Velleman VM148 Programmable Thermostat USER MANUAL


Velleman VM148 Programmable Thermostat 




Temperature sensor – Temperatuur sensor

  • Use a shielded cable as an extension cable for the sensor.





  • general purpose panel mount thermostat
  • usable for heating or cooling purposes, (central heating, airco, incubator,… )
  • separate output-ON and output-OFF settings (hysteresis)
  • direct manual temperature adjustment
  • bright red LED read-out
  • calibrate option
  • under– and overflow indication


  •  temperature range:
    • °C: -18°C ~ + 60°C
    • °F: 0°F ~ +146°F
  • temperature resolution: ± 0.5°C or ± 2°F
  • accuracy: +/- 2°C, fine-tune till +/- 0,5°C
  • readout update interval: 1 second
  • relay contact: NO – 3A (max. 230V)
  • power supply: 9 – 12V DC
  • power consumption: < 70mA
  • weight: 50g

Factory settings

  • Temp°A = 22°C
  • Temp°B = 20°C
  • Temp correction = 0°
  • Temp display = °C


This product is guaranteed against defects in components and construction from the moment it is purchased and for a period of TWO YEARS starting from the date of sale. This guarantee is only valid if the unit is submitted together with the original purchase invoice. VELLEMAN Components Ltd limits its responsibility to the reparation of defects or, as VELLEMAN Components Ltd deems necessary, to the replacement or reparation of defective components. Costs and risks connected to the transport, removal, or placement of the product, or any other costs directly or indirectly connected to the repair, will not be reimbursed by VELLEMAN Components Ltd. VELLEMAN Components Ltd will not be held responsible for any damages caused by the malfunctioning of a unit.


  • All repairs should be executed by qualified technicians.
  • Avoid the installation of the module in locations with standing or running water or excessive humidity. Indoor use only!
  • Handle the module gently and carefully. Dropping it can damage the circuit board.
  • Never exceed the protection limit values indicated in the specifications.
  • As safety requirements vary, please check with your local authorities.
  • Facilitate the operation of the device by familiarising yourself with its adjustments and indications.
  • Velleman modules are not suitable for use or as part of life support systems, or systems that might create hazardous situations of a kind.


Thank you for choosing Velleman. This multifunctional digital thermostat module allows you to control and monitor the room temperature.

Modules needed
Apart from the VM148 module, you will be needing a 12VDC power supply. Use an external contactor with currents higher than 3A.


  • The module allows you to maintain the room temperature between 2 programmed limits. Example: The room temperature must not drop below 20°C. Once the heating is activated, the room temperature must reach 22°C before being deactivated.
  • Control of the air conditioning system.
  • Temperature monitoring in e.g. a housing or greenhouse, of a liquid…).

General definitions
Hysteresis: The temperature difference between temp° A and temp °B (min. 0.5°C). Temp°A will automatically rise by 0.5°C if the two temperature settings have been programmed identically.


Heating mode: Activation of the heating when the measured temperature ≤ programmed temperature B until the measured temperature > programmed temperature A. Heating mode is activated when temp°A > temp°B.
Cooling mode: Activation of the air conditioning system when the measured temperature > programmed temperature B until the ambient temperature drops below programmed temperature A. Cooling mode is activated when temp°A < temp°B. A red dot is displayed in the right corner below when the relay, and consequently the connected device, is activated. Temperature display: The actual temperature and the settings can be displayed in ° Celsius and ° Fahrenheit.


The actual measured temperature is displayed at power-on or in normal mode.




  • UnFL – Underflow error: The measured temperature is lower than the minimum measurable temperature (min. temp° = -18°C of 0°F).
    OvFL – Overflow error: The measured temperature is higher than the maximum measurable temperature (max. temp° = +60°C of 146°F).
    SEnS – Sensor error: Sensor problem or faulty connection.

Press ENTER to display the operation mode of the temperature controller.



This handy function allows you to modify the temperature directly without reprogramming the max. and min. values (temp° A and temp° B). The limit values will automatically shift with the temperature modification. Shortly press UPVelleman-VM148-Programmable-Thermostat-fig-7 or DOWN Velleman-VM148-Programmable-Thermostat-fig-8in the temperature display to display the average target temperature


Repeatedly press UP Velleman-VM148-Programmable-Thermostat-fig-7or DOWN Velleman-VM148-Programmable-Thermostat-fig-8to rise or lower the target temperature. Example: Set the target temperature to 25°C; temp° A and temp° B will automatically be modified to 26°C and 24°C.


Remove the power supply to the module. Hold ENTER pressed and re-establish the power supply to the module. DEF (default) will be displayed. Release the ENTER button. The display will show the firmware version code.

Modifications and typographical errors reserved – © Velleman Components nv – HVM148G – 2009 – ED1



Velleman VM148 Programmable Thermostat USER MANUAL


Velleman VM148 Programmable Thermostat USER MANUAL





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