(Air) Admittance Valve (toilet)

There is an alternative valve in the plumbing world that can be fitted to a toilet, taking the place of your original siphon type that is probably fitted as we speak. The air admittance valve as it is called is much like a very large non-return type of valve. Air is allowed to enter your system through the valve but will not allow foul smelling air escape into the atmosphere around your toilet. Therefore if a negative pressure is in the drain of the system, the valve opens rather than the trap water being dragged out. This valve can be fitted by Mill Hill Plumbers .

These (air) admittance valves are available in a large range of sizes and sometimes the main waste drainage stack is terminated by this sort of valve type. The general use of this valve is when there are two soil stacks in the same building or where there are many buildings that are close to each other and this type of valve actually negates the need to route the highest point of the soil discharge stack out through the roof. Because of this, there is no extra work needed to fit tiles etc. This ensures that there is no additional work required for tiles etc. and protects the building from rainwater ingress. This type of valve (air admittance) really should be installed above the critical level (or spill level) of an appliance. If not done, then, if a block occurs it will back up with water and render the valve non watertight. A Mill Hill Plumber is familiar with this system. As long as the valve is well insulated it can be fitted in exposed locations like loft spaces, as condensation in the pipework can freeze.



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