Thermal Insulation; Ventilation; Electrical Considerations - York YK Manual

FORM 160.75-EG1 (519)
Application Data (Cont'd)

THERMAL INSULATION

No appreciable operating economy can be achieved by thermally insulating the chiller.
However, the chiller's cold surfaces should be insulated with vapor barrier insulation suf-
ficient to prevent condensation. A chiller can be factory-insulated with 3/4" (19 mm) or 1
1/2" (38 mm) thick insulation, as an option. This insulation will normally prevent conden-
sation in environments with dry bulb temperatures of 50°F to 90°F (10°C to 32°C) and
relative humidities up to 75% [3/4" (19 mm) thickness] or 90% [1 1/2" (38 mm) thickness].
The insulation is painted and the surface is flexible and reasonably resistant to wear. It is
intended for a chiller installed indoors and, therefore, no protective covering of the insula-
tion is usually required. If insulation is applied to the waterboxes at the job site, it must be
removable to permit access to the tubes for routine maintenance.

VENTILATION

The ASHRAE Standard 15 Safety Code for Mechanical Refrigeration requires that all ma-
chinery rooms be vented to the outdoors utilizing mechanical ventilation by one or more
power driven fans. This standard, plus National Fire Protection Association Standard 90A,
state, local and any other related codes should be reviewed for specific requirements.
Since the YK chiller motor is air-cooled, ventilation should allow for the removal of heat
from the motor.
In addition, the ASHRAE Standard 15 requires a refrigerant vapor detector to be em-
ployed for all refrigerants. It is to be located in an area where refrigerant from a leak would
be likely to concentrate. An alarm is to be activated and the mechanical ventilation started
at a value no greater than the TLV (Threshold Limit Value) of the refrigerant.

ELECTRICAL CONSIDERATIONS

Motor Voltage – Low voltage motors (200 V to 600 V) are furnished with six leads. Me-
dium voltage (2300 V to 13800 V) motors have three leads. Motor circuit conductor size
must be in accordance with the National Electrical Code (NEC), or other applicable codes,
for the motor full load amperes (FLA). Flexible conduit should be used for the last several
feet to the chiller in order to provide vibration isolation. Table 5 - Motor Voltage Variations
on page 47 lists the allowable variation in voltage supplied to the chiller motor. The unit
name plate is stamped with the specific motor voltage, and frequency for the appropriate
motor.
Starters – A separate starter is not required if the chiller is equipped with a Variable
Speed Drive (VSD). The YK Chillers are also available with a factory mounted and wired
YORK Solid-State Starter for low and medium voltage applications. Other types of re-
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mote mounted starters are available. Electromechanical starters must be furnished in
accordance with YORK Standard Specifications (R-1132) (Form 160.76-PA1). This will
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ensure that starter components, controls, circuits, and terminal markings will be suitable
for required overall system performance. Remote-mounted medium voltage YORK Sol-
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id-State Starters are also available.
Controls – A 115 volt, single-phase, 60 or 50 Hertz 2 KVA power supply must be fur-
nished to the chiller from a separate, fused disconnect or from a control transformer in-
cluded as an option with electromechanical starters. No field control wiring is required
when the low voltage YORK Variable Speed Drive or Solid-State Starter is supplied.
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JOHNSON CONTROLS 45