Medium
S.39 on Glow-worm Energy

Your boiler has detected that the external safety switch for your underfloor heating system is currently turned off or disconnected, so it has paused heating to that area to prevent damage.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Underfloor heating contact open

From this model's manual
Verified against the Glow Worm Energy installation & service manual, page 33.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

S.38View →S.40View →

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