How to Clear a Frozen Condensate Pipe (UK Emergency Guide)

Identify the freeze

Boiler shows EA338 (Worcester), F28 (Vaillant), E133 (Baxi). Follow the plastic condensate pipe from the boiler outside — any external run <32 mm freezes first.

Thaw safely

Pour warm — never boiling — water over the exposed section. Work from the visible end back toward the wall. Reset the boiler; give 3–5 minutes for ignition.

• Use a hot-water bottle wrapped around the pipe for stubborn blockages.
• For long horizontal runs, thaw the low point first (siphon trap outside).
• Never use a blowtorch — plastic pipe melts at 60 °C.

Permanent fix

Re-run in 32 mm minimum internal pipe, lagged with waterproof foam, minimum 3° fall. Terminate to a soakaway or waste stack inside where possible.