High
S.54 on Vaillant ecoMAX 824E

Your boiler has paused because it cannot detect enough water flow or pressure to operate safely without overheating.

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

Low water–level waiting period

From this model's manual
Verified against the Vaillant Ecomax 613 installation & service manual, page 45.
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 boiler's internal sensors detect that water isn't moving through the heat exchanger quickly enough to safely carry heat away. The most common reasons are a failing circulation pump that can't push the water round, or a build-up of air and debris that is restricting the flow and causing the temperature to rise too rapidly.

This issue is more frequent in autumn when heating systems are turned back on after summer, as pump components can seize up 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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