FloPlast AV32 32mm Air Admittance Valve-Compression, White

Product Information

As good and useful as air admittance valves can be they can also cause some problems, especially when they become old and worn. Sometimes a pipe vent above roof level is not always possible, this is where you might use an air admittance valve. Reasons why you may not be able to use a vent above roof level is that there may be a neighbour with a loft conversion, or surrounding taller buildings, or when the building has roof windows. As a general rule, a soil pipe vent should never be vented less than 3m from a window otherwise you or your neighbours will be gassed out by foul odours coming from the vent! Sometimes it may be easier to use the air admittance valve inside even if there are roof windows, but to simply box it in using plasterboard to hide it as a pipe would usually. Air admittance valve installation height One final point to mention is that there are 2 different types of air admittance valve; the large 110mm valve for use with soil pipework and a smaller 32mm or 40mm version for use on sink, bath, basin etc. smaller bore waste pipes. Let's get one thing clear straight off the bat...if your property uses a sewage treatment plant, septic tank, or cesspool instead of a connection to the mains drains, there must be AT LEAST one open vent in the system to prevent a dangerous build-up of gases. Air Admittance Valves can be installed in addition to, but should never be installed in place of a vent pipe for off-mains systems.

In most cases installing one in a standard home should be fine, the Building Regulations mainly cover extreme situations such as high-rise buildings, where there may be many waste pipes and different levels that require a fine balance to be maintained. Specific Size Air Admittance Valves: Ranging from 32mm to 110mm, these valves cater to specific pipe diameters, offering a more precise fit and seal for systems with known pipe sizes. When they aren’t, to fix any issues that arise, a handy product called an Air Admittance Valve is used, find out all about them and how they are used below. What is the Purpose of an Air Admittance Valve?In terms of how an air admittance valve works, the whole system revolves around a spring loaded valve. The valve labeled D in the below image is held under the pressure of a light spring which holds the valve closed during times of non activity. The final task is to now fit the AAV in its location on top of the T-piece, but before this can be done you will need to cut and fit a vertical section of pipe that will sit the valve above the highest point that waste water can enter the waste pipe. Universal Waste Pipe Air Admittance Valves: These valves are adaptable to all sizes of waste pipes and are suitable for most residential and commercial applications. This equalization of pressure prevents the foul air in the pipework from escaping as any and all water seals e.g. U and P-traps remain intact. In almost all instances they are installed internally. Only those made especially for use outside can be used externally as they need to be weather and frost proof to prevent them freezing up and stopping working, in which case the above issues can occur.

Durgo Valves are used in various scenarios where conventional venting is not possible or practical. They are typically employed in internal plumbing systems where connection to an external vent is difficult, such as in high-rise buildings, basement bathrooms, or in renovations where access is limited. Types of Durgo Valves With the case of smaller valves, as mentioned, they only need to feature where localised siphoning issues occur. How do Air Admittance Valves Work?If you are fitting into existing pipework, you will need to install a "T-piece" or equal-T as it’s known. The T-piece will allow the existing drainage to still work plus provide a spur for the section of vertical pipe the valve can be fitted onto. With this in mind, as this does happen, it’s essential that your valve is placed in a location that can be easily accessed. In the majority of cases and in most homes in the UK, the balance of pressure within a waste pipe system is maintained through a soil vent system. This is just a vertical extension of the soil pipe system that stops beyond the highest drainage point in the property.

With all the pipework in place and the valve securely fitted, allow enough curing time for the solvent adhesive and then give the valve a test to make sure all is working ok and the issue that caused you to install the valve in the first place has now been resolved. Installing 110mm Air Admittance Valves Locate the highest point in the room, in most cases this will be the sink plug hole and use a spirit level to transfer the height of this point over to your install area and then mark the wall. Note: One final point to establish is that a 110mm air admittance valve will only need to be installed if the soil pipe itself isn’t vented e.g. can’t run up and out of the roof or external wall as it normally would do. How high should you install the air admittance valve? The short answer is a minimum of 200mm above any water entry point. So if you imagine your soil pipe run, then durgo valve / AAV must be fitted above the highest connection to the soil pipe from any sink, bath or toilet that is connected to it. Usually you’ll find the installed at the very end of the soil pipe. If you need to, you can install them in line using a soil pipe junction.You can, but it’ll need to be the right one. Most air admittance valves are designed only for use inside, so if you’re planning on doing this you will need to buy one that is suitable for external use. The only real reason for doing this would be if there was nowhere suitable to vent the pipe in the usual way, such as as mentioned previously, too close to a window, or not able to get above roof level. As I said before an open vent must be installed more than 3 meters away from a window and this is not always possible. In this scenario you could use an AAV that is rated for external use, as these can be placed close to the window as they will not allow escape of foul smelling gasses. Air Admittance Valves are very cleverly designed to allow the free entry of air into the pipework system without allowing any foul odours or gases to escape out. They achieve this through the use of a diaphragm that keeps the valve closed under normal atmospheric pressure (or if pushed up by positive pressure in the system) but opens it when pulled down by negative pressure in the system. As we have looked at above, there are 2 different types of air admittance valve. In the majority of cases the one that you’ll be fitting will be the smaller version to take care of localised pressure issues. The air admittance valve is a one way ventilation system that allows air into the drainage system when there is negative pressure, but does not allow any air out due to a sealing mechanism, which preventing foul smells from spreading.

Rubber Finger/Push-fit: The bottom of the valve features fairly stiff rubber banded bellow-like belt. The “fingers” of the belt are pushed down into the top of the pipe and grip the inside holding it in place. To ease fitting some washing up liquid is often used to help it slip down into place. As it can be easily pulled out, if there are any issues it can easily be removed for repair or replaced.A modern alternative to solving the pressure problem in soil and waste systems is through the use of Air Admittance Valves. Solvent Weld Fixing: This basically involves the same methods as when you cut and joined the T-piece in the steps above. Take the solvent weld and apply it to the top of the vertical pipe and also inside the collar of the AAV. Place the AAV on top of the pipe and ensure that it is pushed down and seated correctly. Leave it to cure for the manufacturers recommended time (normally around 24 hours) As the pipe is not capped and left fully open, air can easily be pulled down through to ensure the correct balance is maintained in the pipework. An added bonus is that any gases can also escape up and out if needed. Cut a piece of pipe to length, clean any burrs off, apply some solvent weld and then push it into the T-piece and ensure it’s vertically upright.