Boiler displays E14 and locks out

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

• Check external condensate pipe: In freezing weather, look for ice at the outlet or along the plastic condensate pipe. If frozen, thaw gently with warm (not boiling) water or warm towels.
• Inspect trap (engineer): The internal condensate trap/siphon may be blocked with debris. A competent person should remove, clean, and refill it with water before refitting.
• Verify pipe fall: Ensure the condensate pipe runs with a continuous fall to the drain and is not kinked or back-falling.
• Engineer tasks: Clean or replace the condensate trap, check for leaks, and confirm correct routing and insulation of the condensate pipe.