Page 143 - HVAC Pump Handbook

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HVAC Pump Performance

140 HVAC Pumps and Their Performance

Figure 6.4 Power balance at constant speed. (From Centrifugal and
Axial Flow Pumps, A.J. Stepanoff, Ph.D, John Wiley and sons, New
York, NY 1957.)

Recirculation losses are caused by circulation of the water within
the volute or bowl. The water does not flow smoothly in and out of the
impeller. At flows through the pump that are less than that at the
best efficiency point, the water recirculates and causes substantial
losses.
Hydraulic losses are the losses that are caused by the friction devel-
oped by the water flowing through the impeller and volute or bowl.
Again, this demonstrates that the losses in small pumps with low spe-
cific speeds are going to be greater than those for large, low-specific-
speed pumps.

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