Page 17
XPG20 SERIES
Evacuating the System
NOTE
Remove cores from service valves (if not already done).
1. Open both manifold valves and start the vacuum pump.
2. Evacuate the line set and indoor unit to an
absolute pressure
of 23,000 microns (29.01 inches of mercury).
NOTE
During the early stages of evacuation, it is desirable to close the manifold gauge valve at least once. A rapid rise in pressure indicates
a relatively large leak. If this occurs,
repeat the leak testing procedure
.
NOTE
The term
absolute pressure
means the total actual pressure within a given volume or system, above the absolute zero of pressure. Abso-
lute pressure in a vacuum is equal to atmospheric pressure minus vacuum pressure.
3. When the absolute pressure reaches 23,000 microns (29.01 inches of mercury), close the manifold gauge valves, turn off the vacuum pump
and disconnect the manifold gauge center port hose from vacuum pump. Attach the manifold center port hose to a dry nitrogen cylinder with
pressure regulator set to 150 psig (1034 kPa) and purge the hose. Open the manifold gauge valves to break the vacuum in the line set and indoor
unit. Close the manifold gauge valves.
4. Shut off the dry nitrogen cylinder and remove the manifold gauge hose from the cylinder. Open the manifold gauge valves to release the dry
nitrogen from the line set and indoor unit.
5. Reconnect the manifold gauge to the vacuum pump, turn the pump on, and continue to evacuate the line set and indoor unit until the absolute
pressure does not rise above 500 microns (29.9 inches of mercury) within a 20−minute period after shutting off the vacuum pump and closing
the manifold gauge valves.
6. When the absolute pressure requirement above has been met, disconnect the manifold hose from the vacuum
pump and connect it to an upright cylinder of HFC−410A refrigerant. Open the manifold gauge valve 1 to 2 psig
in order to release the vacuum in the line set and indoor unit.
7. Perform the following:
A
Close manifold gauge valves.
B
Shut off HFC−410A cylinder.
C
Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with core
tool while maintaining a positive system pressure.
D
Replace the stem caps and secure finger tight, then tighten an additional one−sixth (1/6) of a turn as illustrated.
OUTDOOR UNIT
TO SUCTION
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
MICRON GAUGE
VACUUM PUMP
A34000 1/4 SAE
TEE WITH
SWIVEL
COUPLER
50
MANIFOLD GAUGE SET
HFC−410A
RECOMMEND MINIMUM
3/8" HOSE
A
Connect low side of manifold gauge set with 1/4 SAE in−line tee to
suction
line service valve
B
Connect high side of manifold gauge set to
liquid
line service valve
C
Connect micron gauge available connector on the 1/4 SAE in−line tee.
D
Connect the vacuum pump (with vacuum gauge) to the center port of
the manifold gauge set. The center port line will be used later for both
the HFC−410A and nitrogen containers.
A
B
C
D
HIGH
LOW
1
2
3
4
5
6
7
8
9
10
11 12
1/6 TURN
NITROGEN
USE REGULATOR TO
FLOW NITROGEN AT 1
TO 2 PSIG.
Evacuating the system of non−condensables is critical for proper operation of the unit. Non−condensables are defined as any gas that will not
condense under temperatures and pressures present during operation of an air conditioning system. Non−condensables and water suction
combine with refrigerant to produce substances that corrode copper piping and compressor parts.
