Boiler displays E04, condensate alarm, boiler stops

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

Steps:

• Inspect condensate pipe: Check the plastic pipe from the boiler to the drain for kinks, blockages, or freezing (common in cold weather). Thaw gently with warm towels if frozen; do not use open flame.
• Clean condensate trap: Remove the trap under the boiler, empty it, and rinse out sludge. Refill with clean water before refitting to maintain the water seal.
• Check pipe slope: Ensure the condensate pipe runs downhill continuously to the drain with adequate fall.
• Reset boiler: Restore power and reset. Confirm that condensate flows freely when the boiler runs.

Professional help: If E04 persists, a technician should check any condensate level sensors and the internal routing.