I thought the 'coincidence' thing was unlikely, but there could have been a 'surge of pressure' or something I suppose. The boiler has had no spare parts fitted in 5 years - hasn't gone wrong before - so I thought it was about time anyway.
I turned off the water, not the boiler. A plumber, some...
I have a Biasi24S that is ok for ch but not for dhw.
The story is that I had to turn off the water at the main to carry out some work in the bathroom. That completed I turned the water back on to discover that I could no longer get hot water from a tap and the flow was very slow from that tap...