Thanks for the help Tony. I will try as you suggest wrt cleaning the plate HE.
Yes - I replaced the whole diverter valve.
There is no cycling of hot and cold. The DHW flow gives a reasonable shower, but I suspect it could be better if half the heat weren't going round the CH circuit...
Boiler: Sime Friendly Format 80e
Problem: Radiators get hot when DHW is run.
I had assumed this was the diverter valve, so ordered a new assy. (part: 6102806) and fitted. But it hasn't really fixed the problem, though it does seem to be marginally better.
When someone has a shower (say, a...
Boiler: Worcester 35CDi
Problem: gradual loss of pressure
Suspected Fault: expansion vessel
The boiler runs fine but after pressurising it loses pressure over a couple of days, and eventually settles down to about 0.5 bar. At this point the rads. dont really get hot properly, and it is...