York YR Mechanical Specifications Form 160.81-EG1, Refrigerant System, General, Control Panel

Mechanical Specifications (continued)FORM 160.81-EG1

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-

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 (-

6.6to 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

14 YORK INTERNATIONAL