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Thermostat low

Heat pump not starting — Programmable thermostat set too low

Daikin · Altherma Heat Pumps

What does Thermostat low mean?

The heat pump may not activate to provide heating if your programmable room thermostat is set to a temperature lower than the desired warmth for the room. It needs to be set above the current room temperature to start.

Common Causes

  • The programmable room thermostat is set below the temperature required to trigger the heat pump

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the current temperature setting displayed on your programmable thermostat.

  2. 2

    Increase the thermostat's set temperature to a level above the current room temperature.

  3. 3

    Confirm that the heating schedule is active and the system is in heating mode.

Browse all codes in this manual (10)
Verified technical data. Last updated: April 2026

Related Faults

Fault codeSystem not operating — Fault code displayed on controllerNo green light (DHW)Cannot adjust domestic hot water settings — DHW function is offNo green light (Room Temp)Cannot adjust room temperature settings — Room temperature function is off
Source: Daikin Altherma Heat Pumps
Open Manual (Page 11)Search more codes in this manual