Thanks Matt!! That's such a relief to heat. In fact the code went away.
I got a bit worried by the noise first and thought that was an error code for some fault. Yes, not only did I do a reset but during it and I also switched it off at the main. The noise has gone now. I wonder what it was! Will cut off the tiles so that an engineer can properly access it next time the service is due.
Alex
March 2008