Important adjustment in IoT features: Split heating circuits and domestic hot water


In our API we have coupled heating circuits (HC) and domestic hot water (DHW) support closely together to keep the backwards compatibility between Legacy devices and devices based on our Viessmann One Base control platform, also called E3. Viessmann One Base provides the DHW and HCs as independent systems with a chance to access DHW and HC-features as independent features.

What is being adjusted?

The planned adjustments brings the following changes to our IoT features:

  • adjust heating.circuits.N.operating.modes.* by removing existent DHW dependencies

  • remove heating.circuits.N.operating.modes.dhw* operating modes

  • adjust to only show the following states for the “value” property: auto, heating, cooling, heatingCooling or testMode

The DHW operating can in future be requested through the following new features:

  • introduce >> Shows whether the DHW is off

  • adjust >> Shows the current DHW operating mode with the possible states for the “value” property: balanced, comfort, eco, off

This change only affects our Viessmann One Base (E3) control platform (wifi integrated devices). For legacy devices, i.e. using a Vitoconnect, there are no changes. However, this also means, depending on the device, requesting and changing the DHW operating mode differs.

How to find out which device (legacy / One Base) is used?

To find which device you have, you can use the following request to check the devices of your installation:


        curl -X GET{{installationID}}/gateways/{{gatewaySerial}}/devices/

In the response, you find the list of devices, containing information about the type of device:


    "data": [
            "gatewaySerial": {{gatewaySerial}},
            "id": {{deviceId}},
            "boilerSerial": {{boilerSerial}},
            "boilerSerialEditor": "DeviceCommunication",
            "bmuSerial": null,
            "bmuSerialEditor": null,
            "createdAt": "2020-11-16T07:06:56.267Z",
            "editedAt": "2022-10-27T11:16:06.670Z",
            "modelId": "E3_Vitodens_300_0421",
            "status": "Online",
            "deviceType": "heating",
            "roles": [


The “roles” parameter lists the different types the device is assigned to. Here, you will find either the type:E3 or type:legacy. This information then tells you how to check the DHW operating modes.

When will this change take effect?

The adjustments will go live January 2023. From this date, you can only request the DHW operating mode for E3 using the described new way.