Energy Saving with DST’s 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 can increase operating efficiency, lower carbon emissions and reduce running costs; factors that may be crucial for environmental certification. PLCs (C2 and C4) 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
– synchronize the operation of key components
– monitor protection devices, trips and alarms
– adjust unit capacity to maintain required humidity, temperature or airflow

One supplier

DST offers a number of systems which controls both humidity and temperature. This means you do not need to coordinate multiple installations – everything is supplied optimised, from a single supplier.

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

EH3-T3-webbDST’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 T2 & EH4) or an external controller (BMS), the dehumidifier drying capacity can be finely tuned to accurately maintain the required set point.

PLC C4: Controlling both humidity and temperature – online and on site

The PLC C4 is easy to use thanks to the user-friendly touch screen. The user can easily overview and manage the process of controlling both humidity and temperature. The user may also set regulator values and view the process-data. It is possible to manage the start-up process, control, see the functions as well as start and stop the dehumidifier via internet. The C4 also offers great expansion possibilities since it is easy to add on different functions. All functions are tested by DST at factory before delivery.

  • For advanced RZ, CZ or Flexisorb unit control.
  • Graphic touch display, 5.7”
  • Communication via Modbus TCP/IP, or remote access* through Ethernet.
  • Cost-effective process control online.
Humidity control with electronic humidistat and regulator EH3 T2 and humidistat EH4

EH3 T2, Electronic humidistat and regulator

  • Relative humidity (RH) in %
  • Absolute humidity in g/kg
  • Dewpoint °Cdp
  • Temperature °C / K / °F
  • PI Regulator for humidity or temperature
  • Two step humidistat
  • Two independent potential free closing contacts

EH4 , electronic humidistat

  • Two-step humidistat
  • Sensor with quick respons
  • Two independent potential free closing contacts
  • %RH display with two dioids indicates e.g. too high RH
Energy Saving with EH4, EH3 T2 and PLC C2

Energy Saving 1
The reactivation heater power output is regulated in two steps. Our humidity controller EH3 T2 or EH4 adjusts the drying capacity between High, Low & Off, as required to maintain the humidity (or dew point) between two programmable set points.

Energy Saving 2
The reactivation heater power is fully regulated between zero and full capacity using either binary (multi-step) or linear (triac or actuator) control. Using our humidity controller EH3 T2 + PLC C2 or an external control signal (BMS + PLC C2), the drying
capacity is finely adjusted to accurately maintain the required set point (humidity or dew point).
Energy Saving 3
Used on steam reactivated dehumidifiers only, the reactivation air fan is regulated between 20% and full flow using a motor frequency inverter. The reactivation temperature is maintained at a high level. Using our humidity controller EH3 T2 + PLC C2 or an external control signal (BMS + PLC C2), the drying capacity is finely adjusted to accurately maintain the required set point (humidity or dew point).

Preventing condensation and corrosion using EH3 T2 

A temperature sensor attached to the coldest surface is paired with a room humidity sensor. Our EH3 T2 simultaneously monitors surface temperature, relative humidity and dew point of the room air. Our humidity controller EH3 T2 accurately adjusts the drying capacity to maintain the required RH set point. Should the air dew point exceed the monitored surface temperature, EH3 T2 will automatically override the RH set point, increasing its control output to the dehumidifier. EH3 T2 regulates the drying capacity to control both RH and dew point while ensuring least possible energy is consumed.


Humidity and temperature control with C4

Integrating output temperature control in the dehumidification process makes it possible to reduce the total energy consumption thanks to interaction of the humidity and temperature parameters. Cooling and heating coils are built into the dehumidifier. DST is able to offer both DX cooling and coils for chilled water. Heating can be done with either hot water, electricity or steam heating.


Modbus communication via TCP/IP or RTU gives the actual values for temperature and humidity, possibility to start/stop the dehumidifier as well as alarm readouts and operation indicators.

Remote access

PLC C4 can be mirrored locally on one or more computers via a network connection.



Contact us to learn more about Energy Saving for DST dehumidifiers.

Energy saving (PDF)