SP4702-15-R-0022 _Spec_Section_23_64_15.pdf

SECTION 23 64 15

ROTARY-SCREW WATER CHILLERS (AIR-COOLED)

PART 1 GENERAL

1.01 SECTION INCLUDES

A. Chiller package.

B. Charge of refrigerant and oil.

C. Controls and control connections.

D. Chilled water connections.

E. Integral Hydronic Pumping Package.

F. Starters.

G. Electrical power connections.

H. Manufacturer-supplied Sound Attenuator

1.02 REFERENCES

A. ANSI/ARI 550/590-98 - Standard for Water Chilling Packages using the Vapor Compression Cycle.

B. ANSI/ASHRAE 15 - Safety Code for Mechanical Refrigeration.

C. ANSI/ASHRAE 90.1-1999 - Energy Efficient Design of New Buildings.

D. ANSI/ASME SEC 8 - Boiler and Pressure Vessel Code

E. ANSI/NEMA MG 1 - Motors and Generators.

F. ANSI/UL 1995 - Central Cooling Air Conditioners.

G. ANSI/AFBMA 9-1978 - Load Ratings and Fatigue Life for Ball Bearings. Bearings must have life of not less than L10 200,000 hours.

H. ARI 370 - Sound Rating of Large Refrigeration and Air-conditioning Equipment

1.03 SUBMITTALS

A. Submit drawings indicating components, assembly, dimensions, weights and loadings, required clearances, and location and size of field connections. Indicate accessories where required for complete system.

B. Submit product data indicating rated capacities, weights, specialties and accessories, electrical requirements and wiring diagrams.

C. Submit manufacturer's installation instructions.

1.04 OPERATION AND MAINTENANCE DATA

A. Submit operation data.

B. Include start-up instructions, maintenance data, controls, and accessories.

C. Submit maintenance data.

Section 23 64 15

1.05 REGULATORY REQUIREMENTS

A. Conform to ANSI/ARI 550/590-98 Standard for testing and certified rating of Water Chilling Packages using the Vapor Compression Cycle.

B. Conform to ANSI/UL 1995 code for construction of water chillers. In the event the unit is not UL approved, the manufacturer shall, at his expense, provide for a field inspection by a UL representative to verify conformance to UL standards. If necessary, contractor shall perform modifications to the unit to comply with UL, as directed by the UL representative.

C. Conform to ANSI/ASME SEC 8 Boiler and Pressure Vessel Code for construction and testing of water chillers.

D. Conform to ANSI/ASHRAE 15 code for construction and operation of water chillers.

1.06 STORAGE AND HANDLING

A. Comply with manufacturer's installation instructions for rigging, unloading, and transporting units.

B. Protect units from physical damage. Factory coil shipping covers shall be provided at the factory and kept in place until completion of installation.

C. Unit controls shall be capable of withstanding 203 Deg F (95 Deg C) storage temperatures in the control compartment for an indefinite period of time.

1.07 Warranty

A. Manufacturer shall provide 1st Year Parts & Labor Warranty for whole chiller including refrigerant.

B. Manufacturer shall provide 5 year Parts & Labor Warranty for compressor/motor/drive-line including refrigerant.

C. Provide 1st Year Factory Certified Start-up.

1.08 Proof of Prior Acceptable Installations

The contractor shall submit detailed submittals of locations within 500 miles of Columbus Ohio where similar equipment installations have occurred within the past 3 years, including equipment sizes, models provided, record of failures/adjustments, and contact information for maintenance and/or engineering personnel at the installation.

PART 2 PRODUCTS

2.01 SUMMARY

A. The contractor shall furnish and install air-cooled water chillers as shown as scheduled on the contract documents. The chillers shall be installed in accordance with this specification and perform at the specified conditions as scheduled.

B. APPROVED MANUFACTURERS

1. Trane

2. Carrier

3. York

2.02 COMPRESSORS

A. Construct chiller using semi-hermetic helical rotary screw compressors with dual independent circuits. Reciprocating compressors are not acceptable.

B. Statically and dynamically balance rotating parts.

C. Provide oil lubrication system with oil charging valve and oil filter to ensure adequate lubrication during starting, stopping, and normal operation.

