237300 - Indoor Central-Station Air-Handling Units.pdf

SYRACUSE VA MEDICAL CENTER

DESIGN 3RD AND 4TH FLOOR D-WING RENOVATION

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SECTION 23 73 00

INDOOR CENTRAL-STATION AIR-HANDLING UNITS

PART 1 - GENERAL

1.1 DESCRIPTION

A. Air handling units including integral components specified herein.

B. Definitions: Air Handling Unit (AHU): A factory fabricated and tested assembly of modular sections consisting of housed-centrifugal fan with

V-belt drive, single or multiple plenum fans with direct-drive, coils, filters, and other necessary equipment to perform one or more of the following functions of circulating, cleaning, heating, cooling, humidifying, dehumidifying, and mixing of air. Design capacities of units shall be as scheduled on the drawings.

1.2 RELATED WORK

A. General mechanical requirements and items, which are common to more than one section of Division 23: Section 23 05 11, COMMON WORK RESULTS FOR

HVAC AND STEAM GENERATION.

B. Sound and vibration requirements: Section 23 05 41, NOISE AND VIBRATION

CONTROL FOR HVAC PIPING AND EQUIPMENT.

C. Piping and duct insulation: Section 23 07 11, HVAC, PLUMBING, AND BOILER

PLANT INSULATION.

D. Piping and valves: Section 23 21 13 / 23 22 13, HYDRONIC PIPING / STEAM

AND CONDENSATE HEATING PIPING.

E. Heating and cooling coils and pressure requirements: Section 23 82 16, AIR COILS.

F. Return and exhaust fans: Section 23 34 00, HVAC FANS.

G. Requirements for flexible duct connectors, sound attenuators and sound absorbing duct lining, and air leakage: Section 23 31 00, HVAC DUCTS and

CASINGS.

H. Air filters and filters' efficiency: Section 23 40 00, HVAC AIR CLEANING

DEVICES.

I. HVAC controls: Section 23 09 23, DIRECT-DIGITAL CONTROL SYSTEM FOR HVAC.

J. Testing, adjusting and balancing of air and water flows: Section 23 05

93, TESTING, ADJUSTING, AND BALANCING FOR HVAC.

K. Types of motors: Section 23 05 12, GENERAL MOTOR REQUIREMENTS FOR HVAC

AND STEAM GENERATION EQUIPMENT.

L. Types of motor starters: Section 26 29 11, LOW-VOLTAGE MOTOR STARTERS.

M. General Commissioning: Section 01 91 00, GENERAL COMMISSIONING

REQUIREMENTS

N. HVAC Commissioning: Section 23 08 00, COMMISSIONING OF HVAC SYSTEMS

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1.3 QUALITY ASSURANCE

A. Refer to Article, Quality Assurance, in Section 23 05 11, COMMON WORK

RESULTS FOR HVAC AND STEAM GENERATION.

B. Air Handling Units Certification

1. Air Handling Units with Housed Centrifugal Fans: The air handling units shall be certified in accordance with AHRI 430 and tested/rated in accordance with AHRI 260.

2. Air Handling Units with Plenum Fans:

a. Air Handling Units with a single Plenum Fan shall be certified in accordance with AHRI 430 and tested/rated in accordance with AHRI

260.

b. Air handling Units with Multiple Fans in an Array shall be tested and rated in accordance with AHRI 430 and AHRI 260.

C. Heating, Cooling, and Air Handling Capacity and Performance Standards:

AHRI 430, AHRI 410, ASHRAE 51, and AMCA 210.

D. Performance Criteria:

1. The fan BHP shall include all system effects for all fans and v-belt drive losses for housed centrifugal fans.

2. The fan motor shall be selected within the rated nameplate capacity, without relying upon NEMA Standard Service Factor.

3. Select the fan operating point as follows:

a. Forward Curve and Axial Flow Fans: Right hand side of peak pressure point.

b. Air Foil, Backward Inclined, or Tubular Fans Including Plenum

Fans: At or near the peak static efficiency but at an appropriate distance from the stall line.

4. Operating Limits: AMCA 99 and Manufacturer’s Recommendations.

E. Units shall be factory-fabricated, assembled, and tested by a manufacturer, in business of manufacturing similar air-handling units for at least five (5) years.

1.4. SUBMITTALS:

A. The contractor shall, in accordance with Section 01 33 23, SHOP

DRAWINGS, PRODUCT DATA, AND SAMPLES, furnish a complete submission for all air handling units covered in the project. The submission shall include all information listed below. Partial and incomplete submissions shall be rejected without reviews.

