Automatic Air Vent (AAV)
Also known as: auto vent, automatic bleed valve, automatic air eliminator
A self-operating vent that automatically releases trapped air from the highest points of a heating system without any manual intervention. Prevents noisy pipework and cold spots.
At the highest point of the heating system or mounted at the boiler on the flow pipe.
Small brass or plastic fitting with a cap on top, 15 mm or 1/2 inch BSP. The cap should be slightly loose to allow air to escape.
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Always turn off the water supply before replacing any part. If in doubt, consult a qualified plumber. Gas components must only be worked on by a Gas Safe registered engineer. Unvented (pressurised) hot water systems must be worked on by a G3-qualified engineer. Prices shown are indicative — check retailers for current pricing.