SECTION (15733) - DEDICATED OUTDOOR AIR UNITS

Transcription

1 PART 1 GENERAL 1.01 SUMMARY SECTION (15733) - DEDICATED OUTDOOR AIR UNITS A. Section Includes: 1. Dedicated Outdoor-Air Units with Energy Recovery B. Related Sections: 1.02 REFERENCES 1. Section (15050) Common Work Results for HVAC 2. Section (15090) Common Motor Requirements for HVAC Equipment 3. Section (15070) Vibration Control for HVAC Piping and Equipment 4. Section (15075) Identification for HVAC Piping and Equipment 5. Section (15950) Testing, Adjusting and Balancing for HVAC 6. Section (15900) Instrumentation and Control for HVAC 7. Section (15940) Sequence of Operation for HVAC Controls 8. Division (15194) Facility Natural-Gas Piping 9. Division 26 (16) Sections for electrical connections. A. Air-Conditioning, Heating and Refrigeration Institute (AHRI) Publications: "Forced Circulation Air-Cooling and Air-Heating Coils "Performance of Air-to-Air Heat Exchangers for Energy Recovery Ventilation Equipment B. American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Publications: Ventilation for Acceptable Indoor Air Quality (ANSI Approved) Energy Code for Commercial and High-Rise Residential Buildings C. ASTM International (ASTM) Publications: (Former American Society for Testing and Materials) 1. B117 "Standard Practice for Operating Salt Spray (Fog) Apparatus" D. National Fire Protection Association (NFPA) Publications: "National Electric Code" 2. 90A Standard for the Installation of Air Conditioning and Ventilating Systems 1.03 SUBMITTALS A. General: Submit the following in accordance with Conditions of Contract and Division 01 Specification Sections. B. Submit Letter of Conformance in accordance with Section (01330) indicating specified items selected for use in project with the following supporting data. 1. Product Data including manufacturer's technical data, clearly indicated for each model, including: rated capacities, operating characteristics, dimensions, weights (shipping, installed, and operating), furnished specialties, accessories, and installation and startup instructions. PAGE 1

2 2. Shop Drawings from manufacturer detailing 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. 3. Wiring Diagrams detailing wiring for power, signal, and control systems. Clearly differentiate between manufacturer-installed and field-installed wiring. 4. Commissioning report, including pre-functional testing checklists, indicating the results of unit startup, testing and commissioning requirements. 5. Maintenance data for energy recovery units to include in the operation and maintenance manual specified in Division 01 and in Section "Common Work Results for HVAC." 1.04 QUALITY ASSURANCE A. AHRI Certification: Units and their components shall be factory tested according to the applicable portions of AHRI 1060, "Performance of Air-to-Air Heat Exchangers for Energy Recovery Ventilation Equipment," and AHRI 410, "Forced Circulation Air-Cooling and Air- Heating Coils," and shall be listed and bear the label of the Air-Conditioning, Heating and Refrigeration Institute (AHRI ). 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. Comply with NFPA 70 for components and installation. D. 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 NFPA National Electrical Code, Article 100. E. Comply with ASHRAE/IESNA Standard , Section 7 "Construction and Startup." 1.05 DELIVERY, STORAGE, AND HANDLING A. Deliver rooftop units as factory-assembled units with protective crating and covering. B. Coordinate delivery of units in sufficient time to allow movement into building. C. Handle rooftop units to comply with manufacturer's written rigging and installation instructions for unloading and moving to final location COORDINATION A. Coordinate installation of roof curbs, equipment supports, and roof penetrations EXTRA MATERIALS A. Furnish extra materials described in Section (01790) Spare Parts and Materials that match products installed and that are packaged with protective covering for storage and identified with labels describing contents WARRANTY A. General Warranty: The manufacturer shall warrant all equipment for a period of one (1) year from date of substantial completion. Extended warranty specified in this Article shall not deprive Owner of other rights Owner may have under other provisions of the Contract Documents and shall be in addition to, and run concurrent with, other warranties made by Contractor under requirements of the Contract Documents. PAGE 2