B. Manufacturer's Literature and Data:

1. Submittals for AHUs shall include fans, drives, motors, coils, humidifiers, sound attenuators, mixing box with outside/return air dampers, filter housings, and all other related accessories. The

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23 73 00 - 3 contractor shall provide custom drawings showing total air handling unit assembly including dimensions, operating weight, access sections, flexible connections, door swings, controls penetrations, electrical disconnect, lights, duplex receptacles, switches, wiring, utility connection points, unit support system, vibration isolators, drain pan, pressure drops through each component (filter, coil etc).

2. Submittal drawings of section or component only will not be acceptable. Contractor shall also submit performance data including performance test results, charts, curves or certified computer selection data; data sheets; fabrication and insulation details. If the unit cannot be shipped in one piece, the contractor shall indicate the number of pieces that each unit will have to be broken into to meet shipping and job site rigging requirements. This data shall be submitted in hard copies and in electronic version compatible to AutoCAD version used by the VA at the time of submission.

3. Submit sound power levels in each octave band for the inlet and discharge of the fan and at entrance and discharge of AHUs at scheduled conditions. In absence of sound power ratings refer to

Section 23 05 41, NOISE AND VIBRATION CONTROL FOR HVAC PIPING AND

EQUIPMENT.

4. Provide fan curves showing Liters/Second (cubic feet per minute), static pressure, efficiency, and horsepower for design point of operation and at maximum design Liters/Second (cubic feet per minute).

5. Submit total fan static pressure, external static pressure, for AHU including total, inlet and discharge pressures, and itemized specified internal losses and unspecified internal losses. Refer to air handling unit schedule on drawings.

C. Maintenance and operating manuals in accordance with Section 01 00 00, GENERAL REQUIREMENTS. Include instructions for lubrication, filter replacement, motor and drive replacement, spare part lists, and wiring diagrams.

D. Submit written test procedures two weeks prior to factory testing.

Submit written results of factory tests for approval prior to shipping.

E. Submit shipping information that clearly indicates how the units will be shipped in compliance with the descriptions below.

1. Units shall be shipped in one (1) piece where possible and in shrink wrapping to protect the unit from dirt, moisture and/or road salt.

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2. If not shipped in one (1) piece, provide manufacturer approved shipping splits where required for installation or to meet shipping and/or job site rigging requirements in modular sections. Indicate clearly that the shipping splits shown in the submittals have been verified to accommodate the construction constraints for rigging as required to complete installation and removal of any section for replacement through available access without adversely affecting other sections.

3. If shipping splits are provided, each component shall be individually shrink wrapped to protect the unit and all necessary hardware (e.g.

bolts, gaskets etc.) will be included to assemble unit on site (see section 2.1.A4).

4. Lifting lugs will be provided to facilitate rigging on shipping splits and joining of segments. If the unit cannot be shipped in one piece, the contractor shall indicate the number of pieces that each unit will have to be broken into to meet shipping and job site rigging requirements.

1.5 APPLICABLE PUBLICATIONS

A. The publications listed below form a part of this specification to the extent referenced. The publications are referenced in the text by the basic designation only.

B. Air-Conditioning, Heating, and Refrigeration Institute (AHRI)/(ARI):

410-01..................Standard for Forced-Circulation Air-Heating and

Air-Cooling Coils

430-09..................Central Station Air Handling Units

C. Air Movement and Control Association International, Inc. (AMCA):

210-07..................Laboratory Methods of Testing Fans for Rating

D. American Society of Heating, Refrigerating and Air-conditioning

Engineers, Inc. (ASHRAE):

170-2008................Ventilation of Health Care Facilities

E. American Society for Testing and Materials (ASTM):

ASTM B117-07a...........Standard Practice for Operating Salt Spray (Fog)

Apparatus

ASTM D1654-08...........Standard Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive

Environments

ASTM D1735-08...........Standard Practice for Testing Water Resistance of Coatings Using Water Fog Apparatus

ASTM D3359-08...........Standard Test Methods for Measuring Adhesion by

Tape Test

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F. Military Specifications (Mil. Spec.):

MIL-P-21035B-2003.......Paint, High Zinc Dust Content, Galvanizing

Repair (Metric)

G. National Fire Protection Association (NFPA):

NFPA 90A................Standard for Installation of Air Conditioning and Ventilating Systems, 2009

H. Energy Policy Act of 2005 (P.L.109-58)

PART 2 - PRODUCTS

2.1 AIR HANDLING UNITS

A. Manufacturers:

1. Provide AHU as manufactured by Air Enterprises, or approved equal.

B. General:

1. AHUs shall be fabricated from insulated, double-wall aluminum.

2. The contractor and the AHU manufacturer shall be responsible for ensuring that the unit will not exceed the allocated space shown on the drawings, including required clearances for service and future overhaul or removal of unit components. All structural, piping, wiring, and ductwork alterations of units, which are dimensionally different than those specified, shall be the responsibility of the contractor at no additional cost to the government.

