36C26120R0017-017.doc

02-11

SECTION 23 81 00

DECENTRALIZED UNITARY HVAC EQUIPMENT

PART 1 - GENERAL

1.1 DESCRIPTION

A.

This section specifies self-contained, rooftop, air conditioners.

B.

Definitions:

1.

Energy Efficiency Ratio (EER): The ratio of net cooling capacity is Btu/h to total rate of electricity input in watts under designated operating conditions (Btu hour/Watt).

2.

Seasonal Energy Efficiency Ratio (EER): The ratio of the total cooling output of an air conditioner during its normal annual usage period for cooling in Btu/h divided by total electric energy input in watts during the same period (Btu hour/Watt).

3.

Unitary: A Unitary Air Conditioner consists of one or more factory-made assemblies which normally include an evaporator or cooling coil, a compressor and condenser combination, and may include a heating function as well.

4.

Where such equipment is provided in more than one assembly the separated assemblies are to be designed to be used together and the requirements of rating are based upon use of matched assemblies.

1.2 RELATED WORK

A.

Section 01 00 00, GENERAL REQUIREMENTS: Requirements for pre-test of equipment: Seismic requirements for non-structural equipment.

B.

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

C.

Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and EQUIPMENT: Requirements for different types of vibration isolators and noise ratings in the occupied areas.

D.

Section 23 07 11, HVAC and BOILER PLANT INSULATION: Requirements for piping insulation.

E. Section 23 08 00 – COMMISSIONING OF HVAC SYSTEMS: Requirements for commissioning, systems readiness checklists, and training.

1.3 QUALITY ASSURANCE

A.

Refer to specification Section 23 05 11, COMMON WORK RESULTS FOR HVAC.

B.

Safety Standards: ASHRAE Standard 15, Safety Code for Mechanical Refrigeration.

1.4 SUBMITTALS

A.

Submit in accordance with specification Section 01 33 23, SHOP DRAWINGS, PRODUCT DATA, and SAMPLES

B.

Manufacturer’s literature and data:

1.

Sufficient information, including capacities, pressure drops and piping connections clearly presented, shall be included to determine compliance with drawings and specifications for units noted below:

a.

Unitary air conditioners:

1) Self-contained units

2) Split systems

3) Rooftop units b.

Window air conditioners c.

Through-the-wall packaged terminal air conditioning units d.

Gas-Fired Furnaces

2.

Unit Dimensions required clearances, operating weights accessories and start-up instructions.

3.

Electrical requirements, wiring diagrams, interlocking and control wiring showing factory installed and portions to be field installed.

4.

Mounting and flashing of the roof curb to the roofing structure with coordinating requirements for the roof membrane system.

C.

Certification: Submit proof of specified ARI Certification.

D.

Performance Rating: Submit catalog selection data showing equipment ratings and compliance with required sensible-to-heat-ratio, energy efficiency ratio (EER), and coefficient of performance (COP).

E.

Operating and Maintenance Manual: Submit three copies of Operating and Maintenance manual to Resident Engineer three weeks prior to final inspection.

F.

Completed System Readiness Checklists provided by the Commissioning Agent and completed by the contractor, signed by a qualified technician and dated on the date of completion, in accordance with the requirements of Section 23 08 00 COMMISSIONING OF HVAC SYSTEMS.

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.

Federal Specifications (Fed. Spec.):

A-A-50502-90 Air conditioner (Unitary Heat Pump) Air to Air (3000-300,000 Btu)

C.

Military Specifications (Mil. Specs.):

MIL-PRF-26915D-06

Primer Coating, for Steel Surfaces

D.

Air-Conditioning, Heating, and Refrigeration Institute (AHRI):

210/240-08 Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment

270-08 Sound Rating of Outdoor Unitary Equipment

310/380-04 Standard for Packaged Terminal Air-Conditioners and Heat Pumps (CSA-C744-04)

340/360-07 Performance Rating of Commercial and Industrial Unitary Air-Conditioning and Heat Pump Equipment

520-04 Performance Rating of Positive Displacement Condensing Units

E.

