How Air Admittance Valves Work
When a toilet is flushed, the rubber product
of water creates a pressure inside the soil pipe. If the pipe is vented at the top of the run (i.e. open to the atmosphere), air is drawn in to the technique to balance this pressure. If however there is no vent & hence no air can be drawn in to the pipe, this pressure will generate a siphoning yiwu sourcing agent
. This effect in turn causes water to be drawn out of any nearby basin, sink or bath trap, allowing drain odours to enter in to the room.
An Air Admittance Valve is a tiny mechanical Push in fitting
that is usually fitted on to the top of a 110mm soil pipe to permit air to be drawn in to the drainage technique. All above ground drainage systems ought to be vented, to prevent the build up of pressure in the technique & to enable appliance traps (often known as U bends) to work correctly.
Normally the vent is an open finish at the top of the solenoid valve
, usually protected by a vent terminal, which is a kind of guard which prevents birds from entering. However, there's regulations in place to prevent pipes from terminating close to opening windows, including roof windows. This usually means that the pipe has to be high to finish above the level of the eaves - & on a technique that is run inside the house this means that the pipe will must penetrate the roof itself.
The best way to get around this sexy mother of the bride dresses
is to put in an air admittance valve (sometimes known as a Durgo valve). It is a cleverly designed valve which opens when internal pressure builds up, & draws air in to the technique. Crucially, when the valve opens no air is allowed to escape, meaning that all drainage gases & odours are contained within the drainage technique.
The very latest generation of PVC profile
includes a range that can be fitted externally. This range is obtainable in different colours & it allows outside soil pipes to be terminated at a much lower level than traditional vent pipes that require to go above the eaves level, making the installation of the whole technique a much safer job.
These fittings are usually installed within Rubber gasket
& inside ducts or cupboards. They require to be fitted above the "spill over level", which is the highest point that water can reach in the drainage technique. As the mechanism is very fine, the internal parts of the air admittance valve require to be protected against dust & frost. This is usually achieved by the fitting of a polystyrene cover which is supplied with the valve.
Air admittance valves are now a commonplace alternative to high level Molding rubber
, & plenty of thousands are installed each year all over the world.