Installation
and operation

manual. Print version

терморегулятор terneo sx
In the box: thermostat, frame, temperature sensor with connected wire, installation and operation manual, the packing box

Content

Content

Purpose

Purpose

The terneo s thermostat is designed to maintain 
a constant temperature between 5 and 40 °C in underfloor heating systems based on: electric heating cables or membrane, as well as water floors using 
a normally closed electrothermal servo with 
an operating voltage of 230 V.

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‍The thermostat's non-volatile memory saves all your settings during a power outage.

Durability and reliability of the power relay:
– Provides protection against frequent switching 
with less than 1 minute between switching events. The thermostat will notify you of the protection by 
a flashing dot on the right side of the screen.
– Please note that switching the relay as close 
as possible to the moment when the voltage sine wave passes through zero may lead to slight deviations due to different trip times for different relay models.

Heating based on electric convectors, infrared panels and other electric heaters is controlled by placing a temperature sensor in the air.

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Technical data

Technical data

Maximum load current (for category AC-1)
16 А
Adjustment range
5...40 °С
Temperature hysteresis by floor
1 °С
Measured temperature range:
analog: –27...+120 °С
digital: –55...+125 °С
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Maximum power load (for category AC-1)
3 000 VА
Input voltage
230 V ±10%
Weight in the complete set
0,18 kg ±10%
Temperature sensor (in set)
NTC thermo-resistor 10 kOhm at 25 ° C (R10)
Length of the sensor connected cable
3 m
Supported sensor types:
analog:
NTC 4.7, 6.8, 10, 12, 15, 33, 47 kOhm at 25 °C
digital:
D18
Number combinations under heat, at least
50 000 cycles
Number of combinations 
without heating, no less than
20 000 000 cycles
Overall dimensions (w·h·d)
75 х 75 х 35 mm
Inner overall dimensions
of decorative frame
45 х 45 mm
Cross section of connection wires
no more than 2,5 mm²
Compatibility with frames  from other manufacturers
Schneider Electric Unica
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Installation

Installation

‍Read this document carefully before installing and using the thermostat. This will help to avoid possible hazards, errors, and misunderstandings.

‍The thermostat is designed for indoor installation at a height ranging from 1,4–1,6 meters from the floor level. The ambient temperature during installation should be within –5...+45 °C. When installing in a bathroom, toilet, kitchen, or pool, place the thermostat in a location not exposed to accidental splashes. Minimize the risk of moisture and liquids entering the installation area.

☝️Recommendations for connecting loads more then 10 A. The terneo thermostat may not handle a current 
of 16 A and could overheat in the presence of unfavorable factors such as poor heat dissipation 
from the socket, high ambient temperature, or poor installation quality. We guarantee stable operation 
of the thermostat with a current up to 10 A. If the current exceeds 10 A, we recommend connecting the heating cable through a contactor (magnetic starter) rated for the required current. See diagram 2.

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To protect against short circuits, install an automatic circuit breaker (CB) with a rating of up to 16 A in the phase wire break before the thermostat.

To protect against electric shock, install an SSD (safety shutdown device). See diagram 1.

For installation you need:
— make a hole in the wall with a diameter of 60 mm 
for the mounting box and channels for power supply and sensor wires;
— bring the heating system power and sensor wires 
to the mounting box;
— make connections according to this manual;
— secure the thermostat in the mounting box.

The terminals of the thermostat are designed for wires with a cross-section of no more than 2.5 mm². It is recommended to use soft copper wire, which can be tightened in the terminals using a screw-driver with a blade width not exceeding 3 mm and a torque of 
0.5 N·m.

The use of aluminum is not desirable. A screwdriver with a blade width greater than 3 mm may cause mechanical damage to the terminals, which can result in the loss of warranty service rights.

Place the sensor in the floor screed using a mounting tube, such as a 16 mm diameter metal-plastic tube, which bends once with a radius of at least 5 cm and is inserted into the heating zone for 50 cm. To ensure the sensor can be replaced in the future, seal the end of the tube with a copper plug or insulation tape. Sealing with a copper plug will provide more accurate floor temperature measurements. Insert the sensor into the tube after the screed has hardened. Strip and crimp the ends of its wire with insulated terminals.

If necessary, reduction and increasing (up to 20 m) of sensor connecting wires is acceptable. For extending, use a separate cable with a cross-section of 
0,5... 0,75 mm². Near the sensor connecting wires should not be the power cables, they may be interfere.

Figure 1. 
Mounting the thermostat and underfloor heating
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Electrical connection diagram

Electrical connection diagram

‍The analog sensor (R10) is connected to terminals 1 and 2. The colors of the wires are not important. The digital sensor (D18) is connected with a blue wire to terminal 2 and a white wire to terminal 1. If the thermostat enters the Timed Emergency Mode, try connecting the blue wire to terminal 1 and the white wire to terminal 2. If the thermostat does not detect the sensor after both attempts, contact the Service Center.

‍The supply voltage (230 V ±10%, 50 Hz) is applied to terminals 4 and 5, the phase (L) is determined by the indicator and connected to terminal 5, and the neutral (N) is connected to terminal 4. Connect the load (connecting wires from the heating element) to terminals 3 and 6.

Important! Install and check the load before installing and connecting the thermostat.

Diagram 1. 
Connection of the circuit breaker and SSD
Diagram 2. 
Wiring and simplified internal circuit.
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Exploitation

Exploitation

‍According to the data from the temperature sensor. 
The thermostat located in the floor controls the heating: turns off the heating when the desired temperature is reached and turns it on when it drops by 1 °C. When the buttons are not in use, the brightness 
of the display and screen decreases by up to 30%.

Temperature selection

(factory setting 25 °С)
Use "+" and "–" to select the temperature. When the load is applied to the underfloor heating, the red indicator light will turn on.

‍When connected and during operation, the thermostat displays the current temperature of the remote sensor. If it is lower than the set temperature, the load is energized. In this case, the indicator lights up red.

‍Use "+" or "–" buttons to change the heating temperature. First, the screen displays the operating mode, then the set temperature of this mode.

If you want to securely protect the settings from children or unauthorized access, press and hold the "+" and "–" simultaneously for 6 seconds until "Loc" appears on the screen, or in case of unlocking, "unLoc" will appear.

Settings using buttons

Use "≡" to select a menu item, and "+" and "+" buttons to change the parameters. The first time you press the button, the parameter will start blinking, the second time it will change. 5 seconds after the last press, the display returns to the temperature display.
Timer for delayed heating start
Time counter load operation
Timer for delayed heating start settings
Temperature correction
Sensor type

Settings via holding the "" or "–" buttons

Sleep Mode
Reset to Factory Settings
Firmware version

Possible issues and solutions

Possible issues
and solutions

Screen is flashing "oht" |overheat|
Screen displays "OC" |open circuit| or "SC" |short circuit|
The screen displays "Ert" |error temperature|
The load is switched off, the screen and indicator are off
When the screen turns on it displays 5 sec "Er0"

Additional information

Additional information

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Version of instruction S24