Handbook of air conditioning and refrigeration / Shan K

Compared to a plant-distribution-building loop, a plant-distributed building loop has the following
advantages:
● It saves the installation cost of variable-speed distribution pumps, related controls, and pump
room space.
● If the pressure differential between the distribution supply and return mains at the building entrance
�H s,r is greater than the pressure loss of the building loop �p bg either at design load or at
part-load, then a plant-distributed building loop can save more pumping energy.
On the other hand, a plant-distributed building loop requires variable-speed building pumps of
higher head which means more attention to pump noise control in the building’s mechanical room.
Multiple Sources-Distributed Building Loop
WATER SYSTEMS 7.57
Many conversions and retrofits of campus-type chilled water systems require existing chilled water
plants in addition to the developed central plant. In these cases, there are buildings with chilled water
sources (chillers); buildings with chilled water coils and loads; and buildings with chilled water
sources and loads connected to the same plant-distributed building loop, as shown in Fig. 7.23a. A
FIGURE 7.23 A multiple sources-distributed building loop. (a) Schematic diagram; (b) building with sources and loads.