The HHIC has produced some guidance notes for Householders experiencing Frozen Condensate Pipes in the extreme cold weather. Follow this link for more information:
http://www.centralheating.co.uk/checklists/frozen-condensate-pipes/frozen-condensate-guidance-households
http://www.centralheating.co.uk/checklists/frozen-condensate-pipes/frozen-condensate-guidance-households