GUIDE SPECIFICATION SECTION236219-1
Revised 16 February 2016Water-Cooled Condensing Units
SECTION 236219 – WATER-COOLED CONDENSING UNITS
PART 1 GENERAL
RELATED DOCUMENTS
Contractors, manufacturers, manufacturer representatives, vendors, suppliers, etc. are cautioned that requirements of the Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 1 Specification sections, apply to work of this section. Sections 230210, 230220, 230240, 230510, 230511, 230533, 230593, 230596, and 230924, must be reviewed for compliance with the requirements of this section.
QUALITY ASSURANCE
AHRI Compliance:
Capacity ratings for condensing units shall be in accordance with AHRI Standard 365, Standard for Commercial and Industrial Unitary AirConditioning Equipment, for units of 135 MBH capacity or greater, AHRI Standard 210/240, Standard for Unitary Air-Conditioning Equipment, for units of capacity less than 135 MBH.
Rate water-cooled condensing unit sound power levels according to AHRI 575, Method of Measuring Machinery Sound Within an Equipment Space.
ASHRAE Compliance: Refrigeration system of condensing units shall be constructed in accordance with ASHRAE 15, Safety Code for Mechanical Refrigeration.
ASME Compliance: Evaporators, condensers, economizers, etc. in which the refrigerant or water pressure exceeds 15 psig shall be constructed and tested and stamped in accordance with Section VIII, Division 1 of ASME Boiler and Pressure Vessel Code for not less than 150 psig waterside working pressure and be registered with the National Board of boiler and pressure vessel inspections.
Building Code Compliance: Condensing units, air-, water-, or evaporatively cooled, shall meet or exceed the minimum efficiency rating required by the International Energy Conservation Code.
Extended Warranty: The Contractor shall provide an extended parts and labor warranty on each refrigeration compressor in addition to guarantees and warranties required under the General Conditions to the Construction Contract.
The parts portion of the warranty shall be directly from the manufacturer to the Owner.
The labor portion of the warranty shall also be provided directly from the manufacturer to the Owner.
Exception: Where a manufacturer labor warranty is not available, the Contractor shall provide a labor warranty directly to the Owner.
This warranty shall provide for repair or replacement of the covered compressor, including removal and/or replacement of refrigerant, that becomes inoperative as a result of defects in materials or workmanship within 4 years after the date ending the initial 1-year guarantee period for the Project.
Acoustic Criteria: HVAC equipment shall be selected and installed to comply with the acoustic criteria defined in Section 230510.
SUBMITTALS
General: Submittals shall demonstrate compliance with technical requirements by reference to each subsection of this specification. Where a submitted item does not comply fully with each and every requirement of the Specifications, the submittal shall clearly indicate such deviations. Identification requirements for non-complying features of items are very specific. See Section 230210 for exact requirements.
Manufacturer's Data: Submit manufacturer's technical product data, including rated capacities of selected model clearly indicated, weights (shipping, installed, and operating), dimensions, required clearances, and methods of assembly of components, furnished specialties and accessories, and installation and startup instructions.
Wiring Diagrams: Submit laddertype wiring diagrams for power and control wiring required for final installation of condensing units and controls. Clearly differentiate between portions of wiring that are factoryinstalled and portions to be fieldinstalled.
PART 2 PRODUCTS
WATER-COOLED CONDENSING UNITS
Description: Factory assembled and tested, consisting of scroll compressors, water-cooled condensers, bases, and unit controls.
Scroll Compressor(s):
Provide positive-displacement, direct drive, suction gas-cooled scroll compressors with hermetically sealed casing. Compressors shall be one or more of the following types, as hereinafter specified, factory-assembled, -piped, and -wired and controlled to provide total cooling capacity.
Constant speed, single stage, induction motor
Variable Speed, internal permanent magnet motor with integral driver/inverter
Where three (3) or fewer compressors are required, a single refrigerant circuit may be provided. Where more than three compressors are required, an equal number of compressors shall be installed on two independent refrigerant circuits.
Each refrigerant circuit shall include an electronic expansion valve, refrigerant charging connections, a hot-gas muffler, individual compressor suction and discharge shutoff valves, a liquid-line shutoff valve, a replaceable-core filter-dryer, a sight glass with moisture indicator, a liquid-line solenoid valve, and an insulated suction line.
Where multiple compressors are piped together on a common refrigerant circuit, multiple oil return lines shall be provided to serve each compressor.
