I have 3 generic thermostats for:
- 2 central heating zones,
- hot water cylinder.
They are on a UK S-plan system, which means water supply from the boiler is shared by these 3 zones via independent valves, 1 per zone. When heating water, the boiler is set to a higher flow temperature than it is for central heating (in central heating mode the boiler uses weather compensation to lower the flow temperature depending on outside temperature). This means I do not want hot water thermostat and central heating thermostat to activate simultaneously. Typical installations use a timer to switch between central heating and hot water but this is non-ideal (for example in periods of high hot water usage). A better approach is “domestic hot water priority”, which temporarily disables central heating when heating water.
What solution would you recommend for implementing such mechanism in Home Assistant? I was thinking about several solutions:
- Having a logical “CH and not HW” operation in the switch for CH heater/valve. How?
- Temporarily disabling CH thermostats when hot water thermostat is active.
What tools to use? Automations, switch templates, input booleans?
I can probably implement something with automations myself but I wonder if there are any better solutions.
This is what I have done, it works well but, honestly, I wish HomeAssistant had boolean functions, similar to “combine sensors” helper for numerical states.
I have defined three input_boolean.heating_* toggles one for each zone and defined the following monstrous automation, essentially implementing 4x 3-input boolean functions. Then I assigned these toggles to one thermostat each (not shown here).
alias: Hot Water Priority
description: ""
trigger:
- platform: state
entity_id:
- input_boolean.heating_hot_water
- platform: state
entity_id:
- input_boolean.heating_upstairs
- platform: state
entity_id:
- input_boolean.heating_downstairs
condition: []
action:
- choose:
- conditions:
- condition: state
entity_id: input_boolean.heating_hot_water
state: "on"
sequence:
- service: switch.turn_off
data: {}
target:
entity_id: switch.heating_downstairs
- service: switch.turn_off
data: {}
target:
entity_id: switch.heating_upstairs
- service: switch.turn_off
data: {}
target:
entity_id: switch.switch_ch_mode
- service: switch.turn_on
data: {}
target:
entity_id: switch.switch_hot_water
- conditions:
- condition: and
conditions:
- condition: state
entity_id: input_boolean.heating_upstairs
state: "on"
- condition: state
entity_id: input_boolean.heating_downstairs
state: "on"
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_hot_water
state: "on"
sequence:
- service: switch.turn_off
data: {}
target:
entity_id: switch.switch_hot_water
- service: switch.turn_on
data: {}
target:
entity_id: switch.switch_ch_mode
- service: switch.turn_on
data: {}
target:
entity_id: switch.heating_upstairs
- service: switch.turn_on
data: {}
target:
entity_id: switch.heating_downstairs
- conditions:
- condition: and
conditions:
- condition: state
entity_id: input_boolean.heating_upstairs
state: "on"
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_downstairs
state: "on"
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_hot_water
state: "on"
sequence:
- service: switch.turn_off
data: {}
target:
entity_id: switch.switch_hot_water
- service: switch.turn_on
data: {}
target:
entity_id: switch.switch_ch_mode
- service: switch.turn_on
data: {}
target:
entity_id: switch.heating_upstairs
- service: switch.turn_off
data: {}
target:
entity_id: switch.heating_downstairs
- conditions:
- condition: and
conditions:
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_upstairs
state: "on"
- condition: state
entity_id: input_boolean.heating_downstairs
state: "on"
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_hot_water
state: "on"
sequence:
- service: switch.turn_off
data: {}
target:
entity_id: switch.switch_hot_water
- service: switch.turn_on
data: {}
target:
entity_id: switch.switch_ch_mode
- service: switch.turn_off
data: {}
target:
entity_id: switch.heating_upstairs
- service: switch.turn_on
data: {}
target:
entity_id: switch.heating_downstairs
- conditions:
- condition: and
conditions:
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_hot_water
state: "on"
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_upstairs
state: "on"
- condition: not
conditions:
- condition: state
entity_id: input_boolean.heating_downstairs
state: "on"
sequence:
- service: switch.turn_on
data: {}
target:
entity_id: switch.switch_ch_mode
- service: switch.turn_off
data: {}
target:
entity_id: switch.switch_hot_water
- service: switch.turn_off
data: {}
target:
entity_id: switch.heating_upstairs
- service: switch.turn_off
data: {}
target:
entity_id: switch.heating_downstairs
mode: single