---
title: "MQTT Water Heater"
description: "Instructions on how to integrate MQTT Water Heater into Home Assistant."
ha_category:
  - Water Heater
ha_release: 2023.7
ha_iot_class: Local Polling
ha_domain: mqtt
---

The `mqtt` water heater platform lets you control your MQTT enabled Water Heater devices.

## Configuration

<a id='new_format'></a>

To enable this water heater platform in your installation, first add the following to your `configuration.yaml` file:

```yaml
# Example configuration.yaml entry
mqtt:
  - water_heater:
      name: Boiler
      mode_command_topic: "basement/boiler/mode/set"
```

{% configuration %}
availability:
  description: A list of MQTT topics subscribed to receive availability (online/offline) updates. Must not be used together with `availability_topic`.
  required: false
  type: list
  keys:
    payload_available:
      description: The payload that represents the available state.
      required: false
      type: string
      default: online
    payload_not_available:
      description: The payload that represents the unavailable state.
      required: false
      type: string
      default: offline
    topic:
      description: An MQTT topic subscribed to receive availability (online/offline) updates.
      required: true
      type: string
    value_template:
      description: "Defines a [template](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) to extract device's availability from the `topic`. To determine the devices's availability result of this template will be compared to `payload_available` and `payload_not_available`."
      required: false
      type: template
availability_mode:
  description: When `availability` is configured, this controls the conditions needed to set the entity to `available`. Valid entries are `all`, `any`, and `latest`. If set to `all`, `payload_available` must be received on all configured availability topics before the entity is marked as online. If set to `any`, `payload_available` must be received on at least one configured availability topic before the entity is marked as online. If set to `latest`, the last `payload_available` or `payload_not_available` received on any configured availability topic controls the availability.
  required: false
  type: string
  default: latest
availability_template:
  description: "Defines a [template](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) to extract device's availability from the `availability_topic`. To determine the devices's availability result of this template will be compared to `payload_available` and `payload_not_available`."
  required: false
  type: template
availability_topic:
  description: The MQTT topic subscribed to receive availability (online/offline) updates. Must not be used together with `availability`.
  required: false
  type: string
current_temperature_template:
  description: A template with which the value received on `current_temperature_topic` will be rendered.
  required: false
  type: template
current_temperature_topic:
  description: The MQTT topic on which to listen for the current temperature. A `"None"` value received will reset the current temperature. Empty values (`'''`) will be ignored.
  required: false
  type: string
device:
  description: 'Information about the device this Water Heater device is a part of to tie it into the [device registry](https://developers.home-assistant.io/docs/en/device_registry_index.html). Only works through [MQTT discovery](/integrations/mqtt/#mqtt-discovery) and when [`unique_id`](#unique_id) is set. At least one of identifiers or connections must be present to identify the device.'
  required: false
  type: map
  keys:
    configuration_url:
      description: 'A link to the webpage that can manage the configuration of this device. Can be either an `http://`, `https://` or an internal `homeassistant://` URL.'
      required: false
      type: string
    connections:
      description: 'A list of connections of the device to the outside world as a list of tuples `[connection_type, connection_identifier]`. For example the MAC address of a network interface: `"connections": [["mac", "02:5b:26:a8:dc:12"]]`.'
      required: false
      type: list
    hw_version:
      description: The hardware version of the device.
      required: false
      type: string
    identifiers:
      description: 'A list of IDs that uniquely identify the device. For example a serial number.'
      required: false
      type: [list, string]
    manufacturer:
      description: 'The manufacturer of the device.'
      required: false
      type: string
    model:
      description: 'The model of the device.'
      required: false
      type: string
    name:
      description: 'The name of the device.'
      required: false
      type: string
    suggested_area:
      description: 'Suggest an area if the device isn’t in one yet.'
      required: false
      type: string
    sw_version:
      description: 'The firmware version of the device.'
      required: false
      type: string
    via_device:
      description: 'Identifier of a device that routes messages between this device and Home Assistant. Examples of such devices are hubs, or parent devices of a sub-device. This is used to show device topology in Home Assistant.'
      required: false
      type: string
enabled_by_default:
  description: Flag which defines if the entity should be enabled when first added.
  required: false
  type: boolean
  default: true
encoding:
  description: The encoding of the payloads received and published messages. Set to `""` to disable decoding of incoming payload.
  required: false
  type: string
  default: "utf-8"
entity_category:
  description: The [category](https://developers.home-assistant.io/docs/core/entity#generic-properties) of the entity.
  required: false
  type: string
  default: None
initial:
  description: Set the initial target temperature. The default value depends on the temperature unit, and will be 43.3°C or 110°F.
  required: false
  type: integer
icon:
  description: "[Icon](/docs/configuration/customizing-devices/#icon) for the entity."
  required: false
  type: icon
json_attributes_template:
  description: "Defines a [template](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) to extract the JSON dictionary from messages received on the `json_attributes_topic`. Usage example can be found in [MQTT sensor](/integrations/sensor.mqtt/#json-attributes-template-configuration) documentation."
  required: false
  type: template
json_attributes_topic:
  description: "The MQTT topic subscribed to receive a JSON dictionary payload and then set as sensor attributes. Usage example can be found in [MQTT sensor](/integrations/sensor.mqtt/#json-attributes-topic-configuration) documentation."
  required: false
  type: string
max_temp:
  description: Maximum set point available. The default value depends on the temperature unit, and will be 60°C or 140°F.
  type: float
  required: false
min_temp:
  description: Minimum set point available. The default value depends on the temperature unit, and will be 43.3°C or 110°F.
  type: float
  required: false
mode_command_template:
  description: A template to render the value sent to the `mode_command_topic` with.
  required: false
  type: template
mode_command_topic:
  description: The MQTT topic to publish commands to change the Water Heater operation mode.
  required: false
  type: string
mode_state_template:
  description: A template to render the value received on the `mode_state_topic` with.
  required: false
  type: template
mode_state_topic:
  description: The MQTT topic to subscribe for changes of the Water Heater operation mode. If this is not set, the operation mode works in optimistic mode (see below).
  required: false
  type: string
modes:
  description: A list of supported modes. Needs to be a subset of the default values.
  required: false
  default: ['off', 'eco', 'electric', 'gas', 'heat_pump', 'high_demand', 'performance']
  type: list
name:
  description: The name of the Water Heater. Can be set to `null` if only the device name is relevant.
  required: false
  type: string
  default: MQTT Water Heater
object_id:
  description: Used instead of `name` for automatic generation of `entity_id`
  required: false
  type: string
optimistic:
  description: Flag that defines if the water heater works in optimistic mode
  required: false
  type: boolean
  default: "`true` if no state topic defined, else `false`."
payload_available:
  description: The payload that represents the available state.
  required: false
  type: string
  default: online
payload_not_available:
  description: The payload that represents the unavailable state.
  required: false
  type: string
  default: offline
payload_off:
  description: The payload that represents disabled state.
  required: false
  type: string
  default: "OFF"
payload_on:
  description: The payload that represents enabled state.
  required: false
  type: string
  default: "ON"
power_command_template:
  description: A template to render the value sent to the `power_command_topic` with. The `value` parameter is the payload set for `payload_on` or `payload_off`.
  required: false
  type: template
power_command_topic:
  description: The MQTT topic to publish commands to change the water heater power state. Sends the payload configured with `payload_on` if the water heater is turned on via the `water_heater.turn_on`, or the payload configured with `payload_off` if the water heater is turned off via the `water_heater.turn_off` service. Note that `optimistic` mode is not supported through `water_heater.turn_on` and `water_heater.turn_off` services. When called, these services will send a power command to the device but will not optimistically update the state of the water heater. The water heater device should report its state back via `mode_state_topic`.
  required: false
  type: string
precision:
  description: The desired precision for this device. Can be used to match your actual water heater's precision. Supported values are `0.1`, `0.5` and `1.0`.
  required: false
  type: float
  default: 0.1 for Celsius and 1.0 for Fahrenheit.
qos:
  description: The maximum QoS level to be used when receiving and publishing messages.
  required: false
  type: integer
  default: 0
retain:
  description: Defines if published messages should have the retain flag set.
  required: false
  type: boolean
  default: false
temperature_command_template:
  description: A template to render the value sent to the `temperature_command_topic` with.
  required: false
  type: template
temperature_command_topic:
  description: The MQTT topic to publish commands to change the target temperature.
  required: false
  type: string
temperature_state_template:
  description: A template to render the value received on the `temperature_state_topic` with.
  required: false
  type: template
temperature_state_topic:
  description: The MQTT topic to subscribe for changes in the target temperature. If this is not set, the target temperature works in optimistic mode (see below). A `"None"` value received will reset the temperature set point. Empty values (`'''`) will be ignored.
  required: false
  type: string
temperature_unit:
  description: Defines the temperature unit of the device, `C` or `F`. If this is not set, the temperature unit is set to the system temperature unit.
  required: false
  type: string
unique_id:
   description: An ID that uniquely identifies this Water Heater device. If two Water Heater devices have the same unique ID, Home Assistant will raise an exception.
   required: false
   type: string
value_template:
  description: Default template to render the payloads on *all* `*_state_topic`s with.
  type: template
  required: false
{% endconfiguration %}

