YVAA Style A Air-Cooled Screw Liquid Chillers ... - Johnson Controls

FORM 201.28-NM1.1
ISSUE DATE: 8/29/2012
PREPARATION
Commissioning of this unit should only
be carried out by Johnson Controls Authorized
personnel.
Commissioning personnel should be thoroughly familiar
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.
Inspection
Proper electrical lock out and tag out
procedures must be followed.
Inspect unit for installation damage. If found, take action
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 leak(s) 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 assure the refrigerant temperature
in the evaporator does not go below the freezing
point with liquid refrigerant in the evaporator. 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 - TECH-
NICAL DATA on Page 49.
SECTION 6 - COMMISSIONING
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 should 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
fixed orifice and the evaporator for adjusting
charge. Charge should be added
as liquid with the pump ON and liquid
flowing 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" (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 to 3.1 gallons (7.5 to
11.6 liters) are present in each refrigerant system.
JOHNSON CONTROLS 81
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