Right, this is the second time this week. I have had the heating on all the time but for the second time, have a frozen pipe. Fairly normal in these conditions but the strange thing is it is the HOT water that has frozen. I appreciate that the water in the pipes gets cold and can freeze, that isn't what's puzzling me. The COLD mains is still running fine, how come. If the cold coming from the mains and into the boiler isn't freezing, and the cold water in the taps is fine, why on earth is the hot water system freezing up?
None of the pipes are outside apart from a 10 foot mains section, but this isn't freezing.