Control Modes and Setpoints

This guide provides details on the ALPHA HWR's control modes and setpoint configuration.

Overview

The ALPHA HWR pump supports multiple control modes, each designed for specific application requirements. Control modes can be configured via:

Physical operating panel (limited modes)
Mobile application (all modes)
alpha-hwr library (all modes via CLI or Python API)

Reading Current Setpoint

CLI

# Read current control mode and setpoint
alpha-hwr control status

Python API

from alpha_hwr import AlphaHWRClient

async with AlphaHWRClient("AA:BB:CC:DD:EE:FF") as client:
    await client.authenticate(fast_mode=True)

    # Read current setpoint
    setpoint_info = await client.control.get_mode()

    if setpoint_info:
        print(f"Control Mode: {setpoint_info.control_mode.name}")
        print(f"Setpoint: {setpoint_info.setpoint}")
        print(
            f"Range: {setpoint_info.min_setpoint} - {setpoint_info.max_setpoint}"
        )

Control Modes Available via Operating Panel

Temperature Control - AUTOADAPT

Description: Ensures comfort via integrated temperature estimator, suitable for all hot-water recirculation applications with a dedicated return line.

Features:

Automatically adjusts flow according to temperature setpoint
Ensures hot water availability throughout the house
Meets minimum flow requirement for tankless water heaters
Flow rate: 1-4 GPM (automatically adjusted)
Temperature range: 95-102°F (35-39°C)

Use Case: General hot-water recirculation with optimal energy efficiency

Temperature Control

Description: Ensures comfort via flow limits based on predefined pipe diameters.

Features:

Maintains temperature between 95-102°F (35-39°C)
Flow limits designed to reduce flow-accelerated corrosion
Operates on maximum curve until reaching flow limits

Flow Limits by Pipe Diameter:

1/2": 1.5 GPM
3/4": 2.3 GPM
1": 3.8 GPM

Use Case: Systems where flow-accelerated corrosion is a concern

Continuous Operation - 24/7

Description: Ensures comfort through continuous operation in constant curve III with flow limits.

Features:

Continuous operation
Flow limits based on predefined pipe diameters
Reduces flow-accelerated corrosion and noise

Flow Limits (adjustable via Bluetooth interface):

1/2": 1.5 GPM
3/4": 2.3 GPM
1": 3.8 GPM

Use Case: Applications requiring 24/7 hot water availability

Control Modes Available via Bluetooth Interface

The ALPHA HWR supports 5 primary control modes specifically optimized for hot water recirculation.

1. Temperature Control (Mode 27)

Description: Controls pump operation to maintain water temperature within a specified range. This is the recommended mode for most DHW applications.

Features: - Min/Max Temperature: Configurable range (default 35-39°C). - AUTOADAPT: Automatic flow adjustment (1-4 gpm) to maintain comfort and efficiency. - Flow Limits: Can be limited based on pipe diameter to prevent corrosion.

Example:

# Set range 35-39°C with AUTOADAPT enabled
alpha-hwr control set-temperature --min 35 --max 39 --autoadapt

# Set range 40-45°C with AUTOADAPT disabled and 1.5 GPM limit
alpha-hwr control set-temperature --min 40 --max 45 --no-autoadapt

2. Cycle Time Control (Mode 25)

Description: Pump operates at maximum curve with configurable on/off cycles.

Parameters: - On time: 1-60 minutes - Off time: 1-60 minutes

Example:

# Set 5 minutes ON, 15 minutes OFF
alpha-hwr control set-cycle-time --on 5 --off 15

3. Constant Curve / Constant Speed (Mode 2)

Description: Pump runs at a fixed rotational speed (RPM).

Features: - Setpoint: 1000-4500 RPM. - Flow Limits: Optional GPM limit to prevent noise and corrosion.

Example:

# Set to 2500 RPM with 2.3 GPM limit (3/4" pipe)
alpha-hwr control set-speed 2500

4. Constant Pressure (Mode 0)

Description: Maintains a fixed head pressure regardless of flow.

Setpoint: 0.5-6.0 meters.

Example:

alpha-hwr control set-pressure 1.5

5. Constant Flow (Mode 8)

Description: Maintains a fixed flow rate regardless of head pressure.

Setpoint: 0.1-10.0 m³/h (the client's range; the pump clamps to its own).

Example:

alpha-hwr control set-flow 0.5

Flow Limitation and Pipe Diameters

The ALPHA HWR allows setting a maximum flow limit to prevent flow-accelerated corrosion (FAC) and noise in the system. Limits are typically chosen based on pipe diameter:

Pipe Diameter	Recommended Limit
1/2"	1.5 GPM
3/4"	2.3 GPM
1"	3.8 GPM

CLI:

alpha-hwr control limiters

Proportional Pressure (Mode 1)

Proportional pressure mode is also fully supported and adjusts pressure along a curve based on flow.

CLI:

alpha-hwr control set-proportional 1.2

Deprecated/Unsupported Modes

These are defined in the GENI protocol but are designed for heating systems (radiators, underfloor) rather than DHW recirculation.

Mode	Status
AUTOADAPT Generic (5)	Raises. The pump has no wire byte for it; it used to fall through to Constant Speed and report success.
Proportional Diff. Pressure (26)	Raises. Not in this firmware.
AUTOADAPT Radiator (13)	Mode switches; setpoint is not implemented
AUTOADAPT Underfloor (14)	Mode switches; setpoint is not implemented
AUTOADAPT Combined (15)	Mode switches; setpoint is not implemented

Use Temperature Control (Mode 27) instead — alpha-hwr control set-temperature --min 35 --max 39. Details in autoadapt_modes.md.

