Medium
F86 on Glow-worm Ultracom 35 Store

Your boiler has detected an issue with the sensor or connection for an underfloor heating system, causing it to temporarily lock out to keep your home safe.

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 fault; Floor heating contact open; Sensor disconnected or defective

From this model's manual
Verified against the Glow Worm/Glow Worm Ultracom 35 Store 4701915 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.

Engineer required

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

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Related fault codes

F85View →F87View →

All 70 fault codes on the Ultracom 35 Store

Seeing a different code? Every code this model can display, in one place.

d.94ErrF00F01F1F02F03F3F10F11F12F13F20F22F23F24F26F27F28F29F32F49F61F62F63F64F65F67F68F70F71F72F73F74F76F77F79F81F83F84F85P.05P.06P.07S.00S.01S.02S.03S.04S.05S.06S.07S.08S.20S.21S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.53S.54S.96S.98

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