Boiler cycles on but quickly shuts off with gurgling sounds inside unit

Safety first: Allow the boiler to cool before bleeding air. Turn off power when opening vents.

• Step 1 – Check system pressure: Ensure cold pressure is within the recommended range (typically 12–20 psi). Add water if needed.
• Step 2 – Bleed boiler air vent: Locate the automatic air vent on top of the boiler. Loosen the cap slightly to allow trapped air to escape, then retighten once water appears.
• Step 3 – Purge primary loop: Use purge valves on the boiler's primary loop to flush air until a steady stream of water flows.
• Step 4 – Replace faulty air vent: If the vent is leaking or not releasing air, replace it with a compatible automatic air vent.

Persistent gurgling indicates remaining air; repeat bleeding or have a professional perform a full system purge.