My heating not working but I have hot water on a potterton mk2 10/16 also were is the diverted located I have had all the floor boards up followed the pipe work from the boiler all around the house thrugh the loft but can't find it would it be in th boiler its self on this model
Last made in 1988 and only 68% efficient.
Any diverter valve will not be inside the boiler case - if there is one the installers will have put it somewhere - mine is in the airing cupboard.
http://www.homeheatingguide.co.uk/efficiency-tables.php?model=000658