Page 306 - HVAC Pump Handbook

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Basics of Pump Application for HVAC Systems

Basics of Pump Application for HVAC Systems 303

TABLE 10.8 kW Input Calculations for a System with Two 100 Percent Capacity
Pumps (Only one pump runs at a time)

System System Water Fitting Pump Pump Pump Drive Input
gal/min head, ft hp loss, ft head, ft rpm effy effy kW
300 30.9 2.3 0.1 31.0 845 36.9 70.6 6.7
600 33.2 5.0 0.3 33.5 898 59.2 75.3 8.5
900 36.7 8.3 0.7 37.4 972 72.5 79.5 11.0
1200 41.4 12.5 1.3 42.0 1057 80.5 83.2 14.4
1500 47.2 17.9 2.0 49.2 1162 84.8 86.1 19.1
1800 54.1 24.6 2.9 50.8 1273 87.2 88.4 25.1
2100 62.0 32.9 3.9 57.0 1393 88.4 89.9 32.8
2400 71.0 43.0 5.1 66.0 1516 89.0 91.3 42.4
2700 81.0 55.2 6.5 87.5 1645 89.2 92.4 54.0
3000 92.0 69.7 8.0 100.0 1780 89.2 93.0 68.1

NOTE: Pump efficiencies are in percent.

1. The single 100 percent capacity, variable-speed pump, from 1200 to
3000 gal/min is the most efficient. This is due to the higher pump
and wire-to-shaft efficiencies.
2. For very light loads less than 1000 gal/min, the 50 percent capacity
pump is the most efficient.

TABLE 10.9 Total kW Input for Two 50 Percent Capacity Pumps
System System Water Fitting Pump Pump Pump Drive Input
gal/min head, ft hp loss, ft head, ft rpm effy effy kW
One pump running
300 30.9 2.3 0.3 31.2 879 59.1 66.0 4.5∗
600 33.2 5.0 1.3 34.4 970 83.0 74.1 6.3∗
900 36.7 8.3 2.9 39.6 1097 87.0 81.1 9.5∗
1200 41.4 12.5 5.1 46.5 1265 82.9 85.9 14.8∗
1500 47.2 17.9 8.0 55.2 1451 77.4 89.2 22.6
1800 54.1 24.6 11.5 65.6 1654 72.7 91.4 33.5
Two pump running
300 30.9 2.3 0.1 31.0 853 35.2 62.1 8.0
600 33.2 5.0 0.3 33.5 912 57.6 68.1 9.7
900 36.7 8.3 0.7 37.4 980 71.7 73.1 12.1
1200 41.4 12.5 1.3 42.7 1067 79.8 77.8 15.5
1500 47.2 17.9 2.0 49.2 1164 84.2 81.8 20.2∗
1800 54.1 24.6 2.9 57.0 1266 86.3 85.0 26.3∗
2100 62.0 32.9 3.9 66.0 1387 87.1 87.2 34.4∗
2400 71.0 43.0 5.1 76.2 1510 87.2 89.3 44.2∗
2700 81.0 55.2 6.5 87.5 1638 86.9 90.9 56.3∗
3000 92.0 69.7 8.0 100.0 1760 86.5 91.9 71.2∗
NOTE: Pump efficiencies are in percent.
∗ Denotes most efficient operation and correct number of pumps to operate at each system
gal/min.

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