Boiler locks out intermittently, especially in cold weather, and the condensate pipe outside may be icy.

Safety: Turn off power before working near the condensate pipe. Do not use open flames to thaw pipes.

Steps:

• Locate the white plastic condensate pipe exiting the boiler and running to a drain.
• If the external section is frozen (hard to touch, visible ice), pour warm (not boiling) water along the pipe to thaw it.
• Once thawed, reset the boiler and observe operation.
• Consider insulating the external condensate pipe and increasing its diameter or rerouting internally; this should be done by a heating engineer.