Lennox KHA180 User Manual

Page 13
KHA180, 240
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, add
refrigerant to the system.
 Add or remove charge in increments.
 Allow the system to stabilize each time
refrigerant is added or removed.
7− Use the following approach method along with the
normal operating pressures to confirm readings.
TABLE 3
KHA180 NORMAL OPERATING PRESSURES
Outdoor
Coil En-
tering
Air Temp
Circuit 1 Circuit 2
Dis. +10
psig
Suc. +5
psig
Dis. +10
psig
Suc. +5
psig
65F 270 138 270 135
75F 312 139 312 135
85F 356 142 356 136
95F 403 144 404 138
105F 455 147 458 140
115F 512 147 515 145
TABLE 4
KHA240 NORMAL OPERATING PRESSURES
Outdoor
Coil En-
tering
Air Temp
Circuit 1 Circuit 2
Dis. +10
psig
Suc. +5
psig
Dis. +10
psig
Suc. +5
psig
65F 275 135 278 135
75F 315 138 318 136
85F 359 140 364 138
95F 407 142 413 140
105F 457 144 466 141
115F 517 146 527 145
C−Charge Verification − Approach Method − AHRI Testing
1− Using the same thermometer, compare liquid
temperature to outdoor ambient temperature.
Approach Temperature = Liquid temperature (at
condenser outlet) minus ambient temperature.
2− Approach temperature should match values in table
5. An approach temperature greater than value
shown indicates an undercharge. An approach
temperature less than value shown indicates an
overcharge.
3− The approach method is not valid for grossly over or
undercharged systems. Use table 3 or 4 as a guide
for typical operating pressures.
TABLE 5
APPROACH TEMPERATURES
Unit
Liquid Temp. Minus Ambient Temp.
1st Stage 2nd Stage
180 & 240
12°F + 1
(6.7°C +
0.5)
12°F + 1
(6.7°C +
0.5)
D−Compressor Controls
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 indoor coil
temperature falls below 29F (−2C) to prevent coil
freeze−up. Switches reset when indoor coil
temperature reaches 58F (15C).
3− Defrost Switches (S6, S9)
Defrost switches close to initiate defrost when liquid
line temperature falls to 35F (1.7C). The defrost
switch is located on the liquid line between the
outdoor expansion valve and the distributor
4− Defrost Termination Switches (S46, S104)
Defrost pressure switches open to terminate defrost
when vapor line (discharge pressure during cooling
and defrost) pressure reaches 450 psig (3103 kPa).
5− Defrost Controls (CMC1, CMC2)
Defrost is liquid line temperature initiated and
operates for 14 minutes unless terminated by vapor
line pressure drop.
When the liquid line temperature drops below 35°F,
the defrost switch closes and signals the defrost
control that a defrost cycle is needed. If the defrost
switch is still closed after 60 minutes (default), a
defrost cycle begins and operates for 14 minutes.
The defrost pressure switch can terminate the defrost
cycle before the 14 minutes elapses if vapor line
pressure reaches 450 +
10 psi.
6− Electric heat is energized during defrost to maintain
discharge air temperature.

Lennox KHA180 Specifications

General

Brand	Lennox
Model	KHA180
Category	Heat Pump
Language	English