if your boiler is staying on permanatly then you are getting a permanent switch live to your boiler, the first place the live comes from is the programmer/clock, test this by using a continuity tester and test for continuity across live and central heating on ( with power isolated and programmer removed test across the pins on the actual programmer not back plate, if no continuity you could have a loose wire touching another ) DO NOT ATTEMPT TO REMOVE OR REWIRE THIS SYSTEM IF YOU DONT KNOW WHAT YOU ARE DOING IT WILL COST A LOT TO REWIRE AND RECTIFY
MIKE
January 2006