Open Heat

This projects provides a firmware for an ESP8266 to control radiator valves.

Status

Early beta

Hardware

• ESP8266
• Radiator Valve
  • The linked valve is taken apart and only the motor and temperature sensor is used. Therefore the cheapest version without support or bluetooth for wifi is sufficient
• BME280
  • This can be used instead the temperature sensor from the Eqiva valve. Using this requires less intricate soldering.
• HT7333 voltage regulator

Pin configuration

Pins can be configured via the webinterface. The current defaults are:

Battery

To extend the battery lifetime this project is using the following batteries

Battery holder:

• https://de.aliexpress.com/item/32969695165.html

Battery:

• https://de.aliexpress.com/item/1005003394481523.html

To monitor their voltage the ADC of the ESP is used. This requires to solder a voltage divider, with 100k and 33k Ohm resistance. For details, see the schematics. Please note that at this point it's not possible to configure the resistance values via the web interface. Please note that a nodemcu already comes with a voltage divider for the ADC. To use the battery management you have to de-solder these resistors

Building

Run init.sh to properly initialize the project. To build run

platformio -c clion run --target release -e nodemcuv2

Setup

Connect to the WiFi OpenHeatESP... with password "OpenHeat". Open 192.168.4.1 in your browser and start configuration. Save config and the ESP will reboot and connect to your Wifi.

Uploading

esptool.py --before no_reset --after hard_reset --chip esp8266 --port "/dev/ttyUSB0" --baud 921600 write_flash 0x0 ".pio/build/nodemcuv2/firmware.bin"

Updating

Download the latest firmware from releases and upload it on the web-ui. Make sure to download the correct version, otherwise your MCU has to be flashed via USB again.

The initial configuration allows the configuration of a user name and password for update purposes. This is to improve security a bit and not anyone in your network can flash a new firmware. For security purposes this data only can be changed in the configuration mode and not via the webinterface. To enable the configuration mode again restart your device twice in 10s.

MQTT

The heater can be controlled via mqtt and integrated into home assistant. It offers the following topics, all of them are prefixed with the configured topic ($TOPIC):

• Set target temp: $TOPIC/temperature/target/set
• Get target temp: $TOPIC/temperature/target/get
• Get measured temp: $TOPIC/temperature/measured/get
• Get measured humidity: $TOPIC/humidity/measured/get
• Get battery percentage: $TOPIC/battery/percentage
• Get battery voltage: $TOPIC/battery/voltage
• Get current mode (can be off or heating): $TOPIC/mode/get
• Set current mode (can be off or heating): $TOPIC/mode/set
• Get current modem sleep time: $TOPIC/modemsleep/get (time is milliseconds)
• Set current modem sleep time: $TOPIC/modemsleep/set (time is milliseconds)
  • Be careful when setting this.
  • If it's set to a small value the device will consume a lot of battery
  • If it's set to a large value you won't receive temperatures and battery updates in a high frequency and you won't be able to change the operation mode
  • This feature is intended to set the sleep time overnight to something like 1h to save battery

The battery percentage assumes a voltage between 3.1 and 4.2 volts

Example configuration for home assistant:

climate:
  - platform: mqtt
    modes:
      - "off"
      - "heat"
    name: Living room
    temperature_command_topic: "$TOPIC/temperature/target/set"
    temperature_state_topic: "$TOPIC/temperature/target/get"
    current_temperature_topic: "$TOPIC/temperature/measured/get"
    mode_command_topic: "$TOPIC/mode/set"
    mode_state_topic: "$TOPIC/mode/get"
    retain: true

optional if you also want to monitor the battery state:

  - platform: mqtt
    state_topic: "$TOPIC/battery/voltage"
    name: "Bed Heater Voltage"

  - platform: mqtt
    state_topic: "$TOPIC/battery/percent"
    name: "Bed Heater Percent"

Debugging

All commands must be sent with retain flag to allow the device to read the value as soon as it comes out of sleep

• Enable debugging and web interface, WARNING this consumes a lot more power is not intended to be used for battery operation:

  mosquitto_pub -h hassbian -t "$TOPIC/debug/enable" -m "true" -r

• Set log level

   mosquitto_pub -h hassbian -t "$TOPIC/debug/loglevel" -m "$LEVEL" -r   

  Level can be a value between 0 (highest log level = all logs) and 5 (lowest log level = only fatal errors)

• Receive logs

  mosquitto_sub -h hassbian -t "$TOPIC/log"

Receiving logs

Serial

platformio -c clion device monitor -e nodemcuv2 -f esp8266_exception_decoder

MQTT

Subscribe to topic $TOPIC/log

Browser

Logs are displayed in the web ui at the bottom of the page.

Code analysis

cmake -DCMAKE_BUILD_TYPE=nodemcuv2 --CMAKE_EXPORT_COMPILE_COMMANDS=YES ..
scan-build-11 make

Case

The case is designed to hold to valve, a dual 18650 battery holder and an 60x40mm circuit board. At this moment the case has not been printed nor tested yet.

Contributions

As this project is still in a very early stage no contributions will be accepted at the moment.

Attributions and libraries

• Big thanks to @Anycubic for continued bug reports, testing and several improvements and ideas
• Special thanks to traumflug and their regulator implementation in ISTAtrol. Although it was heavily modified and improved the I-Regulator still forms the base of the valve control.
• WiFi Manager is inspired by https://github.com/roberttidey/WiFiManager/blob/feature_fastconnect/WiFiManager.cpp

  Libraries

• ESP Async WebServer
• ESP AsyncTCP
• AsyncTCP
• ESP_DoubleResetDetector
• Adafruit BME280 Library
• MQTT