W1209 Temperature Controller Q&A

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Below are commonly asked questions regarding the W1209 Digital Thermostat Temperature Controller Module. 

For detailed installation, operation and programming instructions, see theĀ W1209 Digital Thermostat Temperature Controller Module Installation and Operating Instructions

Can the W1209 display Fahrenheit temperatures?

No, it only displays in Celsius.  

Does the W1209 allow for a temperature range? I want to keep something between 45-50 C. So if the temperature falls below 45, it will want it to heat up to 50, then shut off until it falls below 45 again. Will it handle that?


Referring to itsĀ installation and operating instructions:

  • Set parameter P0 to Heating Mode;
  • Set the hysteresis parameter P1 to 5 degrees;
  • Set the trigger setpoint to 45

When the temperature drops below 45, the unit will close its relay, turning on your heating element. When the temperature rises to 50 (controlled by the 5 degrees we set the hysteresis to), it will open the relay, turning off your heating element.

Keep in mind that the W1209 is a temperature-controlled switch. When it turns on, it closes its relay contacts, and when it turns off it opens the relay contacts. You need to connect your heating element to a separate power supply, with the relay acting just like a light switch to turn on and off the power from the power supply to the heating element based upon the temperature.

Is there a way to adjust the temperature readings? I have two W1209’s and they display a slightly different temperature. 

Yes, you can program an offset to calibrate the temperature using parameter P4. 

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