Water heater is on

The Water heater is on condition passes when a water heater entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more] is currently on. Use it to gate an automation so it runs only when a specific water heater, or every targeted water heater, is already heating or ready to heat.

When you target more than one water heater, the condition’s Condition passes if option controls how the check combines results. You can require any targeted water heater to be on, or demand that all of them are.

Using this condition from the user interface

If you prefer building automations visually, Home Assistant walks you through this condition step by step. You pick what to check, tweak a few options, and save. No YAML knowledge required.

To use Water heater is on in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the And if section, select Add condition.
4. Select what you want to check. Under By target (see Targets), pick the area your water heater is in, or select a device, a specific entity, a floor, or a label.
5. From the conditions shown for that target, select Water heater is on.
6. Under Condition passes if (see Behavior), pick Any or All.
7. Under For at least, enter how long the water heater must stay on before the condition passes.
8. Select Save.

Options in the UI

Using this condition in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required.

In YAML, Water heater is on is referred to as water_heater.is_on. A basic example looks like this:

condition: water_heater.is_on
target:
  entity_id: water_heater.utility_room

This passes when water_heater.utility_room is currently on.

To require all targeted water heaters to stay on for 5 minutes:

condition: water_heater.is_on
target:
  label_id: basement_water_heaters
options:
  behavior: all
  for: "00:05:00"

Options in YAML

YAML sometimes provides additional options for more complex use cases that are not available through the UI.

Targets of the condition

This condition requires a target. The target is the object that Home Assistant will check. You can point the condition at a single entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more], a device, an area, a floor, or a label, and Home Assistant will evaluate every matching water_heater entity behind that target.

• Entity: one specific water_heater entity, such as water_heater.living_room.
• Device: every water_heater entity that belongs to a device.
• Area: every water_heater entity in a room or area.
• Floor: every water_heater entity on a floor.
• Label: every water_heater entity that shares a label.

You can also select different target types in one condition. For example, you can add a specific entity and an area as targets in the same condition to check both of them at once.

Behavior with multiple targets

When you target more than one entity (or select an area, floor, or label that contains several), the Condition passes if option controls how the results combine:

• Any (default): the condition passes if at least one of the targeted entities matches. For example, if you check three smoke sensors and only one of them detects smoke, the condition still passes. This is useful for questions like “is there smoke anywhere in the house?”
• All: the condition passes only when every targeted entity matches. For example, if you check the same three smoke sensors, the condition passes only once all three report cleared. This is useful for “is the entire house safe now?” checks, so your automation does not send an all-clear while one room still has a reading.

Good to know

• This condition checks whether the water heater is on, regardless of which operation mode it is using.
• unavailable and unknown do not count as on for this condition.
• With Any, unavailable and unknown water heaters are skipped. With All, they make the condition fail.
• To react when the water heater turns on instead of checking its current state, use Water heater turned on.

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, open an automation, and add this condition. Trigger the automation with and without the condition met, and watch whether it continues or stops.

More examples

Real scenarios where this condition gates an automation. Copy any example and adapt it to your setup.

Automation: raise the target temperature only when the water heater is on

When overnight rates begin, raise the target temperature, but only if the water heater is already on.

• Trigger: State: Utility rate changes to low
• Condition: Water heater is on
  • Target: Utility room water heater
• Action: Set water heater target temperature

alias: "Store more hot water during low-rate periods"
triggers:
  - trigger: state
    entity_id: sensor.utility_rate
    to: "low"
conditions:
  - condition: water_heater.is_on
    target:
      entity_id: water_heater.utility_room
actions:
  - action: water_heater.set_temperature
    target:
      entity_id: water_heater.utility_room
    data:
      temperature: 55

Automation: notify when all basement water heaters are back on

Every 30 minutes, check whether all targeted basement water heaters have stayed on for 5 minutes. If they have, send a notification.

• Trigger: Time pattern: Every 30 minutes
• Condition: Water heater is on
  • Target: Basement water heaters
  • Condition passes if: All
  • For at least: 00:05:00
• Action: Send a notification message
  • Target: My Device (notify.my_device)

alias: "Check that basement water heaters are running"
triggers:
  - trigger: time_pattern
    minutes: "/30"
conditions:
  - condition: water_heater.is_on
    target:
      label_id: basement_water_heaters
    options:
      behavior: all
      for: "00:05:00"
actions:
  - action: notify.send_message
    target:
      entity_id: notify.my_device
    data:
      message: "All basement water heaters have stayed on for 5 minutes."

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the condition you’re using and what you expected to happen, or share on our subreddit /r/homeassistant.

Related conditions

These conditions work well alongside this one:

• Water heater is off: Tests if one or more water heaters are off.

• Water heater operation mode: Tests if one or more water heaters are set to a specific operation mode.