Page 215 - HVAC Pump Handbook

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The Use of Water in HVAC Systems

212 The HVAC World

central plant generation of hot and chilled water is not included in
the distribution system COP. Plant COP is determined in the chap-
ters on chillers and boilers.

All hot water radiation system. This system consists of just radiation of
various types without fans or blowers and is shown in Fig. 8.1. The
equation for COP is:
−
− T 1) 0.147 Q s (T 2 T 1)
500 Q s (T 2
COP (8.2)
3413 W p W p
where Q hot water system flow, gal/min
s
T system supply water temperature, °F
2
T system return water temperature, °F
1
W kilowatt input to pump motors
p
Air-water system. This system is a combination of radiation and air-
handling units and is typical of a large percentage of hot water and
chilled water systems. They are shown in Fig. 8.2 and the equation for
the COP is developed in Eq. 8.3.
−
0.147 Q s (T 2 T 1)
COP
+
W p W f (8.3)
where W kilowatt input to fan motors
f
(T − T ) difference between the supply and return water
2 1
temperatures

Pumps W p T 1 Q s

From boilers
Radiators

T 2
To boilers
Figure 8.1 All-radiation system.

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