Boiler displays E15, no burner operation, often after condensate issues

Safety first: Isolate power. Condensate is mildly acidic; wear gloves and eye protection when handling.

• Check external condensate pipe: Inspect the plastic condensate discharge pipe from the ACV boiler to the drain. In cold weather, look for ice. Thaw gently with warm (not boiling) water or a warm cloth.
• Inspect trap (visual): If accessible, check the condensate trap under the boiler for sludge or debris. A competent person can remove and rinse it with clean water, then refit ensuring seals are correct.
• Ensure proper fall: The condensate pipe should slope continuously downward to the drain. Sagging sections can trap water and cause blockages.
• Reset boiler: After clearing, reset the boiler and observe operation.
• Professional help: If E15 persists, a technician should check any condensate level sensor and internal routing.