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Control Modes - Complete Support Matrix

This document provides an overview of all 32 control modes defined in the GENI protocol and their support status on the Grundfos ALPHA HWR pump.

Executive Summary

The ALPHA HWR is a domestic hot water recirculation pump designed for residential heating systems. Hardware testing reveals it supports 6 out of 32 control modes - those specifically related to hot water recirculation applications.

Support Statistics: - Fully Supported: 6 modes (19%) - Not Supported: 26 modes (81%)

Complete Mode Support Matrix

Mode Name Support SubID Register Notes
0 CONSTANT_PRESSURE Full 15 0x18 Constant head pressure
1 PROPORTIONAL_PRESSURE Full 17 0x01 Proportional pressure curve
2 CONSTANT_SPEED Full 13 0x02 Fixed RPM operation
5 AUTO_ADAPT Raises 11 - No wire byte on this pump; set_mode refuses it
7 CLOSED_LOOP_SENSOR Not Supported - - Generic sensor control
8 CONSTANT_FLOW Full 39 0x08 Constant flow rate — setpoints are SI m³/s on the wire
9 CONSTANT_LEVEL Not Supported - - Water level control (tanks/sumps)
10 FLOW_ADAPT Not Supported - - Adaptive flow control
11 CONSTANT_DIFF_PRESSURE Not Supported - - Differential pressure sensors required
12 CONSTANT_DIFF_TEMP Not Supported - - Temperature differential control
13 AUTO_ADAPT_RADIATOR Mode only 19 0x0D Switches; setpoint not implemented
14 AUTO_ADAPT_UNDERFLOOR Mode only 21 0x0E Switches; setpoint not implemented
15 AUTO_ADAPT_RADIATOR_AND_UNDERFLOOR Mode only 23 0x0F Switches; setpoint not implemented
16 CONSTANT_DOSING Not Supported - - Chemical dosing (pools/industrial)
17 DISINFECTANT_CONTROL Not Supported - - Chemical dosing (pools/water treatment)
18 FLOCCULENT_CONTROL Not Supported - - Chemical dosing (water treatment)
19 PH_CONTROL Not Supported - - pH dosing (pools/industrial)
20 PID_CONTROL Not Supported - - Generic PID algorithm
21 CONSTANT_RELATIVE_SETPOINT Not Supported - - Relative setpoint adjustment
22 LEVEL_CONTROL Not Supported - - Water level control
23 ZONE_PUMP_CONTROL Not Supported - - Multi-zone systems
24 USER_DEFINED Not Supported - - Custom mode
25 DHW_ON_OFF_CONTROL Full 91/421 0x19 Cycle time control (on/off minutes)
26 PROPORTIONAL_DIFF_PRESSURE Raises - - Not in this firmware; set_mode refuses it
27 TEMPERATURE_RANGE_CONTROL Full 91/430 0x1B Temperature range control (min/max) — the HWR mode. The pump validates this object not at all; the client's 20–70 °C bound is the only guard.
28 COMFORT_VALVE_CONTROL Not Supported - - Valve control
29 ON_OFF_CONTROL Not Supported - - Simple on/off
30 CONSTANT_VOLTAGE Not Supported - - Voltage control (industrial/testing)
128 SYSTEM_AIR_VENTING Not Supported - - Air venting control
254 NONE N/A - - No control mode active

Supported Modes (6 modes)

1. Constant Pressure (Mode 0) - Full Support

Description: Maintains constant head pressure regardless of flow rate.

Use Case: Standard residential circulation, consistent pressure delivery

Hardware Support: - SubID 15 in Object 86 (factory configuration) - Mode switching works reliably - Register 0x18 for setpoint writes - Limits: 0.10-4.57 m (typical)

Implementation: 

await client.control.set_constant_pressure(1.5)  # 1.5 meters

CLI: 

alpha-hwr control set-pressure 1.5

2. Proportional Pressure (Mode 1) - Full Support

Description: Adjusts pressure proportionally to flow rate along a curve.

Use Case: Energy-efficient operation, reduces pressure at low flow

Hardware Support: - SubID 17 in Object 86 - Mode switching works reliably - Register 0x17 for setpoint writes - Limits: 0.10-4.57 m (typical)

Implementation: 

await client.control.set_proportional_pressure(1.2)  # 1.2 meters max

CLI: 

alpha-hwr control set-proportional 1.2

3. Constant Speed (Mode 2) - Full Support

Description: Maintains constant motor RPM regardless of system conditions.

