Add ouman_eh_800 integration documentation

source/_integrations/ouman_eh_800.markdown

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+---
+title: Ouman EH-800
+description: Instructions on how to integrate the Ouman EH-800 heating controller with Home Assistant.
+ha_category:
+  - Sensor
+ha_release: 2026.6
+ha_iot_class: Local Polling
+ha_config_flow: true
+ha_codeowners:
+  - '@Markus98'
+ha_domain: ouman_eh_800
+ha_platforms:
+  - sensor
+ha_integration_type: device
+ha_quality_scale: bronze
+related:
+  - url: https://ouman.fi/en/product/ouman-eh-800-and-eh-800b/
+    title: Ouman EH-800 manufacturer website
+  - url: https://ouman.fi/wp-content/uploads/2022/04/XM1054B-N-00.pdf
+    title: Ouman EH-800 user manual
+---
+
+The **Ouman EH-800** {% term integration %} integrates the [Ouman EH-800](https://ouman.fi/en/product/ouman-eh-800-and-eh-800b/) heating controller with Home Assistant. It allows you to monitor your EH-800 device directly from Home Assistant over your local network.
+
+The Ouman EH-800 is a heating controller used for water-based central heating systems. It supports up to two heating circuits (H1 and H2) with control curves based on the outside temperature.
+
+## Supported devices
+
+The following devices are supported by this integration:
+
+- **Ouman EH-800**
+
+The Ouman EH-800B is **not supported** as it does not have network connectivity.
+
+## Prerequisites
+
+Before setting up the Ouman EH-800 integration, make sure:
+
+- Your Ouman EH-800 controller is connected to your local network.
+- The device has a reachable <abbr title="Internet Protocol">IP</abbr> address, subnet mask, and a configured username and password. Refer to the [device manual](https://ouman.fi/wp-content/uploads/2022/04/XM1054B-N-00.pdf#page=41) for setup instructions.
+- The device's web interface (`http://<ip_address>:<port>`) is reachable from Home Assistant.
+
+{% warning %}
+The Ouman EH-800 only supports unencrypted <abbr title="HyperText Transfer Protocol">HTTP</abbr> and does not adhere to modern security standards. In addition, the device exposes all of its values to anyone who can reach it over the network. Authentication is not required for read operations, only for writes. Keep the device on your local network only. Exposing the device directly to the internet is **strongly discouraged**.
+{% endwarning %}
+
+{% include integrations/config_flow.md %}
+
+### Configuration parameters
+
+{% configuration_basic %}
+URL:
+  description: The <abbr title="Uniform Resource Locator">URL</abbr> of the Ouman EH-800 web interface, for example `http://192.168.1.100`.
+Username:
+  description: The username configured on the Ouman EH-800 device.
+Password:
+  description: The password configured on the Ouman EH-800 device.
+{% endconfiguration_basic %}
+
+## Supported functionality
+
+The integration creates one **Ouman EH-800** device for the controller and one sub-device for each active heating circuit. Sub-devices are named **Heating circuit 1** and **Heating circuit 2** (referred to as H1 and H2 throughout this document and on the controller), with the circuit name configured on the controller appended when available (for example, `Heating circuit 1 Radiator heating`). Sensors are assigned to the device they belong to.
+
+### Sensors
+
+The exact set of sensors depends on which features and circuits are active on your device. Sensors enabled by default include:
+
+- **Outside temperature**: The outside temperature measured by the controller.
+- **H1/H2 supply water temperature**: The current supply water temperature for the heating circuit.
+- **H1/H2 supply water temperature setpoint**: The target supply water temperature calculated by the controller.
+- **H1/H2 valve position**: The current position of the mixing valve, in percent.
+- **H1/H2 room temperature**: The room temperature measured by the room sensor (when installed).
+- **H1/H2 room temperature setpoint**: The target room temperature.
+
+Additional diagnostic sensors are exposed but disabled by default. See [enabling or disabling entities](/common-tasks/general/#enabling-or-disabling-entities) to enable them if needed:
+
+- **H1/H2 curve supply water temperature**: The supply water temperature derived from the heating curve.
+- **H1/H2 delayed room temperature**: A smoothed/delayed room temperature reading.
+- **H1 fine adjustment effect**: The temperature offset from the manual fine-adjustment.
+- **H1 room sensor potentiometer**: The room temperature offset from the room sensor's adjustment knob.
+- **H2 delayed outdoor temperature effect**: The delayed outdoor temperature effect applied to the H2 setpoint.
+
+## Data updates
+
+This integration uses local {% term polling %} to fetch data from the Ouman EH-800 controller every 60 seconds.
+
+## Known limitations
+
+- **Read-only**: The integration currently only reads values from the controller. Adjusting setpoints, changing operation mode, or controlling the relay is not yet supported.
+
+## Removing the integration
+
+This integration follows standard integration removal. No extra steps are required.
+
+{% include integrations/remove_device_service.md %}