Jetson
www.JetsonHVAC.com
42
Table 6 Minimum Volume (Gallon/Ton)
Allowable Swing
(+/-°F)
Minimum Volume
(gallon/ton)
10
3.00
9
3.33
8
3.75
7
4.29
6
5.00
5
6.00
4
7.50
3
10.00
2
15.00
1
30.00
This same detailed equation can be generalized
to another common loop volume sizing
method:
loop time
. As a general guideline, a
minimum 3-minute loop time is required for
the evaporator chilled water system. In a
typical water-cooled application, the nominal
fluid flow through the evaporator is 2.4
gpm/ton.
At nominal flows, a 3-minute loop time is
equivalent to a minimum loop volume of 7.2
gallon/ton (2.4 gpm/ton x 3 min = 7.2
gallon/ton) and would have an allowable
leaving fluid temperature swing of +/- 4.2°F
At nominal flows, a 2-minute loop time is
equivalent to a minimum loop volume of 4.8
gallon/ton. (2.4 gpm/ton x 2 min = 4.8
gallon/ton) and would have an allowable
leaving fluid temperature swing of +/- 6.25°F.
Notice, in the preceding example, if this
system was selected for a 45°F leaving water
temperature, the temperature will vary
between 42°F to 48°F (recall the variation
tolerance +/- 3°F) with the cycling of the
compressors at the water loop volume of 641
gallons. The final selection should ensure the
leaving water temperature does not drop below
42°F (or 40°F if using a high-capacity
evaporator). If a leaving water temperature
below 42°F (or 40°F if using a high-capacity
evaporator) is indicated then the loop volume
should be increased or glycol should be
included with the design.
Glycol
If the fluid loop contains glycol, the required
water loop volume should be multiplied by the
correction factor in Table 3.
Table 7 Glycol Correction Factors
% by Weight
Glycol Volume Correction Factor
Ethylene
Propylene
10
1.038
1.017
20
1.066
1.033
30
1.100
1.058
40
1.140
1.092
50
1.192
1.142
It may be necessary to install a storage tank in
the system to provide the necessary volume for
close temperature control. When this is done,
the tank should be installed in the loop between
the fluid leaving from the chiller and the
supply to the building. Figure A1 illustrates a
proper expansion tank usage.
Figure 14 Expansion Tank Usage
Summary of Contents for FWCD Series
Page 1: ...FWCD Series Chillers Installation Operation Maintenance...
Page 2: ...Jetson www JetsonHVAC com 2...
Page 30: ...Jetson www JetsonHVAC com 30 Figure 4 FWCD array dimensions brazed plate condenser...
Page 31: ...Jetson www JetsonHVAC com 31 Figure 5 FWCD dimensions shell and tube condenser...
Page 32: ...Jetson www JetsonHVAC com 32 Figure 6 FWCD array dimensions shell and tube condenser...
Page 33: ...Jetson www JetsonHVAC com 33 Figure 7 FWCD dimensions remote condenser...
Page 34: ...Jetson www JetsonHVAC com 34 Figure 8 FWCD array dimensions remote condenser...
Page 82: ...Jetson www JetsonHVAC com 82 Wiring Figure 26 FWCD wiring schematic...
Page 83: ...Jetson www JetsonHVAC com 83 Figure 27 FWCD wiring schematic continued...
Page 84: ...Jetson www JetsonHVAC com 84 Figure 28 FWCD dual circuit secondary wiring schematic...
Page 85: ...Jetson www JetsonHVAC com 85 Figure 29 FWCD dual circuit secondary wiring schematic continued...
Page 86: ...Jetson www JetsonHVAC com 86 Figure 30 Field wiring FWCD single unit single circuit...
Page 87: ...Jetson www JetsonHVAC com 87 Figure 31 Field wiring FWCD single unit dual circuit...