Air Movement and Control Association (AMCA):

210-07 Laboratory Methods of Testing Fans for Aerodynamic Performance Rating (ANSI)

410-96 Recommended Safety Practices for Users and Installers of Industrial and Commercial Fans

F.

American National Standards Institute (ANSI):

S12.51-02(R2007) Acoustics - Determination of Sound Power Levels of Noise Sources Using Sound Pressure - Precision Method for Reverberation Rooms (same as ISO 3741:1999)

G.

American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE):

2008 Handbook HVAC Systems and Equipment

15-10 Safety Standard for Refrigeration Systems (ANSI)

H.

American Society of Testing and Materials (ASTM):

B117-09 Standard Practice for Operating Salt Spray (Fog) Apparatus

I.

American Society of Civil Engineers (ASCE)

ASCE 7-10

Minimum Design Loads for Buildings and Other Structures

J.

National Electrical Manufacturer's Association (NEMA):

MG 1-09 (R2010)

Motors and Generators (ANSI)

ICS 1-00 (R2005, R2008)

Industrial Controls and Systems: General Requirements

K.

National Fire Protection Association (NFPA) Publications:

90A-09 Standard for the Installation of Air-Conditioning and Ventilating Systems

PART 2 - PRODUCTS

2.1 UNITARY AIR CONDITIONERS - GENERAL

A.

Applicable ARI Standards:

1.

Cooling Capacity 39.6 kW (135,000 Btu/h) and More: AHRI 340/ 360.

2.

Cooling Capacity Less Than 39.6 kW (135,000 Btu/h): AHRI 210/240. Units shall be listed in the ARI Directory of Certified Unitary Air-Conditioners.

B.

Performance Rating: Cooling capacity of units shall meet the sensible heat and total heat requirements shown in the contract documents. In selecting unit size, make true allowance for "sensible to total heat ratio" to satisfy required sensible cooling capacity.

C.

Machinery Guards: Provide guards as shown in AMCA 410 for belts, chains, couplings, pulleys, sheaves, shafts, gears and other moving parts regardless of height above the floor. Drive guards may be excluded where motors and drives are inside factory fabricated casings.

D.

Corrosion Prevention: Unless specified otherwise, equipment fabricated from ferrous metals that do not have a zinc coating or a duplex coating of zinc and paint shall be treated for prevention of rust with a factory coating or paint system that will withstand 125 hours in a salt-spray fog test, except that equipment located outdoors shall be tested for 500 hours. The salt-spray fog test shall be in accordance with ASTM B117 using a 20 percent sodium chloride solution. Immediately after completion of the test, the coating shall show no signs of blistering, wrinkling or cracking, no loss of adhesion, and the specimen shall show no signs of rust beyond 3 mm (1/8-inch) on both sides from the scratch mark.

2.2 Rooftop AIR CONDITIONERS

A.

Casing: Formed and reinforced double-wall insulated panels, fabricated to allow removal for access to internal parts and components, with joints between sections sealed. Exterior casing of 1.3 mm (0.052 inch) thick galvanized steel with factory-painted finish, with pitched roof panels and knockouts with grommet seals for electrical and piping connections and lifting lugs. Galvanized inner casing of 0.86 mm thick. Casing insulation and adhesive shall comply with NFPA 90A or NFPA 90B and comply with ASTM C 1071, Type I and shall be 13 mm (1/2 inch) thick. Space between double wall panels filled with foam insulation and sealed moisture tight. Removable cam latched access panel to allow access to internal parts.

B.

Corrosion Prevention: Paint shall be treated for prevention of rust with a factory coating or paint system that will withstand 500 hours in a salt-spray fog test. The salt-spray fog test shall be in accordance with ASTM B117 using a 20 percent sodium chloride solution.

C.

Airstream Surfaces: Surfaces in contact with the airstream shall comply with requirements in ASHRAE 62.1-2007.

D.

