Tasmota 8.4.0 Thermostat + Openhab

Tags: #<Tag:0x00007f617da97348> #<Tag:0x00007f617da96f88>

Hello gentlemen.
Does anyone know how to set the thermostat function in Tasmota 8.4.0 + DS18B20 temperature sensor?
I tried using the commands here: https://tasmota.github.io/docs/Thermostat/ but I can’t make it work properly.
My items:

Group   OfficeThermostat  "OfficeThermostat"   <temperature>
Number  OfficeTherm       "OfficeThermostat"                    (OfficeThermostat)    { channel="mqtt:topic:office_thermostat:temperature" }
Number  OfficeThermSet    "Setpoint"                            (OfficeThermostat)    { channel="mqtt:topic:office_thermostat:temperatureset" }
Switch  OfficeThermSW     "OfficeThermSW"                       (OfficeThermostat)    { channel="mqtt:topic:office_thermostat:power" }

My sitemaps:

         Setpoint  item=OfficeThermSet   minValue=10  maxValue=35 step=1
         Text      item=OfficeTherm      label="OfficeTherm [%.1f °C]" icon="temperature"
         Switch    item=OfficeThermSW    

I added a link to each button in the Paper UI and openhab sends the setpoint commands to the tasmota and correctly displays the temperature read by the DS18B20 sensor.

If anyone uses this combination please do a little step by step tutorial on how to set the thermostat in Tasmota 8.4.0

Thank you

This sounds like it works - what specifically doesn’t work?

I have no idea how to implement the thermostat function in tasmota.
If you have done this please put a step by step tutorial here.
Thank you

Sounds like a Tasmota support issue, rather than an OpenHAB one, but let’s see - what device are you using Tasmota on?

EDIT: And just to check - you compiled the binary file yourself? This feature isn’t available on downloadable binaries.

What does your .things file contain? I don’t have a definition for the temperatureset Channel, but the definitions for the power and temperature channels should look as below. Note in particular that the stateTopic prefix for the sensor is tele rather than stat

Bridge mqtt:broker:MyMQTTBroker [host="192.168.178.50", secure=false, username="MyUserName", password="MyPassword"] {
  Thing topic yourThing "Thermostat" @ "Wherever" {
    Channels:
      Type switch : PowerSwitch [stateTopic="stat/yourTopic/POWER", commandTopic="cmnd/yourTopic/POWER", on="ON", off="OFF"]
      Type number : Temperature [stateTopic="tele/yourTopic/SENSOR", transformationPattern="JSONPATH:$.DS18B20.Temperature"]
   }
}
1 Like

I use the Wemos D1mini module and I made a video with everything I set in Tasmota and OpenHab.
Everything seems to work fine until minute 34:59 so:

  1. Why does the thermostat turn off the switch if the setpoint is set to a temperature higher than the one read by the sensor?
  2. Why if I turn off the power to the Wemos D1mini module or if I press the reset button all the settings related to the Thermostat are lost?
    https://youtu.be/ZEVY7E4yvTs

I’m afraid I don’t know - you’re much better off heading over to the Tasmota project and asking.

Do double check all the information on the page you linked - switching off might be intentional, depending upon the duty cycle etc settings that you have applied…

Again, I think you’ll have more luck asking the Tasmota project.

Maybe it’s set for cooling?

(PS the mention of “ramp up mode” makes me think that whoever wrote this is not an expert in control algorithms; and there’s no mention of PID control…)

It seems to have three control modes: ramp-up, PI, and a hybrid of the two which is the default.

Indeed. It is a totally weird approach to try to “solve” a well studied problem that already has a perfectly defined solution…

2 Likes

This feature looks very interesting. I am planing to use it on my infloor heating system which utilizes a thermostat in almost every room. I already have the temperature sensors ready with OH.
I need to install two Sonoff 4CH units and start testing…

Do not compile Tasmota with Arduino IDE anymore.
We dropped support for. Tasmota is only tested (and build) with PlatformIO.
Using Arduino IDE can result in faulty firmware with unexpected behaviours
Some features will for sure NOT work.

Greets Jason2866
Edit: You can find now a thermostat build on my special Tasmota builds github:
Tasmota Thermostat