As negative pressure occurs, the valve opens to allow air into the pipe.
This can be in situations where there isn’t a pipe outlet that is more than 3 metres from a window or in situations where the building has roof windows – the pipe can let out bad odours so situating this near a window can be a bad idea!Īn air admittance valve uses a clever system that is activated by negative pressure. The other alternative is to use an air admittance valve in situations where an open pipe outlet isn’t possible. This allows air to be drawn into the pipe from the external environment, preventing it from being drawn from sinks, basins and other sources within the home, thus removing the issues associated with it. This pressure change issue is traditionally solved with an open pipe outlet that is installed on the roof. This can cause a number of issues, including unpleasant odours being released into the home, wastewater coming up from the trap into the sink or basin, poor drainage of water and gargling sounds when drainage occurs. Particularly from plugholes in baths, sinks and showers. To readdress the balance, air tends to be drawn into the pipe from anywhere possible. Pressure changes occur when a toilet is flushed or any water flows within the waste pipe because air is carried along the pipe with it.
Traditional Express Cast Iron Soil PipeĪir admittance valves, also known as AAVs or durgo valves, are valves that help to re-balance the pressure within a soil pipe to normal levels.