3 B. Extended Warranty: Manufacturer's standard form in which manufacturer agrees to replace components of rooftop air conditioners that fail in materials or workmanship within specified warranty period. 1. Extended Warranty Period for Compressors: Manufacturer's standard, but not less than five years from date of Substantial Completion. 2. Extended Warranty Period for Heat Exchangers: Manufacturer's standard, but not less than 10 years from date of Substantial Completion. 3. Extended Warranty Period for Energy Wheels: Manufacturer's standard, but not less than 5 years from date of Substantial Completion. PART 2 PRODUCTS 2.01 MANUFACTURERS A. Approved Manufacturers: 1. Dedicated Outdoor Air Unit a. "Rebel"; Daikin ( ) b. SolutionAir ; JAFT Corp ( x-108) c. RN Series ; AAON, Inc. ( ) d. "TotalAire (QS) Series"; Desert Aire ( ) e. Model ERCH ; Greenheck Fan Corporation ( ) f. "Complevent"; Munters Corporation ( ) g. "OAU"; Trane ( ) h. Seresco ( ) i. Advantix Systems ( ) 2.02 DEDICATED OUTDOOR-AIR UNITS WITH ENERGY RECOVERY A. Description: Packaged self-contained, outdoor rooftop, DX/gas, 100% outside air, energy recovery unit of capacities and characteristics as scheduled on the drawings. 1. Each unit shall be completely factory assembled, piped, wired, tested and shipped in one piece. 2. Unit shall be capable of varying the amount of outside air delivered to the space based on occupancy, humidity, indoor air quality and differential pressure. 3. In the event that the space dry bulb temperature begins to deviate from set point, the DOAS shall be capable of varying the outside air supply air temperature to supplement the cooling or heating requirements of the space. 4. Unit shall be capable of varying the moisture content of outside air to the space based on space humidity. To maintain 59 grains of moisture per pound of dry air space conditions, the DOAS must be able deliver air down to 39 F dew point supply air at low air volume conditions. 5. Units shall be designed to cool or dehumidify with entering air temperatures of F and operate in heating mode down to -40 F. Units shall be capable of supplying air with a maximum of 59 grains of moisture per pound of dry air, or less if specified, at both the dry bulb / mean coincidental wet bulb and dew point / mean coincidental dry bulb temperatures at the 0.4% ASHRAE design conditions for the location of the installation. PAGE 3

4 Units not capable of delivering 59 grains of moisture per pound of dry air, or less if specified, at both design conditions are unacceptable. 6. Units shall provide 100% outdoor air directly to the space, or delivered to the terminal unit(s) supply air duct. Mixed Air units are NOT acceptable. B. Unit Cabinet: 1. Unit shall be specifically designed for outdoor rooftop application with a fully weatherproof cabinet. The unit roof shall be sloped or cross-broken to assure drainage. Unit base shall overhang the roof curb for water run-off. Rain break overhangs shall be provided above access doors. 2. Cabinet shall be of double wall, insulated design. The cabinet exterior shall be constructed of painted 20 gauge or heavier G90 galvanized steel, or unpainted Type 5052 marine grade aluminum using 12 gauge panels & 8 gauge structural members, or unpainted Type 304 stainless steel using 18 gauge panels & 14 gauge structuratl members. The interior shall be Type 5052 aluminum or Type 304 stainless of similar gauge to the cabinet exterior. The cabinet shall be weatherproof and suitable for outdoor construction and the entire floor shall be designed to operate as a drain pan so that in the event that rain would enter the cabinet, it will drain via the condensate drain connection. Insulation shall be in accordance with the requirements of ASHRAE Standard , and shall be non-wicking and moisture resistant. The insulation must not be capable of supporting any biological growth of any kind. All insulation shall have a smoke and fire rating of 5-5 and shall be rated Class A. The insulation shall have a VOC content of zero (0). 3. Paint finish shall be capable of withstanding at least 2500 hours, with no visible corrosive effects, when tested in a salt spray and fog atmosphere in accordance with ASTM B test procedure. 4. Unit shall have insulated, hinged access doors with quarter turn handles and full perimeter gasketed seals. Door fastening screws are not acceptable. 5. Unit shall be factory pre-rigged for a 4-point crane lift. 6. All openings through the base pan of the unit shall have upturned flanges of at least 1/2 in height around the opening through the base pan. 7. Unit shall have a factory-installed cleanable, insulated, double-sloped condensate drain connection of aluminum or stainless steel. 8. Outdoor and exhaust air openings shall have a hood or louver with bird screen. Construction and color shall match cabinet. 9. Dampers: a. Motor operated outside air damper assembly constructed of extruded aluminum, hollow core, airfoil blades with rubber edge seals and aluminum end seals. Damper blades shall be gear driven and designed to have no more than 15 CFM of leakage per sq. ft. of damper area when subjected to 2 w.g. air pressure differential across the damper. b. Gravity type backdraft damper at the exhaust discharge. 10. All evaporator, condenser and water coils shall be cleanable. All coils shall be a maximum of 4 rows thick, 10 fins per inch and include a minimum of a 4 inch clean-out access between coils. The floor below the coil shall be suitable for drainage of the cleaning solution. All coils must be coated in order to reduce corrosion from contaminants from outside air and moisture and increase watershed capability. The PAGE 4