Condenser-Coil Fan: Propeller, mounted on shaft of permanently lubricated motor.

G.

Relief-Air Fan: Propeller, shaft mounted on permanently lubricated motor.

H.

Seismic Fabrication Requirements: Fabricate fan section, internal mounting frame and attachment to fans, fan housings, motors, casings, accessories, and other fan section components with reinforcement strong enough to withstand seismic forces defined in Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and EQUIPMENT when fan-mounted frame and RTU-mounted frame are anchored to building structure.

I.

Fan Motor: Comply with requirements in Section 23 05 12, GENERAL MOTOR REQUIREMENTS FOR HVAC and STEAM GENERATION EQUIPMENT.

J.

Supply-Air Refrigerant Coil: Aluminum -plate fins and seamless internally grooved. Polymer strip shall prevent all copper coil from contacting steel coil frame or condensate pan. Coil split shall be interlaced. Coil shall have baked phenolic coating.

K.

Condensate Drain Pan: Formed sections of stainless-steel sheet, a minimum of 50 mm (2 inches) deep and complying with ASHRAE 62.1-2007. Drain connections shall be threaded nipple.

L.

Outdoor-Air Refrigerant Coil: Aluminum -plate fins and seamless internally grooved. Polymer strip shall prevent copper coil from contacting steel coil frame or condensate pan. Coil shall have baked phenolic coating.

M.

Hot-Gas Reheat Refrigerant Coil: Aluminum -plate fins and seamless internally grooved. Polymer strip shall prevent copper coil from contacting steel coil frame or condensate pan. Coil shall have baked phenolic coating.

N.

Electric-Resistance Heating Coil: Resistance wire of 80 percent nickel and 20 percent chromium, supported and insulated by floating ceramic bushings recessed into casing openings, fastened to supporting brackets, and mounted in galvanized-steel frame.

1.

Terminals: Stainless-steel machine-staked terminals secured with stainless-steel hardware.

2.

Overtemperature Protection: Disk-type, automatically reset, thermal-cutout, safety device; serviceable through terminal box.

3.

Overcurrent Protection: Manual-reset thermal cutouts, factory wired in each heater stage.

4.

Control Panel: Unit mounted with disconnecting means and overcurrent protection and shall include magnetic contactors.

5.

Step Controller: Have pilot lights and override toggle switch for each step.

6.

SCR Controller: Have pilot lights operate on load ratio, a minimum of five steps.

7.

Time-delay relay.

8.

Airflow proving switch.

O.

Refrigerant Circuit Components:

1.

Number of Independent Refrigerant Circuits: Two.

2.

Compressor: Hermetic, scroll, mounted on vibration isolators; with internal overcurrent and high-temperature protection, internal pressure relief.

P.

Refrigerant: R-410A unless otherwise indicated.

Q.

Refrigeration Specialties:

1.

Expansion valve with replaceable thermostatic element.

2.

Refrigerant filter/dryer.

3.

Manual-reset high-pressure safety switch.

4.

Automatic-reset low-pressure safety switch.

5.

Minimum off-time relay.

6.

Automatic-reset compressor motor thermal overload.

7.

Brass service valves installed in compressor suction and liquid lines.

8.

Low-ambient kit high-pressure sensor.

9.

Hot-gas reheat solenoid valve with a replaceable magnetic coil.

10.

Hot-gas bypass solenoid valve with a replaceable magnetic coil.

11.

Four-way reversing valve with a replaceable magnetic coil, thermostatic expansion valves with bypass check valves, and a suction line accumulator.

R.

Air Filtration: Minimum arrestance according to ASHRAE 52.1, and MERV rating according to ASHRAE 52.2.

1.

Glass Fiber: Minimum [80] percent arrestance, and MERV [5].

S.

Outdoor-Air Damper: Linked damper blades, for 0 to 25 percent outdoor air, with motorized damper filter.

T.

