Spirala heat pump
Controls Spirala heat pump temperature setpoints and monitors system sensors via Modbus RTU.
This template connects a Spirala heat pump to ModbusCloud via Modbus RTU at 19200 baud. It reads 21 registers covering tank, room, outdoor, and compressor temperatures plus power and fault status. It also writes temperature setpoints for heating circuits, DHW, rooms, and cooling mode.
- Protocol
- Modbus RTU
- Connection
- RS485, 19200 baud
- Registers
- 22, read and write
- Brand
- Spirala
- Key readings
- Accumulation tank temperatures (circuit 1 and 2) · DHW tank temperature · Outlet and return heating water temperatures · Compressor outlet temperature · Actual and desired machine power · Fault relay
- Available commands
- Desired temperature circuit 1 and 2 · Desired DHW and room temperatures · Desired machine power limitation · Switch system to cooling
- Last updated
Registers (22)
21 read, 7 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| DHW tank temperature | °C | Read | |||
| Accumulation tank temperature circuit 1 | °C | Read | |||
| Room temperature 1 | °C | Read | |||
| Fault relay | Read | ||||
| Accumulation tank temperature circuit 2 | °C | Read | |||
| Cooling sensor temperature | °C | Read | |||
| Outdoor temperature | °C | Read | |||
| Room temperature 2 | °C | Read | |||
| Desired power from PV | % | Read | |||
| Actual machine power | % | Read | |||
| Desired machine power limitation | % | Read and write | |||
| Outlet heating water temperature | °C | Read | |||
| Return heating water inlet temperature | °C | Read | |||
| Primary inlet water temperature | °C | Read | |||
| Temperature primary water outlet | °C | Read | |||
| Compressor outlet temperature | °C | Read | |||
| Desired temperature of circuit 1 | °C | Read and write | |||
| Desired temperature of circuit 2 | °C | Read and write | |||
| Desired DHW temperature | °C | Read and write | |||
| Desired room temperature 1 | °C | Read and write | |||
| Desired room temperature 2 | °C | Read and write | |||
| Switch the system to cooling | Write |
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Use cases
- Monitor accumulation tank, DHW, and compressor temperatures on a live cloud dashboard for remote diagnostics.
- Create an alert when the fault relay activates so you can respond to heat pump errors immediately.
- Adjust desired DHW and heating circuit temperatures remotely without visiting the installation site.
- Track actual versus desired machine power to identify efficiency losses over time.
- Switch the Spirala heat pump between heating and cooling mode remotely from the ModbusCloud platform.
- Set a machine power limitation during peak tariff hours to reduce electricity costs for your customer.
Installation
Connect the ModbusCloud gateway RS485 terminals (A, B, GND) to the corresponding RS485 terminals on the Spirala heat pump switchboard module and add 120 ohm termination resistors at both ends of the bus.
Configure the gateway serial port for Modbus RTU at 19200 baud, 8 data bits, 1 stop bit, odd parity (parity setting 1).
Verify that the Modbus slave address on the Spirala heat pump matches the address configured in the ModbusCloud template.
Import the Spirala heat pump template from the ModbusCloud template library into your project.
Confirm that temperature scaling (factor 256) is correctly applied in the template for both read and write registers.
Test the connection by reading a known sensor value, such as the DHW tank temperature, and comparing it with the value displayed on the heat pump controller.
Things to watch for
Why are temperature readings extremely high or showing raw numbers instead of degrees Celsius?
Spirala temperature registers use a scaling factor of 256. Divide each raw reading by 256 to get the value in degrees Celsius. Ensure the template applies this division automatically.
What baud rate and parity settings does the Spirala heat pump require?
The Spirala heat pump communicates at 19200 baud with odd parity (parity 1) over Modbus RTU. Mismatched settings will cause communication timeouts.
Can I safely close all thermostatic radiator heads while the heat pump is running?
No. Before closing all heads, you must switch off the heat pump by writing a desired temperature of zero. Blocking condenser flow can damage the unit. For circuits without a buffer tank, always keep at least one radiator open.
Do I need termination resistors on the RS485 bus?
Yes. Install 120 ohm termination resistors at both ends of the RS485 bus, one at the gateway and one at the Spirala heat pump terminals. Missing termination can cause intermittent communication errors.
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