Lennox KHA SERIES, Manual

Page: 32 / 49

Page 32
IV− SYSTEMS SERVICE CHECKS
Refrigerant Charge and Check
WARNING−Do not exceed nameplate charge under any condition.
This unit is factory charged and should require no further
adjustment. If the system requires charge,
reclaim the
charge, evacuate the system and add required name-
plate charge.
NOTE − System charging is not recommended below 60
_
F
(15
_
C). In temperatures below 60
_
F (15
_
C) , the charge
must be weighed into the system.
If weighing facilities are not available, or to check the
charge, use the following procedure:
1− Attach gauge manifolds and operate unit in cooling
mode until system stabilizes (approximately five min-
utes).
2− Check each system separately with all stages operat-
ing.
3− Use a thermometer to accurately measure the outdoor
ambient temperature.
4− Apply the outdoor temperature to tables 5 through 9 to
determine normal operating pressures.
5− Compare the normal operating pressures to the pres-
sures obtained from the gauges. Minor variations 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.
Correct
any system problems before proceeding.
6− If discharge pressure is high, remove refrigerant from
the system. If discharge pressure is low, reclaim the
charge, evacuate the system then add refrigerant.
D
Add or remove charge in increments.
D
Allow the system to stabilize each time refriger-
ant is added or removed.
7− Use the following approach method along with the nor-
mal operating pressures to confirm readings.
TABLE 5
KHA024S NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air Temp
Dis. + 10 psig Suct. +5 psig
65
_
F
226 147
75
_
F
258 148
85
_
F
304 151
95
_
F
351 154
105
_
F
402 157
115
_
F
460 160
TABLE 6
KHA030S NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air Temp
Dis. + 10 psig Suct. +5 psig
65
_
F 235 145
75
_
F
273 148
85
_
F 316 151
95
_
F
363 153
105
_
F 416 156
115
_
F
476 158
TABLE 7
KHA036S NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air
Temp
Dis. + 10 psig Suct. +5 psig
65
_
F
247 140
75
_
F 289 143
85
_
F
331 145
95
_
F 381 148
105
_
F
434 151
115
_
F 492 154
TABLE 8
KHA048S NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air
Temp
Dis. + 10 psig Suct. +5 psig
65
_
F
272 139
75
_
F 313 142
85
_
F
359 145
95
_
F 410 148
105
_
F
465 150
115
_
F 529 152
TABLE 9
KHA060S NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air
Temp
Dis. + 10 psig Suct. +5 psig
65
_
F
265 136
75
_
F
304 139
85
_
F
348 141
95
_
F 397 144
105
_
F
447 147
115
_
F 507 149