High
P3.0-3.5 bar on Potterton Powermax HE

Your boiler has shut down because there is too much water pressure in the system, which could lead to leaks if not addressed.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Pressure too high, boiler off

From this model's manual
Verified against the Potterton Powermax He installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the water pressure inside your heating system exceeds the safe operating limit of 3.0 bar. The most common reasons are a filling loop valve being left slightly open or the internal expansion vessel losing its air charge, which prevents it from absorbing the natural expansion of water as it heats up.

This issue often surfaces during the first cold spell of autumn when the heating is turned on for the first time in months, causing the water to expand and reveal a failing expansion vessel.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Avoid the next call-out bill

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