does the heating work? If not then the problem does not lie wth the diaphragm or hot water microswitch , does the pump run ? does the fan run? there are hundreds of reasons why the boiler wont work , can you be a bit more specific about at what point the controls side are not functioning. if you are in sussex area ring sussex gas on 01273583052 , they are vokera agents and will not rip you off
mark, June 2008