Happy Christmas to you all. Wondering if somone may have an answer to my query. Moved into our current house last year.My central heating all works well, but the last four days the Sunvic 270 programmer ( guess at 8-10 years old) and Ideal Classic boiler (similar age)"clunk" at the same time. The clunking happens every 2 to 5 seconds after the boiler has fired up and only when HW and CH are both ON. This can go on for up to a couple of minutes, but if you switch off either the HW or the CW while its clunking it stops clunking instantly. The boiler stays lit, and the flame seems unaffected by the clunking. You can feel the programmer vibrate when it clunks and the red lights on the programmer flicker with each clunk. In my laymans speak, I am guessing that the programmer is defunct and trying to tell the boiler to light when it is already lit. Is my guesswork correct?. Any help much appreciated. Regards.