D. Provide compressor with automatic capacity reduction equipment consisting of suction valve unloaders or capacity control slide valve (rotary). Use lifting mechanism operated by oil pressure. Compressor must start unloaded for soft start on motors.

E. Provide constant speed 3600 rpm compressor motor, suction gas cooled with solid state sensor and electronic winding overheating protection, designed for across-the-line starting.. Furnish with starter. Compressor motor power factor shall be .90 or greater, to provide for more efficient operation. If the compressor motor power factor is less than .90, power factor correction capacitors must be installed.

F. Provide crankcase heater to evaporate refrigerant returning to crankcase during shut down. Energize heater when compressor is not operating.

2.03 EVAPORATOR

A. Insulate the evaporator, evaporator heads, and suction lines (all cold surfaces) with 0.75 inch (20mm) minimum thick flexible elastomeric rubber closed cell insulation with a maximum k value of 0.26.

B. Provide shell and tube type evaporator, seamless or welded steel construction with cast iron or fabricated steel heads, seamless internally finned copper tubes, roller expanded into tube sheets.

C. Design, test, and stamp refrigerant side for 300 psig working pressure and water side for 215 psig working pressure, in accordance with ANSI/ASME SEC 8.

D. Provide water drain connection, vent and fittings for factory installed leaving water temperature control and low temperature cutout sensors.

E. Water connections shall be grooved pipe. Evaporator shall have only one entering and one leaving connection. If manufacturer provides 2 separate evaporators, contractor shall provide manifold and pressure gauges to ensure equal flow is provided to each evaporator.

2.04 INTEGRAL HYDRONIC PUMPING PACKAGE

A. A factory installed hydronic pumping package shall be furnished complete from chiller manufacturer. Pumping package shall consist of: dual pumps, suction diffusers, triple duty valves, VFDs with bypass and fused disconnect, pressure and temperature gauges, flow switch and strainer.

Contractor shall provide bypass line with motorized modulating 2-way control valve and pressure sensor. Bypass line shall be sized to maintain minimum flow through chiller. Control valve shall modulate based on a signal from the pressure sensor. The VFDs shall also modulate based on the same signal. The bypass line shall be field-installed due to lower system pressure drop losses.

B. The pumps shall be close coupled, foot mounted, single stage, end suction, vertical split case design, in cast iron bronze fitted (or all bronze or all iron) construction specifically designed for quiet operation. Suitable standard operations at 225 F and 175 PSIG working pressure or optional operations at up to 250 F and 250 PSIG working pressures.

Working pressures shall not be de-rated at temperatures up to 250F. The pump internals shall be capable of being services without disturbing piping connections.

C. Not Used.

D. The unit shall be factory equipped with an angle pattern flow straightening fitting equipped with a combination diffuser-strainer-orifice cylinder, flow straightening vanes, and start-up strainer. The combination diffuser-strainer-orifice cylinder shall be designed to withstand pressure differential equal to the system pump shutoff head and shall have a free area equal to five times the cross section area of the pump suction opening. The length of the flow straightening vanes shall be no less than 2-1/2 times the diameter of the system pump suction connection. The flow-straightening fitting shall be of cast iron and rated for a Maximum Working Pressure of 175 PSIG. The full-length carbon steel flow straightening vanes shall provide non-turbulent flow to the suction side of the system pump. The start-up strainer shall be of 16-mesh bronze and will need to be permanently removed after the fill and flush period of start-up is complete. All internal components shall be replaceable.

E. The unit shall be factory equipped with a combination straight/angle pattern valve designed to perform the functions of a non-slam check valve, throttling valve, shutoff valve, calibrated balancing valve, and a system flow meter. The valve shall be of heavy-duty cast iron construction and rated for a maximum working pressure of 175 PSIG at 250°F. The valve shall be fitted with a soft seat (brass), replaceable brass disc, brass stem, and chatter preventing stainless steel spring. The valve design shall permit repacking under full system pressure. Each valve shall be equipped with brass readout valves (with integral check valve) for taking differential pressure readings across the orifice to accurately balance the system to specified design conditions.

