Daikin Altherma Heat Pumps
10 fault codes documented
System not operating — Fault code displayed on controller
If your system continues to malfunction after a power reset, look for a specific fault code (typically a letter followed by a number, like '7H') displayed on the Daikin controller. This indicates a particular system issue that needs professional attention.
Cannot adjust domestic hot water settings — DHW function is off
If there is no green light visible above the domestic hot water symbol on the controller, the domestic hot water function is currently switched off. This prevents you from adjusting its settings.
Cannot adjust room temperature settings — Room temperature function is off
If no green light is visible above the room temperature symbol on the controller, the room temperature function is currently switched off. This prevents you from adjusting the room temperature settings.
No hot water — Tank is empty or cold
If you find that you have run out of hot water outside of your scheduled heating times, the cylinder may be empty or not heated sufficiently. You can activate a boost function to quickly heat the water.
System not operating — Mains power switched off
Your Daikin Altherma heat pump system will not function if the mains power supply is interrupted or switched off. This includes any dedicated switches for the indoor unit and the outdoor unit.
Radiator too cold — TRV set too low
If a radiator in your home feels too cold, it's possible that its Thermostatic Radiator Valve (TRV) is set to a low level, limiting the heat output to that specific room.
Reduced heating efficiency — Outdoor unit clogged or blocked
The efficiency of your heating system can be reduced if the rear of the outdoor unit becomes clogged with leaves or debris, or if the front is blocked by external objects. This can restrict airflow and impact performance.
System still fails to operate normally — Temporary fault
If you have already checked the basic points (radiators, thermostat, power) and the system is still not operating as expected, a temporary internal fault might be preventing normal function. A full system reset may resolve this.
Heat pump not starting — Programmable thermostat set too low
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.
Domestic hot water temperature cannot be adjusted — Weather compensation active
If you see the cloud symbol on the display, it means the domestic hot water temperature is automatically controlled based on weather compensation. In this mode, manual adjustment from the home menu is not possible.