Frozen condensate pipe: the 10-minute fix that saves a call-out
By DemoRod · 28 January 2026 · Gas Safe registered engineers
On the first freezing morning of winter, half the boiler breakdowns we attend are a frozen condensate pipe. You can usually fix it yourself.
How to tell
The boiler shows a fault code (Worcester EA/227, Vaillant F28/F29, Ideal L2, Baxi E133) and you may hear a gurgling noise. There is a white plastic pipe, about 22 mm, running from the boiler through the wall and down outside.
Thaw it safely
1. Pour warm, not boiling water along the pipe, concentrating on the bends and the open end where ice forms first.
2. A hot-water bottle or microwaveable heat pack held against the pipe works well and cannot crack the plastic.
3. Reset the boiler once the pipe is clear.
Never use a blowtorch or heat gun and never stand on a ladder in icy conditions.
Stop it happening again
- Lag the external run with waterproof pipe insulation.
- Ask us to re-route or upsize the pipe to 32 mm with a steeper fall; it is a small job and Gas Safe engineers are used to it.
- Set the heating to run low overnight in a cold snap rather than switching off entirely.
Need help with this?
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