A room shows no temperature ("—")

Usually a flat sensor — the system falls back to the valve meanwhile.

If a room shows "—" instead of a temperature, its thermometer hasn't reported recently. The system automatically falls back to the radiator valve's own temperature where one is present, so heating keeps working.

What to check

• The room's thermometer battery — a flat battery is the most common cause. Replace it.
• That the sensor is within range of the bridge.
• Give it a few minutes after a battery change to start reporting again.