Outdoor- and Return-Air Mixing Dampers: Parallel- or opposed-blade galvanized-steel dampers mechanically fastened to cadmium plated for galvanized-steel operating rod in reinforced cabinet. Connect operating rods with common linkage and interconnect linkages so dampers operate simultaneously.

U.

Damper Motor: Modulating with adjustable minimum position.

V.

Relief-Air Damper: Gravity actuated or motorized, complying with ASHRAE/IESNA 90.1-2004, and having bird screen and hood.

W. Electrical Power Connection: A single connection of power to unit with control-circuit transformer with built-in overcurrent protection.

X.

Controls:

1.

Basic Unit Controls:

a.

Control-voltage transformer.

b.

Wall-mounted thermostat or sensor with heat-cool-off switch.

c.

Fan on-auto switch.

d.

Fan-speed switch.

e.

Automatic changeover.

f.

Adjustable deadband.

g.

Exposed set point.

h.

Exposed indication.

i.

Degree F indication.

j.

Unoccupied-period-override push button.

k.

Data entry and access port to input temperature set points, occupied and unoccupied periods, and output room temperature, supply-air temperature, operating mode, and status.

l.

Unit-mounted annunciator panel with lights to indicate power on, cooling, heating, fan running, filter dirty, and unit alarm or failure.

m.

DDC controller or programmable timer and interface with HVAC instrumentation and control system and to digital display outdoor-air temperature, supply-air temperature, return-air temperature, economizer damper position, indoor-air quality, and control parameters. Interface with BMS/DDC system via BACnet open protocol.

2.

DDC controller shall have volatile-memory backup.

3.

Safety Control Operation:

a.

Smoke Detectors: Stop fan and close outdoor-air damper if smoke is detected and with additional contacts for alarm interface to fire alarm control panel.

b.

Fire Stats: Stop fan and close outdoor-air damper if air greater than 54 deg C (130 deg F)] enters unit and with additional contacts for alarm interface to fire alarm control panel.

c.

Fire Alarm Control Panel Interface: Control interface to coordinate with operating sequence described in Section 28 31 00, FIRE DETECTION and ALARM.

d.

Low-Discharge Temperature: Stop fan and close outdoor-air damper if supply air temperature is less than 4 deg C (40 deg F)].

e.

Defrost Control for Condenser Coil: Pressure differential switch to initiate defrost sequence.

4.

Scheduled Operation: Occupied and unoccupied periods on 365 -day clock with a minimum of 4 programmable periods per day.

5.

Unoccupied Period: Heating Setback: 5.6 deg C (10 deg F)].

6.

Cooling Setback: System off.

7.

Override Operation: Two hours unless otherwise indicated.

8.

Supply Fan Operation:

a.

Occupied Periods: Run fan continuously.

b.

Unoccupied Periods: Cycle fan to maintain setback temperature.

9.

Refrigerant Circuit Operation:

a.

Occupied Periods: Cycle or stage compressors to match compressor output to cooling load to maintain discharge temperature. Cycle condenser fans to maintain maximum hot-gas pressure. Operate low-ambient control kit to maintain minimum hot-gas pressure.

b.

Unoccupied Periods: Compressors off 11.

Electric-Resistance Heating-Coil Operation:

a.

Occupied Periods: Stage / Modulate coil to maintain discharge temperature.

b.

Unoccupied Periods: Energize coil to maintain setback temperature.

c.

Supplemental Electric Heat Operation: Electric-resistance heating coil with compressor for heating with outdoor temperature below minus 4 deg C (25 deg F).

12.

Fixed Minimum Outdoor-Air Damper Operation:

a.

Occupied Periods: Open to 25 percent.

b.

Unoccupied Periods: Close the outdoor-air damper.

13.

Economizer Outdoor-Air Damper Operation:

a.

Occupied Periods: Open to 25 percent fixed minimum intake, and maximum 100 percent of the fan capacity to comply with ASHRAE Cycle II. Controller shall permit air-side economizer operation when outdoor air is less than 15 deg C (60 deg F). Use outdoor-air temperature to adjust mixing dampers. Start relief-air fan with end switch on outdoor-air damper. During economizer cycle operation, lock out cooling.

b.