3. These units shall be constructed for indoor installation. The units shall be factory fabricated and field assembled. The unit manufacturer shall be completely responsible for the unit installation.

4. AHUs shall be fully assembled by the manufacturer in the factory in accordance with the arrangement shown on the drawings. The unit shall be assembled into the largest sections possible subject to shipping and rigging restrictions. The correct fit of all components and casing sections shall be verified in the factory for all units prior to shipment. All units shall be fully assembled, tested, and then split to accommodate shipment and job site rigging. On units not shipped fully assembled, the manufacturer shall tag each section and include air flow direction to facilitate assembly at the job site.

Lifting lugs or shipping skids shall be provided for each section to allow for field rigging and final placement of unit.

5. The AHU manufacturer shall provide the necessary gasketing, caulking, and all screws, nuts, and bolts required for assembly. The manufacturer shall provide a factory-trained and qualified local representative at the job site to supervise the assembly and to assure that the units are assembled to meet manufacturer's

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23 73 00 - 6 recommendations and requirements noted on the drawings. Provide documentation to the Contracting Officer that the local representative has provided services of similar magnitude and complexity on jobs of comparable size. If a local representative cannot be provided, the manufacturer shall provide a factory representative.

6. Gaskets: All door and casing and panel gaskets and gaskets between air handling unit components, if joined in the field, shall be high quality which seal air tight and retain their structural integrity and sealing capability after repeated assembly and disassembly of bolted panels and opening and closing of hinged components. Bolted sections may use a more permanent gasketing method provided they are not disassembled.

7. Structural Rigidity: Provide structural reinforcement when required by span or loading so that the deflection of the assembled structure shall not exceed 1/200 of the span based on a differential static pressure of 1991 PA (8 inch WG) or higher.

8. Provide hygienic unit design with interior suitable for washing down.

The use of support members framed within the unit casing which will allow for trapping of debris between the supports and casing will not be allowed. Unit insulation must be completely encapsulated.

C. Base:

1. Provide a heavy duty steel base for supporting all major AHU components. Bases shall be constructed of wide-flange steel I-beams, channels, or minimum 125 mm (5 inch) high 3.5 mm (10 Gauge) steel base rails. Welded or bolted cross members shall be provided as required for lateral stability. Contractor shall provide supplemental steel supports as required to obtain proper operation heights for cooling coil condensate drain trap and steam coil condensate return trap as shown on drawings.

2. AHUs shall be completely self-supporting for installation on steel support pedestals as shown on drawings.

3. The unit shall be constructed on an all-aluminum or stainless-steel structural base. The base shall be designed to distribute loads properly to a suitable mounting surface and be braced to support internal components without sagging, pulsating or oil canning.

4. The unit base shall be provided with sumps in areas as indicated on the drawings. Sumps to be welded and guaranteed waterproof to serve as a drain pan to prevent building water damage from the unit.

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5. The base floor shall be minimum 3/16” thick aluminum plate welded at all joints and to structural members. Floor material shall have safety-tread surface. The base floor shall be designed for a minimum live load of 100 pounds per square foot throughout the unit. The base floor is to be supported with adequate stiffening members to prevent oil canning. Caulking, gaskets and mechanical fasteners to guarantee seals and water tightness of joints will not be acceptable.

Base shipping splits shall be provided as needed based on unit rigging limitations. Shipping splits shall be designed with a raised flange for connecting of base sections. The raised flange shall allow the base sections to be bolted together and maintain a minimum of 2” deep sump. Base joining methods that require field welding are not acceptable. Where indicated, furnish and install floor drains, flush with the floor, with nonferrous grate cover and stub through floor for external connection.

6. The perimeter support members shall be properly sized to support all major components and the housing during rigging, handling and operation of the unit.

7. The underneath side of the base pan and base perimeter shall be insulated with minimum 2” thick 1.5-pcf high density polyisocyanurate foam insulation to form a vapor barrier. Vapor barrier is then protected by a 0.040” thick aluminum sheet attached to the bottom of the base.

8. Each section of the unit base shall contain a minimum 1” NPT drain to facilitate system washdown, maintenance removal. Areas in the base of every AHU section where potential standing water cannot be removed through drains are not acceptable. Clean out drains shall be provided with removable caps of non-corrosive material.

