Page 237 - HVAC Pump Handbook

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The Use of Water in HVAC Systems

234 The HVAC World

190
Pump discharge loss
Chiller loss
170
Pump head

150
Coil 1 is at no load
Coil 2 is at 100% load
System head (ft.) 130 Coil 1 Coil 2 41.6 psi
96.0'
110
88.9'
the plant
38.5 psi Coil furthest from
90

70

Pump suction loss
50
Chilled water distribution system (no scale)
Figure 8.8 Hydraulic gradient full load. (From Patterson Pump Company, HVAC
Pumps and Systems Manual, 2004.)

coil control valve must be selected correctly to maintain the desired
flow in the coils, whether there is near full load or little load on the
chilled water system.

8.6 Elimination of Pump
Head-Wasting Devices
Whenever we add a mechanical device to a water system, we should
ask why do we need it and what energy does it cost in the form of lost
pump head? Here are four mechanical devices that must be removed
wherever possible.

Balance valves, manual and automatic. As we saw in the previous
section, variable-volume water systems cannot be balanced with
any kind of a balance valve. Since most, sizable HVAC water sys-
tems are variable volume with variable speed pumps, there is no

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