Hargassner boiler control
Monitors and controls Hargassner touch-control biomass boilers via Modbus TCP.
This template connects Hargassner touch-control biomass boilers to ModbusCloud via Modbus TCP. It reads accumulator temperatures and boiler output, and provides write access to heating circuit setpoints, hot water tank targets, and room temperature specifications.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 48, read and write
- Brand
- Hargassner
- Key readings
- Accumulator Temperature Top/Middle/Bottom · Boiler Output
- Available commands
- Boiler temp. set value · Room temp. spec. for HC · HWT target temperature · Set temp. flow heat circuit
- Compatible models
- Eco-HK · Eco-PK · Nano-PK · Neo-HV · Classic · HSV · HKR
- Last updated
Registers (48)
4 read, 44 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Accumulator Temperatur Bottom | °C | Read | |||
| Accumulator Temperatur Middle | °C | Read | |||
| Accumulator Temperatur Top | °C | Read | |||
| Boiler Output | % | Read | |||
| Boiler temp. | °C | Write | |||
| Boiler temp. - set value | °C | Write | |||
| Return temperature | °C | Write | |||
| Set value - return temp. | °C | Write | |||
| Accum. fill level | Write | ||||
| Highest demand | Write | ||||
| Temp. - external heat | °C | Write | |||
| Current error number | Write | ||||
| Fuel storage level | Write | ||||
| Outside temperature | °C | Write | |||
| Outside temp. - average | °C | Write | |||
| External heat circuit target temp. | °C | Write | |||
| Temp. - flow - heat circuit A | °C | Write | |||
| Set temp. - flow - heat circuit A | °C | Write | |||
| Room sensor - remote control - HC A | °C | Write | |||
| Set temp. - room sensor - heat circuit A | °C | Write | |||
| Status - HC A | Write | ||||
| Remote Status - HC A | Write | ||||
| Room temp. spec. for HC A | °C | Write | |||
| Temp. - flow - heat circuit 1 | °C | Write | |||
| Set temp. - flow - heat circuit 1 | °C | Write | |||
| Room sensor - remote control - HC 1 | °C | Write | |||
| Set temp. - room sensor - heat circuit 1 | °C | Write | |||
| Status - HC 1 | Write | ||||
| Remote Status - HC 1 | Write | ||||
| Room temp. spec. for HC 1 | °C | Write | |||
| Temperature HWT A | °C | Write | |||
| HWT A target temperature | °C | Write | |||
| HWT A status | Write | ||||
| Temperature HWT 1 | °C | Write | |||
| HWT 1 target temperature | °C | Write | |||
| HWT 1 status | Write | ||||
| MBUS channel 1 flow temperature | °C | Write | |||
| MBUS channel 1 return temperature | °C | Write | |||
| MBUS channel 1 output | Write | ||||
| MBUS channel 1 flow | Write | ||||
| MBUS channel 1 energy | Write | ||||
| Malfunction | % | Write | |||
| Pump - HC A | Write | ||||
| Pump - HC 1 | Write | ||||
| HWT A pump | Write | ||||
| HWT 1 pump | Write | ||||
| HWT A circulation pump | kW | Write | |||
| HWT 1 circulation pump | kW | Write |
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Use cases
- Monitor accumulator temperatures at top, middle, and bottom layers to verify buffer stratification in real time.
- Adjust heating circuit flow temperature setpoints remotely without visiting the installation site.
- Create an alert when boiler output drops below a threshold, indicating potential maintenance needs.
- Log hot water tank target temperatures over time to optimize domestic hot water scheduling.
- Compare room temperature specifications with actual values across multiple Hargassner installations from one dashboard.
- Track boiler performance across a portfolio of biomass heating systems for energy reporting purposes.
Installation
Insert the Hargassner Modbus dongle into the touch-control board and activate Modbus by setting parameter D24 on the boiler.
Connect the ModbusCloud Gateway to the same local network as the Hargassner boiler via Ethernet.
Configure the gateway with the boiler's IP address and the correct Modbus TCP port (typically 502).
Import the Hargassner boiler control template in the ModbusCloud platform and assign it to the gateway.
Verify that accumulator temperatures and boiler output values appear correctly on the ModbusCloud dashboard before leaving site.
Things to watch for
I see zero or incorrect values for accumulator temperatures. What is wrong?
The read registers for accumulator temperatures use float32 encoding, spanning two addresses each (e.g. 6149-6150). Make sure your gateway is configured for 32-bit float register reads with the correct byte order. If values still look wrong, try swapping the word order.
How do I enable Modbus on my Hargassner boiler?
You need the Hargassner Modbus dongle inserted into the touch-control board. Then activate the Modbus interface by setting parameter D24 in the boiler's configuration menu.
Which Hargassner models are compatible with this template?
The template works with all Hargassner touch-control boilers that support the Modbus dongle. Confirmed models include Eco-HK, Eco-PK, Nano-PK, Neo-HV, Classic, HSV, and HKR.
Can I write setpoints to the boiler, or is the template read-only?
The template includes write registers for boiler temperature set value, heating circuit flow temperature, hot water tank target temperature, and room temperature specification. These use uint16 encoding and allow remote adjustment from the ModbusCloud dashboard.
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