Page 24
FIGURE 27
REFRIGERANT STAGES - 150H
TRADITIONAL FIN/TUBE COIL
1
2
(BOTH FANS ARE ENERGIZED
WITH A Y1 DEMAND)
CONDENSER COIL
STAGES 1 & 2
EVAPORATOR
COIL STAGE 1
EVAPORATOR
COIL STAGE 2
B4
B5
FIGURE 28
1
2
(ALL FANS ARE ENERGIZED IN LOW SPEED WITH A Y1
DEMAND AND HIGH SPEED WITH A Y2 DEMAND)
EVAPORATOR
COIL
OUTDOOR
COIL
OUTDOOR
FAN 2
OUTDOOR
FAN 3
REFRIGERANT STAGES - 094U, 122U, 152U
TRADITIONAL FIN/TUBE COIL
B4
OUTDOOR
FAN 1
B21
B5
C-Refrigerant Charge and Check - All-Aluminum Coil
092H, 102H, 120H Units
WARNING-Do not exceed nameplate charge under
any condition.
This unit is factory charged and should require no further
adjustment. If the system requires additional refrigerant,
reclaim the charge,
evacuate the system,
and
add
required nameplate 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:
IMPORTANT - Charge unit in standard cooling mode.
1- Make sure outdoor coil is clean. Attach gauge
manifolds and operate unit at full CFM in cooling mode
with economizer disabled until system stabilizes
(approximately five minutes). Make sure all outdoor air
dampers are closed.
2- Check each system separately with all stages
operating. Compare the normal operating pressures
(see tables 7 - 9) to the pressures obtained from the
gauges. Check unit components if there are
significant differences.
3- Measure the outdoor ambient temperature and the
suction pressure. Refer to the appropriate circuit
charging curve to determine a target liquid
temperature.
Note - Pressures are listed for sea level applications.
4- Use the same thermometer to accurately measure the
liquid temperature (in the outdoor section).
If measured liquid temperature is higher than
the target liquid temperature, add refrigerant to
the system.
If measured liquid temperature is lower than
the target liquid temperature, recover some
refrigerant from the system.
5- Add or remove charge in increments. Allow the
system to stabilize each time refrigerant is added or
removed.
6- Continue the process until measured liquid
temperature agrees with the target liquid
temperature. Do not go below the target liquid
temperature when adjusting charge. Note that
suction pressure can change as charge is adjusted.
7- Example LGH/LCH092 Circuit 1: At 95°F outdoor
ambient and a measured suction pressure of
130psig, the target liquid temperature is 97°F. For a
measured liquid temperature of 106°F, add charge in
increments until measured liquid temperature agrees
with the target liquid temperature.
