Water Heater Control Guide¶

Learn how to control your Domestic Hot Water (DHW) system through Home Assistant.

Overview¶

If your Hitachi system includes a DHW (Domestic Hot Water) heater, it appears as a water_heater entity in Home Assistant. This provides full control over your hot water production.

Available Controls: - 🌡️ Temperature - Set target water temperature - ⚙️ Operation Mode - Off, Eco, Performance (Boost) - 📊 Status - Current water temperature monitoring

Entity Naming¶

Water heater entities follow this naming convention:

Format: water_heater.{device_name}_dhw

Examples: - water_heater.remote_dhw - water_heater.hitachi_dhw

Operation Modes¶

The water heater supports three operation modes:

Off Mode¶

Description: DHW heating is disabled

When to use: - Extended periods away from home - Summer when hot water not needed - Maintenance or service

Energy use: None

service: water_heater.set_operation_mode
target:
  entity_id: water_heater.remote_dhw
data:
  operation_mode: "off"

Eco Mode (Standard)¶

Description: Normal energy-efficient hot water production

When to use: - Normal daily operation - Standard hot water needs - Energy-conscious heating

Energy use: Standard/efficient

Behavior: - Heats water to target temperature - Maintains temperature efficiently - Uses standard heating cycle

service: water_heater.set_operation_mode
target:
  entity_id: water_heater.remote_dhw
data:
  operation_mode: "eco"

Performance Mode (Boost)¶

Description: Rapid heating for high hot water demand

When to use: - Filling a bath - Multiple showers needed - High hot water demand events - Recovering from low temperature

Energy use: High/intensive

Behavior: - Aggressive heating cycle - Prioritizes DHW over space heating - Reaches target temperature quickly

service: water_heater.set_operation_mode
target:
  entity_id: water_heater.remote_dhw
data:
  operation_mode: "performance"

[PLACEHOLDER: Screenshot showing water heater modes in UI]

Temperature Control¶

Setting Target Temperature¶

The water heater allows you to set your desired hot water temperature.

Temperature Range: Typically 30°C to 55°C - Minimum: 30°C (sufficient for most uses) - Maximum: 55°C (prevents legionella, maximum efficiency) - Recommended: 50-55°C for domestic use

Via UI: 1. Open the water heater entity 2. Use temperature controls 3. Adjust to desired temperature

Via Service Call:

service: water_heater.set_temperature
target:
  entity_id: water_heater.remote_dhw
data:
  temperature: 50

Via Automation:

automation:
  - alias: "Morning Hot Water Boost"
    trigger:
      - platform: time
        at: "06:00:00"
    action:
      - service: water_heater.set_temperature
        target:
          entity_id: water_heater.remote_dhw
        data:
          temperature: 55

Current Temperature¶

Monitor the actual water temperature:

{{ state_attr('water_heater.remote_dhw', 'current_temperature') }}

Target Temperature¶

Check the current setpoint:

{{ state_attr('water_heater.remote_dhw', 'temperature') }}

Complete Attributes¶

Water heater entities provide these attributes:

water_heater.remote_dhw:
  state: eco  # or off, performance
  attributes:
    current_temperature: 48
    temperature: 50
    min_temp: 30
    max_temp: 55
    operation_list:
      - "off"
      - eco
      - performance
    operation_mode: eco
    supported_features: 3

Lovelace UI Examples¶

Basic Water Heater Card¶

type: thermostat
entity: water_heater.remote_dhw

[PLACEHOLDER: Screenshot of water heater thermostat card]

Detailed Water Heater Card¶

type: vertical-stack
cards:
  - type: thermostat
    entity: water_heater.remote_dhw
    name: Hot Water

  - type: entities
    title: DHW Status
    entities:
      - entity: water_heater.remote_dhw
        name: Operation Mode
      - type: attribute
        entity: water_heater.remote_dhw
        attribute: current_temperature
        name: Current Temperature
        suffix: "°C"
      - type: attribute
        entity: water_heater.remote_dhw
        attribute: temperature
        name: Target Temperature
        suffix: "°C"

Mode Control Buttons¶

type: horizontal-stack
cards:
  - type: button
    name: "Off"
    icon: mdi:water-off
    tap_action:
      action: call-service
      service: water_heater.set_operation_mode
      service_data:
        entity_id: water_heater.remote_dhw
        operation_mode: "off"

  - type: button
    name: "Eco"
    icon: mdi:leaf
    tap_action:
      action: call-service
      service: water_heater.set_operation_mode
      service_data:
        entity_id: water_heater.remote_dhw
        operation_mode: eco

  - type: button
    name: "Boost"
    icon: mdi:fire
    tap_action:
      action: call-service
      service: water_heater.set_operation_mode
      service_data:
        entity_id: water_heater.remote_dhw
        operation_mode: performance