F. Insulate the chilled water supply and return suction lines, piping components, and bypass line (all cold surfaces) with 0.75 inch (20mm) minimum thick flexible elastomeric rubber closed cell insulation with a maximum k value of 0.26.

G. Entire unit shall be single point power and factory wired in accordance with NFPA 70. Controls wiring for pump start-stop functionality shall be wired to appropriate controls device, and shall be fully native BACnet configuration, such that the unit can be immediately and fully integrated with existing base energy management and control system (Siemens Insight system). Wiring shall be labeled and color-coded. Pumping package shall be factory-wired to chiller power supply/disconnect and provide the installing contractor with single-point power connections in the field. All three-phase motors shall be protected from short circuits by current limiting fuses.

2.05 CHILLER PUMP VFD DRIVES

A. Furnish complete variable frequency VFDs as specified herein for the fans and pumps designated on the drawing schedules to be variable speed. All standard and optional features shall be included within the VFD enclosure, unless otherwise specified. VFD shall be housed in a metal NEMA 1 enclosure, or other NEMA type according to the installation and operating conditions at the job site. The VFD’s UL listing shall allow mounting in plenum or other air handling compartments. If a NEMA 12 enclosure is required for the plenum rating, the manufacturer must supply a NEMA 12 rated VFD.

B. The VFD shall convert incoming fixed frequency three-phase AC power into a variable frequency and voltage for controlling the speed of three-phase AC motors. The motor current shall closely approximate a sine wave. Motor voltage shall be varied with frequency to maintain desired motor magnetization current suitable for centrifugal pump and fan control and to eliminate the need for motor de-rating.

C. With the motor’s rated voltage applied to the VFD input, the VFD shall allow the motor to produce full rated power at rated amps, RMS fundamental volts, and speed without using the motor's service factor. VFDs utilizing sine weighted/coded modulation (with or without 3rd harmonic injection) must provide data verifying that the motors will not draw more than full load current during full load and full speed operation.

D. The VFD shall include an input full-wave bridge rectifier and maintain a fundamental power factor near unity regardless of speed or load.

E. The VFD and options shall be tested to ANSI/UL Standard 508. The complete VFD, including all specified options, shall be assembled by the manufacturer, which shall be UL-508 certified for the building and assembly of option panels.

Assembly of the option panels by a third-party panel shop is not acceptable. The appropriate UL stickers shall be applied to both the VFD and option panel, in the case where these are not contained in one panel. When these VFDs are to be located in Canada, CSA or C-UL certifications shall apply. Both VFD and option panel shall be manufactured in ISO 9001 certified facilities.

F. The VFD shall have DC link reactors on both the positive and negative rails of the DC bus to minimize power line harmonics. VFDs without DC link reactors shall provide a minimum 3% impedance line reactor.

G. The VFD’s full load amp rating shall meet or exceed NEC Table 430-150. The VFD shall be able to provide full rated output current continuously, 110% of rated current for 60 seconds and 160% of rated current for up to 0.5 second while starting.

H. The VFD shall be able to provide full torque at any selected frequency from 28 Hz to base speed to allow driving direct drive fans without derating.

I. An automatic energy optimization selection feature shall be provided standard in the VFD. This feature shall automatically and continually monitor the motor’s speed and load and adjust the applied voltage to maximize energy savings and provide up to an additional 3% to 10% energy savings.

J. Input and output power circuit switching shall be able to be accomplished without interlocks or damage to the VFD.

Switching rate may be up to 1 time per minute on the input and unlimited on the output.

K. An automatic motor adaptation test algorithm shall measure motor stator resistance and reactance to optimize performance and efficiency. It shall not be necessary to run the motor or de-couple the motor from the load to run the test.

L. Galvanic and/or optical isolation shall be provided between the VFD’s power circuitry and control circuitry to ensure operator safety and to protect connected electronic control equipment from damage caused by voltage spikes, current surges, and ground loop currents. VFDs not including either galvanic or optical isolation on both analog I/O and discrete I/O shall include additional isolation modules.