## Optimistic mode

If a property works in *optimistic mode* (when the corresponding state topic is not set), Home Assistant will assume that any state changes published to the command topics did work and change the internal state of the entity immediately after publishing to the command topic. If it does not work in optimistic mode, the internal state of the entity is only updated when the requested update is confirmed by the device through the state topic. You can enforce optimistic mode by setting the `optimistic` option to `true`. When set, the internal state will always be updated, even when a state topic is defined.

## Using Templates

For all `*_state_topic`s, a template can be specified that will be used to render the incoming payloads on these topics. Also, a default template that applies to all state topics can be specified as `value_template`. This can be useful if you received payloads are e.g., in JSON format. Since in JSON, a quoted string (e.g., `"foo"`) is just a string, this can also be used for unquoting.

Say you receive the operation mode `"off"` via your `mode_state_topic`, but the mode is actually called just `off`, here's what you could do:

{% raw %}

```yaml
mqtt:
  - water_heater:
      name: Boiler
      modes:
        - "off"
        - "eco"
        - "performance"
      mode_command_topic: "basement/boiler/mode/set"
      mode_state_topic: "basement/boiler/mode/state"
      mode_state_template: "{{ value_json }}"
```

{% endraw %}

This will parse the incoming `"off"` as JSON, resulting in `off`. Obviously, in this case you could also just set `value_template: {% raw %}"{{ value_json }}"{% endraw %}`.

Similarly for `*_command_topic`s, a template can be specified to render the outgoing payloads on these topics.

## Example

A full configuration example looks like the one below.

{% raw %}

```yaml
# Full example configuration.yaml entry
mqtt:
  - water_heater:
      name: Boiler
      modes:
        - "off"
        - "eco"
        - "performance"
      mode_state_topic: "basement/boiler/mode"
      mode_command_topic: "basement/boiler/mode/set"
      mode_command_template: "{{ value if value=="off" else "on" }}"
      temperature_state_topic: "basement/boiler/temperature"
      temperature_command_topic: "basement/boiler/temperature/set"
      current_temperature_topic: "basement/boiler/current_temperature"
      precision: 1.0
```

{% endraw %}