Low
d.21 on Glow-worm MicraCom

Your boiler is simply indicating whether the 'warm start' feature—which keeps water inside the boiler pre-heated for faster taps—is currently switched on or off.

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

Status of the warm start for domestic hot water

From this model's manual
Verified against the Glow Worm Micracom installation & service manual, page 41.
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

Navigate to the boiler control panel menuLocate the warm start or comfort mode settingsToggle the setting to your preferred 'on' or 'off' position

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d.20View →d.22View →

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