Use Case: Testing, diagnostics, special applications

Hardware Support: - SubID 13 in Object 86 - Mode switching works reliably - Register 0x04 for setpoint writes - Limits: 1000-4500 RPM (typical)

Implementation: 

await client.control.set_constant_speed(2500)  # 2500 RPM

CLI: 

alpha-hwr control set-speed 2500

4. Constant Flow (Mode 8) - Full Support

Description: Maintains constant flow rate by adjusting pump speed.

Use Case: Applications requiring precise flow control

Hardware Support: - SubID 39 in Object 86 - Mode switching works reliably - Register 0x15 for setpoint writes - Limits: 0.10-3.00 m³/h (typical)

Implementation: 

await client.control.set_constant_flow(0.5)  # 0.5 m³/h

CLI: 

alpha-hwr control set-flow 0.5

5. Temperature Control with AutoAdapt (Mode 27) - Full Support

Description: Temperature range control with automatic flow adjustment (AutoAdapt feature).

Use Case: Hot water recirculation maintaining temperature within specified range with automatic flow optimization (1-4 gpm)

Hardware Support: - This is the ALPHA HWR's primary temperature control mode - Confirmed via live hardware verification (factory default mode) - Uses Object 91 (Setpoint), SubID 430 (0x01AE) for configuration - Supports dual setpoints (Minimum and Maximum Temperature) - AutoAdapt: Flow rate automatically adjusts between 1-4 gpm based on system demand

Implementation: 

# Set temperature range: 35°C min, 39°C max
await client.control.set_temperature_range_control(35.0, 39.0)

CLI: 

alpha-hwr control set-temperature --min 35 --max 39

Note: This mode combines temperature range control WITH the AutoAdapt flow adjustment feature. The "AutoAdapt" mentioned in ALPHA HWR documentation refers to this mode's automatic flow adjustment capability, not to modes 13/14/15 (which are for heating system pumps).

6. Cycle Time Control (Mode 25) - Full Support

Description: Operates the pump in on/off cycles at configurable intervals for domestic hot water (DHW) recirculation.

Use Case: DHW recirculation systems where intermittent pump operation maintains water temperature while saving energy.

Hardware Support: - Mode switching works reliably (mode byte 0x19, suffix 38 C6 76 EF) - Successfully operates on ALPHA HWR hardware - Supports configurable ON/OFF durations (1-60 minutes)

Configuration object: Object 91 Sub 421 (dhw_on_off_control_configuration_obj), holding [flow setpoint f32 m³/s][on minutes][off minutes] — measured as 0.227 m³/h, 5, 15. Not Sub 430, which is the temperature-range object and which this used to read and write by mistake. Sub 421 is written as a read-modify-write so the flow setpoint it also carries survives.

Implementation: 

result = await client.control.set_cycle_times(5, 15)  # verified
print(result.status, result.on_minutes, result.off_minutes)

CLI: 

alpha-hwr control set-cycle-time --on 5 --off 15
alpha-hwr control get-cycle-time

Unsupported Modes

Why These Modes Are Not Supported

The ALPHA HWR is a residential hot water recirculation pump, not a general-purpose industrial pump or heating system pump. The unsupported modes fall into these categories:

1. Heating System Modes (Not DHW)

Modes 13, 14 and 15 target radiator and underfloor heating rather than DHW recirculation. They are partially supported, which is worth stating precisely: the mode switches, and the setpoint does not. set_mode accepts them; the deprecated pressure setters are documented in the library's own source as using "incorrect pressure-based setpoints"; and set_temperature_control() switches the mode and then returns False with "not yet implemented" — so a False there does not mean nothing changed.

Details in autoadapt_modes.md. Use Mode 27 instead.

Note: The ALPHA HWR uses Mode 27 (TEMPERATURE_RANGE_CONTROL) for temperature control with AutoAdapt flow adjustment. Modes 13/14/15 are GENI protocol modes for heating system pumps.

2. Sensor Requirements Not Met

  • Mode 11 (CONSTANT_DIFF_PRESSURE): Requires differential pressure sensors
  • Mode 26 (PROPORTIONAL_DIFF_PRESSURE): Requires differential pressure sensors
  • Mode 12 (CONSTANT_DIFF_TEMP): Requires temperature differential sensors

2. Chemical Dosing (Pools/Industrial)

  • Mode 16 (CONSTANT_DOSING): Chemical metering pumps
  • Mode 17 (DISINFECTANT_CONTROL): Chlorine/disinfectant dosing
  • Mode 18 (FLOCCULENT_CONTROL): Flocculation dosing
  • Mode 19 (PH_CONTROL): pH adjustment dosing

3. Level Control (Tanks/Sumps)

  • Mode 9 (CONSTANT_LEVEL): Water level maintenance
  • Mode 22 (LEVEL_CONTROL): Water level regulation

