cold snap rules
If your boiler packs in don't panic, silly. Simply read the instructions you filed in a safe place and establish that the condensate (!) outlet is frozen and needs remedied. You do this by pouring lots of kettles of hot water over that pipe thing on the front of the house. The weird farting noise and alarming cracking of ice are just a distraction. Of course, it should have been insulated, see, it says so in the instructions, but, no, I'm not going to insist that the man who installed it gets out of his bed and comes and sorts it out at 10pm on a Friday three years later. In any case, look, it's mended now.