Hargassner boiler control

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

1. 1Insert the Hargassner Modbus dongle into the touch-control board and activate Modbus by setting parameter D24 on the boiler.
2. 2Connect the ModbusCloud gateway (MCG or MLP series) to the same local network as the Hargassner boiler via Ethernet.
3. 3Configure the gateway with the boiler's IP address and the correct Modbus TCP port (typically 502).
4. 4Import the Hargassner boiler control template in the ModbusCloud platform and assign it to the gateway.
5. 5Verify that accumulator temperatures and boiler output values appear correctly on the ModbusCloud dashboard before leaving site.

Things to watch for

01

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.

02

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.

03

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.

04

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.

Registers (48)

4 read / 44 write

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