Lennox International Inc 06/11 50672801 Evacuating Line Set and Indoor Coil, 2EVACUATE the System

1/6 TURN

Evacuating Line Set and Indoor Coil

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.

CONNECT GAUGE SET

1NOTEA Connect low side of manifold gauge set with 1/4 SAE in−line tee to vapor line service valve

BConnect high side of manifold gauge set to liquid line service valve

CConnect micron gauge available connector on the 1/4 SAE in−line tee.

DConnect 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

OUTDOOR

UNIT

HFC−410A

VACUUM PUMP

LOW HIGH

	A34000 1/4 SAE TEE WITH		MANIFOLD
			GAUGE SET
	SWIVEL COUPLER
A
	500
	C	MICRON	TO VAPOR
			SERVICE VALVE
		GAUGE

B	TO LIQUID LINE
	SERVICE VALVE

RECOMMEND

MINIMUM 3/8" HOSE

D

2EVACUATE 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	ure
indicates a relatively large leak. If this occurs, repeat the leak testing procedure.
NOTE	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.

CWhen the absolute pressure reaches 23,000 microns (29.01 inches of mercury), perform the following:

S S S S S

Close manifold gauge valves

Close valve on vacuum pump and turn off vacuum pump

Disconnect manifold gauge center port hose from vacuum pump

Attach manifold center port hose to a dry nitrogen cylinder with pressure regulator set to 150 psig (1034 kPa) and purge the hose.

Open manifold gauge valves to break the vacuum in the line set and indoor unit.

SClose manifold gauge valves.

DShut 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.

EReconnect 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.

FWhen 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.
		11	12	1
S	Shut off HFC−410A cylinder.
		10		2
S
	Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with core	9		3
	tool while maintaining a positive system pressure.	8		4
S	Replace stem caps and secure finger tight, then tighten an additional one−sixth (1/6) of a turn as illustrated.	7	6	5

Figure 13. Evacuating Line Set and Indoor Coil

506728−01 Page 18