• Ceiling radiant system in residential building
  • Ceiling radiant system in residential building

Ceiling radiant system in residential building

HVAC controls and applications


The ceiling radiant system is a hydronic system for room heating and cooling, which was added to the floor version over time; in common it maintains the characteristic of having a low temperature difference between the heat transfer fluid and the room air.

The heat transfer fluid circulates inside circuits made up of metal or plastic pipes integrated in a suspended false ceiling; the series of panels are fed by distribution manifolds installed above the circuits served. In residential applications, the false ceiling has a plasterboard finish towards the rooms, suitable for civil buildings, and an insulation layer towards the top.

The system is invisible and uses the whole surface of the ceiling as a large terminal for the thermal exchange prevailing at radiation. As in the case of the floor radiant system, the ceiling radiant panels only handle the heat loads of a sensible type; in general, the ceiling solution offers a higher yield in cooling.

The radiant ceiling system shown in the example is used to heat and cool the rooms of a residential building. This particular system is a combined system; it combines the ceiling radiant panels with one or more units for energy recovery ventilation (ERV), whose basic function is the renewal of the room air with high efficiency heat recovery. In this case, moreover, they are complete machines for the air handling of the rooms, able to support the operation of the system in summer cooling, also performing the functions of dehumidification (with reduction of the cooling latent load) and handling of part of the sensible cooling load.

Usually these machines do not serve a single room, but several rooms or an area of a building. In the residential sector, for example, it is common to use one machine for the living zone and a second one for the night zone. The installation is typically made in a central position with respect to the served zone, for example recessed in the false ceiling in the hallway or in the corridor.

Ekinex devices Other system components
A) Time / astronomical digital switch EK-TM1-TP 1) Energy recovery ventilation (ERV) unit with dehumidification and cooling integration
B) GPS module EK-GPS-1 2) Contact for dehumidification start / stop
C) Binary output EK-FE1-TP 3) Contact for cooling integration start / stop
D) Actuator-controller for electrothermal drives EK-HE1-TP 4) Valve with ON / OFF servomotor
E) Room thermostat EK-EQ2-TP 5) Seasonal valve with ON / OFF servomotor (towel warmer)
F) NTC temperature sensor (air) EK-STL-10K-3435 6) Towel warmer
  7) Circolating pump
  8) Zone valve (ceiling radiant system) with ON / OFF servomotor
  9) Distribution manifold for radiant ceiling circuits
  10) Condensation sensor (with signal contact)
  11) Ceiling radiant system panels (series)
  12) Thermal generator (warm fluid)
  13) Thermal generator (cold fluid)
  14) Boiler room manifold (flow)
  15) Boiler room manifold (return)
Control with Ekinex

The EK-TM1-TP time / astronomical digital switch (A) ensures that the system is allowed to operate according to predefined time scheduling and is constantly synchronised with date and time by the GPS module (optional) EK-GPS-1 (B).

The room thermostat EK-EQ2-TP (E) measures temperature and relative humidity and is installed in a position exposed to the air flow generated by the machine (1).

In heating or cooling mode, at the request of the thermostat, the actuator-controller EK-HE1-TP (D) controls the opening of the zone valve (8) of the radiant ceiling. If necessary, an additional NTC temperature sensor (F) can be connected to the room thermostat (E) to carry out adjustment based on a weighted average temperature value.

At the seasonal switchover to cooling mode, the actuator-controller (D) closes the seasonal valve (5) to avoid feeding the towel warmers with cold heat transfer fluid. The contacts for the start / stop of the cooling integration (2) and dehumidification (3) are activated by the binary output EK-FE1-TP (C). Cooling integration is activated when the temperature measured by the room thermostat (E) exceeds the setpoint value by a predefined offset value (for example: 1.5 °C). Dehumidification is activated when the relative humidity measured by the room thermostat (E) exceeds the threshold value predefined in the system design (for example: 50%).

A sensor (10) to detect the formation of condensation during cooling operation can be connected to the room thermostat (E). This optimization makes it possible to increase the operational safety of the system, closing the circuits involved by means of the zone valve (8) if the thermohygrometric conditions should cause the beginning of condensation on the cooled surfaces.

The optional Delégo supervision (not shown in the diagram) allows you to monitor and control the entire home automation system through an App for smartphones.

Focus on the EK-EQ2-TP thermostat
The ekinex® room thermostat EK-EQ2-TP (E) allows the measurement of the temperature and relative humidity of the room air mass by means of integrated sensors with the possibility of sending values on the KNX bus.


The relative humidity measurement significantly expands the room air conditioning functions and increases the comfort and safety of the room. Thanks to the calculation of the dew temperature, it is possible to carry out active strategies to protect against the formation of condensation when using radiant panel systems for summer cooling. In combination with the ekinex® actuatorscontrollers for HVAC functions, the device allows a complete independent climatization for each room or zone, adding to the function of controller for heating and cooling the possibility to effectively control the dehumidification and humidification of the rooms.

The display also allows you to view a series of information such as:

  • temperature (measured and setpoint in °C o °F);
  • relative humidity (measured and setpoint in %);
  • CO2 concentration (received by the KNX bus in ‰);
  • perceived temperature (calcolated according to the Humidex index in °C);
  • outdoor temperature (received by the KNX bus or a NTC sensor in °C o °F).
Using configurable inputs

Thanks to the two configurable inputs of the device, the thermostat allows additional functions to be carried out that can increase comfort and energy saving, without the need for additional input bus devices.

If configured as analogue, to the input is only allowed the connection of a NTC temperature sensor with characteristic resistance value 10 kΩ at 25°C, ß = 3435 (ekinex® codes EK-STx-10K-3435 with x = E, I, C, L).

Input configuration Predefined applications
Digital (DI) window contact
card holder contact
condensation sensor
Analogue (AI) heat exchange battery temperature sensor
room temperature sensor
stratification temperature sensor
floor surface temperature sensor
outside temperature sensor
NTC generic temperature sensor
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