This is to ensure the correct operation of the air admittance valve, otherwise there is a risk that the water seal The pipe - that is to say, where a washbasin is connected to the pipework, the air admittance valve must be higher than the overflow Into the room/roof space and prevents the water seals in traps along the pipework from being broken.Īn air admittance valve must be installed so that it is positioned above the highest flood level of the appliances fitted to The inrush of air through the open valve prevents the foul air in the pipe from escaping

This intake of air equalises the air pressure and the sealingĭiaphragm falls back sealing the valve. Sealing diaphragm and allows air to be drawn in - see right lower. When an appliance discharges into the drain, a slight negative air pressure is produced in the drain pipework which lifts the

Unless an air admittance valves is specifically described as being for external use, it should only be installed internally.Ī sealing diaphragm which under its own weight or slight spring pressure is normally held closed, thus sealing the foul air within The main advantage in using air admittance valves externally is that they reduce the amount of pipework which would otherwise be necessary to take the stack opening sufficient far from any window or other opening in the building. Their use also reduce the amount of pipework needed to fit an external, open soil or ventilating stack.Īir admittance valves used externally are specifically designed to operate within specified environmental conditions which must be checked against the intended installation location. One great advantage of using air admittance valves internally is that they remove the need for holes through the roof or external Those installed internally are generally fitted within rooms or Air admittance valves are used to provided venting for soil and ventilating stacks - most types are for installation within a building, others are specifically designed for outside use.

Keeney air admittance valve reviews