Stiebel Eltron Heating & Cooling
Controls Stiebel Eltron heat pumps via Modbus TCP through the ISG Web gateway.
This template connects Stiebel Eltron heat pumps (WPM, WPL, LPZ series) to ModbusCloud via Modbus TCP through the ISG Web gateway. It reads temperatures, operating modes, and fault states, and allows control of room and hot water temperature setpoints.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 22, read and write
- Brand
- Stiebel Eltron
- Key readings
- Outside temperature · Supply flow temperature HC1/HC2 · Buffer temperature (actual/target) · Hot water storage temperature · Heatpump error and fault number · Heatpump operating mode
- Available commands
- Heatpump operating mode · Comfort/Eco room temperature HC1/HC2 · Hot water comfort/eco temperature
- Compatible models
- WPM · LPZ · WPL · ISG Web
- Last updated
Registers (22)
20 read, 7 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| 519 - State Target Buffer temperature | °C | Read | |||
| 518 - Actual Buffer temperature | °C | Read | |||
| 513 - Actual Supply Flowtemperature Heatpump | °C | Read | |||
| 508 - Actual Supply Flowtemperature HC1 | °C | Read | |||
| 516 - Actual Return Flowtemperature Heatpump | °C | Read | |||
| 510 - State Target Supply Flowtemperature HC1 | °C | Read | |||
| 2504 - State Heatpump Error | Read | ||||
| 1501 - State Heatpump Operating mode | Read and write | ||||
| 1504 - State Heating Curve HC1 | Read | ||||
| 2508 - State Heatpump Faultnumber | Read | ||||
| 522 - Actual Hot Water Storage temperature | °C | Read | |||
| 523 - State Target Hot Water Storage temperature | °C | Read | |||
| 507 - Actual Outsidetemperature | °C | Read | |||
| 511 - Actual Supply Flowtemperature HC2 | °C | Read | |||
| 512 - State Target Supply Flowtemperature HC2 | °C | Read | |||
| 1502 - State Comfort Roomtemperature HC1 | °C | Read and write | |||
| 1505 - State Comfort Roomtemperature HC2 | °C | Read and write | |||
| 1503 - State Eco Roomtemperature HC1 | °C | Read and write | |||
| 1506 - State Eco Roomtemperature HC2 | °C | Read and write | |||
| 1507 - State Heating Curve HC2 | Read | ||||
| 1511 - Hot Water Eco temperature | °C | Write | |||
| 1510 - Hot Water Comfort temperature | °C | Write |
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Use cases
- Monitor outside temperature, flow temperatures, and buffer tank status on a live cloud dashboard for your customer.
- Create an alert when a heat pump fault or error state is detected to reduce response time for service calls.
- Adjust room temperature comfort and eco setpoints remotely to match occupancy schedules or seasonal changes.
- Integrate hot water temperature control with PV surplus availability to optimize self-consumption of solar energy.
- Track heating circuit operating modes over time using historical data to verify system efficiency and runtime balance.
- Compare actual buffer temperature against target values to identify control deviations early.
Installation
Connect the Stiebel Eltron ISG Web gateway to your local network and ensure the Modbus TCP interface is enabled (upgrade firmware or purchase the software update if required).
Connect your ModbusCloud Gateway to the same local network as the ISG Web device.
Note the IP address of the ISG Web and confirm it is reachable from the ModbusCloud gateway.
Import the Stiebel Eltron Heating and Cooling template in the ModbusCloud portal and assign the correct IP address and Modbus TCP port (default 502).
Verify that register readings such as outside temperature and buffer temperature appear correctly on the ModbusCloud dashboard.
Test a writable control, such as changing the hot water comfort temperature setpoint, and confirm the change is reflected on the ISG Web display.
Things to watch for
Do I need a separate software update for the ISG Web to use Modbus TCP?
Older ISG Web versions require a chargeable software update from Stiebel Eltron to activate the Modbus TCP interface. Newer ISG Web models have this interface built in. Check with your Stiebel Eltron distributor before purchasing.
Why are my temperature readings off by one register?
Stiebel Eltron documentation lists register numbers that are offset by 1 from the actual Modbus addresses. Register 519 in the manual corresponds to address 518. The template already accounts for this offset.
Which Stiebel Eltron models are supported by this template?
The template is designed for WPM (version 3 and above), WPL, and LPZ series heat pumps connected through the ISG Web gateway. Verify ISG compatibility with your specific model before installation.
What data format do the temperature registers use?
Temperature registers use uint16 or int16 format and report values in degrees Celsius. No additional scaling factor is needed for most registers.
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