The following short video offers a quick comparison between an A and B rated AAVs.
As illustrated in the video , where low quality AAVs (‘B’ rated in accordance with EN12380) are used these have to be installed ABOVE the flood level of the fixture. This is because they are not able to withhold the pressure of rising water due to a blockage and they effectively become the location of the flood level.
This means that additional, and commonly unsightly, pipework needs to be installed to be able to reposition the AAV above the flood level of the fixture, and thereby prevent the risk of water from flooding into the living space through the AAV.
By contrast, the Studor AAVs (which are ‘A’ rated in accordance with EN12380) are manufactured to high standards which ensure that they may be installed BELOW the flood level of the fixture up 1 metre below, as they will not leak and will withhold the pressure of risking water due to a blockage – they are tested to 10,000 Pa.
For more information have a look at the Studor Mini-Vent
studor.net/mini-vent