Page 240 - HVAC Pump Handbook

Rishel_CH08.qxd 21/4/06 6:16 PM Page 237

The Use of Water in HVAC Systems

The Use of Water in HVAC Systems 237

230
Building pump shut-off head 227 ft.
building pressure or 98 psig
210
Building hydraulic gradient
190
Building pump - 60 ft. head

170
System head (ft.) 150 Loss across
Return valve

130
96.0' return valve
41.6 psi
110 Coil furthest
from the plant

90

70

50
Chilled water distribution system (no scale)
Figure 8.10 Hydraulic gradient for figure 8.9. (From Patterson Pump
Company, HVAC Pumps and Systems Manual, 2004.)

Closed systems utilize external pressure to maintain the desired
operating pressure. This is accomplished through the use of makeup
water that is fed through a pressure regulator. Since they are closed
systems, they have an expansion tank to accommodate thermal expan-
sion and contraction caused by changes in system water temperature.
Following is a similar listing for closed systems described in this book.
Chillers and their pumps Chap. 14
Chilled water systems Chap. 15
Closed condenser water systems Chap. 16
Closed thermal storage systems Chap. 17
District heating and cooling Chap. 18
Hot water boilers Chap. 19

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