Elite ELS072S4S, Installation Instructions Manual

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Page 19
Refrigerant Charge
ELS units have a factory holding charge of 2 pounds of
HFC-410A in each circuit. Additional refrigerant will need
to be added during installation (table 2).
TABLE 2. Adding Refrigerant
Models
Stage 1
lbs
for 25ft
line set
Stage 2
lbs
for 25ft
line set
Liq.
Line
Dia.
Suction
Line
Dia.
Ounces
Adjustment
per foot of
line set
1
ELS072S4S 18.5 N/A 3/8 1-1/8 0.7
ELS090S4S 21.75 N/A 5/8 1-1/8 1.7
ELS120S4S 23 N/A 5/8 1-1/8 1.7
ELS120S4D 12 12 3/8 1-1/8 0.7
ELS150S4D 15 15.5 3/8 1-1/8 0.7
ELS180S4D 23.75 23.5 5/8 1-1/8 1.7
ELS240S4D 22.5 23.5 5/8 1-1/8 1.7
1
If line set length is greater than 25 feet, add this amount
to each circuit. If line set is less than 25 feet, subtract this
amount from each circuit. Refer to Lennox Refrigerant
Piping Design and Fabrication Guidelines for more infor-
mation.
NOTE - Refrigerant line sets longer than 200 feet (60 me-
ters) are not recommended. For assistance contact Len-
nox Application Department.
To charge the system, use either of the following proce-
dures:
CHARGE PROCEDURE – NORMAL OPERATING
PRESSURES
1 - Connect a manifold gauge set to the service valves:
A - Low pressure gauge to vapor service port.
B - High pressure gauge to liquid valve service port
2 - Operate system until pressures and temperatures
stabilize (5 minutes minimum).
3 - Use a thermometer to measure the outdoor
ambient temperature. The outdoor temperature will
determine which charging procedure to use.
Outdoor Temp > 65ºF (18ºC)
1 - Apply the outdoor ambient temperature to table
4 or 5 to determine normal operating pressures.
Compare the normal operating pressures to the
pressures obtained from the connected gauges.
If discharge pressure is high, remove refrigerant
from the system. If discharge pressure is low, add
refrigerant to the system.
A - Add or remove charge in increments.
B - Allow the system to stabilize at least 5 minutes each
time refrigerant is added or removed
2 - 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.
3 - Verify the charge, as described in the approach
method.
CARDBOARD OR
PLASTIC SHEET
OUTDOOR COIL SHOULD BE BLOCKED ONE SIDE AT A TIME
WITH CARDBOARD OR PLASTIC SHEET UNTIL PROPER
TESTING PRESSURES ARE REACHED.
FIGURE 10. Blocking Outdoor Coil
Outdoor Temp < 65ºF (18ºC)
1 - When the outdoor ambient temperature is below
65F (18C) it may be necessary to restrict the air flow
through the outdoor coil to achieve liquid pressures
in the 325-375 psig (2240-2585 kPa) range. These
higher pressures are necessary for checking the
charge. Block equal sections of the outdoor coil on
all coil sides until the liquid pressure is in the 325-
375 psig range (figure 11).
2 - Charge the unit using the approach method in the
next section.
CHARGE PROCEDURE – APPROACH METHOD
Use the following approach method along with the normal
operating pressures to confirm readings.
1 - Using the same thermometer, compare liquid
temperature at service valve to outdoor ambient
temperature.
Approach Temperature = Liquid temperature minus
ambient temperature
2 - Approach temperature should be as indicated in
table 3 for each stage. An approach temperature
greater than this value indicates an undercharge.
An approach temperature less than this value
indicates an overcharge.
A - Add or remove charge in increments.
B - Allow system to stabilize at least 5 minutes each
time refrigerant is added or removed.
3 - Do not use the approach method if system pressures
do not match pressures in table 4 except when the
outdoor ambient temperature is below 65ºF (18ºC).
The approach method is not valid for grossly over or
undercharged systems.