Whilst taking a shower, water started leaking from bottom of copper cylinder, cylinder situated on left hand side of unit.

George Tweddle, February 2016

The black plastic part is actually a pressure relief device or prd,you may need to pull it out and then re-insert it,the metal fork should be straightened before refitting ( it holds the prd in place ) if it pops out again there is a blockage in the hose or shower head

toptrish, February 2016