esphome configuration for my Open Energy Monitor thermostat

thermostat.yaml

# This is an esphome configuration file for the OpenEnergyMonitor Thermostat
# The primary objectives of this configuration file are:
# 1) The temperature used as the sensor for the thermostat should be read from 
#    homeassistant, this lets you use an average or change the room the 
#    temperature is based on depending on the time of day etc.
# 2) If homeassisant goes offline the thermostat keeps working.
# To this end there is a sensor "average_temperature" which is recieved from hass
# and a second sensor "combined_temperature" which decides based on if a device 
# is connected to the native API or not to use this sensor or the local sensor 
# attached to the thermostat.
# Finally, when the last device disconnects from the Native API the thermostat 
# will be put into heat mode with a default setpoint, meaning that it will keep
# itself at a useful temperature even though it is disconnected from hass.

esphome:
  name: thermostat
  platform: ESP8266
  board: esp_wroom_02

wifi:
  networks:
    - ssid: !secret wifi_ssid
      password: !secret wifi_password
      
  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Thermostat Fallback Hotspot"
    password: ""

web_server:
  port: 80
  ota: false
  
captive_portal:
logger:
api:
ota:

status_led:
  pin: GPIO16
  
switch:
  - platform: gpio
    pin: GPIO5
    id: relay
    name: "Thermostat Relay"
    
i2c:
  sda: GPIO4
  scl: GPIO5
  scan: false
  
dallas:
  - pin: GPIO2

binary_sensor:
  # If you press the button on the thermostat set it to 23C
  - platform: gpio
    pin:
      number: GPIO0
      inverted: True
    name: "Thermostat Button"
    on_click:
      - then:
        - climate.control:
            id: thermo
            mode: HEAT
            target_temperature: 23°C
            
  # If the API connection to home assistant is interrupted then we revert to 
  # using the local temp sensor and we turn the heating on and default it to 20C
  - platform: status
    name: "Thermostat Status"
    id: statussensor
    on_release:
      then:
        - climate.control:
            id: thermo
            mode: HEAT
            target_temperature: 20°C

sensor:
  - platform: dallas
    index: 0
    id: thermostat_temperature
    name: "Kitchen Temperature"

  - platform: homeassistant
    name: "Average Temperature"
    entity_id: sensor.average_temperature
    internal: true
    id: average_temperature
    unit_of_measurement: "°C"
    
  - platform: template
    name: Combined Temperature
    id: combined_temperature
    lambda: |-
      if (id(statussensor).state) {
        return id(average_temperature).state;
      } else {
        return id(thermostat_temperature).state;
      }
    update_interval: 10s
    unit_of_measurement: "°C"
    
climate:
  - platform: thermostat
    id: thermo
    name: "Central Heating"
    sensor: combined_temperature
    min_idle_time: 30s
    min_heating_off_time: 60s
    min_heating_run_time: 60s
    default_target_temperature_low: 20 °C
    away_config:
      default_target_temperature_low: 14 °C
    heat_action:
      - switch.turn_on: relay
    idle_action:
      - switch.turn_off: relay