Custom Water Heater Dashboard¶

type: vertical-stack
cards:
  - type: markdown
    content: "## Domestic Hot Water"

  - type: glance
    entities:
      - entity: water_heater.remote_dhw
        name: Mode
      - entity: water_heater.remote_dhw
        name: Current
        attribute: current_temperature
      - entity: water_heater.remote_dhw
        name: Target
        attribute: temperature

  - type: horizontal-stack
    cards:
      - type: button
        name: "Eco"
        icon: mdi:leaf
        icon_height: 40px
        tap_action:
          action: call-service
          service: water_heater.set_operation_mode
          service_data:
            entity_id: water_heater.remote_dhw
            operation_mode: eco

      - type: button
        name: "Boost"
        icon: mdi:fire
        icon_height: 40px
        tap_action:
          action: call-service
          service: water_heater.set_operation_mode
          service_data:
            entity_id: water_heater.remote_dhw
            operation_mode: performance

  - type: thermostat
    entity: water_heater.remote_dhw

Automation Examples¶

Morning Boost for Showers¶

automation:
  - alias: "Morning DHW Boost"
    description: "Boost hot water before morning showers"
    trigger:
      - platform: time
        at: "06:00:00"
    condition:
      - condition: time
        weekday:
          - mon
          - tue
          - wed
          - thu
          - fri
    action:
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: performance
      - service: water_heater.set_temperature
        target:
          entity_id: water_heater.remote_dhw
        data:
          temperature: 55
      - delay: "01:00:00"
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: eco

Temperature Schedule¶

automation:
  - alias: "DHW Temperature Schedule"
    trigger:
      - platform: time
        at: "06:00:00"
        id: morning
      - platform: time
        at: "22:00:00"
        id: night
    action:
      - choose:
          - conditions:
              - condition: trigger
                id: morning
            sequence:
              - service: water_heater.set_temperature
                target:
                  entity_id: water_heater.remote_dhw
                data:
                  temperature: 55

          - conditions:
              - condition: trigger
                id: night
            sequence:
              - service: water_heater.set_temperature
                target:
                  entity_id: water_heater.remote_dhw
                data:
                  temperature: 45

Vacation Mode¶

automation:
  - alias: "Vacation - Turn Off DHW"
    trigger:
      - platform: state
        entity_id: input_boolean.vacation_mode
        to: "on"
    action:
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: "off"

  - alias: "Return From Vacation - Enable DHW"
    trigger:
      - platform: state
        entity_id: input_boolean.vacation_mode
        to: "off"
    action:
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: eco
      - service: water_heater.set_temperature
        target:
          entity_id: water_heater.remote_dhw
        data:
          temperature: 50

Energy Optimization¶

automation:
  - alias: "DHW Heat During Cheap Electricity"
    trigger:
      - platform: time
        at: "02:00:00"  # Off-peak hours
    condition:
      - condition: numeric_state
        entity_id: water_heater.remote_dhw
        attribute: current_temperature
        below: 50
    action:
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: performance
      - wait_template: "{{ state_attr('water_heater.remote_dhw', 'current_temperature') >= 55 }}"
        timeout: "03:00:00"
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: eco

Low Temperature Alert¶

automation:
  - alias: "Alert on Low DHW Temperature"
    trigger:
      - platform: numeric_state
        entity_id: water_heater.remote_dhw
        attribute: current_temperature
        below: 40
        for: "00:30:00"
    action:
      - service: notify.mobile_app
        data:
          title: "Hot Water Low"
          message: "DHW temperature is {{ state_attr('water_heater.remote_dhw', 'current_temperature') }}°C"
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: performance

Boost Button (Helper)¶

Create an input_boolean helper for manual boost:

# configuration.yaml
input_boolean:
  dhw_boost:
    name: DHW Boost Mode
    icon: mdi:fire

automation:
  - alias: "DHW Boost Button On"
    trigger:
      - platform: state
        entity_id: input_boolean.dhw_boost
        to: "on"
    action:
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: performance

  - alias: "DHW Boost Button Off"
    trigger:
      - platform: state
        entity_id: input_boolean.dhw_boost
        to: "off"
    action:
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: eco

  - alias: "DHW Auto-disable Boost After 2 Hours"
    trigger:
      - platform: state
        entity_id: input_boolean.dhw_boost
        to: "on"
        for: "02:00:00"
    action:
      - service: input_boolean.turn_off
        target:
          entity_id: input_boolean.dhw_boost

Monitoring & Notifications¶

Temperature Tracking¶

Track water temperature over time:

# configuration.yaml
sensor:
  - platform: history_stats
    name: DHW Heating Time Today
    entity_id: water_heater.remote_dhw
    state: "performance"
    type: time
    start: "{{ now().replace(hour=0, minute=0, second=0) }}"
    end: "{{ now() }}"

