read this
here is mine
- platform: generic_thermostat
name: "Gas Heater"
heater: switch.gas_heater
target_sensor: sensor.bt_lounge_temperature
min_temp: 15
max_temp: 30
ac_mode: False
target_temp: 20.8
initial_hvac_mode: "off"
cold_tolerance: 0.2
hot_tolerance: 0.2
away_temp: 16