SECTION 23 74 13 PACKAGED, OUTDOOR, CENTRAL-STATION AIR-HANDLING UNITS PART 1 - GENERAL 1.1 RELATED DOCUMENTS A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section. 1.2 SUMMARY A. This Section includes packaged, outdoor, central-station air-handling units (rooftop units) with the following components and accessories: 1. Hot water heating coils. 2. Chilled water cooling coils. 3. Direct-Expansion cooling 4. Scroll Compressors 5. Variable frequency controllers 6. Economizer outdoor- and return-air damper section. 7. Roof curbs. 1.3 SUBMITTALS A. Product Data: Include manufacturer's technical data for each model indicated, including rated capacities of selected model clearly indicated; dimensions; required clearances; shipping, installed, and operating weights; furnished specialties; accessories; and installation and startup instructions. B. Shop Drawings: Detail equipment assemblies and indicate dimensions, weights, loadings, required clearances, method of field assembly, components, and location and size of each field connection. Detail mounting, securing, and flashing of roof curb to roof structure. Indicate coordinating requirements with roof membrane system. 1. Wiring Diagrams: Detail wiring for power, signal, and control systems and differentiate between manufacturer-installed and field-installed wiring. C. Commissioning Reports: Indicate results of startup and testing commissioning requirements. Submit copies of checklists. D. Maintenance Data: For equipment to include in the maintenance manuals. 1.4 QUALITY ASSURANCE 23 74 13 / 1
PROJ. NO. 03652.01 A. ARI Certification: Rooftop air-handling units and their components shall be factory tested according to the applicable portions of ARI 430, "Central-Station Air-Handling Units," and shall be listed and bear the label of the Air-Conditioning and Refrigeration Institute (ARI). B. UL and NEMA Compliance: Provide motors required as part of air-handling units that are listed and labeled by UL and comply with applicable NEMA standards. C. Listing and Labeling: Provide electrically operated components specified in this Section that are listed and labeled. 1. The Terms "Listed" and "Labeled": As defined in the National Electrical Code, Article 100. D. Comply with NFPA 70. 1.5 DELIVERY, STORAGE, AND HANDLING A. Deliver rooftop units as factory-assembled units with protective crating and covering. B. Handle rooftop units to comply with manufacturer's written rigging and installation instructions for unloading and moving to final location. 1.6 COORDINATION A. Coordinate installation of roof curbs, equipment supports, and roof penetrations. 1.7 EXTRA MATERIALS A. Furnish extra materials described below that match products installed, are packaged with protective covering for storage, and are identified with labels describing contents. 1. Fan Belts: One set for each belt-driven fan. 2. Filters: One set of filters for each unit. PART 2 - PRODUCTS 2.1 MANUFACTURERS A. Manufacturers: Subject to compliance with requirements, provide products by one of the following: 1. AAON. (RN and RQ Series) 2.2 ROOFTOP AIR HANDLING UNITS A. General: Provide rooftop air handling units of capacities and characteristics as scheduled on the drawings. 237413 / 2
1. Each unit shall be completely factory assembled, piped, wired, tested and shipped in one piece. The unit shall have single point power connection. Units shall be specifically designed for outdoor rooftop application and include a weatherproof cabinet. Modified interior air handling units are not acceptable. 2. All units shall have decals and tags to indicate caution areas and aid unit service. Unit nameplates shall be fixed to the main control panel door. Electrical wiring diagrams shall be attached to the control panels. Installation and maintenance bulletins shall be supplied with each unit. B. Cabinet, Casing and Frame: 1. The frame and unit base shall be made of minimum 14 gauge galvanized steel; cabinet shall be constructed of minimum 22 gauge galvanized steel. The unit base shall overhang the roof curb for water runoff and shall have a formed recess that seats on roof curb gasket to provide a positive weathertight seal. Unit cabinet shall be designed to operate at total static pressures up to 6-inches wg. 2. Exterior surfaces shall be phosphatized and coated with baked-on enamel. Hinged doors shall be provided for access to each unit section and shall be constructed of galvanized steel with flush mounted single lever, staggered engagement latching mechanism. 