Page 25
TABLE 10
120H Normal Operating Pressures
Outdoor Coil Entering Air Temperature
65 °F 75 °F 85 °F 95 °F 105 °F 115 °F
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Circuit 1
113 251 113 290 112 331 116 383 117 439 120 520
120 254 123 293 124 338 126 388 127 441 129 510
139 264 142 303 144 345 147 393 146 445 148 510
155 278 160 314 164 357 167 403 169 456 173 512
Circuit 2
110 251 111 287 111 329 114 388 117 454 120 538
119 249 120 291 122 336 124 389 126 447 128 520
139 259 142 297 143 337 145 390 144 444 149 514
155 274 160 307 164 349 166 393 169 448 170 510
Suction Pressure (psig)
115°
105°
95°
85°
75°
65°
60
70
80
90
100
110
120
130
100 110 120 130 140 150 160 170 180
Liquid Temperature (° F)
120H Charging Curves
Circuit 1
Circuit 2
Outdoor Temperature (°F)
C-Compressor Controls
See unit wiring diagram to determine which controls are
used on each unit. Optional controls are identified on
wiring diagrams by arrows at junction points.
1- High Pressure Switches (S4, S7)
Compressor circuits are protected by a high pressure
switch which cuts out at 640 psig +
10 psig (4413 kPa
+
70 kPa).
2- Freezestats (S49, S50)
Switches de-energize compressors when evaporator
coil temperature falls below 29°F (-2°C) to prevent
evaporator freeze-up. Switches reset when
evaporator coil temperature reaches 58°F (15°C).
3- Crankcase Heater (HR1, HR2)
Compressors have belly band compressor oil heaters
which must be on 24 hours before running
compressors. Energize by setting thermostat so that
there is no cooling demand, to prevent compressor
from cycling, and apply power to unit.
To Next Page
Loading...
Need help?
General
