Specifications

Catalog WSC/WDC-4 91
2. Tubes shall be enhanced for maximum heat transfer, rolled into steel tube sheets
and sealed with Locktite or equal sealer. The tubes shall be individually
replaceable and secured to the intermediate supports without rolling.
3. Provide sufficient isolation valves and condenser volume to hold full refrigerant
charge in the condenser during servicing or provide a separate pumpout system and
storage tank sufficient to hold the charge of the largest unit being furnished.
4. The water sides shall be designed for a minimum of 150 psig or as specified
elsewhere. Vents and drains shall be provided.
5. Chilled water minimum refrigerant temperature shall be 33°F.
6. An electronic or thermal refrigerant expansion valve shall control refrigerant flow
to the evaporator. Fixed orifice devices or float controls with hot gas bypass are
not acceptable because of inefficient control at low load conditions. The liquid
line shall have a moisture indicating sight glass.
7. The evaporator and condenser shall be separate shells. A single shell containing
both vessel functions is not acceptable because of the possibility of internal leaks.
8. Interstage economizers shall be used between each compressor stage for increased
efficiency.
9. Reseating type spring loaded pressure relief valves according to ASHRAE-15
safety code shall be furnished. The evaporator shall be provided with single or
multiple valves. The condenser shall be provided with dual relief valves equipped
with a transfer valve so one valve can be removed for testing or replacement
without loss of refrigerant or removal of refrigerant from the vessel. Rupture disks
are not acceptable.
10. The evaporator, suction line, and any other component or part of a component
subject to condensing moisture shall be insulated with UL recognized 3/4 inch
closed cell insulation. All joints and seams shall be carefully sealed to form a
vapor barrier.
11. Provide Factory-mounted thermal dispersion flow switches on each vessel to
prevent unit operation with no flow, furnished, installed and wired by the
contractor.
D. Prime Mover: Squirrel cage induction motor of the hermetic type of sufficient size to
efficiently fulfill compressor horsepower requirements. Motor shall be liquid refrigerant
cooled with internal thermal overload protection devices embedded in the winding of each
phase. Motor shall be compatible with the starting method specified hereinafter. If the
Contractor chooses to provided an open drive motor or compressor, verify in the submittal
that the scheduled chiller room ventilation system will accommodate the additional heat
and maintain the equipment room at design indoor temperature based on 95°F outdoor
ambient ventilation air available.
If additional cooling is required, manufacturer shall be responsible for the installation,
wiring and controls of a cooling system. Chiller selection shall compensate for tons and
efficiency loss to make certain the owner is not penalized.
E. Motor Starters:
1. The main motor starters are to be factory mounted and fully wired to the chiller
components and factory tested during the run test of the unit.
-- OR --
The main motor starters are to be furnished by the chiller manufacturer and
shipped loose for floor mounting and field wiring to the chiller package. They
shall be free-standing with NEMA-1 enclosure designed for top entry and bottom
exit and with front access.
2. For air-cooled motors the chiller manufacturer shall be responsible for providing
the cooling of the refrigeration machinery room. The sensible cooling load shall
be based on the total heat rejection to the atmosphere from tow refrigeration units.
3. For open motor unit, an oil reservoir shall collect any oil and refrigerant that leaks
past the seal. A float device shall be provided to open when the reservoir is full,
directing the refrigerant/oil mixture back into the compressor housing.