Boiler frequently shows air in system; gurgling noises from radiators and boiler.

Safety first: Allow the system to cool before bleeding air vents.

• Bleed system thoroughly: Bleed all radiators and any manual air vents on high points.
• Check automatic air vent: Ensure the cap is slightly open and not blocked. Replace the vent if it leaks or fails to release air.
• Inspect for leaks: Small leaks can draw in air when the system cools. Look for staining around joints and valves.
• Maintain correct pressure: On sealed systems, keep pressure within the recommended range to minimise air ingress.