Temperature control

The thermostat acquires the room temperature via its built-in sensor and maintains the setpoint by delivering 2-position valve control commands.

The switching differential is 2 K in heating (adjustable via parameter P30).


The display shows the current room temperature, the currently selected fan speed (adjustable via parameter P54) or the setpoint of the current operating mode (adjustable via parameter P06). If EXT/INT air circulation is enabled, the corresponding symbol indicates the type of air flow. The factory setting displays the current room temperature.

Symbol indicates floor heating. The small symbol means that the relay output is energized.

For VRF mode, indicates Auto VRF mode, indicates cooling, indicates heating, indicates ventilation and indicates dehumidification.

Setpoint adjustment and limitations

The factory setting for the basic setpoint is 21 ℃. The setpoint can be adjusted via the +/- buttons. The minimum (P09) and maximum (P10) setpoint limitations can be used to save energy.

There are two different concepts below:

P09<P10 (comfort concept) - typical use case

If the minimum setpoint (P09) is set below the maximum setpoint (P10), the heating setpoint can be adjusted between these two limits. The users desired setpoint and the unit controls the room temperature accordingly.

P09≥P10 (energy saving concept)

If the minimum limit P09 is set above the maximum limit P10

  • The setting range of heating setpoint is 5 ℃…P10 rather than 5…40 ℃.
  • The setting range of cooling setpoint is P09…40 ℃.

As a result, the maximum heating setpoint or minimum cooling setpoint can be limited, thus saving energy and lowering costs.

Air flow selection

When P25 = 1, the following can be selected by users.

  • : Internal circulation (i.e. no fresh air from outside)
  • : External circulation ( i.e. fresh air via heat recovery unit)

FAU ECO mode (P02 = 2, P25 = 1)

FAU ECO mode can be enabled via setting P02 = 2 (i.e. FAU ECO can be selected) and P25 = 1 (i.e. external and internal circulations must be enabled).

When FAU ECO mode is selected, the fresh air fan controller automatically switches between internal and external circulations for the air flow as per the ratio defined by P26. E.g., when P26 = 1:5, the controller switches to external circulation for 10 minutes, then internal circulation for 50 minutes. The mode setting repeats automatically within one hour. Other ratios can be selected via P26.

Fan type and fan speed adjustment

3-speed fan type (P54 = 3) is the factory setting. When P54 is set to:

  • 1, the fan type is 1-speed fan.
  • 2, the fan type is 2-speed fan.
  • 4, the fan type is ECM fan.

Only 1 manual fan speed can be selected for 1-speed fan.

Only 2 manual fan speeds can be selected for 2-speed fan.

Only 3 manual fan speeds can be selected (low, medium and high) for 3-speed fan and ECM fan.


Keylock can be activated or deactivated via parameter P14 (see Control parameters) when the unit is in ON and OFF mode.