M. VFD shall minimize the audible motor noise through the used of an adjustable carrier frequency. The carrier frequency shall be automatically adjusted to optimize motor and VFD efficiencies while reducing motor noise.

N. PROTECTIVE FEATURES

1) A minimum of Class 20 I2t electronic motor overload protection for single motor applications and thermal-mechanical overloads for multiple motor applications shall be provided.

2) Protection against input transients, loss of AC line phase, output short circuit, output ground fault, overvoltage, undervoltage, VFD overtemperature and motor overtemperature. The VFD shall display all faults in plain English. Codes are not acceptable.

3) Protect VFD from sustained power or phase loss. The VFD shall provide full rated output with an input voltage as low as

90% of the nominal. The VFD will continue to operate with reduced output with an input voltage as low as 164 V AC for 208/230 volt units, 313 V AC for 460 volt units, and 394 volts for 600 volts units.

4) The VFD shall incorporate a motor preheat circuit to keep the motor warm and prevent condensation build up in the stator.

5) VFD package shall include semi-conductor rated input fuses to protect power components.

6) To prevent breakdown of the motor winding insulation, the VFD shall be designed to comply with IEC Part 34-17. Otherwise the VFD manufacturer must ensure that inverter rated motors are supplied.

7) VFD shall include a “signal loss detection” circuit to sense the loss of an analog input signal such as 4 to 20 mA or 2 to 10 V

DC, and shall be programmable to react as desired in such an instance.

8) VFD shall function normally when the keypad is removed while the VFD is running and continue to follow remote commands. No warnings or alarms shall be issued as a result of removing the keypad.

9) VFD shall catch a rotating motor operating forward or reverse up to full speed.

10) VFD shall be rated for 100,000 amp interrupting capacity (AIC).

11) VFD shall include current sensors on all three output phases to detect and report phase loss to the motor. The VFD will identify which of the output phases is low or lost.

12) VFD shall continue to operate without faulting until input voltage reaches 300 V AC on 208/230 volt units, 539 V AC on

460 volt units, and 690 volts on 600 volt units.

O. INTERFACE FEATURES

1) Hand/Start, Off/Stop and Auto/Start selector switches shall be provided to start and stop the VFD and determine the speed reference.

2) The VFD shall be able to be programmed to provide a 24 V DC output signal to indicate that the VFD is in Auto/Remote mode.

3) The VFD shall provide digital manual speed control. Potentiometers are not acceptable.

4) Lockable, alphanumeric backlit display keypad can be remotely mounted up to 10 feet away using standard 9-pin cable.

5) The keypads for all sizes of VFDs shall be identical and interchangeable.

6) To set up multiple VFDs, it shall be possible to upload all setup parameters to the VFD’s keypad, place that keypad on all other VFDs in turn and download the setup parameters to each VFD. To facilitate setting up VFDs of various sizes, it shall be possible to download from the keypad only size independent parameters.

7) Display shall be programmable to display in 9 languages including English, Spanish and French. All displays shall be able to be selected as either Imperial (inch-pound) or metric system units.

8) The display shall have four lines, with 20 characters on three lines and eight large characters on one line.

9) A red FAULT light, a yellow WARNING light and a green POWER-ON light shall be provided. These indications shall be visible both on the keypad and on the VFD when the keypad is removed.

10) A quick setup menu with factory preset typical HVAC parameters shall be provided on the VFD eliminating the need for macros.

11) The VFD shall include a standard EIA-485 communications port and capabilities to be connected at a future date to a

Johnson Controls N2 Metasys or Siemens FLN system at no additional cost to the owner. The connection shall be software selectable by the user.

12) As a minimum, the following points shall be controlled and/or accessible:

1) VFD Start/Stop

2) Speed reference

3) Fault diagnostics

4) Meter points

(1) Motor power in HP

(2) Motor power in kW

(3) Motor kW-hr

(4) Motor current

(5) Motor voltage

(6) Hours run

(7) Feedback signal #1

(8) Feedback signal #2

(9) DC link voltage

(10) Thermal load on motor

(11) Thermal load on VFD

(12) Heatsink temperature

13) Four additional Form C 230 volt programmable relays shall be available for factory or field installation within the VFD.