4. Specialized Applications

  • Mode 7 (CLOSED_LOOP_SENSOR): Generic external sensor control
  • Mode 10 (FLOW_ADAPT): Adaptive flow algorithms
  • Mode 20 (PID_CONTROL): Generic PID control
  • Mode 21 (CONSTANT_RELATIVE_SETPOINT): Relative setpoint adjustment
  • Mode 23 (ZONE_PUMP_CONTROL): Multi-zone systems
  • Mode 24 (USER_DEFINED): Custom control algorithms
  • Mode 28 (COMFORT_VALVE_CONTROL): Valve control systems
  • Mode 29 (ON_OFF_CONTROL): Simple on/off operation
  • Mode 30 (CONSTANT_VOLTAGE): Voltage control (motor testing)
  • Mode 128 (SYSTEM_AIR_VENTING): Automated air venting

Technical Discovery

All 32 GENI protocol modes were systematically tested on real ALPHA HWR hardware to determine compatibility. The categories below reflect the results of this hardware-in-the-loop verification.

Investigation Details

  • Hardware: Grundfos ALPHA HWR (Family 52, Type 7, Version 2)
  • Tool: tools/probe_all_modes.py

Summary Table

Category Tested Supported
Pressure/Flow Control 4 4
Temperature Control 1 1
DHW Cycle Control 1 1 (limited)
Heating System Modes 3 0
Industrial/Dosing/Other 23 0
Total 32 5 fully + 1 limited

Implementation Status

Library Support

Verified setters — return a WriteResult saying what the pump actually stored, which is not always what you asked for:

  • set_setpoint(mode, value) — modes 0, 1, 2, 8
  • set_mode_verified(mode) — mode only, no setpoint, no run-state change
  • set_enabled(on) — run state
  • set_temperature_range(min_c, max_c, autoadapt=None) — mode 27
  • set_cycle_times(on_min, off_min) — mode 25

Primitive setters — return bool, do not read back. True means the frame was accepted, not that your value is in the pump:

  • set_constant_pressure(value_m) — mode 0
  • set_proportional_pressure(value_m) — mode 1
  • set_constant_speed(value_rpm) — mode 2
  • set_constant_flow(value_m3h) — mode 8 (converted to SI m³/s on the wire)
  • set_temperature_range_control(min_c, max_c, autoadapt=True) — mode 27
  • set_cycle_time_control(on_min, off_min) — mode 25
  • read_limiters() — Object 86 Sub 600 (MaxFlow) and Sub 601 (MinFlow)

Deprecated Methods (for heating systems, not ALPHA HWR): - set_temperature_control(on_temp, off_temp, heating_type) - Uses modes 13/14/15 (not for DHW) - set_autoadapt_radiator(value_m) - Mode 13 (not for DHW) - set_autoadapt_underfloor(value_m) - Mode 14 (not for DHW) - set_autoadapt_combined(value_m) - Mode 15 (not for DHW)

Refused outright: - Mode 5 (AUTO_ADAPT) and mode 26 (PROPORTIONAL_DIFF_PRESSURE) raise ValueError — the pump has no wire byte for either. Mode 5 used to fall through to Constant Speed and report success.

CLI Support

Available Commands: 

alpha-hwr control set-pressure <meters>
alpha-hwr control set-proportional <meters>
alpha-hwr control set-speed <rpm>
alpha-hwr control set-flow <m3h>
alpha-hwr control set-temperature --min <temp_c> --max <temp_c> [--autoadapt/--no-autoadapt]
alpha-hwr control set-cycle-time --on <minutes> --off <minutes>
alpha-hwr control limiters
alpha-hwr control get-cycle-time

Deprecated Commands (removed from CLI):

These methods still exist in the service layer for GENI protocol compatibility but are not exposed in the CLI since they are not applicable to ALPHA HWR (they are for heating system pumps, not DHW pumps).

Recommendations

For Users

  1. Use Supported Modes Only: Stick to the 5 fully supported modes + Mode 25 (cycle time control) for reliable operation.
  2. Temperature Control: Use Mode 27 (set-temperature --min --max) which includes AutoAdapt flow adjustment.
  3. Understand Pump Limitations: ALPHA HWR is optimized for domestic hot water recirculation, not heating systems or industrial applications.

For Developers

  1. No Further Investigation Needed: All GENI protocol modes have been verified for ALPHA HWR compatibility.
  2. Mode 25 Protocol: See issue #14 for ongoing work to document the cycle time parameter protocol.
  3. Documentation Complete: Support matrix is fully documented for the 5 ALPHA HWR modes.

References

  • AutoAdapt Modes: docs/protocol/autoadapt_modes.md
  • Investigation Results: mode_investigation_results.json
  • GENI Protocol: Grundfos GENI profile specification