5 coating shall be a thermal set acrylic having an ASTM B117 salt test rating that exceeds 1000 hours. Coatings shall be hydrophobic to aid in draining water from the coil. Interlaced coils shall NOT be acceptable. Units with coils that have more than 10 fins per inch or that have lanced fins are NOT acceptable. 11. Color coded wiring diagrams shall be laminated in plastic and permanently affixed inside the control compartment. 12. Unit shall have decals and tags to indicate unit lifting and rigging, service areas and caution areas. 13. Unit nameplates shall be fixed to the main control panel door. C. Roof Curb: (DOAS-2) 1. Roof curb shall be constructed of similar metal as the cabinet construction. Curbs are to be factory welded construction providing full perimeter support, cross structure support and air seal for the unit. Curb shall be as described on the drawings. D. Supply and Exhaust Fans: 1. Plenum supply fan shall be backward inclined, direct drive with factory installed variable frequency drive, non-overloading, and designed for high efficiency operation at higher static pressures with lower noise levels. Blowers shall be constructed of epoxy-coated steel for corrosion resistance. 2. Exhaust fan shall be backward inclined, direct drive type, non-overloading, and designed for high efficiency operation at higher static pressures with lower noise levels. Blowers shall be constructed of epoxy-coated steel for corrosion resistance. 3. Fans shall be statically and dynamically balanced. 4. The fan assembly shall be Blower and motor base is to be mounted on 4 spring and rubber isolators having minimum 3/4-inch deflection. Blower to be isolated from the cabinet with a flexible connector having a fire rating. 5. Fan shaft bearings shall be heavy duty, permanently lubricated, self-aligning ball or roller pillow block type. Bearings shall have a minimum life (L-10) of 80,000 hours at maximum operating speed and horsepower for each construction level. E. Air-Cooled Condenser: 1. The condensing section shall be equipped with vertical discharge, propeller type, direct drive fans with corrosion-resistant blades and supports. Direct drive fans shall be directly connected to and supported by the motor shaft. Fans shall be statically and dynamically balanced. 2. Condenser coils shall have enhanced surface aluminum plate fins mechanically bonded to the copper tubes with all joints brazed. F. Refrigerant System: 1. Unit shall be factory charged with R-410A refrigerant. 2. Compressors: a. Fully hermetic, scroll type compressors with crankcase heater, overload protection and short cycle protection with minimum on and off timers. b. Compressors shall be mounted on the compressor manufacturer s recommended rubber vibration isolators and shall be isolated from the base pan and supply air to avoid transmission of noise from the compressor into the building. Vibrasorb PAGE 5

