Frozen condensate pipe: the winter classic

Every proper cold snap, thousands of UK boilers stop on the same morning for the same reason: the condensate pipe — the small plastic pipe that drains slightly acidic water from a condensing boiler — freezes where it runs outside, backs up, and the boiler shuts itself down.

How to recognise it

• It's below freezing outside, and the boiler was fine yesterday
• A gurgling or slurping sound from the boiler
• A fault code — commonly EA on Ideal, F1 on some models, or a 'condensate' warning (check your manual)
• A white/grey plastic pipe runs from the boiler through the wall and outside

The safe fix

• Find where the plastic pipe runs outside — the freeze is usually at the open end or an elbow
• Pour warm (never boiling) water over the frozen section, or hold a hot water bottle on it
• Boiling water can crack the pipe — warm from the tap is enough
• Once thawed, reset the boiler using its reset button

Stopping it happening again

The long-term fixes are simple: insulate the outside run with waterproof foam lagging, and where the run is long or shallow-falling, re-run it in wider pipe with a steeper fall so water can't sit and freeze. Ten minutes of pipework in autumn beats a cold house in January — we can sort it as part of any service visit.