• Fits 32mm, 40mm and 50mm waste: The valve fits a 32mm solvent weld socket on its own, and the stepped adaptor in the box takes it up to a 40mm or 50mm socket
• Check your size before ordering: UK solvent weld waste is named by bore, so 32mm, 40mm and 50mm pipe measure roughly 36mm, 43mm and 56mm across the outside
• Helps stop smells and gurgling: Opens to let air into the waste pipe as water drains, so the trap keeps its water seal and drain odours stay out of the room
• Indoor vent for sinks and showers: For basins, sinks, baths, showers and washing machines in kitchens, bathrooms and utility rooms where a pipe cannot be run outside
• Fit it the right way: Install upright, indoors, with the valve above the water level of the highest trap it serves. It adds a vent to a branch, it does not replace the main stack vent
• White or black ABS: Pick the colour that matches your pipework. In the box: one air admittance valve and one 40mm/50mm stepped adaptor

This LavaTap air admittance valve is a compact internal vent for 32mm, 40mm and 50mm solvent weld waste pipe. It lets air into the waste system when water drains, so the trap under your sink, basin, bath or shower keeps its water seal. That helps stop drain smells coming back into the room and cuts the gurgling and slow draining caused by a siphoned trap.

Sizes: the valve fits a 32mm solvent weld socket directly. For 40mm or 50mm pipework, fit it into the stepped adaptor supplied, then fit the adaptor into the socket. UK solvent weld waste is named by bore, so measure the outside of your pipe first: about 36mm for 32mm pipe, 43mm for 40mm pipe and 56mm for 50mm pipe. This valve is for waste pipe only. It is not a 110mm soil stack valve.

Where to use it: kitchens, bathrooms, en suites, utility rooms and under sink cupboards, wherever a branch pipe needs venting and a pipe cannot be run outside. It suits basins, kitchen sinks, baths, showers, washing machines and dishwashers.

How to fit: install the valve upright, indoors, at a point above the water level of the highest trap it serves, and leave space around the top so air can get in. An air admittance valve adds ventilation to a branch. It does not replace the open vent at the top of the main soil stack, which the drainage system still needs.

In the box: one air admittance valve and one 40mm/50mm stepped adaptor. Available in white or black to match your pipework.