Daily Report¶

automation:
  - alias: "Daily DHW Report"
    trigger:
      - platform: time
        at: "20:00:00"
    action:
      - service: notify.mobile_app
        data:
          title: "Daily Hot Water Report"
          message: >
            Current: {{ state_attr('water_heater.remote_dhw', 'current_temperature') }}°C
            Target: {{ state_attr('water_heater.remote_dhw', 'temperature') }}°C
            Mode: {{ states('water_heater.remote_dhw') }}

Troubleshooting¶

Water Not Heating¶

Symptoms: Temperature not increasing

Possible Causes: 1. Mode is Off - Check operation mode 2. Target temperature reached - Already at setpoint 3. System prioritizing space heating - Heat pump priority 4. Alarm condition - Check for system alarms

Solutions: - Set mode to Performance for immediate heating - Check that target > current temperature - Verify no alarms on climate entities - Check CSNet Manager app for status

Temperature Dropping Quickly¶

Symptoms: Water temperature decreases rapidly

Possible Causes: 1. High usage - Multiple draws 2. Insufficient capacity - Tank size vs demand 3. Mode set to Eco - Not keeping up with demand

Solutions: - Switch to Performance mode during high-demand periods - Increase target temperature - Schedule boost periods before known high usage - Check for leaks or system issues

Controls Not Responding¶

Symptoms: Commands sent but no effect

Possible Causes: 1. Connection issue - Network or API problem 2. CSNet Manager offline - Cloud service down 3. Manual override - Physical controller changed settings

Solutions: - Check climate entity connectivity - Verify internet connection - Check CSNet Manager app - Restart integration if needed

Tips & Best Practices¶

✅ DO¶

Use Eco mode for normal daily operation
Use Performance mode for high-demand periods (baths, multiple showers)
Set temperature to 50-55°C for legionella prevention and efficiency
Schedule boost periods before predictable high-usage times
Turn off when away for extended periods to save energy
Monitor temperature regularly to ensure adequate supply

❌ DON'T¶

Don't set temperature below 50°C long-term (legionella risk)
Don't exceed 55°C (unnecessary energy use, scaling risk)
Don't leave in Performance mode continuously (wastes energy)
Don't turn off/on frequently (causes wear)
Don't ignore low temperature alerts (may indicate system issues)

💡 Pro Tips¶

Coordinate with heating schedule - DHW heating reduces space heating capacity
Use off-peak electricity - Schedule boost during cheap rate periods
Preheat before high usage - Performance mode 30-60 minutes before needed
Monitor patterns - Adjust schedule based on actual usage
Winter boost - May need higher temperatures when inlet water is colder
Legionella prevention - Ensure temperature reaches 60°C weekly (usually automatic)

Safety Considerations¶

Legionella Prevention¶

Legionella bacteria can grow in water between 20°C and 45°C.

Recommendations: - Maintain DHW temperature at 50°C minimum - Heat to 60°C weekly for legionella cycle (often automatic) - Don't disable DHW for extended periods without draining

Note: Many Hitachi systems have automatic legionella prevention cycles.

Scalding Prevention¶

Water above 55°C can cause scalding.

Recommendations: - Don't exceed 55°C for domestic use - Install thermostatic mixing valves at points of use - Educate household members about hot water safety - Use lower temperatures (45-50°C) if children or elderly present

Energy Efficiency¶

Best Practices: - Use Eco mode as default - Reserve Performance mode for actual high-demand situations - Insulate pipes to reduce heat loss - Fix leaks promptly to avoid wasted heating - Schedule strategically to align with usage patterns

Integration with Other Systems¶

Solar Hot Water Pre-Heat¶

If you have solar hot water:

automation:
  - alias: "Use Solar Pre-Heat"
    trigger:
      - platform: numeric_state
        entity_id: sensor.solar_hot_water_temperature
        above: 45
    action:
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: eco
      - service: water_heater.set_temperature
        target:
          entity_id: water_heater.remote_dhw
        data:
          temperature: 50

Smart Grid Integration¶

Respond to grid demand:

automation:
  - alias: "Grid Demand Response - Reduce DHW"
    trigger:
      - platform: state
        entity_id: binary_sensor.grid_demand_high
        to: "on"
    action:
      - service: water_heater.set_temperature
        target:
          entity_id: water_heater.remote_dhw
        data:
          temperature: 45
      - service: water_heater.set_operation_mode
        target:
          entity_id: water_heater.remote_dhw
        data:
          operation_mode: eco

Next Steps¶

Explore related documentation: - Climate Control - Control heating zones - Sensors Reference - All available sensors - Advanced Features - Additional system features - Multi-Zone Configuration - Managing multiple circuits

← Back to Climate Control | Next: Sensors Reference →