High
Safety temperature limiter on Ideal Concord Super Series 4

Your boiler has switched itself off because the water inside became too hot, likely due to a circulation issue.

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

Operates if the water flow rate through the boiler is inadequate; requires manual reset by pushing in the 'reset' button.

From this model's manual
Verified against the Ideal Concord Super Series 4 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 inside the boiler exceeds a safe operating temperature, triggering a safety shut-off to prevent damage. It is usually caused by a blockage in the system or a failing pump that is no longer moving hot water away from the heat exchanger quickly enough. In some cases, the internal sensor responsible for monitoring heat may have developed a fault and is providing an incorrect reading.

This issue often surfaces when the heating is first turned on after summer, as pump components can seize during long periods of inactivity.

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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