fix: water_heater: do not set target_temperature_high and target_temperature_low

[Zkdc]

PR Description

Reason & Detail

these values are for target temperature range. It is obviously incorrect to set these values to min_temp and max_temp. Since we can not get/set the device's target temperature range, we should not set these values.

Related issue

[wuwentao]

@Zkdc thank you very much for you PR.
we still need more contributors for current project, welcome to join us.

for this code chanages, we should follow to the official HA developers guide:
https://developers.home-assistant.io/docs/core/entity/water-heater

seems it match the defines, please help to double check.

[wuwentao]

@Zkdc any updates?

[Zkdc]

@Zkdc thank you very much for you PR. we still need more contributors for current project, welcome to join us.

for this code chanages, we should follow to the official HA developers guide: https://developers.home-assistant.io/docs/core/entity/water-heater

seems it match the defines, please help to double check.

Sorry For The Late Reply.

1. According to the discussion in Support TARGET_TEMPERATURE_RANGE for water heater entities home-assistant/architecture#995 (reply in thread) , these values are hysteresis control parameters.
   Here (https://esphome.io/components/climate/bang_bang.html) is a type of controller which uses these values, it heats when temperature is below target_temperature_low and stop heating when reaching target_temperature_high.

2. When not setting these values, it shows state & current temperature on the interface.
   
   Otherwise, it shows the state & target temperature range on the interface.
   
   Since we are setting incorrect values, it becomes less informative.

[rokam]

@wuwentao this change makes sense as all water heaters uses TargetTemp and not RangeTemp.
This will keep the default value (None): https://developers.home-assistant.io/docs/core/entity/water-heater/

[rokam]

LGTM

[wuwentao]

thanks, I can understand it with your detail answer: it heats when temperature is below target_temperature_low and stop heating when reaching target_temperature_high.