9. All equipment within air handling unit shall be provided with a minimum 2" high base to raise equipment off unit floor for housekeeping. Equipment mounted directly on unit floor is unacceptable.

10. Supply air openings to be framed with 2” high water dam continuously welded to the pan to allow proper duct connections and to prevent moisture from entering the openings. Framed openings shall be provided with removable aluminum or 304 stainless steel grating designed and fabricated for a live load of 100 pounds per square foot. Galvanized or painted steel grating will not be accepted.

11. All unit base service openings shall be framed with a minimum 2” high water dam continuously welded to the floor. All pipe and

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23 73 00 - 8 electric conduit chases with openings to building or elements shall be covered with thin gage aluminum or 304 stainless steel.

Penetrations by contractors shall be sealed by the respective contractor.

12. Fastening to floor plate or joining of unit sections to be accomplished by bolting through gasketed joints above the floor line or continuously welding. Fasteners which penetrate base floor plate are not acceptable.

13. Unit to be provided with properly located permanent lifting plates or removable lifting lugs for each section to adequately allow rigging of the unit sections in place.

D. Casing (including wall, floor and roof):

1. Air handling unit casing shall be built up from the unit base or floor with panels. The unit manufacturer shall be the manufacturer of the panel system. Panels shall be load bearing and capable of forming the enclosure without additional structural members. Panels shall be joined together with independent joining member and fastened with closed end aluminum rivets or stainless-steel fasteners. Plated fasteners will not be accepted.

2. All panels shall be double wall all-aluminum construction with minimum 0.040” exterior and interior skin thicknesses. Interior finish to be smooth, mill finish; exterior finish to be a low-reflective textured mill finish. Each panel shall contain an integral frame or be properly supported by a structural framing system. Panel shall have continuous tight seal at the interior and exterior skins completely encapsulating the insulation.

3. The minimum panel thickness shall be 2-1/2” thick with 3-pcf high density polyisocyanurate foam insulation. The panel R value shall be a minimum of 13 or greater.

4. Thickness of the panel skin, core density, rib structural frame spacing shall be regulated to eliminate panel pulsation and restrict the maximum deflection to 1/200 of any span at design load of 1-1/2 times the design positive or negative pressure plus snow and wind loading.

5. Casing system shall be guaranteed to assure the owner that system capacity, performance, and cleanliness standards specified are not compromised. Leakage to be guaranteed at no more than 1/2% of the design volume at 1-1/2 times the design operating pressure or 30 CFM, whichever is greater.

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6. All casing walls shall be of panel construction, including but not limited to the fan discharge walls, mixing section walls and divider wall to the access corridor.

7. Any equipment flashing, internal partitions or other attachments to the casing shall be made in such a way as to ensure a permanent leak-tight connection. Attachments that are bolted, screwed, or welded to or through the casing creating air bypass, air leakage or rust propagation areas are not acceptable.

8. All ductwork penetrations through unit enclosure shall be provided with framed openings of size and arrangement as indicated on drawing.

9. Pipe and conduit penetrations through the unit casings shall be provided by the unit manufacturer and be properly sealed prior to leaving the factory. Penetrations sealed by simply caulking around extension are not acceptable.

10. Provide minimum 24” wide access doors, unless shown of different size on the drawings, for access to all internal components. Access doors shall be installed to open against the greatest pressure relative to air pressure on each side of access door.

a. Access doors shall be of the same construction as panels described above.

b. The access doors shall incorporate two continuous separate gasket seals around the entire periphery of the door. Gasket material shall be UV-resistant, closed cell neoprene; gaskets shall be attached by adhesive and not mechanically held in place. Single gasket seals will not be accepted.

c. Each access door shall contain a thermopane safety glass window

(min. 10” square).

d. Provide 1” dia. test ports with caps on casing upstream and downstream of all coils and filters for pressure and temperature measurement.

e. Each access door shall be mounted with a corrosion-resistant continuous piano hinge and shall have a least two (2) non-corrosive handles operable from either side

f. Hinges: Manufacturers standard, designed for door size, weight and pressure classifications. Hinges shall hold door completely rigid with minimum 45 kg (100 lb) weight hung on latch side of door.

g. Latches: Non-corrosive alloy construction, with operating levers for positive cam action, operable from either inside or outside.

Doors that do not open against unit operating pressure shall allow the door to ajar and then require approximately 0.785 radian (45

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23 73 00 - 10 degrees) further movement of the handle for complete opening.

Latch shall be capable of restraining explosive opening of door with a force not less than 1991 Pa (8 inch WG).

h. Gaskets: Neoprene, continuous around door, positioned for direct compression with no sliding action between the door and gasket.

