1. Connect the thermostat SRT321 to VERA

Vera Lite SEC SRT321

1. Go to “insert mode” by pressing “+” button  in VERA for 2 seconds, or by using the function in the web interface in “Devices” and there select “Add Device” (the orange LED flashes slowly in the Z-Wave Gateway Vera controller).

2. Enable DIP switch 1 of SRT321 thermostat (ON).

3. Spin the wheel of SRT321 up till displaying “L” on the screen.

4. Press the wheel to include the device. The “L” flashes and changes to “LP” and you will see the VERA thermostat on web console interface.

5. Stop “insert mode” in  VERA by clicking on the blue “Refresh” button on the top right. Now you will see the message “Unit busy” in the web console interface for a little while.

6. After Vera has completed the initial configuration, the thermostat device appear on the console . It will be marked with the message: “Wakeup to configure”, in red.

7. Spin the wheel to the letter “n” and press the wheel. This adjusts the room temperature and the warning message disappears.

Vera thermostat

8. Replace the DIP switch # 1 in the normal mode (OFF), remove the battery for 5 seconds and re-insert.

Now you can adjust the temperature of the device in VERA web interface and it will be displayed on the LCD screen of the thermostat. The temperatur update can take up to  30 minutes (1,800 seconds), it might be seem as a mistake, but this is a delayed response that preserves battery life. This period can be set in the configuration window in the “clock interval (seconds):” between 256 (minimun) and 1,800 seconds. A good balance would be 600 secs (10 minutes)

Interval wakeup time

It is possible now also to locally change the temperature by turning the thermostat dial. The configuration and the change will be displayed in the VERA web interface.

After you include the thermostat in Vera, you will have to change some configuration settings in order to make it work properly in the network and report the temperature to Vera. By default Secure Thermostat is set to not do this automatically (see configuration parameter 1 below) so you have to add this parameter yourself and insert a value between 128 – 255. To add a new configuration parameter, you have to click on the little wrench on the Dashboard, go to Device Options and click on ‘Add configuration settings’, then fill in the values for Parameter 1 as below in the pictures.

The unit supports 3 single byte configurations for the temperature sensor functionality of the unit in the range 1 – 3 respectively.

  • Configuration Parameter Number 1:0–127 disables temperature sensor, 128-255 enables temperature sensor. Default = 0.
  • Configuration Parameter Number 2:0-127 = Celsius, 128-255 = Fahrenheit. Default = 0.
  • Configuration Parameter Number 3: 1 – 100 = Delta T in steps of 0.1 degree. Default = 10 (1.0).

Horstmann HRT4 UI5 parameters

Note: sometimes in Windows 7, when you run the command from the computer to the thermostat, the temperature is set to 0. we think it’s a problem with the operating system because Windows XP and MAC works correctly.

2. Connect the actuator SSR303 to VERA

Vera Lite SEC SSR303

1. In VERA go in the “Devices”, then “Add Devices” and click “Add” to start the search for a new device (the orange LED flashes slowly in the Z-Wave Gatewa controller VERA).

2. The actuator when is it not inserted in any Z-Wave network has two red lights are flashing. Press and hold the bottom button > | | <until you see a green light indicates a proper connection to the VERA.

3. on the Vera Web Devices tab  you will see the thermostat and actuator.

3. Associate the thermostatSRT321 to the actuator SSR303

1. Switch DIP switcher # 1 SRT321 thermostat to position ON.

2. Turn the thermostat to the letter “A”, press and the “A” starts flashing.

3. The actuator must be red LED off. Press the lower button >||< and the thermostat will display “AP”, this is a sign that the actuator and thermostat are associated. In this way we are able to activate manualy the actuator from the thermostat even with the Vera litle gateway not working

4. Replace the DIP switch # 1 of SRT321 thermostat in normal mode (OFF).

4. Set the type of boiler (DIL switch settings – TPI temperature control )

DIL switchers

Thermostats with TPI (Time Proportional Integral) have control algorithms in order to reduce thermal shock that occurs normally when using traditional thermostats with two histeresys points.

As a result, a regulatory TPI thermostat maintains comfort level in a much more efficient way than traditional thermostats.

When used with a boiler, the TPI thermostat will help save energy and the control algorithm to manage the boiler to operate in a more consistent way whte compared to older types of thermostats.

The DIP switchers with numbers 7 and 8 must conform  as shown in the diagram:

  • For gas boilers TPI adjustment to 6 cycles per hour (default). TPI 6
  • For oil boilers TPI set to 3 cycles per hour. TPI 3
  • Electric heating TPI adjusted to 12 cycles per hour. TPI 12

TPI thermostat Settings


Acknowledgements: This tutorial has been  posible thanks to

  • Marco Bologni. Pisa. Italy.
  • Javier Garcia Martinez. Leon. Spain.

About the Author

José Miguel Rubio Varas
Cofounder of Domótica Dainci. Since childhood I wanted to become telecommunications engineer. I got tired of being Engineer Power Point and I decided to undertake. I found my passion in Automation. That automation that is not already expensive or a source of problems, but it is for everyone.