Unoccupied Periods: Close outdoor-air damper and open return-air damper.

14.

Outdoor-Airflow Monitor: Accuracy maximum plus or minus 5 percent within 15 and 100 percent of total outdoor air. Monitor microprocessor shall adjust for temperature, and output shall range from 4 to 20 mA.

16.

Interface Requirements for HVAC Instrumentation and Control System:

a.

Interface relay for scheduled operation.

b.

Interface relay to provide indication of fault at the central workstation and diagnostic code storage.

c.

Compatible with BACnet for central HVAC control workstation for adjusting set points, monitoring supply fan start, stop, and operation, inquiring data to include outdoor-air damper position, monitoring occupied and unoccupied operations, monitoring constant and variable motor loads, monitoring variable-frequency drive operation, monitoring cooling load, monitoring economizer cycles and monitoring air-distribution static pressure and ventilation air volume.

Z.

Accessories:

1.

Electric heater with integral thermostat maintains minimum 10 deg C (50 deg F) temperature in gas burner compartment.

2.

Duplex, 115-V, ground-fault-interrupter outlet with 15-A overcurrent protection. Include transformer if required. 3.

Low-ambient kit using variable-speed condenser fans for operation down to 1.7 deg C (35 deg F).

4.

Filter differential pressure switch with sensor tubing on both sides of filter. Set for final filter pressure loss.

5.

Coil guards of painted, galvanized-steel wire.

6.

Hail guards of galvanized steel, painted to match casing.

7.

Concentric diffuser with white louvers and polished aluminum return grilles, insulated diffuser box with mounting flanges, and interior transition.

AA.

Roof curbs: Vibration isolators and wind or seismic restraints shall be as specified in Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and EQUIPMENT. Manufacturer's standard curbs constructed of galvanized steel with corrosion-protection coating, watertight gaskets, and factory-installed wood nailer; complying with NRCA standards.

1. Curb Insulation and Adhesive: Factory applied and complying with NFPA 90A or NFPA 90B and ASTM C 1071, Type I or II. Thickness shall be (50 mm (2 inches). Insulation shall be applied with adhesive and mechanical fasteners to the internal surface of curb. Liner adhesive shall comply with ASTM C 916, Type I. Liner shall be fastened with mechanical fasteners of galvanized steel, suitable for adhesive attachment, mechanical attachment, or welding attachment to duct without damaging liner when applied without causing leakage in cabinet. Liner materials shall have air-stream surface coated with a temperature-resistant coating or faced with a plain or coated fibrous mat or fabric depending on service air velocity. Liner adhesive shall comply with ASTM C 916, Type I.

2.

Curb Height: 355 mm (14 inches).

3.

Wind and Seismic Restraints: Metal brackets compatible with the curb and casing, painted to match RTU, used to anchor unit to the curb, and designed for loads at Project site. Comply with requirements in Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and EQUIPMENT for wind-load requirements.

PART 3 EXECUTION

3.1 INSTALLATION

A.

Roof Curb: Install on roof structure or concrete base, level and secure, according to NRCA's "Low-Slope Membrane Roofing Construction Details Manual," Illustration "Raised Curb Detail for Rooftop Air Handling Units and Ducts." Install RTUs on curbs and coordinate roof penetrations and flashing with roof construction specified in Section 07 72 00, ROOF ACCESSORIES. Secure RTUs to upper curb rail, and secure curb base to roof framing or concrete base with anchor bolts.

B.

Rooftop Unit Support: Install unit level on structural curbs. Coordinate wall penetrations and flashing with wall construction. Secure rooftop units to structural support with anchor bolts.

C.

Install wind and seismic restraints according to manufacturer's written instructions. Wind and seismically restrained vibration isolation roof-curb rails are specified in Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and EQUIPMENT.]

D.

Install units’ level and plumb maintaining manufacturer’s recommended clearances and tolerances.

E.