6 isolators shall be installed in both the suction and discharge tubing of each compressor. c. Compressors shall be mounted in an isolated compartment to permit operation of the unit without affecting air flow when the door to the compartment is open. d. Each compressor shall be individually staged for capacity control. Units exceeding 2,000 cfm shall have a minimum of 3 independent refrigeration circuits that have no shared components. Each circuit must be able to operate at any time without the assistance or aid of any component of the other circuits with the exception of the controls and blower. Any or all components of any single circuit must be constructed in such a way as to be removable without disturbing or disrupting or contaminating any of the other circuits. Each compressor shall be dedicated to an individual evaporator coil, TXV and condenser coil and operate independently. Tandem compressors shall NOT be acceptable. Minimum 2-stage capacity control on units over 10 tons and above. 3. Refrigerant System Specialties for each circuit: a. Refrigerant dryer. b. Adjustable thermostatic expansion valve. c. High and low pressure switches. d. Gage connection ports. e. Liquid line sight glass. f. Service/charging valves. 4. Reheat Coil: Hot gas reheat coil with 0-100% modulating hot gas reheat control valves piped to all reheat refrigerant circuits. 5. Capacity Control: a. Multiple compressor design and Variable Speed Scroll compressor design shall provide 0-100% capacity control for continuous dehumidification upon demand. Energy wasting hot gas bypass refrigerant control shall NOT be acceptable. b. Unit shall be equipped with variable speed low ambient head pressure control to allow operation down to 35 F. 6. Evaporator coil shall have minimum corrosion potential from dissimilar metals. Coil casing shall be either copper, aluminum, stainless steel. Galvanized steel coil casings shall NOT be acceptable 7. Evaporator coil shall be furnished with a double sloped drain pan fabricated of Type 5052 aluminum, or Type 304 stainless steel for the positive drainage of condensate. G. Filter Section: 1. The outdoor air steams shall have 4 thick pleated, high efficiency filters with a minimum MERV-13 rating and the exhaust air steams shall have MERV-8 filters. H. Filter Section: 1. Both outdoor and exhaust air steams shall have 2 thick fiberglass filters with a minimum MERV-7 rating. I. Energy Recovery Wheel: 1. Wheel shall be of the enthalpy type for both sensible and latent recovery; moisture transfer shall occur entirely in the vapor phase. Wheel shall be constructed of alternate PAGE 6

7 layers of corrugated and flat aluminum. Enthalpy wheels shall be permanently bonded with "Micro-Sieve" a desiccant adsorbent specifically developed for the selective transfer of moisture for equal transfer of sensible and latent energy. The air channels shall be formed smooth to ensure laminar airflow for low-pressure drops and allow free passage of particles up to 900 microns. Rotor structure shall be internally reinforced and mounted on pillow block type bearings. The rotor shall also be removable from the frame. Brush seals shall be provided around the periphery of the rotor and between the inlet and outlet air passages to effectively prevent air leakage and cross contamination between airflows. An adjustable purging sector shall be installed to prevent carryover of contaminated exhaust air into the supply air stream. Performance and cross contamination shall be documented through an independent laboratory conducted in accordance with ASHRAE and AHRI standards. 2. Factory provided integral DDC automatic temperature control that shall include remote temperature sensors mounted in each of the four airstreams to monitor exchanger performance. The control shall modulate rotor speed to prevent frost build-up. A rotor bypass section shall be incorporated into the cabinet design to bypass the rotor when conditions are beneficial for overall energy savings. J. Winter Heating Mode 1. Indirect-Fired Gas Heating: K. Controls: a. Gas heating shall be induced-draft combustion type with an energy saving direct spark ignition system and redundant main gas valves. b. Heat exchanger shall be tubular section type, constructed of 20 gauge stainless steel. c. Burners shall be modulating (10:1 turndown) in-shot type constructed of stainless steel and have sufficient staging as to provide the supply air temperature within 2 degrees (F) of the DOAS supply air setpoint, even at startup, regardless of the entering air temperature. As the supply air volume modulates to meet ventilation demands, the supply air temperature shall not rise above or below the set point temperature, +/- 2 degrees (F). d. Gas shall enter the unit at a single location. 1. Dedicated Outdoor-Air Unit Controller: a. The unit shall include a factory installed microprocessor based unit controller which controls the operation of all unit functions including: dampers, supply and exhaust fans, energy recovery wheel, refrigerant system and gas heater. b. Controller shall be capable of the monitoring the following functions, safeties and alarms. 1) Factory-installed dirty filter status for both supply and exhaust filter banks. 2) Factory-installed fan status switch for both supply and exhaust fans. 3) Energy wheel defrost control and air bypass. c. Controller shall be BACNet, Modbus and LonWorks protocol compatible. d. Shall include and alarm indicator and audible alarm signal. 2. Fan current transducer. 3. Supply air temperature sensor. PAGE 7

