York YR Owner's Manual page 14

Mechanical Specifications (continued)
sure Vessel Code, Section VIII, Division 1. Tubes shall
be high-efficiency, internally and externally enhanced
type having plain copper lands at all intermediate tube
supports to provide maximum tube wall thickness at
the support area. Each tube will be roller expanded into
the tube sheets providing a leak proof seal, and be indi-
vidually replaceable. Water velocity through the tubes
will not exceed 12 fps. The condenser will have refrig-
erant relief devices to meet the requirements of the
ASHRAE 15 Safety Code for Mechanical Refrigeration.
Water boxes will be removable to permit tube cleaning
and replacement. Stubout water connections having
victaulic grooves will be provided. Vent and drain con-
nections with plugs will be provided on each water box.
REFRIGERANT SYSTEM
A modulating variable orifice controlled by the OptiView
Control Center to accommodate varying head condi-
tions will meter refrigerant flow to the evaporator.
The condenser shell will be capable of storing the en-
tire system refrigerant charge during servicing. Service
valves will be provided to facilitate removal of refriger-
ant charge from the system.
The unit will be equipped with a suction strainer to pre-
vent any foreign debris introduced to the system during
maintenance or service to be allowed into the motor
housing. Motors cooled by refrigerant must be protected
by means of filter or strainer to protect the motor and
prolong motor life.
OPTIVIEW CONTROL CENTER
General
The chiller will be controlled by a stand-alone micro-
processor based control center. The chiller control panel
will provide control of chiller operation and monitoring
of chiller sensors, actuators, relays and switches.
Control Panel
The control panel will include a 10.4 inch diagonal color
liquid crystal display (LCD) surrounded by "soft " keys
which are redefined based on the screen displayed at
that time. It will be mounted in the middle of a keypad
interface and installed in a locked enclosure. The screen
will detail all operations and parameters, using a graphi-
cal representation of the chiller and its major compo-
nents. Panel verbiage is available in other languages
as an option with English always available. Data can be
displayed in either English or Metric units. Smart Freeze
Point Protection will run the chiller at 36 °F (2.2°C) leav-
14
ing chilled water temperature, and not have nuisance
trips on low water temperature. The sophisticated pro-
gram and sensor will monitor the chiller water tempera-
ture to prevent freeze up. When needed, Hot Gas By-
pass is available as an option. The panel displays count-
down timer messages so the operator knows when func-
tions are starting and stopping. Every programmable
point will have a pop-up screen with the allowable
ranges, so that the chiller can not be programmed to
operate outside of its design limits.
The control panel is provided with a thermal ice stor-
age control mode to enhance system performance dur-
ing ice building operation. In the thermal storage con-
trol mode, the chiller will stay at 100% load until the
setpoint shutdown temperature is reached. To add
greater operating flexibility and eliminate unnecessary
chiller cycling, two different Low Water (Liquid) Tem-
perature Restart Thresholds are programmable, one for
the ice mode and one for the standard cooling mode.
The chiller has the capability to remain in the standard
control mode for temperatures between 20 to 70°F (-
6.6 to 21.1°C) for applications involving a process or
comfort cooling duty that requires leaving chilled liquid
temperature setpoint control.
The chiller control panel also provides:
1. System operating information including:
a. return and leaving chilled liquid temperature
b. return and leaving condenser liquid
temperature
c. evaporator and condenser saturation
temperature
d. oil pressure at compressor and oil filter
differential
e. percent motor current
f. evaporator and condenser saturation
temperature
g. compressor discharge temperature
h. oil temperature
i. percent slide valve position
j. operating hours
k. number of unit starts
2. Digital programming of setpoints through the uni-
versal keypad including:
a. leaving chilled liquid temperature
b. percent current limit
c. pull-down demand limiting
d. six-week schedule for starting and stopping the
chiller, pumps and tower
e. remote reset temperature range
FORM 160.81-EG1
YORK INTERNATIONAL