Medium
F.8 on Viessmann Vitodens 100-W WB1A

Your boiler has lost the ability to read the temperature of your hot water cylinder, preventing it from heating your water correctly.

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

Short circuit, cylinder temperature sensor

From this model's manual
Verified against the Viessmann Vitodens 100 W Wb1a installation & service manual, page 83.
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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