Ill back that up diaphram 99.9% the culprid. Switch of both water and power and replace.-diaphram is activated by opening the tap causes a depression on one side which sends a push rod through the unit usually to a micro switch attached on the other end to activate the boiler. If its the micro switch remove it and take to maplins identical unit £1.99. Just replace it and re wire. switch units can cost £12 +
hope this helped
tom, January 2011
