Amendment -02 05500-081209 Spec 2.pdf

Modernization of the South Building Contract No. 53-3142-4-6049

US Department of Agriculture

July 31, 2009

Amendment 1 15682-1 Air Cooled Water Chillers

SECTION 15682

AIR COOLED WATER CHILLERS

PART 1 - GENERAL

1.1 PRINCIPAL WORK IN THIS SECTION

A. Chiller package.

B. Charge of refrigerant and oil.

C. Controls and control connections.

D. Chilled water connections.

E. Starters.

1.2 SUBMITTALS

A. Product data: Catalog cuts giving rated capacities, weights, specialties and accessories and electrical requirements.

1.3 OPERATION AND MAINTENANCE DATA

A. Include start-up instructions, maintenance data, parts lists, controls, and accessories.

Include trouble- shooting guide.

PART 2 - PRODUCTS

2.1 MANUFACTURERS

A. Technical Systems.

B. York International.

C. McQuay.

D. Trane.

2.2 UNIT DESCRIPTION

A. Provide and install as shown on the plans, factory assembled, factory charged with HFC-

134a refrigerant and factory run-tested, air-cooled, rotary screw compressor packaged chillers in the quantity specified. Each chiller shall consist of multiple semi-hermetic rotary screw compressors, shell-and-tube evaporator, air-cooled condenser section, control system and all components necessary for protected and controlled unit operation.

Amendment 1 15682-2 Air Cooled Water Chillers

2.3 DESIGN REQUIREMENTS

A. General: Provide a complete rotary-screw packaged chiller as specified herein and as shown on the drawings.

B. Performance: Refer to the schedule of performance on the drawings. The chiller shall be capable of stable operation to a minimum of 12.5 percent of full load without hot gas bypass. Performance shall be in accordance with ARI Standard 550/590-98. The standard unit shall be capable of operating at ambient temperatures down to 0°F (-18°C), and up to 105°F (41°C). Scheduled condition is 95°F.

2.4 CHILLER COMPONENTS

A. Compressors: The compressors shall be field serviceable, semi-hermetic, single-rotor screw type with one central helical rotor meshing with two opposing gaterotors.

Compressor capacity shall be controlled with an infinite position slide valve, accurately matching compressor capacity to load. Compressors shall be sound and vibration isolated from the frame by neoprene compression mounts. The manufacturer shall provide a 5-year parts and labor warranty covering all compressor parts.

B. Electric motors: Motors shall be high torque, two-pole, semi-hermetic, induction type with inherent thermal protection and cooled by suction gas.

C. Solid-State Motor Starters (for each compressor): Starter shall be designed using the current generation of reliable solid-state technology. Each starter shall provide controlled motor acceleration and deceleration, and shall extend protections covering the following conditions: phase rotation, electronic thermal overload, over/under current, stalled motor, single phase, high load current and current unbalance. Across-the-line or wye-delta starters are not acceptable. Acceptable solid-state starter manufacturers are General

Electric, Cutler-Hammer, Benshaw or Reliance. The solid state starters shall be capable of self-diagnostics, metering, and have an LED display to include the following operating and fault messages:

1. Operating Messages:

a. Line voltage not present.

b. Voltage present, starter ready.

c. Motor accelerating.

d. Motor at full speed.

e. Motor at full speed, ramp time expired.

f. Stop command received, motor decelerating.

g. Thermal overload has reached 90% to 99%.

h. Thermal overload at 100%, motor stopped.

i. Thermal overload reduced to 60%, motor can restart.

j. Passcode enabled.

k. Passcode disabled.

Amendment 1 15682-3 Air Cooled Water Chillers

l. Thermal overload content in percentage.

2. Fault Messages:

a. System power not three phase.

b. Phase sequence incorrect.

c. Line frequency less than 25 Hz.

d. Line frequency more than 72 Hz.

e. Excessive current unbalance.

f. Operating parameters lost.

g. No current after "Run" command.

h. Undercurrent trip occurred.

i. Overcurrent trip occurred.

j. Control power too low.

k. Motor stalled during acceleration.

l. External fault.

D. Evaporator: The evaporator shall be flooded type with individual refrigerant circuits. The evaporator shall be made up of a carbon steel shell and high efficiency internally finned copper tubes rolled into steel tubesheets. Water side, the evaporator shall be rated at heads. Heads shall be removable for serviceability. Water connections shall be left-handed as shown on the drawings. The evaporator shall be insulated with minimum 1-1/2 inch (38mm) closed cell polyurethane insulation and electrically heated to help provide ambient freeze protection to 0°F (-17°C). The evaporator shall be designed, inspected and stamped in accordance with ASME Section VIII requirements.

E. Condenser: The condenser coils shall have seamless copper tubing, mechanically bonded into aluminum plate-type fins. The fins shall have full drawn collars, completely covering the tubes for protection against atmospheric corrosion and to provide greater heat transfer. A sub-cooling coil shall be an integral part of the main condenser coil. All external coil surfaces shall be protected by PVC coated welded-wire-mesh grills.

