Leak Testing; Evacuation - Lennox HSXA16-024 Installation Instructions Manual

Leak Testing

After the line set has been connected to the indoor and out-
door units, the line set connections and indoor unit must be
checked for leaks.
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
Fire, Explosion and Personal Safety
Hazard.
Failure to follow this warning could
result in damage, personal injury or
death.
Never use oxygen to pressurize or
purge refrigeration lines. Oxygen,
when exposed to a spark or open
flame, can cause damage by fire and/
or an explosion, that could result in
personal injury or death.
WARNING
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
1. Connect the high pressure hose of the manifold gauge
set to the vapor valve service port. (Normally, the high
pressure hose is connected to the liquid line port, how-
ever, connecting it to the vapor port helps to protect the
manifold gauge set from damage caused by high pres-
sure.)
2. With both manifold valves closed, connect the cylinder
of HFC−410A refrigerant. Open the valve on the
HFC−410A cylinder (vapor only).
3. Open the high pressure side of the manifold to allow
HFC−410A into the line set and indoor unit. Weigh in
a trace amount of HFC−410A. [A trace amount is a
maximum of 2 ounces (57 g) refrigerant or 3 pounds
(31 kPa) pressure.] Close the valve on the HFC−410A
cylinder and the valve on the high pressure side of the
manifold gauge set. Disconnect HFC−410A cylinder.
4. Connect a cylinder of dry nitrogen with a pressure reg-
ulating valve to the center port of the manifold gauge
set.
5. Adjust dry nitrogen pressure to 150 psig (1034 kPa).
Open the valve on the high side of the manifold gauge
set in order to pressurize the line set and the indoor
coil.
6. After a few minutes, open a refrigerant port to check
that an adequate amount of refrigerant has been add-
ed for detection (refrigerant requirements will vary with
line lengths). Check all joints for leaks. Purge dry nitro-
gen and HFC−410A mixture. Correct any leaks and re-
check.
IMPORTANT
Leak detector must be capable of sensing HFC re-
frigerant.

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:
low pressure gauge to vapor line service valve
D
high pressure gauge to liquid line service valve
D
2. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of HFC−410A .
3. Connect micron gauge.
4. Connect the vacuum pump (with vacuum gauge) to
the center port of the manifold gauge set.
5. Open both manifold valves and start the vacuum
pump.
6. 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 means 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.
7. 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.
Page 11
HSXA16 SERIES