After power-up, all LCD segments light up for about 3 seconds. Afterwards, the unit starts in Normal mode to display the current room temperature, user navigation icons and status of the application according to the factory settings. Then the unit is ready for commissioning by qualified HVAC staff.

The control parameters of unit can be adjusted to ensure optimum performance of the entire system (see Parameter settings).

Surge protection at power-up

When the thermostats are powered, except all valve outputs (e.g., Q5, Q14), LCD display and key buttons operate normally.

The thermostat outputs start at random to protect the electric system against overload. For all thermostat outputs to work properly requires a short while.

Sensor calibration

The unit has an internal sensor for accurate temperature display. If the temperature display is influenced by its installation location, calibrate the sensor via parameter P05 to adjust the readings.

Setpoint and range limitation

For comfort and to save energy, we suggest to review all setpoint related parameters and adapt them as needed.

External circulation (factory setting)

The unit is set with the factory setting for external circulation () only and 3-speed manual fan (P54 = 3), i.e. P02 = 1, P25 = 0 and P26 = 1 (see Control parameters).

Alternatively, some fresh air units or purifiers are equipped with an ECM fan (P54 = 4). This allows user selection of low, medium and high fan speeds.

Depending on use cases, users can also select P54 = 1 (1-speed fan) or P54 = 2 (2-speed fan).

Internal circulation

When P25 = 1, internal circulation is enabled, i.e. users can select both external and internal circulation.

When P25 = 1, users can select all modes (, ) via setting button .

Selection of FAU ECO mode

Except ON/OFF mode selection, users can select different modes for air flow. When P02 = 2 and P25 = 1, users can select FAU ECO mode via On/Off button .

With FAU ECO mode is selected with the factory setting of P26 = 1 (1:5), the unit switches to external circulation for 10 minutes, then internal circulation for 50 minutes within one hour.

The mode setting repeats automatically within one hour. Other ratios can be selected via P26.