Lennox International Inc. 4HP18LT - Manual (Page 11)

506470-01 Issue 1007
Using an Electronic Leak Detector
1. Connect the high pressure hose of the manifold gauge
set to the suction valve service port. (Normally the high
pressure hose is connected to the liquid line port; however,
connecting it to the suction ports helps to protect the manifold
gauge set from damage caused by high pressure.)
2. With both manifold valves closed, connect the cylinder of
R410A refrigerant. Open the valve on the R410A cylinder
(vapor only).
3. Open the high pressure side of the manifold to allow
R410A into the line set and indoor unit. Weigh in a trace
amount of R410A. (A trace amount is a maximum of 2 oz.
of refrigerant or 3 lbs. pressure.) Close the valve on the
R410A cylinder and the valve on the high pressure side of
the manifold gauge set. Disconnect the R410A cylinder.
4. Connect a cylinder of nitrogen with a pressure regulating
valve to the center port of the manifold gauge set. When
using high pressure gas such as nitrogen for this
purpose, be sure to use a regulator that can control the
pressure down to 1 or 2 psig.
5. Adjust nitrogen pressure to 150 psig. Open the valve on
the high side of the manifold gauge set to pressurize the
line set and the indoor coil.
6. After a short period of time, open a refrigerant port to
make sure that an adequate amount of refrigerant has been
added for detection (refrigerant requirements will vary with
lenths). Check all joints for leaks. Purge nitrogen and R410A
mixture. Correct any leaks and rechecks.
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 piping
and compressor parts.
Use a thermocouple or thermistor electronic vacuum gauge
that is calibrated in microns. Use an instrument that reads
down to 50 microns.
1. Connect the manifold gauge set to the service valve ports
as follows:
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve.
2. Connect micron gauge.
3. Connect the vacuum pump (with vacuum gauge) to the
center port of the manifold gauge set.
Never use oxygen to pressurize refrigeration or air con-
ditioning systems. Oxygen will explode on contact with
oil and could cause personal injury or death.
Page 11
Refrigerant can be harmful if inhaled. Refrigerant must
always be used and recovered responsibly. Incorrect
or irresponsible use of refrigerant can result in personal
injury or death.
WARNING
WARNING
Figure 12
Do Not use a compressor to evacuate a system. Avoid
deep vacuum operation. Extremely low vacuums can
cause internal arcing and compressor failure. Danger
of equipment damage. Damage caused by deep vacuum
operation will void warranty.
WARNING