14) BACnet communication shall be provided for all devices, whether factory or field installation within the VFD.

15) Two set-point control interface (PID control) shall be standard in the unit. VFD shall be able to look at two feedback signals, compare with two set-points and make various process control decisions.

16) Floating point control interface shall be provided to increase/decrease speed in response to contact closures.

17) Four simultaneous displays shall be available. They shall include frequency or speed, run time, output amps and output power. VFDs unable to show these four displays simultaneously shall provide panel meters.

18) Sleep mode shall be provided to automatically stop the VFD when its speed drops below set “sleep” level for a specified time. The VFD shall automatically restart when the speed command exceeds the set “wake” level.

19) The sleep mode shall be functional in both follower mode and PID mode.

20) Run permissive circuit shall be provided to accept a “system ready” signal to ensure that the VFD does not start until dampers or other auxiliary equipment are in the proper state for VFD operation. The run permissive circuit shall also be capable of sending an output signal as a start command to actuate external equipment before allowing the VFD to start.

21) The following displays shall be accessible from the control panel in actual units: Reference Signal Value in actual units, Output Frequency in Hz or percent, Output Amps, Motor HP, Motor kW, kWhr, Output Voltage, DC Bus Voltage, VFD Temperature in degrees, and Motor Speed in engineering units per application (in GPM, CFM, etc.). VFD will read out the selected engineering unit either in a linear, square or cubed relationship to output frequency as appropriate to the unit chosen.

22) The display shall be programmed to read in inches of water column (in-wg) for an air handler application, pressure per square inch (psi) for a pump application, and temperature (oF) for a cooling tower application.

23) VFD shall be able to be programmed to sense the loss of load and signal a no load/broken belt warning or fault.

24) If the temperature of the VFD’s heat sink rises to 80°C, the VFD shall automatically reduce its carrier frequency to reduce the heat sink temperature. If the temperature of the heat sink continues to rise the VFD shall automatically reduce its output frequency to the motor. As the VFD’s heat sink temperature returns to normal, the VFD shall automatically increase the output frequency to the motor and return the carrier frequency to its normal switching speed.

25) The VFD shall have temperature controlled cooling fans for quiet operation and minimized losses.

26) The VFD shall store in memory the last 10 faults and related operational data.

27) Eight programmable digital inputs shall be provided for interfacing with the systems control and safety interlock circuitry.

28) Two programmable relay outputs, one Form C 240 V AC, one Form A 30 V AC, shall be provided for remote indication of

VFD status.

29) Three programmable analog inputs shall be provided and shall accept a direct-or-reverse acting signal. Analog reference inputs accepted shall include two voltage (0 to 10 V DC, 2 to 10 V DC) and one current (0 to 20 mA, 4 to 20 mA) input.

30) Two programmable 0 to 20 mA analog outputs shall be provided for indication of VFD status. These outputs shall be programmable for output speed, frequency, current and power. They shall also be programmable to provide a selected 24 V DC status indication.

31) Under fire mode conditions, the VFD shall be able to be programmed to automatically default to a preset speed.

P. ADJUSTMENTS

1) VFD shall have an adjustable carrier frequency in steps of not less than 0.1 kHz to allow tuning the VFD to the motor.

2) Sixteen preset speeds shall be provided.

3) Four acceleration and four deceleration ramps shall be provided. Accel and decel time shall be adjustable over the range from

0 to 3,600 seconds to base speed. The shape of these curves shall be automatically contoured to ensure no-trip acceleration and deceleration.

4) Four current limit settings shall be provided.

5) If the VFD trips on one of the following conditions, the VFD shall be programmable for automatic or manual reset:

undervoltage, overvoltage, current limit and inverter overload.

6) The number of restart attempts shall be selectable from 0 through 20 or infinitely and the time between attempts shall be adjustable from 0 through 600 seconds.

7) An automatic “on delay” may be selected from 0 to 120 seconds.

Q. BYPASS

Service personnel shall be able to defeat the main power disconnect and open the bypass enclosure without disconnecting power. This shall be accomplished through the use of a specially designed tool and mechanism while meeting all local and national code requirements for safety.

