Could be but If problem persists with EV renewal would suggest sorting out the pressure drop after the combination set. After visit 1 when they recharged the EV and checked the pressure with HW on it was apparently 3.0 bar but you are now only seeing 2.0 bar or less since they installed another PRV to deal with the kitchen tap causing a perceived problem, I would reposition this PRV to serve the kitchen tap only and see if you now get 3.0 bar after the combination valve set. If you don't get 3.0 bar and the pressure is still say 2.0 bar then I would reduce the new EV precharge to 1.8 bar.
OR (if noise problem still there after EV renewal),
simply wind up the cold mains PRV fully and check for 3.0 bar after the combination set and if room allows install NRVs on both the hot and cold at the kitchen tap, the cold mains PRV can then be removed to avoid future confusion.
OR (if noise problem still there after EV renewal),
simply wind up the cold mains PRV fully and check for 3.0 bar after the combination set and if room allows install NRVs on both the hot and cold at the kitchen tap, the cold mains PRV can then be removed to avoid future confusion.
