Leak Testing; Evacuation - Lennox 10ACE Series Installation Instructions Manual

Leak Testing

After the line set has been connected to the indoor and out-
door units, check the line set connections and indoor unit
for leaks.
WARNING
Danger of fire!
Bleeding the refrigerant charge from
only the high side may result in the
low side shell and suction tubing be-
ing pressurized. Application of a braz-
ing torch while pressurized may re-
sult in ignition of the refrigerant and
oil mixture − check the high and low
pressures before unbrazing.
WARNING
Refrigerant can be harmful if it is inhaled. Refriger-
ant must be used and recovered responsibly.
Failure to follow this warning may result in personal
injury or death.
WARNING
Danger of explosion!
Can cause equipment damage, injury
or death. Never use oxygen to pres-
surize a refrigeration or air condition-
ing system. Oxygen will explode on
contact with oil and could cause per-
sonal injury.
WARNING
Danger of explosion!
When using a high pressure gas such
as dry nitrogen to pressurize a refrig-
eration or air conditioning system,
use a regulator that can control the
pressure down to 1 or 2 psig (6.9 to
13.8 kPa).
Using an Electronic Leak Detector or Halide
1. Connect a cylinder of HCFC-22 to the center port of
the manifold gauge set.
2. With both manifold valves closed, open the valve on
the HCFC-22 cylinder (vapor only).
3. Open the high pressure side of the manifold to allow
the HCFC-22 into the line set and indoor unit. Weigh
in a trace amount of HCFC-22. [A trace amount is a
maximum of 2 ounces (57 g) or 3 pounds (31 kPa)
pressure.] Close the valve on the HCFC-22 cylinder
and the valve on the high pressure side of the manifold
gauge set. Disconnect the HCFC-22 cylinder.
505128M 03/06
4. Connect a cylinder of nitrogen with a pressure regulat-
ing valve to the center port of the manifold gauge set.
5. Connect the manifold gauge set high pressure hose to
the vapor valve service port. (Normally, the high pres-
sure hose is connected to the liquid line port; however,
connecting it to the vapor port better protects the man-
ifold gauge set from high pressure damage.)
6. Adjust the nitrogen pressure to 150 psig (1034 kPa).
Open the valve on the high side of the manifold gauge
set which will pressurize line set and indoor unit.
7. After a few minutes, open a refrigerant port to ensure
the refrigerant you added is adequate to be detected.
(Amounts of refrigerant will vary with line lengths.)
Check all joints for leaks. Purge nitrogen and
HCFC-22 mixture. Correct any leaks and recheck.

Evacuation

Evacuating the system of noncondensables is critical for
proper operation of the unit. Noncondensables are defined
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Noncondensables and water vapor combine with
refrigerant to produce substances that corrode copper pip-
ing and compressor parts.
IMPORTANT
Use a thermocouple or thermistor electronic vacuum
gauge that is calibrated in microns. Use an instrument
that reads from 50 microns to at least 23,000 microns.
1. Connect manifold gauge set to the service valve ports
as follows:
low pressure gauge to vapor line service valve
D
high pressure gauge to liquid line service valve
D
2. Connect micron gauge.
3. Connect the vacuum pump (with vacuum gauge) to
the center port of the manifold gauge set.
4. Open both manifold valves and start the vacuum
pump.
5. Evacuate the line set and indoor unit to an absolute
pressure of 23,000 microns (29.01 inches of mercu-
ry). During the early stages of evacuation, it is desir-
able to close the manifold gauge valve at least once to
determine if there is a rapid rise in absolute pressure.
A rapid rise in pressure indicates a relatively large
leak. If this occurs, repeat the leak testing procedure.
NOTE − The term absolute pressure is defined as the
total actual pressure within a given volume or system,
above the absolute zero of pressure. Absolute pres-
sure in a vacuum is equal to atmospheric pressure mi-
nus vacuum pressure.
6. 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 nitrogen cyl-
inder 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.
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