System operating procedures
Pre-starting
Before starting the chiller, make sure the display reads SYSTEM READY TO START.
The panel can only boot up when line power is available to the VSD transformers and the UPS
battery in the power panel is present and connected with its disconnect closed.
CAUTION
After periods of waterside maintenance or prolonged shutdown, vent any air from the chiller water
boxes prior to starting the water pumps. Failure to do so can result in pass baffle damage.
Condenser water temperature control
The YORK YMC
2
chiller is designed to use less power by taking advantage of lower than design
temperatures that are naturally produced by cooling towers throughout the operating year. Exact
control of condenser water such as a cooling tower bypass, is not necessary for most installations.
The minimum entering condenser water temperature for other full and part-load conditions is
provided by the following equation:
where:
ECWT = entering condensing water temperature LCHWT = leaving chilled water
temperature
At initial startup, entering condensing water temperature may be as much as 30°F (16.66°C) colder
than the standby chilled water temperature.
Min ECWT = LCHWT -30°F (16.66°C)
At start-up, the entering condenser water temperature may be as much as 30°F (16.66°C) colder
than the standby return chilled water temperature. Cooling tower fan cycling will normally provide
adequate control of the entering condenser water temperature on most installations.
Start-up
If the chilled water and/or condenser water pumps are manually operated, start the pump. The
Control Center will not allow the chiller to start unless chilled liquid flow is established through the
unit. If the liquid pumps are wired to the Microcomputer Control Center pump run contacts, the
pump will automatically start, therefore, this step is not necessary.
Note: The coolant temperature inside any JCI-supplied liquid-cooled motor starter must be
maintained above the dewpoint temperature in the equipment room to prevent condensing
water vapor inside the starter cabinet. Therefore, an additional temperature-controlled throttle
valve is needed in the flow path for the starter heat exchanger to regulate cooling above the
equipment room dewpoint for applications using cooling sources other than evaporative air-
exchange methods, such as wells, bodies of water, and chilled water. The temperature control
valve should be the type to open on increasing drive coolant temperature, fail-closed, and set
for a temperature above dewpoint. It can be requested as factory-supplied on a chiller order
by special quotation.
19
YMC
2
Mod B with OptiView
™
Control Center
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