I have had this issue over a year. I thought had a faulty regulator so they sent another. also each time since last year have descaled 3 times but really was not that bad at all? What descaler do you use? seemed to be pretty clean and also kinda can tell from over the years my filters stay pretty clean and no build up. I always have and only use rinse through system so that keeps it pretty clean also in between descaling. this is weird though because it only does it when water is hot?
The pressure regulator is one of two chrome cylinders that allow you adjust the water pressure for high pressure or medium pressure depending on what you're cleaning. It could be that the medium pressure regulator is faulty and needs replacement.