8 4. Outside air temperature sensor. 5. Relative humidity sensor. L. Fire Alarm System Interface: 1. Provide dry contact control interface to connect to fire alarm panel, so that unit shuts down in the event the fire alarm system goes into alarm. M. Airflow Monitoring/Control & Building Pressure Control: 1. Provide building pressure differential sensor and controls to maintain building pressure at a user adjustable setting (initially set at 0.05 w.g.). The building pressure sensor is to be accurate to within 0.02 w.g. and is to be self-calibrating. Upon a rise in building pressure, the unit controls are to slow down the supply air fan (through the variable speed drive). The opposite is to happen on a drop in building pressure. N. Electrical: 2.03 MOTORS 1. Unit shall be provided with a factory installed and wired main disconnect switch. Integral branch fusing shall be accomplished through the use of resettable circuit breakers. Replaceable fuses are NOT acceptable. 2. Unit shall be provided with phase and brown-out protection to shut down all motors in the unit if the phases are more than 10% out of balance on voltage, or the voltage is more than 10% under design voltage or on phase reversal. In the event that a poor power condition is detected, the power monitoring feature will instantaneously shut the unit down and isolate the microprocessor controller from the incoming power supply. The Power Monitor feature shall record and save a minimum of 10 fault conditions in the fault history log. The Power Monitor feature shall automatically restart the unit after power has returned within acceptable parameters for a preset period of time. 3. Unit shall be provided with a factory installed and wired 115 volt, 12 amp ground fault service receptacle powered by a 1.5 KVA transformer. The convenient outlet shall be fed by an independent power supply. A. Refer to Division 23 Section "Common Motor Requirements for HVAC Equipment" for general requirements for factory-installed motors. B. Motor Construction: NEMA MG 1, general purpose, continuous duty, Design B. C. Enclosure Type: Open, dripproof. PART 3 EXECUTION 3.01 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 INSTALLATION A. Install units according to manufacturer's written instructions. B. Install units level and plumb, maintaining manufacturer's recommended clearances 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: PAGE 8

9 1. Install piping to allow service and maintenance. 2. Gas Piping: Comply with applicable requirements in Division 22 Section "Natural Gas Piping." Connect gas piping to burner, full size of gas train inlet, and connect with union and shutoff valve with sufficient clearance for burner removal and service. B. Duct installation requirements are specified in other Division 23 Sections. Drawings indicate the general arrangement of ducts FIELD QUALITY CONTROL AND COMMISSIONING A. Verify that installation is as indicated and specified. B. Complete commissioning pre-functional testing and functional testing as part of the following. C. Complete manufacturer's installation and startup checks and perform the following: 1. Level unit on curb or steel, 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. Clean furnace flue and inspect for construction debris. 9. Connect and purge gas line. 10. Adjust vibration isolators. 11. Inspect operation of barometric dampers. 12. Check operation of mixing dampers. D. Lubricate bearings on fan. E. Check fan-wheel rotation for correct direction without vibration and binding. F. Adjust fan belts to proper alignment and tension. G. Start unit according to manufacturer's written instructions. H. Check and record performance of interlocks and protection devices; verify sequences. I. Operate unit for an initial period as recommended or required by manufacturer. J. Check internal isolators. K. Check outside-air damper for proper stroke and interlock with return-air dampers. L. Check controls for correct sequencing of heating, cooling, mixing dampers, and normal and emergency shutdown. M. Perform the following operations for both minimum and maximum firing and adjust burner for peak efficiency. Adjust pilot to stable flame. 1. Measure gas pressure on manifold. 2. Measure combustion-air temperature at inlet to combustion chamber. 3. Measure flue-gas temperature at furnace discharge. PAGE 9

10 4. Perform flue-gas analysis. Measure and record flue-gas carbon dioxide and oxygen concentration. 5. Measure supply-air temperature and volume when burner is at maximum firing rate and when burner is off. Calculate useful heat to supply air. N. Start refrigeration system and 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. 4. Outside-air-coil, discharge-air, dry-bulb temperature. O. 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. P. After starting and performance testing, change filters, vacuum heat exchanger and coils, lubricate bearings, and adjust belt tension DEMONSTRATION A. Engage a factory-authorized service representative to train Owner's maintenance personnel. 1. Conduct training as specified in Section "Training. 2. Train Owner's maintenance personnel on procedures and schedules related to startup and shutdown, troubleshooting, servicing, and preventive maintenance. 3. Review data in the maintenance manuals. END OF SECTION PAGE 10