The radiant heating and cooling systems are operated with a constant flow temperature.The flow temperatures are around 34 °C in the heating mode and around 16 °C in the cooling mode. For regulation, by a submersible sensor in the flow of the system the given temperature is compared with the desired setpoint tempe-rature and the mass flow from the heating or cooling source is controlled accordingly.

Due to the low water content and a spread of 2 to 3 Kelvin, a zone control is carried out as a two-point control by a distributor with actuator. Thus, the valve opens for the corresponding room when required for heating or cooling. The valve closes when the setpoint temperature is reached. Each room is controlled separately by a room controller. The switchover between heating and cooling is done centrally.

In addition, each room is equipped with a dew point sensor, which shuts down the corresponding room zone at risk of falling below the dew point. If the humidity drops again and thus ruled out any condensation, then the system returns to the normal state.

See graphic.

Room Controller
The room controllers are used to control the temperature of the room and to protect the cooling surfaces from condensation by means of a dew point sensor with an integrated processing unit. The room controllers are available in various designs and operate with a supply voltage of 24 volts.

If required, room controllers which are not provided with a processing unit are available too. In that case, a converter may be used. This converter allows the use of any controller for heating and cooling of the panel cooling.

Dew Point Sensor
The dew point sensor registers any possible condensation on the panel cooling and it passes the signal directly to the control room or the converter. The signal from the dew point sensor is detected by the room controller or converter and the assigned area will be closed. These sensors are available for plaster ceilings, drywall ceilings and metal ceilings.

The converter analyzes the signal of its associated dew point sensor. When the sensor is signalling, an integrated changeover contact is actuated. This information can be passed directly to the building control or the supply voltage of its associated actuator is interrupted. The converter allows the use of room controllers, which are not provided with a dew point sensor processing unit.

The system requires for each zone valves to shutoff, for hydraulic balance and a control valve with electric actuator for single room control. The used ball valves that are intended for shutoff are made of corrosion resistant metal or plastic. These valves can be integrated into the distributor. The hydraulic balancing is carried out by balancing valves which assign the individual zones to their setpoint mass flow. These valves can also be integrated in the distributor.

The actuators operate silently and are available for supply voltages of 230 volts or 24 volts. The drive keeps the valve closed without power. After the power supply is applied, the drive opens the corresponding zone and allows the water to circulate through the control area.

Flow Temperature Control
The controller for flow temperature compares constantly the setpoint of the flow temperature with the value on the secondary side. The controller can be switched from heating to cooling mode by a change-over signal. In addition, both for heating and cooling operation a second value can be stored as a reduction value.