evohome2mqtt

Evohome2mqtt

This node.js application is a bridge between the Evohome system and a mqtt server. Your thermostats will be polled every x seconds and the status(es) get published to your (local) mqtt server. As with a bridge it also works the other way around. You can set the temperature for a thermostat with a message to mqtt.

It's intended as a building block in heterogenous smart home environments where an MQTT message broker is used as the centralized message bus. See MQTT Smarthome on Github for a rationale and architectural overview.

Topics

Every message starts with a prefix (see config) that defaults to evohome. So if you change this all the topics change.

Connect messages

This bridge uses the evohome/connected topic to send retained connection messages. Use this topic to check your evohome bridge is still running.

• 0 or missing is not connected (set by will functionality).
• 1 is connected to mqtt, but not to evohome.
• 2 is connected to mqtt and evohome. (ultimate success!)

Status messages

The status of each thermostat will be published to evohome/status/thermostat/zone_name as a JSON object containing the following fields.

• val current temperature.
• state JSON object retrieved from evohome server.
• lc last change.

We also publish the temperature as a single value to evohome/status/thermostat/zone_name/temp.

Setting the temperature

You can control each zone by sending a json message to evohome/set/thermostat/zone_name with the following fields:

• temp is the new temperature.
• minutes is the number of minutes this new temp should be set (optional).

evohome/set/thermostat/livingroom
{
  "temp":20,
  "minutes":48
}

Will set the temperature to 20º for 48 minutes.

An empty message to evohome/set/thermostat/livingroom will revert the livingroom back to the schedule.

Config

You would typically run this app in the background, but first you have to configure it.

git clone https://github.com/svrooij/evohome2mqtt.git
cd evohome2mqtt
npm install
nano config/local.json

You are now in the config file. Enter the following data as needed. See mqtt.connect for options how to format the host. ws://ip_address:port is the easiest.

{
  "mqtt": {
    "host":"mqtt://127.0.0.1",
    "user":null,
    "password":null
  },
  "evohome": {
    "user":"user_or_email",
    "password":"password",
    "updateInterval":60
  }
}

Try to start the application by running npm start or directly by node bridge.js, and the topics should appear on your mqtt server.

Running in the background

If everything works as expected, you should make the app run in the background automatically. Personally I use PM2 for this. And they have a great guide for this.