Unit Start−Up And Operation - Lennox 13CHA SERIES Installation Instructions Manual

Unit Start−Up and Operation
Each 13CHA packaged cooling unit is factory−charged with
R−22 refrigerant. The compressor is hermetically sealed,
internally sprung and base−mounted with rubber−insulated
hold−down bolts.
Pre−Start Check List:
1 − Make sure refrigerant lines do not rub against the cabi-
net or each other.
2 − Inspect all electrical wiring, both factory− and field−
installed, for loose connections.
3 − Check voltage at the disconnect switch. Voltage must
be within the range listed on the unit nameplate. If not,
consult power company and have voltage condition
corrected before starting unit.
4 − Recheck voltage with unit running. If power is not with-
in the range listed on the unit nameplate, stop the unit
and consult the power company. Check unit amper-
age. Refer to unit nameplate for correct running amps.
5 − Make sure filter is in place before unit start−up.
6 − Before placing the unit into full operation, energize the
unit for three false starts. Energize the compressor
just long enough for it to make a few revolutions, wait
five to seven minutes before repeating a second and
third time.
Cooling Sequence of Operation
When the thermostat calls for cooling, the R" to Y" circuit
is closed to energize the compressor contactor. The
contactor brings on both the compressor and outdoor fan.
The thermostat also closes the R" to G" circuit to energize
the circulating air blower. When the cooling demand is
satisfied, the thermostat opens the circuits, as well as the
compressor contactor. The compressor and outdoor fan
80°F db / 67°F wb RETURN AIR
UNIT PRESSURE
13CHA−24
13CHA−30
13CHA−36
Suction Suction
13CHA−42
13CHA−48
13CHA−60
13CHA−24
13CHA−30
13CHA−36
Liquid Liquid
13CHA−42
13CHA−48
13CHA−60
Table 3
Normal Operating Pressures
Air Temperature Entering Outdoor Coil (°F)
65 70 75 80
78 80 82 84
78 79 81 82
79 80 81 83
75 76 78 79
76 77 79 80
78 79 81 82
131 146 161 176
132 148 164 181
146 161 176 191
129 144 159 175
131 146 161 177
143 159 175 191
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immediately stop. The circulating air blower continues
operating through a 90−second delay.
Unit compressors have internal protection. If there is an
abnormal rise in the compressor temperature, the
protector will open and the compressor will stop.
System Performance
For maximum performance of this cooling system, the
operating temperatures and pressure should be checked
and superheat determined at Standard ARI test conditions
of 82_ F outdoor temperature / 80_ F indoor dry bulb / 67_ F
indoor wet bulb. If superheat measured deviates from
values in table 2, refrigerant charge should be adjusted
accordingly for maximum performance.
Suction Superheat Values
Unit Model No.
13CHA−24
13CHA−30
13CHA−36
13CHA−42
13CHA−48
13CHA−60
Verify system performance using table 3 as a general guide.
Table 3 should not be used for charging unit. Minor varia-
tions in these pressures may be expected due to differences
in installations. Significant differences could mean that the
system is not properly charged or that a problem exists with
some component in the system.
Used carefully, this table could serve as a useful service
guide. Data is based on 80°F dry bulb / 67°F wet bulb return
air. Allow unit operation to stabilize before taking pressure
readings.
82 85 90 95
85 86 88 90
83 84 85 87
83 84 85 86
80 81 83 84
81 82 83 85
83 84 85 87
182 191 207 221
187 197 213 229
197 206 221 236
181 190 205 221
183 193 208 223
197 206 221 238
Table 2
Suction Superheat
82_F OD / 80_F IDDB
/ 67_F IDWB
22_F
20_F
20_F
20_F
20_F
20_F
100 104 105 110
91 92 92 93
87 88 88 89
87 88 88 89
87 89 89 90
85 86 86 88
88 89 89 91
238 250 250 268
246 259 259 277
250 262 262 280
236 248 248 267
240 253 253 272
252 264 264 283
115
94
90
90
91
91
92
286
295
298
286
291
302