Evacuating The System - Lennox XC21 Series Unit Information

Evacuating the System

EVACUATING
LINE SET AND INDOOR COIL
1 CONNECT GAUGE SET
NOTE Remove cores from service valves (if not al-
ready done).
A Connect low side of manifold gauge set
with 1/4 SAE in−line tee to vapor line
service valve
B Connect high side of manifold gauge
set to liquid line service valve
C Connect micron gauge
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.
HFC−410A
NITROGEN
2
EVACUATE THE SYSTEM
A Open both manifold valves and start the vacuum pump.
B 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. Absolute pressure in a vacuum is equal to atmospheric pressure minus vacuum pressure.
C 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.
D 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.
E 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.
F 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.
G Perform the following:
S
Close manifold gauge valves.
S
Shut off HFC−410A cylinder.
S
Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with
core tool while maintaining a positive system pressure.
S
Replace the stem caps and secure finger tight, then tighten an additional one−sixth (1/6) of a turn as
illustrated.
A
available
OUTDOOR
UNIT
B
VACUUM PUMP
Page 21
A34000 1/4 SAE TEE WITH
SWIVEL COUPLER
500
MICRON
C
GAUGE
D
MANIFOLD
GAUGE SET
LOW
TO VAPOR
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
RECOMMEND
MINIMUM 3/8" HOSE
1/6 TURN
11 12
1
2
10
9
4
8
5
7
6
HIGH
3
XC21