Dewpoint & Humidity Control

Energy efficient control for DST industrial dehumidifiers

Economy and Environment

With new government efficiency targets and ever-increasing energy prices, it is DST’s policy to use new technologies wherever possible. This ensures that our products continue to use energy effectively and efficiently.

Our programmable logic control (PLC) systems will improve operating efficiency, lower carbon emissions and reduce running costs; factors that may be crucial for environmental certification.

    PLCs (C2, C4 and C7) are tailored to ensure highest operating efficiency is achieved for each specific project.  PLCs can be used independently, with one of our digital controllers (EH3 & EH4) or interlinked with a building management system (BMS).

    The primary functions of the PLC are to:

    • provide a user friendly interface
    • synchronise the operation of key components
    • monitor protection devices, trips and alarms
    • adjust unit capacity to maintain required humidity, airflow and temperature.

    PLC type C2 for industrial dehumidifiers (RLZ, CZ, RF)

    DST’s entry level PLC type C2 is fitted as standard to all our industrial dehumidifiers. A user friendly keypad allows easy access to the menu options and a two-row backlit LCD screen displays important messages to the user. Used in conjunction with one of our humidity controllers (EH3 & EH4) or an external controller (BMS), the dehumidifier drying capacity can be finely tuned to accurately maintain the required set point.

    PLC type C2

    • Digital Inputs: 9
    • Digital Outputs: 7
    • Analogue Inputs: 4
    • Analogue Outputs: 2
    Desiccant Dehumidifier C2:1 Standard PLC
    Bespoke programming of the C4 controller ensures efficient control of the complete drying system and its related processes

    PLC type C4: Controlling Humidity, Temperature and Airflow – Remote & Local

    Our PLC type C4 provides a multi-function control capability. Bespoke programming ensures efficient control of the complete drying system and its related processes.

    A user friendly colour LCD touch screen provides a graphic display of the principal components with live operating data. There is easy access to menu options and the 5.7” backlit screen clearly displays important messages to the user.

    The C4 offers great expansion possibilites since it is easy to add on additional functions. Using our free PC software tool, PLC operation can be monitored and adjusted remotely via the internet.

    PLC type C4

    • Digital Inputs: 16
    • Digital Outputs: 16
    • Analogue Inputs: 4
    • Analogue Outputs: 4

      Type EH3: PI Controller for Humidity & Temperature

      Relative humidity % RH
      Absolute humidity g/kg
      Dew-point °Cdp
      Temperature °C / °K / °F
      Two independent controllers

      Optional features:

      • To prevent condensation, a mounted temperature sensor provides a ‘floating’ set point for dew point control.
      • Duct mounted temperature sensor can also be used for controlling air temperature.
      • Communication through Modbus RTU.
      • Additional displays.

      EH3 Humidity controller for dehumidifiers and humidifiers
      EH4 Humidity controller for dehumidifiers and humidifiers

      Type EH4: Relative Humidity Controller – 2 Relays

      • Two closing contacts: Two independently programmable relays with
        adjustable hysteresis. Possible to use for both dehumidification and
      • Suitable for Hi/Lo/Off control of one unit, On/Off control of two
        separate units or On/Off control of one unit plus remote high/low RH
      • Display and diodes: High visibility RH display (15 mm). Neon lamps
        indicates relay operation. Display flashes if ‘High RH’ set point is
      • Sensor (IP65): Honeywell fast response capacitive type moisture
        sensor. Factory calibrated (accuracy < ±2%RH).
      • Option: Sensors available for wall or duct mounting with 3m cable.
      • Option: Remote mounting of display + keypad using RJ9 low voltage
        extension cables.