What is the benefit of fitting say a 40mm or 50mm air admittance valve. As apposed to an anti vac trap at the appliance? Thanks
Anti vac trap or air admittance valve
- Thread starter Fredstudio
- Start date
Depends on what's on the waste run, if it's just a sink then nothing else needed than an anti vac trap as you're only venting that trap using its small vent.
If there's more on the run than say 1 trapt - appliances etc, then you really want to vent the run. A 40>50mm AAV has a larger larger vent so is able to support more than one trap/outlet at a time. Even then though, supplementary venting is more applicable when there are longer runs with bends and multiple wastes feeding in, shorter lengths shouldn't really need it
If there's more on the run than say 1 trapt - appliances etc, then you really want to vent the run. A 40>50mm AAV has a larger larger vent so is able to support more than one trap/outlet at a time. Even then though, supplementary venting is more applicable when there are longer runs with bends and multiple wastes feeding in, shorter lengths shouldn't really need it
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