Applicatio Manual
Universal Interface 4 DIN/NTC EK- CG2-TP
Revisione 1.0.0 - Aggiornato: 04/09/2017
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MAEKCG2TP_EN
Pag. 24
8.2 Weighted temperature
The device allows the acquisition of the room temperature in 2 ways:
1)
from an external temperature sensor connected to a device input configured as analogic (Inputs
Input 1 or 2 = [AI] room temperature sensor);
2)
via bus from another KNX device, e.g. from an ekinex pushbutton (External sensors (from bus)
Room temperature = enabled);
To optimize or correct the room temperature regulation in special cases (in large rooms, in presence of strong
asymmetry of the temperature distribution, when the installation of the device is in a position not suitable, etc.),
the device can then use a weighted average between two temperature values. The weights are assigned by
the parameter
Relative weight
that assigns a ratio of the two values
8.3 Surface temperature limitation function
The floor heating system (warm water version) provides plastic pipes embedded in the concrete layer or placed
directly under the final coating of the floor (light or "dry" system) filled by heated water. The water releases heat
to the final coating that heats the room by radiation. The standard EN 1264 Floor heating (Part 3: Systems and
components - Dimensioning) prescribes a maximum allowed temperature (T
Smax
) for the surface of the floor that
is physiologically correct defined as:
•
T
Smax
≤ 29°C for zones of normal occupancy;
•
T
Smax
≤ 35°C for peripheral zones of the rooms.
National standards may also limit these temperatures at lower values. Peripheral zones are strips generally located
along the external walls with a maximum width of 1 m.
The floor heating system (electrically powered version) involves the laying under the floor coating of an electric
cable powered by the mains voltage (230 V) or low voltage (for example 12 or 45 V), possibly already prepared in
the form of rolls with constant distance between sections of cable. The powered cable releases heat to the
overlying coating that heats the room by radiation. The regulation is based on measurement of the temperature of
the air mass, but generally requires the monitoring and limiting of the surface temperature by using a NTCtype
sensor which is in contact with the floor surface.
The surface temperature limitation may be realized for several purposes:
•
physiological compatibility (correct temperature at the height of the legs);
•
when the system is used as auxiliary stage for heating. In this case, the heat losses to the exterior
of the building are handled by the main heating stage, while the auxiliary stage only works to keep the
floor temperature at a comfortable level (for example in bathrooms of residential buildings, sports centers
, spas and thermal baths, etc.);
•
protection against damages of the final coating due to an accidental overheating. Note that the
warm water radiant panels are usually already equipped with a safety thermostat (with intervention on
the hydraulic mixing group), while in the case of electrical power this device is not usable and it is common
practice to realize a temperature limitation with a surface temperature sensor connected to the device.
The surface temperature limitation function closes the intercept valves on the distribution manifold when the
temperature measured on the panel rises above set threshold (default value 29°C). The regular operation of the
room thermostat resumes when the measured surface temperature drops below the hysteresis threshold (29°C -
0,3 K). For related alarms please refer to the Appendix.