Secure with high quality mastic to eliminate possibility of gasket slipping or coming loose.

11. Blank-Off: Provide blank-offs as required to prevent air bypass between the AHU sections, around coils, and filters.

12. Casing panels shall be completely removable to allow removal of fan, coils, and other internal components for future maintenance, repair, or modifications. Welded exterior panels are not acceptable.

13. Provide sealed sleeves, metal or plastic escutcheons or grommets for penetrations through casing for power and temperature control wiring and pneumatic tubing. Coordinate with electrical and temperature control subcontractors for number and location of penetrations.

Coordinate lights, switches, and duplex receptacles and disconnect switch location and mounting. All penetrations and equipment mounting may be provided in the factory or in the field. All field penetrations shall be performed neatly by drilling or saw cutting. No cutting by torches will be allowed. Neatly seal all openings airtight.

E. Condensate Drain Pan: Provide drain pans for each coil section and all other coils such as heating coils and heat recovery coils. Drain pan shall be designed to extend entire length and beyond leaving side of cooling coils including headers and return bends. Depth of drain pan shall be at least 43 mm (1.7 inches) and shall handle all condensate without overflowing. Drain pan shall be double-wall, double sloping type, and fabricated from stainless (304) with at least 50 mm (2 inch) thick insulation sandwiched between the inner and outer surfaces. Drain pan shall be continuous metal or welded watertight. No mastic sealing of joints exposed to water will be permitted. Drain pan shall be placed on top of casing floor or integrated into casing floor assembly. Drain pan shall be pitched in all directions to drain line.

1. An intermediate, stainless-steel (304) condensate drip pan with copper downspouts shall be provided on stacked cooling coils. Use of intermediate condensate drain channel on upper casing of lower coil is permissible provided it is readily cleanable. Design of intermediate condensate drain shall prevent upper coil condensate from flowing across face of lower coil.

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2. Drain pan shall be piped to the exterior of the unit. Drain pan shall be readily cleanable.

3. Installation, including frame, shall be designed and sealed to prevent blow-by.

F. Plenum Fans – Single and/or Multiple Fans in an Array:

1. General: Fans shall be Class II (minimum) construction. The fan wheels shall be non-overloading, airfoil type. Impellers shall be statically and dynamically balanced to a level of G6.3 (per ANSI 2-

19) or better. Hubs shall be straight bored, keyed and set screwed to the shaft. Shafts are to be solid steel sized for first critical speed of at least 1.25 times the maximum speed for the class for class I and II fans and 1.42 times the maximum speed for class for class III and IV fans. The fan wheel shall be mounted on the directly-driven motor shaft in AMCA Arrangement 4. Fans shall be dynamically balanced and internally isolated to minimize the vibrations. Provide a steel inlet cone for each wheel to match with the fan inlet. Locate fan in the air stream to assure proper flow.

The fan performance shall be rated in accordance with AMCA 210 or

ASHRAE 51.

2. Bearings are to be heavy duty, grease lubricated, anti-friction, self-aligning, pillow block type and selected for minimum average bearing life (AFBMA L-50) in excess of 200,000 hours at the maximum class RPM. All bearings shall be equipped with regreasable Zerk fittings and lubrication lines extended to accessible location on fan housing for easy access for lubrication.

3. Fan shall be provided with wire mesh protective wheel enclosure and heavy gauge wire inlet screen. In the event inlet vanes are provided, fan will not require inlet screens.

4. Fan shall be cleaned, prime coated and provided with two coats of enamel final coat.

5. Each fan shall be test run at their operating speed or at the maximum

RPM for the particular fan’s construction class prior to shipment.

The fans are to be balanced and records maintained of the readings in the axial, vertical, and horizontal direction on each of the fan’s bearings. Final peak velocity measurements shall not exceed 0.1 in/sec.

6. Allowable vibration tolerances for fan shall not exceed a self-excited vibration maximum velocity of 0.005 m/s (0.20 inch per second) RMS, filter in, when measured with a vibration meter on bearing caps of machine in vertical, horizontal and axial directions

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23 73 00 - 12 or measured at equipment mounting feet if bearings are concealed.

After field installation, compliance to this requirement shall be demonstrated with field test in accordance with Section 23 05 41, NOISE AND VIBRATION CONTROL FOR HVAC PIPING AND EQUIPMENT and Section

23 05 93, TESTING, ADJUSTING, AND BALANCING FOR HVAC. Following fan assembly, the complete fan assembly balance shall be tested using an electronic balance analyzer with a tunable filter and stroboscope.

Vibration measurements shall be taken on each motor bearing housing in the vertical, horizontal, and axial planes (5 total measurements, 2 each motor bearing and 1 axial).

