:shock:
Kev, thanks for replying. I am not a plumber or in fact remotely technical. Do you think I should get a plumber? Is there anything else I need to check? Is this pressure swith easy to find?
Light came on this morning. No CH or HW. Checked pressure, too low added water no above 1 but light wont go out and still not firing. Please tell me this is something simple and obvious! Have opened radiators to bleed and don't seem to be blocked.