3. Unit shall be completely insulated with 2" thick, R-13 closed-cell foam. All interior casing surface shall have solid minimum 24 gauge galvanized sheetmetal liners completely enclosing insulation. Lifting brackets shall be provided on the unit base with lifting holes to accept cable or chain hooks. C. Coil Section: 1. Chilled water (if applicable) and hot water coils shall be fabricated from seamless copper tubing mechanically bonded to rippled and corrugated aluminum fins. Coils shall be factory piped to a location within the unit to permit field connection to building piping distribution systems. Coils shall be factory leak tested under water. Coil capacities shall be ARI certified. 2. A double-sloped, insulated, stainless steel drain pan shall be provided with the cooling coil, and shall extend beyond the leaving side of the coil and under the cooling coil connections. The drain pan shall be connected to a threaded drain connection extending through the unit housing. 3. Drain piping shall be constructed of Schedule 40 PVC pipe with a deep seal p- trap and assembled with Type DWV solvent welded fittings. Terminate piping over a 4-inch thick solid concrete splash block on the roof. 4. Units shall be provided with a pipe chase section for field installation of piping, and accessories. D. Direct Expansion Coil Section (If Applicable): 1. Minimum Number of Refrigerant Circuits: Two (2) a. Exception: Units sized 15 tons total cooling and less may have a single refrigeration circuit. 2. Compressors: Provide direct-drive hermetic, scroll type, mounted on vibration isolators; with internal overcurrent and high-temperature protection, internal pressure relief, and crankcase heater. a. Minimum number of compressors and temperature control stages: Four (4) compressors and four (4) stages of capacity control (plus off). 23 74 13 / 3
PROJ. NO. 03652.01 1) Two (2) compressors will be acceptable if one of the compressors is modulation, variable speed or is a Copeland digital scroll. The minimum capacity step shall be no more than 10% of total unit capacity. 3. Refrigeration Specialties: a. Refrigerant: R-410A b. Expansion valve with replaceable thermostatic element. c. Refrigerant filter/dryer d. Manual-reset high-pressure safety switch. e. Automatic-reset low-pressure safety switch. f. Minimum off-time relay. g. Automatic-reset compressor motor thermal overload. h. Brass service valves installed in compressor suction and liquid lines. E. Direct Driven Supply-Air Fans: Unhoused, backward curved, plenum supply fan; with permanently lubricated, variable-speed motor installed on an adjustable fan base resiliently mounted in the casing. Bearings shall be selected for L50 life at 200,000 hrs. 1. Extended grease lines. 2. 2 static deflection spring isolators. F. Condenser-Coil Fan: Vertical discharge, axial flow, direct drive fans. G. Variable Frequency Drives: Variable air volume fan control shall be provided via an adjustable frequency drive factory installed and wired. Variable frequency drives shall be housed in a conditioned unit section providing ambient temperatures compatible with the operating temperature range of the VFD. VFD shall be as manufactured by Eaton Corp.; Westinghouse & Cutler-Hammer Products; or Square D Co.. 1. Description: NEMA ICS 2, variable-frequency controller, listed and labeled as a complete unit and arranged to provide variable speed of a standard NEMA MG 1, Design B, 3-phase, induction motor by adjusting output voltage and frequency. 2. Design and Rating: Match load type such as fans; and type of connection used between motor and load such as direct or through a power-transmission connection. 3. Isolation Transformer: Match transformer voltage ratings and capacity to system and motor voltages; and controller, motor, drive, and load characteristics. 4. Output Rating: 3-phase, 6 to 66 Hz, with torque constant as speed changes. 5. Starting Torque: 100 percent of rated torque. 6. Speed Regulation: Plus or minus one percent. 7. Ambient Temperature: 0 to 40 deg C. 8. Efficiency: 95 percent minimum at full load and 60 Hz. 9. Internal Adjustability: Include the following internal adjustment capabilities: a. Minimum Speed: 5 to 25 percent of maximum rpm. b. Maximum Speed: 80 to 100 percent of maximum rpm. c. Acceleration: 2 to 22 seconds. d. Deceleration: 2 to 22 seconds. e. Current Limit: 50 to 110 percent of maximum rating. 237413 / 4