7. The plenum fans shall be driven by variable speed drives with at least one back-up drive as shown in the design documents. Use of a drive with bypass is not permitted.

8. Multiple fans shall be installed in a pre-engineered structural frame to facilitate fan stacking. All fans shall modulate in unison, above or below the synchronous speed within the limits specified by the manufacturer, by a common control sequence. Staging of the fans is not permitted. Redundancy requirement shall be met by all operating fans in an array and without the provision of an idle standby fan.

9. Acceptable fan manufacturers: Twin City Fan, Greenheck, New York

Blower

10. Fan Accessories

a. Fan Isolation: Each fan shall have an isolation damper to isolate one of the fans off-line for servicing while the remaining fans continue to operate. Damper shall be per the following:

1. Dampers to be installed with the damper blades positioned vertically. Dampers shall be low leakage, opposed blade design capable of withstanding 8” wg differential pressure at 2,000 fpm approach velocity. Leakage rate not to exceed 6 CFM per ft.2 at 4” wg differential pressure and 2,000 fpm approach.

2. Damper frames shall be made of extruded aluminum. Damper blades shall be extruded aluminum airfoil shape to withstand high velocities and static pressures. Dampers shall be provided with stainless steel blade end seals and extruded silicone blade edge seals.

3. Dampers shall be provided with two sets of linkage; one set concealed in the side frame of the damper and one set mounted from the blades on the face of the damper. Dampers are to be driven from an extended drive rod.

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4. Damper actuators to be mounted by unit manufacturer. Damper actuator to be Johnson Controls – D-3240 series or equal.

5. Acceptable dampers: Arrow ‘AFD-20’, Ruskin ‘CD-50’, TAMCO

1500, or approved equal.

b. Fan Airflow Measurement: Provide an airflow measuring device integral to the fan to measure air volume within +/- 5 percent accuracy. Acceptable measurement device to be Ebtron GTx108-F/An or approved equal.

G. Fan Motor, Drive, and Mounting Assembly (Plenum Fans):

1. Fan Motor and Drive: Motors shall be premium energy efficient type, as mandated by the Energy Policy Act of 2005, with efficiencies as shown in the Specifications Section 23 05 12, GENERAL MOTOR

REQUIREMENTS FOR HVAC AND STEAM GENERATION EQUIPMENT, on drawings and suitable for use in variable frequency drive applications. Refer to

Section 23 05 11, COMMON WORK RESULTS FOR HVAC, for additional motor and drive specifications.

2. Motor shall be of HP as listed on schedule and be selected for a minimum of 10% over calculated BHP. The motor service factor shall be a minimum of 1.15.

3. Motor shall be designed for continuous duty operation, NEMA Design B with class F insulation.

4. The motor shall be suitable for operating with variable frequency drives without undue noise, vibration or deterioration of reliability and life.

5. Motors shall be “Inverter Ready” per NEMA Std. MG1 part 31.4.4.2 and labeled as such. Provide stainless steel nameplate indicating the following:

a) NEMA efficiency index nominal efficient (MB1-12.53BO).

b) AFBMA bearing numbers.

c) Lubrication instructions.

6. Acceptable motor manufactures: Baldor, Marathon Electric, TECO -

Westinghouse

7. The entire fan assembly shall be provided with a minimum of 18” clearance on all unattached sides for proper service access. Fan inlets to be provided with a minimum clearance distance equal to 75% of the wheel diameter.

8. The unit manufacturer shall provide flexible connection between fan and fan wall. Fan assembly shall be provided with thrust arrestors as required to prevent damage to the flex connection. Flex

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23 73 00 - 14 connection material shall be flame retardant fabric suitable for intended use meeting the requirements of NFPA 90A.J.

H. Filter Section: Refer to Section 23 40 00, HVAC AIR CLEANING DEVICES, for filter requirements.

1. Filters including one complete set for temporary use at site shall be provided independent of the AHU. The AHU manufacturer shall install filter housings and racks in filter section compatible with filters furnished. The AHU manufacturer shall be responsible for furnishing temporary filters (pre-filters and after-filters, as shown on drawings) required for AHU testing.

2. Factory-fabricated filter section shall be of the same construction and finish as the AHU casing including filter racks and hinged double wall access doors. Filter housings shall be constructed in accordance with side service or holding frame housing requirements in Section 23

40 00, HVAC AIR CLEANING DEVICES.

I. Diffuser Section: Furnish a diffuser segment with perforated diffuser plate immediately downstream of supply fan to assure uniform distribution of leaving air across the face of the downstream after-filters to create uniform velocity profiles across the entire opening.