Temperature Range Control

Mode ID: 27
Special Handling: Uses dual setpoints (high/low temperature)

Description: Controls pump operation to maintain water temperature within a specified range.

Setpoints:

Low Temperature: Minimum temperature limit
High Temperature: Maximum temperature limit
AutoAdapt Flag: Enable/disable automatic delta temperature adjustment

Default Range: 32.95-41.11°C (91-106°F)
Nominal Range (per manual): 35-39°C (95-102°F)

Reading Temperature Range:

alpha-hwr control status
# Output will show min/max temperatures for this mode

Data Source: Object 91, Sub-ID 430 (TemperatureRangeControlUserSettings, Type 1012)

Setpoint Data Structures

Read state from Sub 7, not Sub 6

Sub 6 is the request object: it reports what was last written, and its control_source byte reads 0 whatever the pump is doing. The pump's actual state — after it has weighed remote, local and alarm influence — is Sub 7, overall_operation_prioritized_request. Measured side by side on hardware.

Sub 6 is also fused: run state, control mode and setpoint travel in one frame, so writing it necessarily asserts all three. Mode changes go through Sub 10 instead.

Standard Modes (Object 86, Sub-ID 6)

Type 303: OperationRequest

Structure:

[ControlSource(1)][OperationMode(1)][ControlMode(1)][Setpoint(4)]

ControlSource: Source of control command
OperationMode: Current operation mode
ControlMode: Active control mode (0-27)
Setpoint: Target value (float32, big-endian)

Limit Configuration (Object 86, Sub-IDs 11-39)

Type 301: FactoryConfig

Standard Format (float32):

[DefaultSetpoint(4)][MinSetpoint(4)][MaxSetpoint(4)][...]

AutoAdapt Generic Format (uint16 with padding):

[DefaultSetpoint(2)][Padding(2)][MinSetpoint(2)][Padding(2)][MaxSetpoint(2)][Padding(2)]

Sub-ID Mapping:

Sub 11: AutoAdapt Generic (uint16)
Sub 13: Constant Speed (float32)
Sub 15: Constant Pressure (float32)
Sub 17: Proportional Pressure (float32)
Sub 19: AutoAdapt Radiator (float32)
Sub 21: AutoAdapt Underfloor (float32)
Sub 23: AutoAdapt Combined (float32)
Sub 39: Constant Flow (float32)

Temperature Range Control (Object 91, Sub-ID 430)

Type 1012: TemperatureRangeControlUserSettings

Structure:

[DeltaTempEnabled(1)][MinTemp(4)][MaxTemp(4)][MinOffTime(1)][MaxOffTime(1)][MinOnTime(1)][MaxOnTime(1)]

DeltaTempEnabled: AutoAdapt flag (bool)
MinTemp: Low temperature limit (float32, °C)
MaxTemp: High temperature limit (float32, °C)
Time limits: On/off timing parameters

Unit Conversions

The library automatically handles unit conversions for display:

Pressure Modes

Stored as: Pascals (Pa)
Displayed as: Meters of water column (m)
Conversion: 1 m H₂O ≈ 9806.65 Pa

Flow Modes

Setpoints stored as: SI m³/s
Telemetry reported as: m³/h
API speaks: m³/h in both directions
Conversion: setpoints are divided by 3600 on the way out

Both encodings are real, and they differ. This is not a mismatch to "fix" — a setpoint written in m³/h reaches the pump 3600× too large and is rejected as out of range, which leaves the stored value untouched and makes the register look frozen. That was issue #28, and it was a write bug, not a read one.

Speed Modes

Stored as: RPM
Displayed as: RPM (no conversion)

Temperature Modes

Stored as: °C
Displayed as: °C (no conversion)

Best Practices

Choose the Right Mode:
For hot water recirculation: Temperature Control - AUTOADAPT
For predictable scheduling: Cycle Time Control
For legacy system replacement: Constant Curve
For multi-zone systems: Constant Pressure
For external control: Constant Flow
Setpoint Selection:
Start with factory defaults
Adjust based on system performance
Use --limits flag to see allowed ranges
Energy Efficiency:
Use AUTOADAPT modes when possible
Enable scheduling for time-based control
Set appropriate temperature ranges (don't overheat)
System Protection:
Respect flow limits for pipe diameter
Monitor for corrosion in high-flow applications
Use minimum flow settings for tankless heaters

Control Modes and Setpoints

Overview

Reading Current Setpoint

CLI

Python API

Control Modes Available via Operating Panel

Temperature Control - AUTOADAPT

Temperature Control

Continuous Operation - 24/7

Control Modes Available via Bluetooth Interface

1. Temperature Control (Mode 27)

2. Cycle Time Control (Mode 25)

3. Constant Curve / Constant Speed (Mode 2)

4. Constant Pressure (Mode 0)

5. Constant Flow (Mode 8)

Flow Limitation and Pipe Diameters

Proportional Pressure (Mode 1)

Deprecated/Unsupported Modes

Temperature Range Control

Setpoint Data Structures

Standard Modes (Object 86, Sub-ID 6)

Limit Configuration (Object 86, Sub-IDs 11-39)

Temperature Range Control (Object 91, Sub-ID 430)

Unit Conversions

Pressure Modes

Flow Modes

Speed Modes

Temperature Modes

Best Practices

See Also