Air Admittance Valves

All soil stacks require venting to admit air into the system in order to break the vacuum when the discharge of a fixture creates a negative pressure flows through the pipes. These vacuums may otherwise empty the traps and allow foul air to escape from the soil stack leaking foul odours indoors. Air admittance valves open in the event of a vacuum to allow air into the soil stack. The valve is otherwise closed and is airtight.

• Designed to reduce the number of ventilating pipes which pass through the roof.
• Valves can be installed in a ventilated duct or the roof space.
• Conventional ventilation is required if more than 5 dwellings in a row are equipped with a valve.
• The valve must not be at risk of freezing and therefore should not be fitted externally. It should also be accessible for inspection and testing.
• Must be fitted above the flood (overflow) level of the highest appliance.

The Marley collar boss was specifically designed to overcome installation problems imposed by the 200mm restricted zone. It allows multiple low level bath or shower waste pipes to be connected to the stack above floor level.

Note: If you are installing a new soil stack or drainage system, or significantly altering an existing system, you will need to inform the Building Control Department at your local Council. You will need to demonstrate that the work carried out conforms to Building Regulations: England & Wales or Scotland