JOHNSON CONTROLS
97
Form 201.28-NM1.1
Issue date: 08/06/2021
6
Section 6 - Commissioning
Preparation
Commissioning of this unit must only
be carried out by Johnson Controls
Authorized personnel.
Commissioning personnel should be thoroughly fa-
miliar with the information contained in this document
before starting the unit.
The following basic checks should be made with the
customer power to the unit switched OFF.
Proper electrical lock out and tag out
procedures must be followed.
Inspection
Inspect unit for installation damage. If found, take ac-
tion and/or repair as appropriate.
Refrigerant charge
Packaged units are normally shipped as standard
with a full refrigerant operating charge. Check that
refrigerant pressure is present in both systems and
that no leaks are apparent. If no pressure is present,
a leak test must be undertaken, the leaks located and
repaired.
Do not evacuate or liquid charge with static water
in the evaporator. Turn the pump on. Take care to
liquid charge slowly to avoid excessive thermal stress
at the charging point and to ensure the refrigerant
temperature in the evaporator does not go below the
freezing point with liquid refrigerant in the evapo-
rator. Once the vacuum is broken, charge into the
evaporator or flash tank with the Condenser Drain
Valve (Flash Tank Feed) open and the chilled liquid
pump ON to the full operating charge, as detailed in
SECTION 5 - TECHNICAL DATA.
Correct system refrigerant charge
The charge on a system should always be checked
when operating for several minutes at full speed with
the system stable. Stable conditions are defined as
operation without fan cycling, economizer cycling,
VI solenoid cycling, or any other system transient
conditions. Ideal refrigerant charge will be reached
when the refrigerant level in the evaporator is near the
middle of the evaporator sight glass.
Refrigerant must not be added or
removed unless the level is at the bottom
or the top of the glass. It is not necessary to
weigh charge unless the entire charge has
been lost. The ease of charging is possible
since the microchannel coils hold only a
small amount of refrigerant charge. A
charging valve is located between the xed
orice and the evaporator for adjusting
charge. Charge must be added as liquid
with the pump ON and liquid owing
through the evaporator.
Service and oil line valves
Open each compressor oil, economizer, and discharge
ball or service valves. If valves are of the back-seat
type, open them fully (counterclockwise) then close
one turn of the stem to ensure operating pressure is fed
to pressure transducers.
Compressor oil
To add oil to a circuit - connect a YORK hand oil pump
(Part No. 470-10654-000) to the 1/4 in. (6.35 mm) oil
charging valve on the oil separator piping with a length
of clean hose or copper line, but do not tighten the
flare nut. Using clean oil of the correct type (“L” oil),
pump oil until all air has been purged from the hose
then tighten the nut. Stroke the oil pump to add oil to
the oil system. While the compressor is running at full
speed, the oil level should be visible in the sight glass
of the oil separator. Approximately 2 gal to 3.1 gal
(7.5 L to 11.6 L) are present in each refrigerant
system.
Avoid levels in either oil separator that are above the
middle of the top sight glass. This may cause excessive
oil carryover in the system.
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