Bolt or weld diffuser plate to a sturdy steel support frame so that it remains rigid. Manufacturer shall include any diffuser section pressure loss in excess of diffuser plate and this value shall be included in unspecified internal losses when selecting fan.

J. Coils: Coils shall be mounted on hot dipped galvanized steel supports to assure proper anchoring of coil and future maintenance. Coils shall be face or side removable for future replacement thru the access doors or removable panels. Each coil shall be removable without disturbing adjacent coil. Cooling coils and glycol-water exhaust heat recovery coils shall be designed and installed to ensure no condensate carry over. Provide factory installed extended supply, return, drain, and vent piping connections. Coils to be selected with maximum face velocity of

500 fpm.

1. Chilled water coils shall have minimum 0.025" thick, 5/8" diameter, copper tubes, 0.0075" copper fins, nonferrous headers with min. 1/2” dia. MPT drain and vent connections. Coil casings shall be minimum

16 gauge 304 stainless steel. Coil fin spacing shall not exceed 10 fpi.

2. Coils shall be individually supported by a stainless-steel rack system. This rack shall allow any one (1) coil to be removed though the unit casing, normal to the direction of air flow, without

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23 73 00 - 15 disturbing any other coil. Coils stacked one on top of the other will not be accepted.

3. Provide removable access panels in the unit casing on each side of the unit for ease of coil removal.

4. Acceptable coil manufacturers: Coilmaster, Heatcraft, Aerofin, Greenheck

5. Hot water heating coils shall have minimum 0.020" thick, 5/8" diameter, copper tubes, 0.0075" aluminum fins, nonferrous headers with min. 1/2” dia. MPT drain and vent connections, and aluminum coil casing. Coil casings shall be minimum 16-gauge galvanized steel;

aluminum or stainless-steel casings required for coils located downstream of cooling coils or humidifiers. Coil fin spacing shall not exceed 10 fpi

K. Humidifier: When included in design, coordinate the humidification requirements with section 23 22 13 Steam and Condensate Heating Piping.

Provide air-handling unit-mounted humidification section with stainless steel drain pan of adequate length to allow complete absorption of water vapor. Provide stainless steel dispersion panel or distributors as indicated, with stainless steel supports and hardware. Absorption distance shall not exceed 18” at desired conditions. Air handling manufacturer shall be responsible for proper absorption distance for steam between humidifier and downstream components. Steam supply and condensate return connections are to be extended and sealed through the casing wall. The condensate connections shall be a minimum of 18” above the unit base to allow for proper trapping; if required, condensate trap to be installed by AHU manufacturer internal to unit. Acceptable humidifier manufacturers are Armstrong, Nortec, Dri-Steem, or approved equal.

L. Sound Attenuators: Refer to Drawings, Specification Section 23 05 41, NOISE AND VIBRATION CONTROL FOR HVAC PIPING AND EQUIPMENT, and Section

23 31 00, HVAC DUCTS AND CASINGS, for additional unit mounted sound attenuator requirements. AHU sound attenuators shall be factory installed as an integral part of AHU.

1. Sound attenuator sections shall be complete with individual battens the full height and full width of the section in order to provide uniform leaving air velocities and lower pressure drops. Modularized sound attenuator assemblies with horizontal air restrictions are not acceptable.

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2. The battens shall be of aluminum construction; filled with a fibrous inert core. Each batten shall consist of a solid aerodynamically styled nose piece with parallel perforated walls. Core material is to be covered with a tight weave cloth to prevent out-migration of fiber materials into the airstream; covering shall be porous material not diminishing the attenuating properties of the attenuators. Unit manufacturer shall guarantee lining cloth provided prevents out-migration of fibers.

3. The attenuator manufacturer shall have published literature documented by independent test laboratories for acoustic performance of the sound attenuators.

4. Custom air handling unit inlet and outlet airborne sound power levels and radiated sound pressure levels shall be guaranteed to meet the specified sound levels and shall be the responsibility of the unit manufacturer.

M. Discharge Section:

Provide aerodynamically designed framed discharge openings or spun bellmouth fittings to minimize pressure loss.

1. Bellmouth fittings shall have minimum radius equal to 20% of the diameter (round or oval) or shortest side (rectangular) to provide optimum performance. Bellmouths with radius less than 2” are not acceptable. Bellmouth to be mounted flush with unit interior edge to minimize exit loss.

