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YORK INTERNATIONAL
each unit. All piping will be ACR copper with brazed joints.
The liquid line will include: a shutoff valve with charging
port; sightglass with moisture indicator; thermal expan-
sion valve; solenoid valve; and high-absorption remov-
able-core filter drier. The entire suction line and the liq-
uid line between the expansion valve and the cooler will
be insulated with flexible, closed-cell, foam insulation.
MICROCOMPUTER CONTROL CENTER
Each unit shall contain a Microcomputer Control Center.
All logic and controls shall be contained within a IP 32
(NEMA 1) cabinet with hinged outer door with positive
acting latches. Inside shall be contained the “user
friendly” and interactive inputs and outputs as follows:
LCD display with light emitting diode back lighting for
easy viewing of data and input buttons for DISPLAY (tem-
peratures, pressure, etc.). ENTRY (enter/cancel inputs,
advance day, change AM/PM), SETPOINTS (change),
CLOCK (set time and schedule), PRINT (calling up op-
erating and shutdown data), PROGRAM (change inputs
from special conditions such as brine chilling) and UNIT
ON/OFF.
The Microcomputer Control Center shall be capable of
displaying the following: return and leaving liquid tem-
perature; return and leaving condenser water tempera-
ture (optional); low leaving liquid temperature cutout set-
ting; system 1 and 2 percent full-load motor current and
suction, discharge (optional) and oil differential pressures;
liquid pulldown control range (selectable for 0.6°C to 1.1°
C [1°F to 2°F] in one-tenth increments above the set-
point); liquid pull-down rate sensitivity (0.3°C to 3.0°C
[0.5°F to 5°F]/minute in 0.05°C [0.1°F] increments); anti-
recycle timer status; compressor run status; no cooling
load condition; day; date; time; out of range message;
daily and holiday scheduling of start/stop times; auto-
matic or manual lead/lag status; lead compressor defini-
tion; number of compressor starts and running hours;
status of hot gas bypass valves (option), liquid line sole-
noid valves, and water pump; last three fault shutdowns
data; number of unloading steps; compressor load and
unload timer status.
The operating program shall be stored in nonvolatile
memory (EPROM) to eliminate chiller failure due to AC
power failure/battery discharge. Programmed setpoints
are retained in lithium battery – backed RTC memory for
5 years minimum.
Provisions shall be included for: pumpdown at shutdown
and recycling pumpdown; a hard copy printout from a
printer (by others) via an RS-232 electrical output; two
steps of demand load limiting and remote chilled liquid
reset from an external building automation system; unit
alarm contacts; chilled water pump or remote air-cooled
condenser control; or Remote Control with printout ca-
pability (up to 2000 feet) via an RS-485 electrical output.
POWER PANEL
The power panel shall contain the compressor power
terminals. U.L. recognized compressor motor starting
contactors which meet l.E.C. requirements, current trans-
former sensing for each compressor power source, for
protection against under current, over current, imbal-
anced current, single phasing compressor stall and
voltage spikes.
Guide Specifications - Cont.