ALPHA HWR control modes

Gain a workable knowledge of the different control modes for the ALPHA HWR and how they work.

In this module, we will introduce the control modes for the ALPHA HWR. You’ll gain a workable knowledge of what the different control modes are and how they work.

The ALPHA HWR is designed for hot water recirculation systems with a dedicated return line and has 3 main control modes:
24/7 mode
Temperature Control

Let’s start with the 24/7 mode.
24/7 mode consists of 3 different settings: I, II, and III.
You can set this control mode on the pump display by selecting the 24/7 icon and using the arrows on the display to select set point I, II, or III.
24/7 mode operates in constant curve 3 with flow limits that are designed for the different pipe sizes shown on the pump display. Each flow limit ensures the average velocity is limited to 2 ft/s for each pipe size. This helps decrease noise… and the risk of flow accelerated corrosion, which can lead to pinholes. This control mode ensures maximum comfort for the homeowner… and increases the reliability of the hot water supply system.

Flow Limit I is suitable for a ½” pipe. When the 24/7 icon is selected with Flow Limit I, the ALPHA HWR will run at full speed until it hits a max flow limit of 1.2 GPM – the recommended flow limitation for this pipe size.
Flow Limit II is suitable for a ¾” pipe and Flow Limit III is suitable for a 1” pipe. When the 24/7 icon is selected with Flow Limit II or Flow Limit III, the same control method will be applied with a max flow limit of 2.3 GPM or 3.8 GPM, respectively.

Now let’s look at Temperature Control.
Temperature Control is designed to work the same way as an aquastat. Instead of adding an external temperature sensor, the ALPHA HWR has integrated sensors that allow it to estimate media temperature.

Temperature Control can be set on the display using the temperature symbol and selecting setting I, II, or III.
If you want to adjust the temperature limits, you will need to use the Grundfos GO app.

Once the Temperature Control mode has been set up and activated, the ALPHA HWR will turn ON and OFF based on default temperatures or the temperatures you specify in the app.

Unless changed in the app, the ALPHA HWR will turn OFF when it reaches a maximum temperature of 102°F. Once the pump turns OFF, the water temperature will decrease until it reaches a minimum temperature limit of 95°F. At this point, the pump will turn back on, and the cycle will repeat. Time-limit fallbacks have been added to prevent the pump from running too long or being off for extended periods. In temperature mode, the pump will operate on it’s max curve until it reaches the max flow limit defined by each pipe size. The flow limits for the ½’’, ¾’’ and 1’’ settings are 1.5, 2.3 and 3.8 GPM respectively.

Now let’s look at AUTOADAPT.
AUTOADAPT is a temperature-based control mode which simplifies installation and commissioning. Compared to 24/7 mode, AUTOADAPT provides additional energy savings without sacrificing comfort. AUTOADAPT is designed to work similarly to Temperature Control. The main difference is that you don't have to choose your set point as AUTOADAPT will continuously adjust it's flow to meet the temperature demands.

When AUTOADAPT is selected, the pump will start running at 3.5 GPM and continuously optimize it's flow to use the least amount of energy while ensuring the temperature demands of the hot water system are met, guaranteeing comfort to the homeowner.
This control mode will also provide enough flow to activate the most common tankless water heaters.

The ALPHA HWR AUTOADAPT algorithm is designed to keep the temperature between 95°F and 102°F to optimize heat energy usage.
If the homeowner would like different temperature settings, you can adjust these values in the Grundfos GO app to meet their comfort requirements.
The pump ON and OFF times can also be changed via the Grundfos GO app.

That covers the ALPHA HWR control modes and how they work.

Course overview

Modules: 8
Completion time
Completion time: 40 minutes
Difficulty level
Difficulty level: Intermediate