Lennox Dave Signature XP21 Installation Instructions Manual page 19

STEP 8 -- EVACUATION
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 com­
pressor parts.
Danger of Equipment Damage. Avoid deep vacuum operation. Do not use compressors to evacuate a system. Extremely
low vacuums can cause internal arcing and compressor failure. Damage caused by deep vacuum operation will void
warranty.
LINE SET AND INDOOR COIL
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
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.
NITROGEN
HFC-410A
gauge available
OUTDOOR
UNIT
VACUUM PUMP
WARNING
A34000 1/4 SAE TEE WITH
SWIVEL COUPLER
A
C
B
D
FIGURE 18
Page 19
LOW
500
MICRON
GAUGE
TO VAPOR
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
RECOMMEND
MINIMUM 3/8" HOSE
MANIFOLD
GAUGE SET
HIGH
XP21 SERIES