2. Openings shall conform to the size and configuration of the ductwork where shown.

3. Smoke dampers shall be furnished and installed by the unit manufacturer for supply air (and return air) openings as shown on the drawings. Dampers shall be as specified below:

a. Dampers shall be parallel blade design capable of with standing 8” wg differential pressure at 2,000 fpm approach velocity. Damper shall meet requirements of Leakage Class I.

b. Damper frames shall be made of extruded aluminum. Damper blades shall be extruded aluminum airfoil shape to withstand high velocities and static pressures. Dampers shall be provided with stainless steel blade end seals and flexible synthetic blade edge seals to keep leakage to a minimum.

c. Damper linkage to be concealed in frame channel outside of the airstream. Dampers shall be provided with extended shaft for connection to actuators.

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d. Damper actuators to include an end-switch and shall be rated for

(120V / 24V).

e. Smoke dampers and operators shall be qualified under UL555S to a minimum elevated temperature of 250o F.

f. Acceptable dampers: Ruskin, Tamco, Greenheck, or approved equal.

N. Electrical and Lighting: Wiring and equipment specifications shall conform to Division 26, ELECTRICAL.

1. All electrical work shall be installed in full compliance with the

National Electric Code, and all local codes and requirements. Where applicable, components shall be UL approved. All wiring and components inside air handling plenums shall be weatherproof and rated for such use. All equipment shall contain a grounding conductor.

2. The electrical contractor shall be responsible for mounting the following devices on the air handler as detailed on the submittal drawings. The required installation labor, conduit, wiring, and miscellaneous fittings shall be provided by the electrical contractor.

3. Unit manufacturer shall provide the following devices as detailed on the submittal drawing. Lighting system to include light fixtures, switches, and a GFCI receptacle per the following:

a. LIGHT FIXTURES: vapor tight LED marine type guarded service light fixture, 16 watt (A-21) bulb. Each access section to be provided with minimum of one (1) light fixture. Fan sections and filter sections to be provided with minimum of two (2) light fixtures.

Access corridors to have a minimum of three (3) light fixtures.

b. LIGHT SWITCHES: 20 AMP, single pole, specification grade, toggle switch in lug type device box with stainless steel cover.

c. GFCI CONVENIENCE OUTLETS: 20 AMP, specification grade, NEMA 5-20R, duplex receptacle in lug type device box with stainless steel cover. Unit to be provided with one (1) convenience outlet on unit exterior at the fan section.

4. Unit manufacturer shall provide a fan motor disconnect for each fan motor.

a. FAN MOTOR DISCONNECTS: 3 pole, 600V, horsepower rated, heavy duty, visible blade, non-fused, NEMA 12 safety switch with 2 pole control circuit interlock if used in conjunction with variable speed drive.

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PART 3 – EXECUTION

3.1 INSTALLATION

A. Install air handling unit in conformance with ARI 435.

B. Assemble air handling unit components following manufacturer's instruc-tions for handling, testing and operation. Repair damaged galvanized areas with paint in accordance with Military Spec. DOD-P-21035. Repair painted units by touch up of all scratches with finish paint material.

Vacuum the interior of air handling units clean prior to operation.

C. Leakage and test requirements for air handling units shall be the same as specified for ductwork in Specification Section 23 31 00, HVAC DUCTS

AND CASINGS except leakage shall not exceed Leakage Class (CL) 12 listed in SMACNA HVAC Air Duct Leakage Test Manual when tested at 1.5 times the design static pressure. Repair casing air leaks that can be heard or felt during normal operation and to meet test requirements.

D. Perform field mechanical (vibration) balancing in accordance with

Section 23 05 41, NOISE AND VIBRATION CONTROL FOR HVAC PIPING AND

EQUIPMENT.

E. Seal and/or fill all openings between the casing and AHU components and utility connections to prevent air leakage or bypass.

3.2 STARTUP SERVICES

A. The air handling unit shall not be operated for any purpose, temporary or permanent, until ductwork is clean, filters are in place, bearings are lubricated and fan has been test run under observation.

B. After the air handling unit is installed and tested, provide startup and operating instructions to VA personnel.

C. An authorized factory representative should start up, test and certify the final installation and application specific calibration of control components. Items to be verified include fan performance over entire operating range, noise and vibration testing, verification of proper alignment, overall inspection of the installation, Owner/Operator training, etc.

3.3 COMMISSIONING

A. Provide commissioning documentation in accordance with the requirements of Section 23 08 00 – COMMISSIONING OF HVAC SYSTEMS for all inspection, start up, and contractor testing required above and required by the

System Readiness Checklist provided by the Commissioning Agent.

B. Components provided under this section of the specification will be tested as part of a larger system. Refer to Section 23 08 00 –

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COMMISSIONING OF HVAC SYSTEMS and related sections for contractor responsibilities for system commissioning.

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