How to save energy by using proportional pressure in water boosting systems
Understand the basic energy and water savings that can be made by operating a Grundfos Hydro MPC booster pump in proportional pressure mode.
Many water booster pumps in commercial buildings are set to operate in constant pressure control mode. However, operating in proportional pressure control mode instead brings significant energy savings and water savings for any type of commercial building.
In this short course, we’re going to look at the potential energy and water savings of operating a Grundfos Hydro MPC in proportional pressure mode, using an example to illustrate the main points. But first, let’s briefly introduce the Grundfos Hydro MPC.
The Grundfos Hydro MPC is a water booster pump that can operate in constant pressure control mode, as well as both linear and squared proportional pressure control mode.
Setting up the pump is easy. The Hydro MPC user interface allows the user to control pump performance, enable the different proportional pressure control modes. Thanks to this interface, the installer has a simple task when it comes to pump setup.
Now, let’s take a closer look at how operating the Grundfos Hydro MPC in proportional pressure mode can bring significant savings to commercial buildings. The following example is based on data that is representative of a typical commercial building.
Imagine a shopping mall. Typically, a shopping mall covers a wide area, but it’s rarely the tallest of buildings. A Grundfos Hydro MPC operating in this building has a 50/50 ratio in terms of static and dynamic losses. The dynamic pressure loss is based on 500m of pipework with a specific pressure loss of 450 Pa/m – plus losses in bends, fittings and components such as valves, manifolds and exchangers. In total, this results in total dynamic pressure losses of 390 kPa. The static loss is based on the height of the building which in this case is 40 metres. This creates a static loss, or lift, of 390 kPa as well.
The remaining data for selecting the right booster set is as follows:
Pressure requirement at the tap at 150 kPa.
Design pump head equals a total of 930 kPa.
And finally, design water flow at 35 m3/h.
Now that the data has been established, product selection and sizing can be entered in Grundfos Product Center. In order to calculate the annual energy consumption, simply enter the data and, in this case, a 2-pump Hydro MPC-E CRE20-6 is selected. Now we can calculate the annual energy consumption in the three different control modes: constant pressure, linear proportional pressure and squared proportional pressure giving you a clear overview of the most beneficial control mode.
And the results say it all. When operating in constant pressure mode, the annual power consumption lands on 25.100 kWh. However, when operating in linear proportional pressure mode, the annual power consumption lands on a considerably lower 19.000 kWh. Squared proportional pressure reduces the annual energy consumption even further, totaling at 16.900 kWh.
As the results demonstrate, proportional pressure is a real game changer in commercial buildings such as shopping malls. Operating this water boosting system in proportional pressure control mode equates to annual energy savings as high as 33%.
At the same time, its ability to adapt the pump head to actual needs brings more user comfort as well as a reduced water bill, while it also reduces wear and tear on pipes, fittings and valves.
So, to sum up, operating a Grundfos Hydro MPC booster pump in proportional pressure control mode in a commercial building such as a shopping mall can potentially bring energy savings of more than 30%, erasing any doubt that proportional pressure control in water booster systems is significantly more energy-efficient for commercial buildings.