Boiler’s automatic air vent is leaking water or spraying mist.

Safety first: Turn off power. Be cautious of hot water near the vent.

• Step 1 – Check cap position: Many automatic vents have a small cap on top. It should be loosened slightly to allow air out but not removed. Tighten slightly to see if leaking stops.
• Step 2 – Inspect for debris: If the vent continues to leak, it may be fouled. Isolate the boiler or zone, relieve pressure, and remove the vent. Inspect for debris and flush with clean water.
• Step 3 – Replace vent: If cleaning does not stop the leak or the vent is corroded, replace it with a new automatic air vent rated for hydronic use.
• Step 4 – Check system pressure: Verify that system pressure is within normal range; chronic overpressure can cause vent leaks.

Note: A leaking vent can introduce oxygen into the system, accelerating corrosion; address promptly.