i got call today saying rcd tripping one side of the board, he called when i was passing , so i popped in and tuned all switches off and turned on one by one and leads me to the fused spur for the gas heating... anyway left to monday now ...... what would you logical approcah be to this, i will start from scratch, has anyone anytips to speed me up as i am slow as a donkey when comes to this fasult finding.... thanks