitable for you with all systems opened up, hopefully the UPS2 will do the job for you.
If the UPS3 isn't residing in some installation miles from you and you still have it, I would reinstate it and run it in PP2 mode!!.
Variable speed (smart) pumps were introduced to further increase energy savings, for example my Wilo circ pump only requires well less than half the power of my original fixed speed pump.
Proportional Speed or PP operation further increases energy savings as the pump pressure or head is reduced automatically with reducing flow requirements ie TRVs closing in or Zone valves closing. Some pumps also have different constant pressure (CP) modes which also give bigger savings but are generally used for UFH applications.
UPS's choice of PP setting's unfortunately was and still is to some extent very poor as they were too low, the UPS2 (your one) was/is particularly poor and UPS didn't actually push the advantages of PP control with this model, some arn't even aware that it has PP control.
The UPS 3 was a fairly good step up in PP settings and also includes CP settings, unfortunately your plumber, no doubt in good faith, thought that it was too powerful, probably based on the 3 fixed speed settings, but it was/is more suitable to you than the UPS2 as you can get a slightly higher flowrate on one of its PP settings (or the CP settings) which may have proved to be more suitable for you with all systems opened up, hopefully the UPS2 will do the job for you.
If the UPS3 isn't residing in some installation miles from you and you still have it, I would reinstate it and run it in PP2 mode!!.
