Page 138 - HVAC Pump Handbook

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Source: HVAC Pump Handbook

Chapter
6

HVAC Pump Performance

6.1 Introduction
This evaluation of HVAC pump performance is limited to centrifugal
pumps. The use of positive-displacement and regenerated turbine
pumps in HVAC systems is for highly specialized low-volume, high-
head applications. They are not used on the water services that con-
sume most of the pumping energy in HVAC systems. Their applica-
tion is so specialized that the performance required of these pumps,
when encountered, should be sought from the manufacturer of the
pump under consideration.
This review of HVAC pump performance will attempt to provide a
general approach that is applicable to all pumps from small circulators
to very large condenser pumps. It is imperative that we understand
how to select HVAC pumps and then how to operate them so that the
energy consumed is as low as economically possible. Efforts will be
made to describe pump performance so that the pumps are selected
properly and operated closely to the pumps’ best efficiency curves.

6.2 Pump Head-Flow Curves
A study of centrifugal pump operations must begin with an evalua-
tion of the basic performance of such a pump. The pressure or head
that is developed by any pump depends on the flow through that
pump. This basic head-flow relationship is called the pump’s head-
flow curve. This was shown in elementary form in Chap. 4 and is now
demonstrated with other accompanying curves in Fig. 6.1. Figure 6.1a

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