JOHNSON CONTROLS
12
FORM 160.84-OM1
ISSUE DATE: 9/21/2017
SECTION 1 - SYSTEM FUNDAMENTALS
glass is located on the side of the shell. The evapora-
tor shell contains dual refrigerant relief valves unless
condenser isolation is installed.
Condenser
The condenser is a shell and tube type, with a discharge
gas baffle to prevent direct high velocity impingement
on the tubes. A separate subcooler is located in the con-
denser to enhance performance. Dual refrigerant relief
valves are located on condenser shells and optional re-
frigerant isolation valves are available.
Water Boxes
The removable compact water boxes are fabricated of
steel. The design working pressure is 150 PSIG (1034
kPa) and the boxes are tested at 225 PSIG (1551 kPa).
Integral steel water baffles provide the required pass
arrangements. Stub-out water nozzle connections with
Victaulic grooves are welded to the water boxes. These
nozzle connections are suitable for Victaulic couplings,
welding or flanges, and are capped for shipment.
Plugged 3/4" drain and vent connections are provided
in each water box. Optional marine waterboxes and
higher pressure ratings are available.
Refrigerant Flow Control
Refrigerant flow to the evaporator is controlled by the
liquid level control valve.
A level sensor senses the refrigerant level in the con-
denser and outputs an analog voltage to the control
panel that represents this level (0% = empty; 100% =
full). Under program control, the control panel modu-
lates the liquid level control valve to control the con-
denser refrigerant level to a programmed setpoint. Oth-
er setpoints affect the control sensitivity and response.
Only a qualified service technician may modify these
settings. The level setpoint must be entered at chiller
commissioning by a qualified service technician.
While the chiller is shut down, the level control valve
will be pre positioned to anticipate run. When the
chiller is started, if actual level is less than the level
setpoint, a linearly increasing ramp is applied to the
level setpoint. This ramp causes the setpoint to go from
the initial refrigerant level to the programmed setpoint
over a programmable period of time. If the actual level
is greater than the setpoint upon run, it immediately
begins to control to the programmed setpoint.
While the chiller is running, the refrigerant level is nor-
mally controlled to the level setpoint.
Variable Speed Drive
A Variable Speed Drive will be factory packaged with
the chiller. It is designed to vary the compressor motor
speed by controlling the frequency and voltage of the
electrical power to the motor. The control logic auto-
matically adjusts motor speed as required to suit lift and
capacity requirements.
Power Panel
The power panel includes the uninterrupted power
supply and power storage battery. These feed essential
loads while the chiller shuts down upon loss of main
chiller power.
Optional Service Isolation Valves
If your chiller is equipped with optional service iso-
lation valves on the discharge and liquid line, these
valves must remain open during operation. These
valves are used for isolating the refrigerant charge in
either the evaporator or condenser to allow service ac-
cess to the system. A refrigerant pump-out unit will be
required to isolate the refrigerant.
Isolation of the refrigerant in this system
must be performed by a qualied service
technician.
Optional Hot Gas Bypass
Hot gas bypass is optional and is used to provide great-
er turndown than otherwise available for load and head
conditions. The OptiView
TM
Control Center will auto-
matically modulate the hot gas valve open and closed
as required. Adjustment of the hot gas control valve
must only be performed by a qualified service techni-
cian.
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