STC 3008 user manual user guide operation manual Nerd Corner

STC 3008 – 2 temperature sensors in one device (full user guide)

Together with the STC 3000, the STC 1000 and the STC 3028, the STC 3008 is one of the extremely popular temperature sensors with automatic relays. The hardware costs less than $ 10 and is particularly suitable for hobbyists. There are countless use-cases and projects for this device. The advantage of the STC 3008 is that there are actually 2 thermostats in one device. The device is also easy to use if you know how. But the Google search unfortunately does not provide any reasonable results for a useful user guide or operation manual. We have therefore documented here how to operate the STC 3008.

This might also be interesting for you: How to use a STC 3000 temperature controller

Power supply and wiring

Wiring the STC 3008 Nerd Corner

On the top of the STC 3008 you can check what type of voltage it is. There are three options to choose from: For alternating voltage (AC) “110-220VAC” and for direct voltage (DC) “12V” and “24V”. Now that you have checked which of the 3 options applies to your own device, you should wire the STC 3080 to the corresponding power source. The socket for the power supply corresponds to the sketch on the top of the STC.

Wiring the STC 3008 user guide operation manual Nerd Corner


As you can see on the top of the STC 3008, “Sensor 1” and “Sensor 2” are next to  the “Power supply”. Right of “Sensor 2” are both relays “Relay 1” for “Sensor 1” and “Relay 2” for “Sensor 2”. You can set a desired temperature for both “Sensor 1” and “Sensor 2”. Suppose we use “Sensor 1” for heating. For this purpose, a heating element is wired to “Relay 1”. In addition to the desired temperature, a minimum temperature is also set. As long as “Sensor 1” is colder than the desired temperature, the heating element is switched on via “Relay 1”. The heating element is only switched off when the temperature of “Sensor 1” has reached the desired temperature or is above it. If the temperature drops below the desired temperature again, the system waits until the initially set minimum temperature is reached. Then the heating element is reactivated and remains active until the desired temperature has been reached.

“Sensor 2” works analogously. Even if the lettering of the second sensor glows blue, you could also use it for heating as described in the paragraph above for “Sensor 1”. It is therefore possible to use both sensors for heating, both for cooling or one for heating and one for cooling. If you want to use “Sensor 2” for cooling, a cooling element should be wired to the associated “Relay 2”. For “Sensor 2” you also set the desired temperature that you would ideally like and a maximum temperature that must not be exceeded. “Sensor 2” now measures whether the temperature is warming up. As soon as the measured value reaches the maximum temperature or goes further, “Relay 2” is switched on and the cooling element is activated. The temperature now cools down until the target value is reached. As soon as this previously set desired temperature has been reached, “Relay 2” switches off the cooling element.

STC 3008 temperature sensor user guide operation manual

Operation manual and user guide for the STC 3008

There is an up and down key for each sensor. If you want to use the sensor for cooling, press the down key for a few seconds. The currently set desired temperature appears and flashes. A new ideal temperature can now be set using the arrow keys. If you stay longer on the up key, the currently set maximum temperature appears. This can be adjusted now. The sensor is now set to activate its cooling relay as soon as it measures a temperature value that exceeds the set maximum temperature. In this case, the relay remains active until the cooling reaches the set ideal temperature.

If you want to use your sensor for heating, also press the button down and hold it until the display flashes. Then you can set the ideal temperature. But since you are now using the sensor for heating, you do not need to set a maximum temperature with the up arrow key. Instead you need to set a minimum temperature. As soon as the temperature drops below this minimum, the sensor activates its relay with the heating element and provides heat until the ideal temperature is reached again. The relay with the heating element only switches off when the ideal temperature is reached.

