Automatic Air Vent
Automatic air vents (purgers) for central heating, underfloor heating and solar systems: 1/2 inch float-type and radiator-type automatic air vent valves.
Products (6)
- Caleffi 5080 Automatic Air Vent for Radiators, 1/2" – $4.36
- Caleffi ROBOCAL Automatic Air Vent, 40 mm, 1/2'', 115 °C, 502640 – $11.06
- Klepsan Automatic Air Vent, 1/2'' – $18.77
- Pakkens Automatic Air Vent, 33 mm, 1/2'' – $7.51
- Welko Automatic Air Vent, 1/2" – $6.63
- Welko Automatic Air Vent, 1/2", 10 Bar – $25.18
Brands: Caleffi · Klepsan · Pakkens · Welko
What does an automatic air vent do?
Air gradually accumulates in closed-loop heating and cooling systems. This air prevents hot water from reaching radiators and pipes, causes gurgling and banging noises from the system, reduces pump efficiency and accelerates corrosion. The automatic air vent (purger) prevents these problems by automatically releasing the air that collects at the high points of the system.
How does it work?
A float is located inside the body of the air vent. When the body is full of water, the float sits at the top and keeps the discharge port closed. When air accumulates, the water level drops, the float moves down and the discharge port opens, letting the air out. Once the air is expelled, the water level rises and the port closes again. This process repeats continuously without any manual intervention.
Where should it be installed?
- At the highest points of the system and at the top ends of riser pipes
- At boiler and hot water cylinder outlets
- On solar collector lines
- On underfloor heating manifolds
- On radiators (using radiator-type automatic air vent valves)
The air vent must be installed in an upright position with the discharge port facing upward. Fitting an isolating valve beneath it allows the air vent to be removed without draining the system.
Maintenance
Dirt and sediment in the system can settle in the float mechanism and cause the air vent to leak water. A dripping air vent must be cleaned or replaced. The cap on the discharge port must be left slightly loose for the device to function; if tightened completely, air cannot be expelled.
Frequently asked questions
Why is the air vent leaking water?
Dirt may have entered the float seat or the gasket may be worn; cleaning or replacement is required.
How many air vents are needed?
It depends on the layout of the system; it is recommended to plan one air vent for each high point and riser end.
What does a radiator-type air vent valve do?
It automatically vents air that accumulates in the radiator, reducing the need for manual bleeding.
Can it be used on a solar system line?
Models specified as suitable for high temperatures must be used.
Should the air vent cap be closed?
No; the discharge cap must be left slightly loose.
Is there an air vent inside a combi boiler?
Many combi boilers have a built-in air purger on the pump; additional air vents may still be required at other high points in the system.
What is the difference between an automatic air vent and a manual bleed valve?
With a manual valve, air is released by opening the valve with a key. An automatic air vent continuously purges accumulated air on its own.