In this module, we will take a closer look at the load side, and how smart pumps in a Distributed Pumping system are able to deliver the right flow and pressure for each individual branch in the system.

We will also highlight the benefits of auto-balancing and comfort when you use smart pumps instead of valves. In a Distributed Pumping system, the load side, or secondary side, functions as an autonomous auto-balanced branch, with several autonomous smart distributed pumps supplying the AHUs (air handling units) or FCUs (fan coil units).

The chilled water produced by chillers is used for the cooling coils in the terminal units, such as the AHUs and FCUs. AHUs and FCUs recondition and circulate the air for multiple zones, as part of a heating, ventilating and air-conditioning, or HVAC system.

AHUs connect to ductwork that distributes the conditioned air into multiple zones through the building, and sometimes via FCUs for single zones.

Grundfos Distributed Pumping makes valves redundant and uses smart pumps instead, in this case the maintenance-free wet runner MAGNA3 circulator with built-in variable speed control.

To prevent back flow, non-return valves are installed for each cooling branch, in case the distributed pump or terminal unit is out of operation.

In a Grundfos Distributed Pumping System, the MAGNA3 pumps can be installed in two configurations:

1. A single dedicated pumps per termi-nal unit, or
2. A single dedicated pump serving several terminal units.

For the two configuration possibilities, flow is based on readings from, respectively, an:

1. Air temperature Sensor in the supply duct, or a
2. Liquid Pressure Sensor in the chilled water return pipe or the internal pressure
sensor in the MAGNA3.

A number of control modes are available with the MAGNA3.

Control mode selection is essential for the correct performance of a Distributed Pumping application.

The way the distributed pumps adjust to the load demand is via the sensor signal, exactly like a conventional temperature control valve.

Typical control modes for the configurations in the specified installation
types are respectively:

1. Constant temperature, or
2. Proportional pressure.

With control of flow, we have control of the energy transfer.

This enables the distributed pumps to achieve almost 80 % of the capacity with just 50 % flow.

However, the key to delivering the right flow for each individual branch of the distributed pumping system is correct sizing, installation and commissioning.

Therefore, an understanding of your system and application is essential to get the benefits of auto-balancing and comfort.

Contact your local Grundfos sales office for further information.