Lennox HS29-012, Unit Information

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Page 11
IV − CHARGING
The unit is factory−charged with the amount of HCFC−22 re-
frigerant indicated on the unit rating plate. This charge is
based on a matching indoor coil and outdoor coil with a 15
foot (4.5 m) line set. For varying lengths of line set, refer to
table 3 for refrigerant charge adjustment. A blank space is
provided on the unit rating plate to list actual field charge.
TABLE 3
LIQUID LINE SET
DIAMETER
Ounce per 5 ft. (ml per mm) adjust line set*
1/4 in. (6mm) 1 ounce per 5 ft. (30 ml per 1524 mm)
5/16 in. (8mm) 2 ounce per 5ft. (60 ml per 1524 mm)
3/8 in. (10 mm) 3 ounce per 5 ft. (90 ml per 1524 mm)
*If line set is greater than 15 ft. (4.5 m) add this amount. If line set
is less than 15 ft. (4.5 m) subtract this amount.
Units are designed for line sets up to 50 ft (15.2 m). Con-
sult Lennox Refrigerant Piping Manual for line sets over
50 ft (15.2 m).
IMPORTANT
If line length is greater than 20 feet (6.1 m) add
this amount. If line length is less than 20 feet (6.1
m), subtract this amount.
A − Pumping Down System
CAUTION
Vacuum operation (operating compressor at 0
psig or lower) can cause internal fusite arcing
resulting in a damaged or failed compressor.
This type of damage will result in denial of
warranty claim.
The system may be pumped down when leak checking the
line set and indoor coil or making repairs to the line set or
indoor coil.
1− Attach gauge manifold.
2− Front seat (close) liquid line valve.
3− Start outdoor unit.
4− Monitor suction gauge. Stop unit when 0 psig is reached.
5− Front seat (close) suction line valve.
B − Leak Testing (To Be Done
Before Evacuating)
1− Attach gauge manifold and connect a drum of dry nitro-
gen to center port of gauge manifold.
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.
NOTE-If electronic leak or Halide detector is used, add a
small amount of HCFC−22 (3 to 5 psig (20kPa to 34kPa)) then
pressurize with nitrogen to 150 psig.
4− Release nitrogen pressure from the system, correct any
leaks and recheck.
CAUTION
When using dry nitrogen, a pressure reducing
regulator must be used to prevent excessive
pressure in gauge manifold, connecting hoses,
and within the system. Regulator setting must
not exceed 150 psig (1034 kpa). Failure to use a
regulator can cause equipment failure resulting
in injury.
C − Evacuating the System
1− Attach gauge manifold. Connect vacuum pump (with vac-
uum gauge) to center port of gauge manifold. With both
manifold service valves open, start pump and evacuate in-
door 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 evacu-
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 test-
ing 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 man-
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 pres-
sure 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
.5mm of mercury absolute pressure or 500 microns
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.