Access 5.x

Humidification


Access can humidify the supply air by regulating the output of a single-stage humidifier. The supply-air humidification is controlled via a PID loop to increase the room (or extract-air) relative humidity to the setpoint value. An analog output is used to modulate the humidifier capacity, increasing the output when room (or extract-air) humidity decreases. A digital output can also be used to start the humidifier.


Supply-air humidification can be monitored and limited by installing an optional RH duct sensor and configuring the appropriate settings. The limitation is defined by “Max limit humidity supply air” and “Hysteresis for max limit humidity supply air”:


For example, if the maximum limit is set to 80% RH and the hysteresis to 20% RH, the controller output will begin to decrease at 60% RH. At the midpoint between 60% and 80% RH (i.e., 70% RH), the controller output will be reduced by 50%. If the duct humidity still reaches 80% RH, the output will be fully reduced.


Humidification is disabled during cool-down mode to allow the humidifier to dry before shutdown.


Configuration example of the humidification




Variable

Available options & Selection

Note


Activate Humidity control

Configuration > Functions > Function activation

Humidity control

… | Humidification |…



Configure function

Configuration > Functions > Humidity control

Humidity control

 Humidification

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

P-band

[100] %RH

PID settings to describe responsiveness of the humidifier

I-time

[300] s

D-time

[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

Humidity supply air

__ %

Setpoint humidity room/extract

[50] %RH

Humidification setpoint

__ %

Humidity control start

Off | On

Humidity control mode

Not active | Humidification