Condensate pipe dripping heavily or backing up; boiler may gurgle or cut out.

Safety first: Condensate is mildly acidic. Wear gloves and eye protection when handling.

• Check external pipe: In cold weather, look for ice on the outside condensate pipe. Thaw gently with warm water if frozen.
• Inspect termination: Ensure the condensate pipe discharges freely into a drain and is not blocked.
• Engineer service: A technician should remove and clean the condensate trap, flush the condensate line, and verify correct pipe sizing and fall according to Worcester Bosch instructions.