Condenser fans shall be propeller type, arranged for vertical air discharge and individually driven by direct drive motors. Each fan shall be housed in its own compartment to eliminate condenser-air cross flow during fan cycling and shall be equipped with a heavy-gauge close-meshed PVC coated fan guard. Fan motors shall be weather protected, three-phase, direct-drive, 1140 rpm, totally enclosed air-over motors with class F insulation or better. Vertical service clearance under the condenser coil shall be minimum six feet for access to the compressor and major components. The condenser shall permit pump-down and storage of the full refrigerant charge for compressor serviceability.

F. Refrigerant Circuit: The unit shall have two or more refrigerant circuits, completely independent of each other. Each circuit shall be equipped with one compressor, one microprocessor controller, a factory-mounted control circuit transformer, oil separator, electronic expansion valve, compressor suction shutoff valve, discharge check valve, liquid line shutoff valves, replaceable core filter-dryers, sight-glass with moisture indicator and insulated suction line. Each circuit shall be capable of operating

Amendment 1 15682-4 Air Cooled Water Chillers independently, not being disabled in the event of fault(s) on the other circuit(s).

G. Unit casing and all structural members and rails shall be painted to meet ASTM B117, 500-hour salt-spray test. The control enclosure and unit panels shall be cleaned, phosphatized and then corrosion resistant urethane painted before assembly.

H. Advanced microprocessor based control system: The control system architecture shall provide distributed-control where each compressor circuit has its own microprocessor controller so in the event that one controller becomes inoperative, the other circuits will continue to operate uninterrupted.

1. Controls shall be Johnson Controls/Lonworks compatible.

2. Control Panel: A NEMA Type 3R weatherproof control panel shall contain the unit control system, control interlock terminals and field-power connection points.

Hinged control panel access doors shall be lockable. Barrier panels shall be provided to protect against accidental contact with line voltage when accessing the control system.

3. Factory-supplied power components shall include: single point power block with circuit breaker, individual contactors and circuit breakers for fan motors, circuit breakers and factory mounted transformers for each control-circuit, unit power terminal blocks for connection to remote disconnect switch, terminals for power supply to the evaporator heater circuit.. Fan motors shall have inherent overload protection and compressor motors shall have three-phase motor overload protection.

4. Control system starting components shall include solid-state start timer.

5. The control logic shall be designed to maximize operating efficiency and equipment life with protections for operation under unusual conditions and to provide a history of operating conditions. The system shall intelligently stage the unit to sustain leaving water temperature precision and stability while minimizing compressor cycling.

6. Equipment protection functions controlled by the microprocessor shall include high discharge pressure, loss of refrigerant, loss of water flow, freeze protection, and low refrigerant pressure.

7. User controls shall include auto/stop switch, chilled water set-point adjustment, anti-recycle timer, and digital display with water temperature and set-point, operating temperatures and pressures, and diagnostic messages.

8. The following features and functions shall be included:

a. Separate control section and password protection for critical parameters.

b. Remote reset of chilled water temperature using a 4-20mA signal.

c. Soft-load operation, protecting the compressor by preventing full-load operation during the initial chilled fluid pull-down period.

d. Provide standardized protocol for LONWORKS®.

e. Non-volatile program memory allowing auto-restart after a power failure without requiring a UPS (un-interruptible power supply).

f. Recording of safety shutdowns, including date-and-time stamp with

Amendment 1 15682-5 Air Cooled Water Chillers system temperatures and pressures. A minimum of six previous occurrences shall be maintained in a revolving memory.

g. Start-to-start and stop-to-start cycle timers, further optimizing motor protection.

h. Lead-lag compressor staging for part-load operation by manual selection or automatically by circuit run hours.

i. Discharge pressure control through intelligent cycling of condenser fans to maximize efficiency.

j. Pro-active compressor unloading when selected operating parameters exceed design settings, such as high discharge pressure or low evaporator pressure.

k. Diagnostic monitoring of unit operation, providing a pre-alarm signal in advance of a potential shutdown, allowing time for corrective action.

2.5 OPTIONS AND ACCESSORIES

A. The following options are to be included:

1. Single point disconnect with branch circuit breakers.

2. Double evaporator insulation.

3. VFD low ambient head pressure control to 0°F (-17°C).

4. Lonmark/Johnson controller.

5. Suction shut-off valve.

6. 115 V convenience outlet.

7. 4 year compressor parts warranty.

PART 3 - EXECUTION

3.1 INSTALLATION

A. Install in accordance with manufacturer's instructions.

B. Connect to electrical service.

C. Arrange piping for easy dismantling to permit tube cleaning.

3.2 MANUFACTURER'S FIELD SERVICES

A. Prepare and start systems under provisions of Division 1.

B. Supply service of factory trained representative for a period of 2 days to supervise testing, dehydration and charging of machine, start-up, and instruction on operation and maintenance to

Owner.

C. Supply initial charge of refrigerant and oil.

3.3 COMMISSIONING

Amendment 1 15682-6 Air Cooled Water Chillers

A. Provide systems demonstration under provisions of Section Division 1.

B. Demonstrate system operation and verify specified performance.

END OF SECTION