Evacuating The System - Lennox Signature XP21 Series Installation And Service Procedure

Evacuating the System

LINE SET AND INDOOR COIL
1
CONNECT GAUGE SET
NOTE REMOVE CORES FROM SERVICE VALVES (IF
NOT ALREADY 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 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.
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 ABSO-
LUTE 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 IN-
DOOR 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:
D
CLOSE MANIFOLD GAUGE VALVES.
D
SHUT OFF HFC−410A CYLINDER.
D
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.
A
OUTDOOR
UNIT
B
VACUUM PUMP
Figure 12. Evacuating System
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 3
4
8
5
7
6
XP21
HIGH