UK trade guideBoiler Spares 5 min readUpdated 11 July 2026

How to Replace the Auto Air Vent on a Potterton Assure 30 (UK)

Step-by-step UK guide to replacing the brass automatic air vent on a Potterton Assure 30. Part numbers, torques, commissioning.

Potterton

The part

Fit a new AAV on Potterton Assure 30 when the boiler airlocks on start-up or the pump makes gurgling noises after refilling.

Isolate safely

Isolate flow and return, unscrew the AAV from the top of the pump head or air separator on Potterton Assure 30.

Fit and commission

Loosen the AAV cap one full turn once refitted — a fully-closed cap defeats the float.

Recommission checklist

Refill the Potterton Assure 30 to 1.2 bar cold. Bleed high-point radiators and the internal AAV.

Run a full flue-gas analysis after 15 minutes. Log the reading against the OEM commissioning envelope in the Benchmark book.

Frequently asked questions

Any special height?
Fit the highest point of the Potterton Assure 30 circuit — that is where entrained air collects.
How often should I service?
Annually — the float sticks with sludge in unfiltered systems.
Do I need to notify the manufacturer?
Only if the Potterton Assure 30 is in warranty — Potterton require log of any part swap for labour claims.
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