R. SERVICE CONDITIONS

1) Ambient temperature, -10 to 40°C (14 to 104°F).

2) 0 to 95% relative humidity, non-condensing.

3) Elevation to 3,300 feet without derating.

4) AC line voltage variation, -10 to +10% of nominal with full output.

5) No side clearance shall be required for cooling of any units. All power and control wiring shall be done from the bottom.

S. QUALITY ASSURANCE

1) To ensure quality and minimize infantile failures at the jobsite, the complete VFD shall be tested by the manufacturer. The

VFD shall operate a dynamometer at full load and speed and shall be cycled during the test.

2) All optional features shall be functionally tested at the factory for proper operation.

T. SUBMITTALS

1) Submit manufacturer’s performance data including dimensional drawings, power circuit diagrams, installation and maintenance manuals, warranty description, VFD's FLA rating, certification agency file numbers and catalog information.

2) The specification lists the minimum VFD performance requirements for this project. Each supplier shall list any exceptions to the specification. If no departures from the specification are identified, the supplier shall be bound by the specification.

3) Harmonic filtering. The seller shall, with the aid of the buyer’s electrical power single line diagram, providing the data required by IEEE-519, perform an analysis to initially demonstrate the supplied equipment will met the IEEE standards after installation. If, as a result of the analysis, it is determined that additional filter equipment is required to meet the IEEE recommendations, then the cost of such equipment shall be included in the bid. A harmonic analysis shall be submitted with the approval drawings to verify compliance with the latest version of IEEE-519 voltage and current distortion limits as shown in table 10.2 and 10.3 at the point of common coupling (PCC). The PCC shall be defined as the consumer–utility interface or primary side of the main distribution transformer.

2.06 CONDENSER AND FANS

A. Chiller shall be able to operate in ambient conditions of 0 degrees F

B. Construct condenser coils of aluminum fins mechanically bonded to seamless copper tubing. Provide sub-cooling circuits.

Air test under water to 506 psig.

C. Provide factory mounted, louvered, painted steel "architecturally pleasing" guard panels. Panel louvers shall cover condenser to protect against hail damage. Wire screens or wire mesh will not be allowed.

D. Provide vertical discharge direct driven propeller type condenser fans with fan guard on discharge. Entire fan assembly shall be statically and dynamically balanced and fan assembly shall be either painted or zinc coated steel. Fan guard shall be either PVC, chrome or zinc coated.

E. Provide fan motors with permanently lubricated ball bearings and built-in thermal overload protection.

1) Fans capable to overcome additional free cooling coil static pressures.

2.07 WATER SIDE ECONOMIZER (WSE)

A. Integral waterside economizer designed, fabricated, and installed by chiller manufacturer. Economizer systems shall carry the same manufacturer’s warranty as the other system components.

B. Shall be fully assembled on the air cooled chiller and include all controls and operating components – no field installed components shall be required.

C. Factory installed controls shall automatically switch the chiller between mechanical-cooling mode and free-cooling mode when ambient temperature allows. No manual intervention shall be required.

D. Integral WSE chilled water return piping shall divert the return water to the economizer coils that shall product partial free-cooling anytime the ambient temperature is lower than the building return water temperature. The water from the economizer coils shall return back to the system chilled water return piping downstream of the pump and before the evaporator barrel so additional mechanical cooling by the chiller can be provided, if needed. When 100% of scheduled cooing capacity is achieved in a free-cooling mode, the compressors shall be disabled and the cooling load shall be achieved by free-cooling only. (See chiller schedule for specific performance requirements)

E. There shall be no more than 1 foot of pressure loss on the system due to the WSE option.

F. Flow switch on the discharge of the evaporator barrel shall be factory wired into the chiller controls as a safety interlock. It shall be set at the minimum flow for the evaporator barrel.

2.09 ECONOMIZER COILS

A. Coils shall be designed with aluminum flat/corrugated fins and copper/copper alloy tubes. Tubes shall have minimum wall thickness of 0.020” and an outside diameter of 0.50”. Plastic, Rubber, or PVC connections are not acceptable.

