universal thermostat for (underfloor/fan) heater

Overview

You can use this flow to create your own thermostat by using a temperature sensor plus a switch, which turn your heating device on or off (e.g Shelly plug S to control a infrared heating panel or Shelly RGBW2 to control up to four 24V floor heating valves)

There is enough room for improvement of the flow, but a goal was to keep it simple and adaptable. Feel free to test it and make your own changes!

Please buy me a coffee if this flow saves time (to create your own flow) and/or energy costs ! :-)

Features

• it's optimised to control it by json based web thermostat plugins for homebridge

{
"currentTemperature":25,
"targetHeatingCoolingState":1,
"currentHeatingCoolingState":1,
"targetTemperature":30
}

• you can add many window sensors as you like or have :-)
• Calendar (CalDav) based heating control is also possible
• heat logic script includes hysteresis parameter ( currently set to 0.2)
• input/outpus via HTML (optional mqtt)

Example

Here is an example of a underfloor heating flow. It shows some important steps, but not all. So basic node-red understanding is required.

1) Parts

• Shelly RGBW2 in white mode (2nd one to control 8 Channels)
• 24V underfloor heating valve (e.g. Möhlenhoff Alpha 5 24V NC)
• 24V Poweradapter (+ some wires)
• Temperature Sensor
• Window Sensor (optional)
• instance, where you can run Node-Red (and homebridge)
• needed nodes in Node-Red: node-red-contrib-boolean-logic-ultimate, node-red-contrib-ical-events)
• CalDav Calendar (I'm using one from a NextCloud instance)

2) Configuration

1. Add required nodes to Node-Red

2. Add the URLs off your Shelly RGBW2

• Ch1 on: http://192.168.xxx.xxx/white/0?turn=on&brightness=100
• Ch1 off: http://192.168.xxx.xxx/white/0?turn=off
• Ch2 on: http://192.168.xxx.xxx/white/1?turn=on&brightness=100
• Ch2 off: http://192.168.xxx.xxx/white/1?turn=off
  ...

3. set up a temp sensor (currently no example available)

4. Configure Calendar (optional)

• set-up a calDav Calendar to the ical node

If "targetHeatingCoolingState" is set to "3" the flow checks the linked calendar for entries. In the location field of a calendar entry you can add the target temperature. See the example in the flow for better understanding.

5. set up Window Sensor (optional, example: Shelly Door/Window)

• insert reporting URL to the Node-Red Http End-Point

6. For testing I added example inject-nodes. So it is easier to understand how it works and you can add your own input/output nodes.

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