Page 8
IV - CHARGING
The unit is factory-charged with the amount of R-22 refrigĆ
erant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with a 25
foot (7620mm) line set. For varying lengths of line set, refer
to table 8 for refrigerant charge adjustment. A blank space
is provided on the unit rating plate to list actual field charge.
LIQUID LINE
1/4 in. (6 mm)
5/16 in. (8mm)
3/8 in. (10 mm)
TABLE 8
Ounce per 5 foot (ml per mm) adjust
from 25 foot (7620 mm) line set*
1 ounce per 5 feet
(30 ml per 1524 mm)
*If line set is greater than 25 ft. (7.62m) add this amount. If line set
is less than 25 feet (7.62m) subtract this amount
SET DIAMETER
2 ounce per 5 feet
(60 ml per 1524 mm)
3 ounce per 5 feet
(90 ml per 1524 mm)
Units are designed for line sets up to 50ft. Consult Lennox ReĆ
frigerant Piping Manual for line sets over 50ft.
IMPORTANT
If line length is greater than 25 feet (7620 mm), add
this amount. If line length is less than 25 feet (7620
mm), subtract this amount.
A - Leak Testing
1- Attach gauge manifold and connect a drum of dry nitroĆ
gen to center port of gauge manifold.
CAUTION
When using dry nitrogen, a pressure reducing regĆ
ulator must be used to prevent excessive presĆ
sure in gauge manifold, connecting hoses, and
within the system. Regulator setting must not exĆ
ceed 150 psig (1034 kpa). Failure to use a regulator
can cause equipment failure resulting in injury.
2- Open high pressure valve on gauge manifold
and pressurize line set and indoor coil to 150 psig
(1034 kPa).
3- Check lines and connections for leaks.
NOTEĆIf electronic leak detector is used, add a trace of reĆ
frigerant to the nitrogen for detection by leak detector.
4- Release nitrogen pressure from the system, correct
any leaks and recheck.
B - Evacuating the System
1- Attach gauge manifold. Connect vacuum pump (with
vacuum gauge) to center port of gauge manifold. With
both manifold service valves open, start pump and
evacuate indoor coil and refrigerant lines.
IMPORTANT
A temperature vacuum gauge, mercury vacuum
(U-tube), or thermocouple gauge should be used.
The usual Bourdon tube gauges are not accurate
enough in the vacuum range.
IMPORTANT
The compressor should never be used to evacuĆ
ate a refrigeration or air conditioning system.
2- Evacuate the system to 29 inches (737mm) vacuum.
During the early stages of evacuation, it is desirable to
stop the vacuum pump at least once to determine if
there is a rapid loss of vacuum. A rapid loss of vacuum
would indicate a leak in the system and a repeat of the
leak testing section would be necessary.
3- After system has been evacuated to 29 inches
(737mm), close gauge manifold valves to center port,
stop vacuum pump and disconnect from gauge manĆ
ifold. Attach an upright nitrogen drum to center port of
gauge manifold and open drum valve slightly to purge
line at manifold. Break vacuum in system with nitrogen
pressure by opening manifold high pressure valve.
Close manifold high pressure valve to center port.
4- Close nitrogen drum valve and disconnect from gauge
manifold center port. Release nitrogen pressure from
system.
5- Connect vacuum pump to gauge manifold center port.
Evacuate system through manifold service valves until
vacuum in system does not rise above 29.7 inches
(754mm) mercury (5mm absolute pressure) within a
20-minute period after stopping vacuum pump.
6- After evacuation is complete, close manifold center
port, and connect refrigerant drum. Pressurize system
slightly with refrigerant to break vacuum.
C - Charging
If the system is completely void of refrigerant, the recomĆ
mended and most accurate method of charging is to weigh
the refrigerant into the unit according to the total amount
shown on the unit nameplate and in table 9.
