55
Refrigerant Charging
Systems with Pressure Fan Cycling for Head Pressure
Control (Standard)
For these systems the general recommendation is to use a clear sight glass as an
indication of proper refrigerant charge, then add another 10% to compensate for
liquid pressure changes during fan cycling. During cooler ambient temperatures
the fan cycle settings should be temporarily changed to yield a 105
°
F minimum
condensing temperature during the charging process. An alternate method is to
temporarily block a portion of the entering air condenser surface to restrict airflow.
In these cases, the settings should be maintained until the evaporator superheat has
been checked and adjusted.
The default pressure fan cycling settings are optimized to maintain a minimum 65
°
F
condensing temperature. These settings may be changed if desired.
Systems with Head Pressure Valves (ORI/ORD)
For these systems the general recommendation is to use a clear sight glass as an
indication of proper refrigerant charge, then add an additional amount for condenser
flooding (See Table on Pages 52-53). During cooler ambient temperatures the
fan cycle settings should be temporarily changed to yield a 105
°
F minimum
condensing temperature during the charging process. An alternate method is to
temporarily block a portion of the entering air condenser surface to restrict airflow.
In these cases, the settings should be maintained until the evaporator superheat has
been checked and adjusted.
The default pressure fan cycling settings should be appropriate for a 150-180 psi
discharge pressure setting on the ORI valve. If other settings are desired, the fan
cycling settings may need to be changed.
Systems with Floating (Low) Head Pressure
For these systems the general recommendation is to use a clear sight glass as an
indication of proper refrigerant charge. During cooler ambient temperatures the fan
cycle settings should be temporarily changed to yield a 105
°
F minimum condensing
temperature during the charging process. An alternate method is to temporarily block
a portion of the entering air condenser surface to restrict airflow. In these cases, the
settings should be maintained until the evaporator superheat has been checked and
adjusted.
There are a number of different fan cycling possibilities for floating head systems.
Generally, fans are turned off with decreasing ambient temperature to save energy.
The first (header) fan is run continuously with the compressor and other fans are
controlled by pressure or ambient temperature.
Please note that special expansion valve and nozzle selections are often required for
floating head pressure applications.
Condenser Flooding Charge, Lbs
(90%) RECEIVER
CAPACITY Lbs
-5F SST
-20F AMB
-25F SST
-20F AMB
-5F SST
20F AMB
-25F SST
20F AMB
MODEL/ REFRIG
SIZE
L6 (R404A/R507)
0602, 0752
81
16
17
14
16
L6 (R404A/R507)
0902, 1002, 1202
81
21
22
19
21
L6 (R404A/R507)
1502
81
28
30
26
28
L6 (R404A/R507)
2202
123
47
50
42
47
L6 (R404A/R507)
2702, 3002
123
65
69
59
65
L6 (R407A,F)
0602, 0752
88
17
18
16
17
L6 (R407A,F)
0902, 1002, 1202
88
23
24
21
23
L6 (R407A,F)
1502
88
31
33
28
31
L6 (R407A,F)
2202
135
51
54
46
51
L6 (R407A,F)
2702, 3002
135
71
75
65
71
L6 (R448A/449A)
0602, 0752
85
17
18
15
17
L6 (R448A/449A)
0902, 1002, 1202
85
22
23
20
22
L6 (R448A/449A)
1502
85
30
32
27
30
L6 (R448A/449A)
2202
131
50
53
45
50
L6 (R448A/449A)
2702, 3002
131
69
73
63
69
Summary of Contents for Mohave
Page 13: ...13 Piping The following are examples of proper piping layout for typical system configurations...
Page 14: ...14 Piping...
Page 38: ...38 Standard Independent Evaporator Power Supply with VFD Condenser Fans Wiring Diagram...
Page 39: ...39 Standard Independent Evaporator Power Supply with VFD Condenser Fans Wiring Diagram...
Page 45: ...45 Defrost Operation Black Piping Inactive Gray Piping Active Hot Gas Defrost Cycle Diagrams...
Page 46: ...46 Defrost Operation Black Piping Inactive Gray Piping Active Hot Gas Defrost Cycle Diagrams...
Page 75: ...75 Notes...