10. Multiple-Motor Capability: Controller suitable for service to multiple motors and furnished with a separate overload relay and protection for each controlled motor. Shut off the controller and motors served by it when an overload relay is tripped. 11. Self-protection and reliability features include the following: a. Input transient protection by means of surge suppressors. b. Snubber networks to protect against malfunction due to system voltage transients. c. Motor Overload Relay: Adjustable and capable of NEMA 250, Class 10 performance. d. Notch filter to prevent operation of the controller-motor-load combination at a natural frequency of the combination. e. Instantaneous overcurrent trip. f. Loss of phase protection. g. Reverse phase protection. h. Under- and overvoltage trips. i. Overtemperature trip. j. Short-circuit protection. k. Harmonic Filters. 12. Automatic Reset/Restart: Attempt 3 restarts after controller fault or on return of power after an interruption and before shutting down for manual reset or fault correction. Restarting during deceleration will not damage controller, motor, or load. 13. Status Lights: Door-mounted LED indicators to indicate the following conditions: a. Power on. b. Run. c. Overvoltage. d. Line fault. e. Overcurrent. f. External fault. 14. Panel-Mounted Operator Station: Start-stop and auto-manual selector switches with manual speed control potentiometer and elapsed time meter. 15. Indicating Devices: Meters or digital readout devices and selector switch, mounted flush in controller door and connected to indicate controller output current, voltage, and frequency. 16. Manual Bypass: Magnetic contactor arranged to safely transfer motor between controller output and bypass controller circuit when motor is at zero speed. Controller-off-bypass selector switch indicator lights set and indicate mode selection. 17. An integral disconnect switch shall be provided. 18. Bypass Controller: NEMA ICS 2, full-voltage, nonreversing motor controller, provides across-the-line starting capability in manual-bypass mode. Provide motor overload protection under both modes of operation with control logic that allows common start-stop capability in either mode. 19. Isolating Switch: Non-load-break switch arranged to isolate variable-frequency controller and permit safe troubleshooting and testing, both energized and deenergized, while motor is operating in bypass mode. 23 74 13 / 5
PROJ. NO. 03652.01 20. Remote Indicating Circuit Terminals: Mode selection, controller status, and controller fault. H. Filter Section: 1. The filter shall be supplied complete with filter rack as an integral part of the unit. Filters shall be accessible from both sides of the unit. 2. The filter section shall be provided with 2" thick, MERV-8 pleated filters designed to slide into the galvanized steel racks. I. Outside Air Section: 1. The outside and return air section shall be designed to form a plenum. Outside air arrangement shall be 0-100% outside air with economizer control. 2. Outside air shall be introduced through louvered intake panels complete with rain lip and bird screen. The units floor of the outside air section shall provide for water drainage. The outside and return air dampers shall be sized to handle 100% of the supply air volume. The dampers shall be arranged to converge the return and outside airstreams in mixing patterns. Low leak dampers shall be provided. Dampers shall be hollow core, air foil type and fully gasketed and side sealed. Leakage shall not exceed 0.3% at 3" S.P. 3. A relief type exhaust air damper shall be provided and shall be located in the return air section to exhaust air out of the back of the unit. Exhaust louvers and bird screen shall be provided to prevent infiltration. Exhaust dampers shall be lined with urethane gasketing on contact edges. Mechanical closure shall be provided on the dampers by means of a motor operator which shall shut the exhaust dampers when the unit is in unoccupied mode. J. Electrical: 1. Each unit shall be wired and tested at the factory before shipment. Wiring shall comply with NEC requirements and shall conform to all applicable UL standards. All electrical components shall be labeled according to the electrical diagram and shall be UL recognized where applicable. Each unit shall have a 115 volt circuit transformer, 115 volt receptacle, and control circuit fuse. 2. The supply air fan motor branch circuit shall be individually fused. The supply air fan motor shall have contactors and external overload protection. 