Humidity and condensation can compromise building occupants' health and comfort, damage interior finishes, and raise heating costs.

The RDPU-CPC (condensation prevention controller) is specially designed for cellars, wine cellars, museums, food production and storage facilities where condensation needs to be prevented.

What is condensation and which parameters are important?
Condensation describes when a gas condenses back into a liquid and is more often used when referring to water vapour condensing back into liquid water. Water condensation usually happens when water vapour cools and appears as droplets on a surface or appears as clouds or water droplets in the sky.

Relative humidity

The ratio of water vapour in the air to the maximum amount of water vapour the air can hold at a particular temperature is expressed as relative humidity (rH). For example, rH of 30% means that the air contains 30% of the moisture it can possibly hold at that particular temperature. When air can hold no more moisture at a given temperature (i.e. the rH is 100%), the air is said to be saturated.

Dew point

The dew point is the temperature to which air must be cooled to become saturated with water vapour. When further cooled, the airborne water vapour will condense to form liquid water (dew). When air cools to its dew point through contact with a surface that is colder than the air, water will condense on the surface. The measurement of the dew point is related to humidity. A higher dew point means there will be more moisture in the air.

As air temperature increases, its capacity to hold moisture also increases, so if air temperature rises and its moisture content remains the same, the rH decreases. 

Condensation and indoor air quality

Too high relative humidity degrees will result in condensation forming on windows, walls and ceilings that are colder than the air temperature and potentially damaging building materials and causing odours in poorly ventilated spaces.

The condensation process will facilitate the growth of moulds and bacteria that can cause respiratory problems and/or allergic reactions. It provides the conditions for dust mite populations to grow, which can affect asthma sufferers.

Condensation prevention
The RDPU controller with CPC firmware can calculate the dew point based on wall temperature, in- and outside temperature and relative humidity.
A supply and/or extraction fan can be controlled to avoid condensation. 

Automatic mode


Relative humidity control

Dew point control

The temperature set point and relative humidity set point can be adjusted via the touch screen. Based on these set points and the measurements of outside and inside temperature & relative humidity, the supply and extraction fan will be controlled automatically to prevent condensation.

How does the RDPU-CPC works?
Indoor and outdoor multifunctional sensors are used to determine the optimum ventilation conditions. In this way, over the entire year, the humid cellar or room air can be replaced with dry air. The room is only ventilated if the outside air is even able to absorb and transport moisture. Dew point temperature is the measurement of absolute humidity in the air. The lower it is, the more water vapour it can absorb. The dew point temperature is measured and evaluated by the ventilation.

Manual mode

Manual mode

Manual Mode represents operation of the fans for a user-defined period of time. After the desired period has expired, the CPC automatically switches to Standby Mode. This mode is especially useful when ventilation is needed for a shorter period.

Interval mode

Interval Mode represents a continual mode of operation. After the desired operating period of the fans has expired, the CPC automatically stops these until the defined full period has expired. Afterwards the controller restarts its operation.

The key features

  • Plug & play - Power over Modbus (PoM) connection
  • CPC calculates the dew point based on wall temperature, inside and outside temperature and relative humidity
  • A supply and/or extraction fan can be controlled to avoid condensation
  • Designed for wine cellars, food production and storage facilities and museums. Locations where condensation needs to be prevented.
  • Automatic or local control

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