In addition, you can reset the device by holding down both arrow keys simultaneously. If you hold both arrow keys upwards at the same time, you can make a few extra settings. The details are explained in this table:

STC 3008 user guide explained functions Nerd corner


  • Display Type: Digital
  • Style: Standing Station
    Temperature sensor: NTC 10K 3435
  • Senor Length: 1.0m
  • Temperature measuring range: -55°C ~ 120°C
  • Resolution: 0.1°C
  • Accuracy:±1°C
  • Power supply: 110-220VAC±10%, 50/60Hz
  • Power consumption: <3W
  • Storage temperature: -30°C ~ 75°C
  • Relative humidity: 20% ~ 85% (No condensate)
  • Relay contact capacity: Two Relay Cool 10A/240VAC; Heat 10A/240VAC

13 thoughts on “STC 3008 – 2 temperature sensors in one device (full user guide)

  1. Wonderful paintings! That is the type of information that are supposed to be shared around the web. Thank you =)

  2. I think other website proprietors should take this website as a model. It is very clean and has a lot of useful content!

  3. Thank you for this very useful information.
    I plan to use both sensors for heating. It is unclear to set the sensor for heating (should I press the “Down” button in the same way as cooling ? if yes, how the sensor switches then its state from cooling to heating ?)
    One more question: does this device turn on as soon as it is connected to supply or does it need to be turned on by button pressing ?

    1. The sensor senses temperature regardless if it’s hot or cold. Just seat in about in the middle of your top and bottom plates. It’ll be fine for pressing the sticky icky. Uses a microscope to make sure trichs are fat.

  4. Buenas tardes,
    tengo el STC-3008, lo estoy probando por 1ª vez y:
    1)Entiendo que cuando la luz roja, por ej, está encendida es cuando el radiador, por ej, estaría funcionando y cuando se apaga deja de funcionar.
    Cuando se enciende la luz roja se escucha clic, a continuación le pongo el polímetro y no marca tensión, debería de marcar 220V
    Cuando se apaga la luz roja se escucha clic también, a continuación le pongo el polímetro y no marca tensión.
    Si pongo el polímetro en la entrada de la red si me marca 220V
    ¿qué es lo que ocurre?
    2)¿Para qué sirve la función de pulsar las dos teclas a la vez?¿puede estar aquí la solución a mi problema?

  5. Do you have any information about calibrating the temp sensors? Out of the box, the two sensors show a difference of 0.5°C at 30°C (measuring the temp of the same environment, obviously!).

  6. The stc 3008 is a very good temperature controller for refrigerators. Can you explain me how I have to wire it up for 2 doors?

    1. Hi Khalid,
      This depends on what you mean. Do you mean a fridge with 2 different temp zones, like a domestic fridge where you can set the fridge temp as well as the freezer temp separately? Well first you need so find out how those 2 temps are effected. E.g. some big fridges have 2 compressors running independently, then it is easy. Others have 1 compressor, and a valve that sends coolant to 1 side or the other. Now you need to figure out which way it goes when the valve is not powered, so that you can determine how to wire it up. One thermostat will typically control the compressor, and the other the valve. But in that way when the valve goes on because that side needs cooling, nothing will actually happen until the other side also needs cooling and thus switches on the compressor. This can be solved with simple use of a basic relay so that both thermostats can switch on the compressor, but only one also switches on the valve. Hope this makes sense

  7. Thanks for the useful guide.

    I think the explanation of the temp setting can be simpler (but I must still refine that simpler explanation). I understood the device by reading the Chinglish & playing with it.
    This unit is great as a replacement controller in camping fridges with dual compartments (with no space for 2 single controllers).
    But the way of setting the temp is a bit odd and also makes it easy for an owner to mess it up, accidentally end up in heating mode, and not understanding what is happening.

    I would like to add:
    Press the 2 Up Arrow simultaneously for 3 seconds: Enter the Setting Mode as in the manual (and on this page)
    Press the 2 Down Arrow simultaneously for 3 seconds: Reset the device & all settings as on this page
    Press the Up & Down Arrow of 1 side simultaneously for 3 seconds: Enter a setting mode for calibration of the temp reading on that side.


  8. Hi there,

    For my woodworking shed I would like to measure the outside temperature and keep the inside temperature 1 degree above (the outside tempurature).
    For example: when the outside temperature is 5 degrees, a heater must increase the inside temperture to 6 degrees and then stop heating.
    Cooling is not important as long the inside temperature is higher than the outside temperature.
    Can I achieve this with the STC-3008?
    Thanks for ypur response!

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