Digital Thermostat M-Therm HT- 08
For M-Therm 24 Volts heating systems
Installation guide
General instructions
This device is not intended for use by persons (including children) with limited physical, sensory or mental abilities or lack of
experience and/or knowledge unless they are being supervised by a person responsible for their safety or if they are having been
instructed by this person on how to use the device. Children should be supervised in order to make sure that they do not play with
the device.
Selection of the place of installation
Please observe the following instructions on how to optimize functioning and energy consumption:
1.1 Place thermostat on inside wall approx. 1.5 meter above floor.
1.2 Avoid position where the measuring of the temperature can be influenced by the surroundings, such as direct sunlight,
proximity to heating and cooling devices, right next to entrance/exit/window, in front of the heating panels, etc.
1.3 Use the programming possibilities of the thermostat to individually adjust the room temperature to your way of living.
Opening the case of the device
2.1 Insert a flat screwdriver into the slot.
2.2 Press carefully, exercising an upward seesaw movement onto the locking
mechanism and take off the front cover of the thermostat.
Inserting the batteries / changing of batteries
3.1 Insert two batteries (AA, LR6) with the correct polarity into the battery compartment as indicated (+ / -).
3.2 Do always change both batteries and only use high-quality alkaline batteries. Replace the batteries as soon as possible when
the display shows the warning „LO“. Remove batteries from the device when it is not in use for an extended time (for instance
in summer) in order to avoid a possible battery leakage.
4. Connecting the thermostat
4.1 On back part of the device, loosen the retaining screw of the protective cover and take off the cover.
4.2 Insert the thermostat cable from the back and connect the two cores of the thermostat cable as follows: the white cable is
connected to connection 2 and the brown cable to connection 3.
4.3 Fit back the protective cover to the base and tighten it with the retaining screw.
4.4 Re-insert the front cover after fixing the base to the wall. Now, you are ready to start programming.
Programming instructions
Set weekday and time
5.1 Set the rotary switch to position (RUN).
5.2 Press the key (clock) to start programming. Beware that the display returns to the main menu after 5 seconds if no key is
5.3 The weekdays (numbers from 1 to 7) will be set first. Press (+) or (-) to select the weekday, for instance Monday = 1,
Tuesday = 2, etc.
5.4 Press (clock) again, while the display is still blinking, to enter programming of hour and minute. Press (+) or (-) to adjust.
5.5 After having set weekday and time, simply wait for 5 seconds: the settings will be saved automatically.
Set comfort temperature / lowered temperature
This thermostat controls the operation of the heating system with two different temperature values. The initial setting of the comfort
temperature is 20.4 °C
and 16.2 °C for the lowered temperature.
6.1 Set the rotary switch to position (RUN).
6.2 Press the sun key (
) twice to move to comfort temperature. Now, you can set the comfort temperature you prefer by using
the keys (+) and (-).
6.3 Wait for 5 seconds after settings are finished. The thermostat saves the value automatically and switches to operating mode.
6.4 For the setting of the lowered night temperature repeat step 6.1 to 6.3 with the moon key (
For an optimal comfort, the difference between day and night temperatures should not be more than 4°C.
Digital Thermostat M-Therm HT- 08
For M-Therm 24 Volts heating systems
Enter weekly program
The programming of the thermostat is based on a 7-day/24-hour weekly program which can be set according to personal
preferences. The factory setting for comfort time is from 6 a.m. to 10 p.m. You can now change these settings according to your
personal wishes.
7.1 Turn the rotary switch to the respective weekday.
7.2 You can set every half hour of the day by means of the keys (+) and (-). The clock indicates the time you are programming.
7.3 Press the sun-key (for comfort temperature) or the moon-key (for lowered night temperature) to change the day or night setting.
For your guidance, the symbols you are currently working on are blinking in the display.
7.4 After having terminated the programming of all weekdays, set the rotary switch back to (RUN) and the thermostat will start to
operate its program.
Manual and temporary room temperature change without influencing the scheduled weekly programming
You can override the programmed room temperature if it is too cold or too warm at a specific moment. This override mode is
temporary and valid only until the next programmed change from (moon) to (sun) or vice versa.
8.1 Set the rotary switch to the position (RUN).
8.2 Press the key (+) or (-) and the current temperature setting will be displayed.
8.3 Press again the keys (+) or (-) to change the current temperature setting.
8.4 The display will be flashing for approx. 8 seconds and then returns to the main menu. The thermostat will start with the
temporarily set temperature until the next programmed change (from sun to moon or vice versa).
8.5 Turn the switch shortly away from (RUN) and immediately back again to (Run) to terminate the manual override and to return to
the scheduled programs.
Holiday mode
The automatic thermostat program can be permanently interrupted in order to set a constant temperature for an arbitrary period, for
instance during your holidays.
9.1 Set the rotary switch to the position (RUN).
9.2 Press the key (HOLD). The display shows "Temp Set“ and "Hold“.
9.3 Set the desired temperature with the keys (+) and (-).
9.4 After having terminated the temperature setting, the display continues flashing for approx. 8 seconds and then switches back to
the display of the ambient temperature. The „Hold“-temperature (temporary temperature) is not displayed. The thermostat will
start running the "holiday"-mode.
9.5 Turn the switch shortly away from (RUN) and immediately back again to (Run) to terminate the „Hold“-function and to return to
the scheduled programs.
10 Problem solving
Possible cause
Elimination of the cause
LED on the transformer shows a
permanent red light (heating
system out of operation)
LED on the heating control
keeps blinking red
(heating system out of
Floor sensor (or resistance for the wall
heating) not or badly connected to the heating
Device is overheating due to trapped heat
Connect floor sensor (or resistance for the
wall heating) correctly (see heating control
Elimination of erroneous obstruction of the
heating control
Eliminate external heat effects due to
intensive solar radiation or other heat
sources (other devices)
System out of operation (LED
Heating control switched off
Temperature selection on the room thermostat
too low
Overstrain of electrical circuit has blown main
Device is overheating due to exterior heat
Fuse of the device has blown
Individual heating elements do
not heat up
Overstrain in individual heating circuits has
blown heating circuit fuse(s).
Heating does not switch on or off
Individual heating panels or heating circuits
are not connected
Batteries in the thermostat are empty
Switch on the power on the device
Set correct temperature on the room
Elimination of circuit overstrain. Disconnect
some devices on the same fuse. Switch on
main fuse
Switch off the control unit. Replace fuse of
the device by a new one of the same type. If
the new fuse blows again after switching the
device on, consult an electrician or the
technical service of your sales point.
Elimination of overstrain of the heating circuit
(not more than 2 heating panels per heating
circuit allowed). Then replace heating circuit
Set up correct electrical connections of the
heating circuits.
Replace batteries