Boiler makes gurgling or trickling water sounds

Safety first: Use caution around hot water.

• Check pressure: Ensure system pressure is adequate (typically 12–15 psi cold).
• Bleed radiators: Open manual air vents on radiators and high points until water flows steadily.
• Inspect air vents: Verify automatic air vents near the boiler are open and not leaking. Replace if they are stuck or corroded.
• Air separator: If the system lacks a proper air separator, consider having one installed.