Why does the new one still weep?

Almost always the expansion vessel — check pre-charge first before condemning the PRV.

Only fit WRAS-approved 3-bar PRVs to keep Potterton Promax 33 HE within its Gas Safe commissioning envelope.

Do I need to notify the manufacturer?

Only if the Potterton Promax 33 HE is in warranty — Potterton require log of any part swap for labour claims.

Fit a new 3-bar PRV on Potterton Promax 33 HE when water dribbles constantly from the outside discharge pipe.

Drain below the PRV, unscrew the old valve and fit new PTFE tape (10 turns clockwise).

On Potterton Promax 33 HE the PRV sits on the hydraulic block — torque to 25 Nm to avoid cracking the plastic manifold.

Refill the Potterton Promax 33 HE 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.

Why does the new one still weep?: Almost always the expansion vessel — check pre-charge first before condemning the PRV.
Any WRAS approval?: Only fit WRAS-approved 3-bar PRVs to keep Potterton Promax 33 HE within its Gas Safe commissioning envelope.
Do I need to notify the manufacturer?: Only if the Potterton Promax 33 HE is in warranty — Potterton require log of any part swap for labour claims.

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