B. Coils shall have headers of type L copper with vents and drains. Connections are copper O.D. sweat connections. Casing shall be manufactured with 14 gauge galvanized steel.

C. Each WSE coil shall have shut off valve on inlet and circuit balancing valve on the outlet.

D. Main headers shall be welded schedule 40 black pipe painted to match the chiller cabinet. Individual coils shall be piped with type L hard copper. Victaulic connections are not acceptable.

E. Header under waterside coils and piping shall be hydrostatically tested to 80 psi, held under pressure for at least 2 hours, and all joints bubble tested.

F. Each WSE system shall be piped to edge of chiller frame and a shut off valve shall be provided at the main inlet and outlet connections.

G. WSE coils shall not block any service access to compressors or other components needing inspection or maintenance.

Removing, draining, replacing, and refilling coils in order to service any components under the condenser coils is not acceptable.

H. Neoprene isolators properly sized for the revised weights of the chiller shall be provided by chiller manufacturer.

2.10 ENCLOSURES

A. House components in 12 gauge galvanized steel frame and mounted on welded structural steel base. Hot-dip galvanized steel frame coating shall be Underwriters Laboratories Inc. (UL) recognized as G90-U, UL guide number DTHW2.

B. Unit panels, and control panels shall be finished with a baked on powder paint. Control panel doors shall have door stays.

Paint system shall meet the requirements for outdoor equipment of Federal Government Agencies.

C. Mount starters and disconnects in weatherproof panel provided with full opening access doors. Provide lockable through-the-door disconnect operating handle external to panel and clearly visible from outside of unit indicating if power is on or off.

D. Casings fabricated from steel that do not have a Zinc coating conforming to ASTM A 123 or ASTM A525 shall be treated for the prevention of corrosion with a factory coating or paint system. The coating or paint system shall withstand 500 hours in a salt-spray fog test in accordance with ASTM B 117. Each specimen shall have a standard scribe mark as defined in ASTM D 1654. Upon completion of exposure, the coating or paint system shall be evaluated and rated in accordance with procedures A and B of ASTM D 1654. The rating of failure at the scribe mark shall be not less than six (average creepage not greater than 1/8 inch). The rating of the unscribed area shall not be less than ten (no failure). Thickness of coating or paint system on the actual equipment shall be identical to that on the test specimens with respect to materials, conditions of application, and dry-film thickness.

2.11 REFRIGERANT CIRCUIT

A. All units shall have 2 refrigeration circuits to provide redundancy, each with one or two (manifolded) compressors on each circuit. Single refrigerant circuit chillers are not acceptable.

B. Provide for each refrigerant circuit:

1. Liquid line shutoff valve.

2. Filter dryer (replaceable core type).

3. Liquid line sight glass and moisture indicator.

4. Electronic or thermal expansion valve sized for maximum operating pressure.

5. Charging valve.

6. Discharge and oil line check valves.

7. Compressor suction and discharge service valves.

8. High side pressure relief valve.

9. Full operating charge of HCFC-22 and oil.

C. Provide Compressor suction service valves and discharge service valves in order to have the ability to isolate the compressor from the rest of the refrigerant system.

D. Capacity Modulation: Provide capacity modulation by either slide valve or unloader valves. Unit shall be capable of operation down to 15%. In the event manufacturer can not provide a unit with modulation down to 15%, Hot Gas Bypass must be provided. Unit shall be able to maintain +/-0.5F leaving water temperature out of the evaporator based on loading/unloading capabilities and water loop size. If unit is not able to maintain +/-0.5F, manufacturer shall provide thermal inertia buffer tank to buffer chiller leaving water temperature fluctuations to the 0.5F tolerance.

2.12 CHILLER CONTROLS

A. The chiller shall be controlled by a remote located digital control system. The remote system shall be able to operate in conjunction with the unit microprocessor-based controller to control/display the following information:

1. Start/Stop Function

2. Chilled Water Setpoint

3. Unit Run Condition

4. Last Diagnostic displayed at the UCM

B. On chiller, mount weatherproof control panel, containing starters, power and control wiring, and molded case disconnect switch (UL approved) with external lockable operator handle. Provide single point power connection on units with MCA less than 500 amps. Provide primary and secondary fused control power transformer and a single 115 volt single phase connection for evaporator heat tape.

