Access can humidify the supply air by controlling the output of a single stage humidifier. The humidification of the supply air is PID regulated to increase relative humidity in the room (or extract air) to the setpoint value. An analog output is used to control a humidifier. The output will increase on decreasing room (or extract air) humidity. A digital output can also be used to start a humidifier.

The humidification of the supply air can be monitored and limited by installing optional RH duct sensor and adjusting appropriate settings. The limitation is determined by "Max limit humidity supply air" and "Hysteresis for max limit humidity supply air":

If the maximum limitation is 80 % RH and the hysteresis is 20 % RH, the controller output signal will begin decreasing at 60 % RH. When halfway to 80 % RH (i.e. when at 70 % RH), half the output signal will be damped. If the humidity in the duct still reaches 80 % RH, the entire output signal will be damped.

Configuration example of the humidification


Available options & Selection


Activate Humidity control

Configuration > Functions > Function activation

Humidity control

… | Humidification |…

Configure function

Configuration > Functions > Humidity control

Humidity control


Indication of what function has been activated

Type of output

| Analog | Step | Analog + Step |

| Analog | - 0..10V signal for capacity

|Step| - relay output for start/stop

PID Settings

Configuration > PID controllers > Humidification


[100] %RH

PID settings to describe responsiveness of the humidifier


[300] s


[0] s

PID output max limit

[100] %

Max output of the PID can be limited

Hardwired interface

Configuration > I/O allocation settings >

Analog inputs > Humidity room/extract air

Any available I/O

Mandatory - humidity sensor for reference

Analog inputs > Humidity supply air

Optional - for limiting humidity of the supply air

Digital outputs > Humidity control start

Interface to the humidifier

Analog outputs > Humidity control

Operational settings

Data & Settings > Humidity control

Humidity room/extract air

__ %

Actual measured RH

Setpoint humidity room/extract

[50] %RH

Max limit humidity supply air

[80] %RH

Limiting of the supply air humidity

Hysteresis for max limit humidity supply air

[20] %RH

Digital output start point

[15] %

DO (Humidity control start) is activated once AO (Humidity control) exceeds 15%

Digital output stop point

[5] %

DO (Humidity control start) is deactivated once AO (Humidity control) falls bellow 5%

Operation overview

Data & Settings > Operation overview > Humidity

Humidity room/extract air

__ %

Overview of the function in action

Setpoint humidity room/extract

[50] %RH

Humidity control

__ %

Humidity control start

Off | On

Humidity control mode

Not active | Humidification