Just spoken with someone who recently had his boiler replaced.
Old boiler located in attached garage basically way too old and costly to keep repairing so over a year ago got replaced with nice new condensing boiler. Worked fine until winter came last year when stopped numerous times as it flooded, as the condensate didn't drain away. This was traced to the external condenate drain pipe freezing as it had quite a run from garage to nearest drain. Anyway original fitter came and sorted and no problems since then.
Anyway this year thinking "wonder what he did to fix it and stop the pipe freezing ?" had a look. Fitter had insulated the pipe outside, but more importantly fitted heating tape on pipe, great idea.....however the heating tape is rated 90W and is permenantly wired into bioler supply, so despite the gas running cost being reduced from £540 previous years to £490 this year but has had to fork out over £70 electrical cost for the year.
Fitter "very appologetically" is coming back to fit a frost stat to the heater.....