Provide each compressor with crankcase oil heater and suction strainer.
Mount each compressor on individual vibration isolators.
//SELECT ONE OF THE TWO FOLLOWING MOTORS. THE USE OF VARIABLE SPEED PERMANENT MAGNET MOTORS IN SCROLL COMPRESSORS IS THE PREFERRED TECHNOLOGY.//
Induction Motors: Constant speed compressors shall be driven by induction synchronous motors, which shall be high-torque, two-pole type with inherent thermal-overload protection on each phase, hermetically sealed and cooled by refrigerant suction gas.
For constant speed compressors, provide unit-mounted and integrated full voltage, across the line starters in accordance with NEMAICS2, ClassA, full voltage, non-reversing, for each compressor.
Permanent Magnet Motors: Variable speed compressors shall be driven by interior permanent magnet (i.e., permanent magnets embedded in the rotor) synchronous type motors, hermetically sealed and refrigerant cooled. Motor shall be started/stopped and speed-controlled via unit-mounted and integrated driver/inverter circuitry.
The driver/inverter shall be specifically designed for the motor and utilize current-switching techniques to simultaneously control both torque and flux current. Speed feedback shall be incorporated to provide accurate (±1%) speed control.
Oil Lubrication System: Provide automatic pump with strainer, sight glass, filling connection, filter with magnetic plug, and initial oil charge for each refrigerant circuit.
Compressor Application: Provide scroll compressors as follows:
The use of constant speed scroll compressors with digital unloading (i.e., “digital scroll compressors”) is prohibited.
For rated capacity of less than 10 tons, a single compressor or “tandem” (two) compressors may be provided.
With one (1) compressor, it shall be variable speed type sized for 100 percent of design cooling load. Minimum chiller capacity shall be 25 percent or less of chiller rated capacity.
With two (2) compressors, one of which shall be variable speed type sized for approximately 33 percent of the design cooling load and one of which shall be constant speed, single stage type with on/off control sized for approximately 67 percent of the design cooling load. Minimum chiller capacity shall be 10 percent or less of chiller rated capacity.
For rated capacity of 10 to 40 tons, “tandem” (two) or “trio” (three) compressors may be provided:
With two (2) compressors, one of which shall be variable speed type sized for approximately 33 percent of the design cooling load and one of which shall be constant speed, single stage type with on/off control sized for approximately 67 percent of the design cooling load. Minimum chiller capacity shall be 10 percent or less of chiller rated capacity.
With three (3) compressors, one of which shall be variable speed type and the other two shall be constant speed, single stage type with on/off control. Each compressor shall be sized for approximately 33 percent of the design cooling load. Minimum chiller capacity shall be 10 percent or less of chiller rated capacity.
Unit Casings: Galvanized steel, finished with baked enamel; with removable panels for access to controls, weep holes for water drainage, and mounting holes in base. Mount service valves, fittings, and gage ports on exterior of casing.
Condenser:
Type: Multipass, shell-and-tube type; with replaceable, seamless, integral-finned copper tubes; positive-liquid sub-cooling circuit; pressure relief device; liquid-level test cock; purge connection; liquid-line shutoff valve; and angle valve for connection of water-regulating valve.
Construction: ASME stamped for refrigerant-side working pressure of 385 psig and water-side working pressure of 250 psig.
Controls: Factory-mounted and -wired panel with the following:
High and low pressure cutouts.
Oil pressure cutout,
Compressor winding thermostat cutout,
3leg compressor overload and single-phasing protection
Condenser fan motors thermal and overload cutouts.
Automatic non-recycling pumpdown and timing device to prevent excessive compressor cycling.
Multi-stage cooling control where two-speed compressors and/or multiple compressors are provided.
PART 3 EXECUTION
INSTALLATION
Regardless of refrigerant piping configuration, routing, and sizes indicated on the Drawings, Contractor shall verify pipe sizing to complement length and elevation of piping as installed. Include all piping accessories necessary to complement length and elevation of piping.
Install condensing units in accordance with manufacturers installation instructions. Install units plumb and level, firmly anchored in locations indicated, and maintain manufacturer's recommended clearances.
Charge systems with refrigerant and oil, and test for leaks. Repair leaks and replace lost refrigerant and oil.
OWNER INSTRUCTION AND TRAINING
Provide Owner instruction and training in accordance with Section 230240.