Boiler shows code 1, burner on for central heating or hot water, but user suspects poor performance

Note: Code 1 on many Intergas boilers indicates normal burner operation, not a fault. If heating or hot water performance is poor while code 1 is displayed, the issue is likely hydraulic or system-related.

• Check radiator temperatures: With heating on, feel radiators. If some are cold at the bottom, they may be sludged and need powerflushing or cleaning by an engineer.
• Bleed radiators: Turn off heating, allow to cool, then bleed radiators with a bleed key to remove trapped air. Re-pressurise the system via the filling loop to 1.0–1.5 bar afterwards.
• Check boiler settings: On the user interface, ensure the CH flow temperature is set appropriately (e.g. 60–70°C for radiators unless using low-temperature systems). Refer to the user manual for adjusting setpoints.
• Hot water performance: If hot water is lukewarm while code 1 is active, the plate heat exchanger may be partially blocked with limescale or sludge. This requires removal and cleaning or replacement by a qualified engineer.
• Call an engineer: If performance remains poor, have a Gas Safe engineer check gas rate, combustion, and system cleanliness.