Climate: on/off state should be independent from the HVAC mode

[Noltari]

Some modern climate systems have a master thermostat in which the HVAC mode can be changed and slave thermostats where the HVAC mode can't be changed (it will be forced to the one from its corresponding master thermostat):

• https://www.home-assistant.io/integrations/airzone
• https://www.home-assistant.io/integrations/airzone_cloud
• https://www.home-assistant.io/integrations/advantage_air

Master Zones allow:

• Changing the HVAC mode.
• Turning on/off.
• Changing the desired temperature.

Slave Zones allow:

• Turning on/off.
• Changing the desired temperature.

On Home Assistant climate entities we don't really support turning on a climate entity, because we consider any HVAC mode != Off as being On.
We should make the on/off status independent from the HVAC mode.
Most of the air conditioners have this behaviour: you can switch them on and off without changing its HVAC mode.

Related discussions:

• Broaden the scope of HVAC_MODE_AUTO or add HVAC_MODE_ON #625
• Add feature flags `ClimateEntityFeature.TURN_OFF` + `ClimateEntityFeature.TURN_ON` #982

[Noltari]

Moreover, some Air Conditioners such as Airzone have a "Stop Mode" (this is an additional HVAC mode), in which the compressor won't be supplied with electricity and the device will be set to the minimum power consumption.

[gjohansson-ST]

Not sure I understand this. If you implement the methods for turn_on and turn_off are you not then in control what they would do when called?

[OnFreund]

I don't know Airzone, but many A/Cs have independent controls for on/off and mode, and allow you to control the mode while off (thus determining what the next "On" state would be). There has been lots of feedback about this when Climate 2.0 was implemented, but unfortunately it wasn't taken into account, and the resulting design was basically optimizing for heat pumps, at the expense of A/Cs.

[BradleyFord]

Agree

The Daikin ACs have separate on/off and modes.

To work around this I need to use a HACS add-in that creates custom climate templates, and also addition code on how to blend together these into one type for HA.

Note: These are heat pump A/Cs

Daikin are one of the most significant players in the industry and often a standard setter

[OnFreund]

In this case you don't even need a standard setter - A/Cs have had separate knobs for mode and on/off for decades :)

[Noltari]

Sorry @gjohansson-ST, but I totally forgot to answer...

Not sure I understand this. If you implement the methods for turn_on and turn_off are you not then in control what they would do when called?

Yes, but there's no ON/OFF button/switch at UI level for climate entities (thermostat cards) and I don't think that it will be possible to add it until proper independent on/off state support is added to climate entities, since you can only call turn_on and turn_off, but you don't have a binary status to show on the UI.

In my opinion, OFF should be removed from HVACMode and another binary attribute with on/off status should be added to ClimateEntity.
Therefore, climate devices which only support a single HVACMode should only be toggable on/off and the HVAC Mode shouldn't be modifiable, being always HEAT (or whatever that climate device supports).