Boiler displays E16, condensate may be visible around base of boiler

Safety: Condensate is mildly acidic. Wear gloves and eye protection when handling. Isolate power before opening the boiler.

User checks:

• Inspect the external condensate pipe for freezing (white plastic pipe, often 21.5 mm). If frozen, thaw gently with warm (not boiling) water or warm towels.
• Do not use naked flames or boiling water on plastic pipework.

Engineer checks:

• Remove and clean the Keston condensate trap, flushing out debris and sludge. Refill the trap with clean water before refitting.
• Check that the condensate pipe has a continuous fall to the drain and is correctly sized and supported.
• Inspect for leaks at condensate connections and repair as needed.
• After clearing, reset the boiler and confirm normal operation without E16 returning.