grundfos pump

This pump supplies hot and cold to the shower and hot to several other taps. It has been in place for around 10 years with no issues. If I put just cold through then it is OK (from a pulse POV but not for a comfortable shower) Recently, when the shower is turned on or indeed any of the taps...

Hi all, this is my first post so I apologise if this has been discussed. I have looked. Also apologise for very long post! I’ll be amazed if anyone actually reads this let alone answers the questions but it’s worth a shot! … We had a Viessmann 222-f fitted to our conversion house. It’s an old...