My Potterton Prima 'F' boiler trips out on regular occasions - sometimes every day or maybe only every few days. The cut out button located at the bottom of the boiler needs to be pushed back in, then everything works OK. The bypass heating circuit is fully open and works well and I changed the circulator pump last year and it also is working OK. Any ideas?

Can I get a new temperature control knob as mine is broken, also the grey plastic bottom cover?

Thanks

Steve, October 2006

The soldered joints on the underside of the control module printed circuit board crack due to heat and time, particularly the joints securing the connector pins to the board. These are known as 'dry joints' and can be re-soldered by a competent electronics technician with an instrument soldering iron and electronics (not plumbing) solder. Apart from disconnecting and removing the module from the tray no other disassembly is needed. I have had two of these fail but being wiser the second time was able to repair it. The cracked joints are easy to see with the aid of a small magnifying glass.

Paul, Guildford, November 2007

I had exactly the same problem, and it was the trip-out thermostat. I replaced it...took 10 mins and Bingo! I presume that they get weak and become too sensitive.

Tony Taunton, October 2006