Vaillant 0010033857 Auto Air Vent

A Vaillant spare, this automatic air vent is suitable for use in EcoTec Pro, EcoFit Sustain, EcoFit Pure and EcoTec Plus boilers. A central heating safety device, the air vent releases built up air. As water flows through the system, a float opens or closes the vent depending on the water level. When the system is full the float is pushed to the top, closing the vent until the water level drops.