Low
S.75 on Viessmann Vitodens 200-W B2HF System

Your boiler is not currently receiving a request for heat because an external control device, such as a thermostat or timer, is switched off or disconnected.

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

No demand; external hook-up, heating circuit 1

From this model's manual
Verified against the Viessmann Vitodens 200 W B2hf System 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.

DIY fix possible

Check your room thermostat is set to a temperature higher than the current room temperature.Ensure your programmer or heating app is set to an 'On' period.Check if any external 'ECO' or 'Holiday' modes are currently active on your control panel.

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