hot water boiler

I'm looking to drain down my hot water (tap) pipe before replacing 15mm with 22mm hot water pipe. I have added a 15mm drain valve to my cold water pipe and plan to do the same to my hot water pipe. This is to stop, after I turn the boiler off and cut the hot water (tap) pipe from leaking...

Hello everyone. I have a Hanstrom hot water tap with an under-sink boiler. A few days ago it started beeping and showing E4 on the display. We can't set the temperature or reset it. Changing the filter didn't help so I disconnected it, put descaler in (Hanstrom suggested this) for about an hour...