Low
S.54 on Vaillant Thermocompact

Your boiler has temporarily paused to protect itself because the water inside is heating up or cooling down much faster than expected.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Delay mode due to flow temperature gradient too steep (approx 10 mins.)

From this model's manual
Verified against the Vaillant Turbomax Plus 824 828e installation & service manual, page 38.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check that all radiator valves throughout your home are fully openEnsure your heating system has the correct water pressure (between 1 and 1.5 bar on the gauge)Wait 10-15 minutes to see if the boiler resumes normal operation automatically

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