1. The unit controller shall utilize the following components to automatically take action to prevent unit shutdown due to abnormal operating conditions, which will allow chiller to continue to produce chilled water in adverse conditions and will perform as follows:

a. High pressure switch that is set 20 PSIG lower that factory pressure switch that will automatically unload the compressor to help prevent a high pressure condenser control trip. One switch is required for each compressor and indicating light shall also be provided.

b. Motor surge protector that is set at 95% of compressor RLA that will automatically unload the compressor to help prevent an over-current trip. One protector is required for each compressor and indicating light shall also be provided.

c. Low pressure switch that is set at 5 PSIG above the factory low pressure switch that will automatically unload the compressor to help prevent a low evaporator temperature trip. One switch is required for each compressor and indicating light shall also be provided.

C. In the above case, the chiller will continue to run in an unloaded state, and will continue to produce some chilled water in an attempt to meet the cooling load. However, if the chiller reaches the trip-out limits, the chiller controls will take the chiller off line for protection, and a manual reset will be required. Once the "near-trip" condition is corrected, the chiller will return to normal operation and can then produce full load cooling.

D. For each compressor, provide wye delta starter.

E. Provide the following safety controls with indicating lights or diagnostic readouts.

1. Low chilled water temperature protection.

2. High refrigerant pressure.

3. Low oil flow protection.

4. Loss of chilled water flow.

5. Contact for remote emergency shut-down.

6. Motor current overload.

7. Phase reversal/unbalance/single phasing.

8. Over/under voltage [Option on 130-400 ton RTAA].

9. Failure of water temperature sensor used by controller.

10. Compressor status (on or off).

F. Provide the following operating controls:

1. Eight (8) or more step leaving chilled water temperature controller which cycles compressors and activates cylinder unloaders or slide valve based on PI algorithms. If manufacturer is unable to provide at least 8 steps of unloading, providing hot gas bypass shall be required. If leaving water temperature control is a concern, a thermal storage tank should be considered for step-unloading chillers.

2. Two minute stop-to-start timer and five minute start-to-start solid state anti-recycle timer to prevent compressors from short cycling. If a greater than 2 and 5 minute anti-recycle timer is provided, hot gas bypass shall be provided to insure accurate leaving water temperature control in low-load applications

3. Load limit thermostat to limit compressor loading on high return water temperature to prevent nuisance trip-outs.

4. High ambient unloader pressure stat that unloads compressors to keep head pressure under control and help prevent high pressure nuisance tripouts on days when outside ambient is above design.

5. Compressor current sensing unloader unit that unloads compressors to help prevent current overload nuisance trip-outs.

6. Auto lead-lag functions that constantly even out run hours and compressor starts automatically. If contractor can not provide this function then cycle counter and hour meter shall be provided for each compressor so owner can be instructed by the contractor on how to manually change lead-lag on compressors and even out compressor starts and running hours.

7. Low ambient lockout control with adjustable set-point.

8. Condenser fan sequencing which automatically cycles fans in response to ambient, condensing pressure and expansion valve pressure differential thereby optimizing unit efficiency.

G. Provide pre-piped gauge board with pressure gauges for suction and discharge refrigerant pressures or digital display of pressures on microprocessor.

H. Provide ammeters for each compressor or digital display of % RLA on microprocessor.

PART 3 EXECUTION

3.01 INSTALLATION

A. Install in accordance with manufacturer's instructions.

B. Align chiller package on steel or concrete foundations.

C. Install units on vibration isolators.

D. Connect to electrical service.

E. Connect to chilled water piping.

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

3.02 MANUFACTURER'S FIELD SERVICES

A. Supply service of factory trained representative for a period of one day to supervise testing, start-up, and instruction on operation and maintenance to Owner. Provide two separate days of training, one eight hour day for the first unit started, and one four hour day for the second unit started.

B. Supply initial charge of refrigerant and oil.

END OF SECTION