Room/ return air humidity P- control with comfort zone

The humidity control module works in a typical sequencing application: humidifying and dehumidifying with an adjustable comfort zone between. In this case, the module uses two separate proportional controllers with internally calculated setpoints for humidification and dehumidification, depending on the value of the input “RoomRelHumSp” and the adjusted comfort zone, defined by parameter HUMDEH-02.

The value of the input  “RoomRelHumSp” can be compensated by the winter- or summer-compensation functions and/ or by the setpoint adjustment input "RelHumSpAdj". The separate humidify and dehumidify P-controllers have their own P-band, respectively defined by parameter HUM-01 and DEH-01.


Note: When the comfort zone HUMDEH-02 is greater than "0", the macro will automatically set the integral time HUMDEH-01  to “0”.

When the comfort zone HUMDEH-02 = "0", the integral time can be set the values different of "0".


Next figure shows the calculated setpoints for the two controllers, and the adjusted comfort zone, which is symmetric around the calculated room air setpoint. The figure shows also the P-band for the humidify controller, totally shifted below its calculated setpoint and the P-band for the dehumidify controller, totally shifted above the calculated setpoint.



The next figure shows the two P-controllers with shifted P-bands and calculated setpoints besides the adjusted comfort zone.



Room/ return air humidity PI-control without comfort zone

When the user sets the comfort zone HUMDEH-02 = "0":




Description

Default value

HUM-01: P-band humidification control

4 %RH

HUM-02: Relative humidity control signal increase per minute

10 %

DEH-01: P-band dehumidification control

6 %RH

DEH-02: Relative humidity control signal increase per minute

10 %

HUMDEH-01: I-time humidify/ dehumidify control

0 sec

HUMDEH-02: comfort zone between humidify/ dehumidify

4 %RH