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Basics of Pump Application for HVAC Systems
Basics of Pump Application for HVAC Systems 297
Figure 10.12 Wire-to-water efficiency curves for Tables
10.4, 10.5, and 10.6.
Figure 10.12 provides the data of Tables 10.4, 10.5, and 10.6 as
curves plotted with system gallons per minute. This figure demon-
strates the advantage of the three-pump variable-speed system
energy-wise over the two-pump variable-speed system. It also shows
the dramatic energy savings of either variable-speed system over the
constant-speed system. Not only do the variable-speed systems save
energy, but they also reduce appreciably the overpressure on the
water system and the radial thrust on the pumps themselves.
It should be noted that these tables are based on standard water at
50°F. If wire-to-water efficiencies are computed for liquids of other
densities or viscosities, the head inserted in the tables should be cor-
rected for the actual density and viscosity.
10.9 Wire-to-Water Efficiency Indication
Wire-to-water efficiency indication for an actual pumping system can
be developed easily through the recording of the system flow, net
pump head, and pumping system kilowatts. This instrumentation for
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