Install water-cooled units with thermometer and pressure gage at the water supply and return connection.

F.

Install vibration spring isolators under base of self-contained unit, with minimum static deflection of 25 mm (1 inch) unless otherwise indicated. Refer to Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and EQUIPMENT G.

Install ground-mounting, compressor-condenser components on 100 mm (4-inch) thick, reinforced concrete base; 100 mm (4 inches) larger on each side than unit. Concrete, reinforcement, and formwork are specified in Section 03 30 00, CAST-IN-PLACE CONCRETE. Coordinate anchor installation with concrete base.

H.

Install ground-mounting, compressor-condenser components on polyethylene mounting base.

I.

Install roof-mounting compressor-condenser components on equipment supports specified in Section 07 72 00, ROOF ACCESSORIES. Anchor units to supports with removable, cadmium-plated fasteners.

J.

Install seismic restraints.

K.

Install compressor-condenser components on restrained, spring isolators with a minimum static deflection of 25 mm (1 inch) unless otherwise indicated. Refer to Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and EQUIPMENT.

L.

Install and connect precharged refrigerant tubing to component's quick-connect fittings. Install tubing to allow access to unit.

M.

Install wall sleeves in finished wall assembly and weatherproof. Install and anchor wall sleeves to withstand, without damage seismic forces as required by code.

3.2 CONNECTIONS

A.

Verify condensate drainage requirements.

B.

Install condensate drain, minimum connection size, with trap and indirect connection to nearest roof drain or area drain.

C.

Install piping adjacent to units to allow service and maintenance.

D.

Gas Piping: Comply with applicable requirements in Section 23 11 23, FACILITY 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.

E.

Install ducts to termination at top of roof curb. Cut roof decking only as required for passage of ducts. Do not cut out decking under entire roof curb.

F.

Connect supply ducts to units with flexible duct connectors specified in Section 23 31 00, HVAC DUCTS and CASINGS.

G.

Install return-air duct continuously through roof structure.

H.

Install normal-weight, 20.7-MPa (3000-psi), compressive strength (28-day) concrete mix inside roof curb, 100 mm (4 inches) thick.

I.

Ground equipment and install power wiring, switches, and controls for self contained and split systems.

J.

Connect refrigerant piping to coils with shutoff valves on the suction and liquid lines at the coil and a union or flange at each connection at the coil and condenser.

K.

Install ducts to the units with flexible duct connections.

L.

Connect piping with shutoff duty valves on the supply and return side of the coil and unions at all connections and with a throttling valve on the return piping near the coil.

M.

Connect piping with shutoff duty valves on the supply and return side of the water cooled condenser and unions at all connections and with a throttling valve on the return piping near the condenser

N.

Connect piping with shutoff duty valves and unions on the steam supply and condensate side of the steam coil. On the condensate line near the coil provide a strainer, trap and shutoff valve.

3.3 FIELD QUALITY CONTROL

A.

Perform tests and inspections and prepare test reports.

B.

Tests and Inspections: After installing units and after electrical circuitry has been energized, test units for compliance with requirements. Inspect for and remove shipping bolts, blocks, and tie-down straps. After electrical circuitry has been energized, start units to confirm proper motor rotation and unit operation. Test and adjust controls and safeties. Replace damaged and malfunctioning controls and equipment. Remove and replace malfunctioning units and retest as specified above.

3.4 InSTRUCTIONS

Provide services of manufacturer’s technical representative for four hours to instruct VA personnel in operation and maintenance of units.

3.5 STARTup and testing

The Commissioning Agent will observe startup and contractor testing of selected equipment. Coordinate the startup and contractor testing schedules with the Resident Engineer and Commissioning Agent. Provide a minimum of 7 days prior notice.

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

3.7 demonstration and training

A.

Provide services of manufacturer’s technical representative for four hours to instruct VA personnel in operation and maintenance of units.

B.

Submit training plans and instructor qualifications in accordance with the requirements of Section 23 08 00 – COMMISSIONING OF HVAC SYSTEMS.

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