3. Main control panel shall be of weatherproof construction with a dead front cover over main power circuit control. A terminal block shall be provided for the main power connection and a terminal board shall be provided for the low voltage control wiring. Knockouts shall be provided in the bottom of the main control panels for field wiring entrance. 4. A main unit non-fused disconnect switch in a NEMA 3R enclosure shall be provided. K. Roof Curbs: 1. Prefabricated 12-gauge galvanized steel mounting curbs furnished by the unit manufacturer shall be provided for field assembly on the roof decking prior to unit shipment. The roof curbs shall be perimeter type with complete perimeter support of the unit. Deliver curbs to the General Contractor for installation 2. The curb shall be a minimum of 16" high and include a nominal 2" x 4" wood nailer strip. 237413 / 6
3. Gasketing shall be provided for field mounting between the unit base and the roof curb. L. Unit Control System: 1. All controls shall be provided by the Building DDC System Supplier (Controls Contractor) as specified in Division 34. 2.3 MOTORS A. Refer to Division 23 Section "Common Motor Requirements for HVAC Equipment" for general requirements for factory-installed motors. PART 3 - EXECUTION 3.1 EXAMINATION A. Examine roof for compliance with requirements for conditions affecting installation and performance of rooftop units. Do not proceed with installation until unsatisfactory conditions have been corrected. 3.2 INSTALLATION A. Install units according to manufacturer's written instructions. B. Install units level and plumb, maintaining manufacturer's recommended clearances. C. Curb Support: Install and secure rooftop units on curbs. 3.3 CONNECTIONS A. Piping installation requirements are specified in other Division 23 Sections. Drawings indicate the general arrangement of piping, fittings, and specialties. The following are specific connection requirements: 1. Install piping to allow service and maintenance. 2. Hot Water and Chilled-Water Piping: Conform to applicable requirements of Division 23 Section "Hydronic Piping." Connect with shutoff valve and union or flange. B. Duct installation requirements are specified in other Division 23 Sections. Drawings indicate the general arrangement of ducts. 3.4 FIELD QUALITY CONTROL A. Verify that installation is as indicated and specified. 23 74 13 / 7
PROJ. NO. 03652.01 B. Complete manufacturer's installation and startup checks and perform the following: 1. Level unit on curb, and flash curbs to unit and to roof. 2. Inspect for visible damage to unit casing. 3. Verify that clearances have been provided for servicing. 4. Check that labels are clearly visible. 5. Verify that controls are connected and operable. 6. Remove shipping bolts, blocks, and tie-down straps. 7. Verify that filters are installed. 8. Adjust vibration isolators. 9. Check operation of dampers. C. Lubricate bearings on fan. D. Check fan-wheel rotation for correct direction without vibration and binding. E. Adjust fan belts to proper alignment and tension. F. Start unit according to manufacturer's written instructions. G. Check and record performance of interlocks and protection devices; verify sequences. H. Operate unit for an initial period as recommended or required by manufacturer. I. Check internal isolators. J. Check outside-air damper for proper stroke and interlock with return-air dampers. K. Check controls for correct sequencing of heating, mixing dampers, and normal and emergency shutdown. L. Measure and record the following: 1. Coil leaving-air, dry- and wet-bulb temperatures. 2. Coil entering-air, dry- and wet-bulb temperatures. 3. Outside-air, dry-bulb temperature. M. Measure and record the following minimum and maximum airflows. Plot fan volumes on fan curve. 1. Supply-air volume. 2. Return-air volume. 3. Relief-air volume. 4. Outside-air intake volume. N. After starting and performance testing, change filters, vacuum coils, lubricate bearings, adjust belt tension, and check operation of power vents. 3.5 DEMONSTRATION A. Engage a factory-authorized service representative to train Owner's maintenance personnel as specified below: 237413 / 8
1. Train Owner's maintenance personnel on procedures and schedules related to startup and shutdown, troubleshooting, servicing, and preventive maintenance. 2. Review data in the maintenance manuals. 3. Schedule training with Owner, through the Architect, with at least 7 days' advance notice. END OF SECTION 23 74 13 / 9