Hardware Reference
The Grundfos ALPHA HWR (Hot Water Recirculation) is a smart circulator pump designed for domestic hot water systems with a dedicated return line. It features integrated sensors and Bluetooth connectivity, allowing for app-based control and monitoring.
Models
There are two primary variants of the ALPHA HWR, differentiated mainly by their performance curves (Head/Flow capability).
| Feature | ALPHA HWR 15-55 | ALPHA HWR 15-29 |
|---|---|---|
| Max Flow Rate (Q) | 13.6 GPM (\(3.1 m^3/h\)) | 11 GPM (\(2.5 m^3/h\)) |
| Max Head (H) | 18 ft (5.5 m) | 9.5 ft (2.9 m) |
| Power Consumption | 2 - 38 W | 2 - 21 W |
Technical Specifications
| Parameter | Value | Notes |
|---|---|---|
| Supply Voltage | 1 x 115 V, ± 10 %, 60 Hz | |
| Max Outlet Pressure | 175 psi (12 bar) | |
| Liquid Temperature | 36 - 203 °F (2 - 95 °C) | Hard water deposits may occur > 140°F |
| Ambient Temperature | 32 - 131 °F (0 - 55 °C) | |
| Relative Humidity | Max 95% | |
| Sound Pressure | < 25 dB(A) | Silent operation |
| Pump Housing | Stainless Steel | |
| Enclosure Class | Type 2 | Indoor use only |
Alarm & Warning Codes
The pump reports internal error states via the status_code field in the telemetry stream.
| Code | Error Type | Description |
|---|---|---|
| 51 | Blocked Motor | The rotor is jammed or blocked by debris. |
| 57 | Dry Running | The pump detects no water in the housing. |
| 40 | Undervoltage | Supply voltage is too low. |
| 4 | Overvoltage | Supply voltage is too high. |
| 35 | Air in Media | Significant air bubbles detected in the system. |
| 72, 76, 85 | Internal Fault | Electronics or internal hardware failure. |
| 29 | Forced Pumping | Water is being forced through the pump by another source. |
| 43 | Impellers Forced | Impellers are being forced forward. |
Hardware Features
Integrated Temperature Sensor
The pump includes an internal sensor that estimates the media temperature. This eliminates the need for an external aquastat in many recirculation setups.
- Note: The sensor value is available in the telemetry stream as
media_temperature_c.
Air Detection & Venting
The ALPHA HWR has a "Continuous Air Detection" feature. If air is detected (Code 35), the pump can run a special venting sequence to push air to the system vent.
Flow Limitation
The pump logic includes safety limits based on pipe diameters to prevent flow-accelerated corrosion. * 1/2" pipes: ~1.5 GPM limit * 3/4" pipes: ~2.3 GPM limit * 1" pipes: ~3.8 GPM limit
Operating Panel vs. Digital Control
The physical operating panel on the pump is limited to selecting three basic modes: 1. AutoAdapt: Temperature control (95-102°F range). 2. Temperature Control: Fixed temp control. 3. Continuous (24/7): Constant Curve III.
Advanced Control: Using the Bluetooth interface unlocks the full range of control modes, including Constant Pressure, Constant Flow, and custom setpoints.