Boiler or nearby piping emits a constant gurgling or trickling water sound

Safety first: Be cautious when venting hot radiators; use a cloth and container.

• Bleed radiators: Starting with the highest radiators, open manual air vents until air stops and water flows steadily.
• Check automatic air vent: On Utica boilers, inspect the automatic air vent (often on top of the boiler). Ensure its cap is slightly open to allow air to escape and that it is not leaking water.
• Verify system pressure: Low pressure can draw air into the system. Adjust fill pressure to the recommended level.
• Repeat as needed: Air removal may require several cycles of bleeding and running the system.