BL087-21 Addendum #2

September 16, 2021

ADDENDUM #2

BL087-21, West Gwinnett Aquatic Center Duct Replacement

QUESTIONS AND ANSWERS:

Q1. Will night work be allowed/required?

A1. Night work will not be required. The construction schedule will be coordinated with the

Department of Community Services and the Aquatics division. The aquatic center will remain open during construction. Please see ATTACHMENT #1 below for scheduled events and busy times at the facility.

Q2. There is no indication on the plans or specs if this duct is to be single wall or double wall?

Please advise if any liner or insulation is required.

A2. Duct shall be single wall with no liner or insulation.

Q3. Notes on the drawings indicate the ductwork is to be aluminum. The spec only specifies galvanized steel duct, no aluminum. Please confirm aluminum duct is required.

A3. Aluminum ductwork is required. See attached revised specification sections.

Q4. Please confirm painting is not part of the scope of work. No notes or specs about painting are included in the bid package.

A4. Painting is not part of the scope of work, except for minor touchup paint as needed.

Q5. Per the duct spec 23 3100, 2.01, C. They have specific duct manufacturers listed. Can we use different manufacturers as long as SMACNA requirements and specification requirements are met?

A5. The last sentence in Specification Section 23 3100-2, Ductwork, 2.01, C shall be changed to read “Manufacturers shall be Semco, Monroe Metals, United Sheet Metal, Lindab, or approved equivalent.”

Thank you, Jake Scarpone

Jake Scarpone Purchasing Associate II

BL087-21 ADDENDUM #2

ATTACHMENT #1

BL087-21 – ADDENDUM #2

ATTACHMENT #2

GWINNETT COUNTY, GEORGIA

WEST GWINNETT AQUATIC CENTER DUCT REPLACEMENT BL087-21

General Provisions - HVAC 23 0010 - 1

R- Section 23 0010 General Provisions – HVAC

Part 1 General

1.01 Description

A. These Mechanical General provisions specified herein apply to all Sections of Division 23.

1.02 Work Included

A. Provide all materials, labor and services as specified in Division 23 and shown on the accompanying drawings.

1.03 Definitions

A. Terms: The following definitions of terms supplement those of the General Conditions and are applicable to all Mechanical Sections.

1. Provide: Furnish, install and connect completely.

2. Piping: Pipe installed with all required fittings, valves and accessories, and forming a complete system.

3. Wiring: Wire or cable installed in raceway with all required boxes, fittings, connectors, and accessories completely installed.

4. Power Wiring: Wiring which supplies the electrical current which flows through a connected motor or heater.

5. Exposed: Revealed to view or subject to weather.

6. Control, interlock and starting circuit wiring: All wiring required by all Mechanical Sections that is not power wiring.

7. Fittings: All connecting pieces of a system.

B. Drawings: The Mechanical Drawings are diagrammatic except where specifically indicated otherwise. Refer to Architectural and Structural Drawings for building dimensions.

C. Materials: Refer to the General Conditions. All material shall be suitable for the service and operating conditions of this Specification.

1.04 Abbreviations:

A. The following abbreviations are used in this Division of the

Specifications: ASTM - American Society for Testing Materials.

General Provisions - HVAC 23 0010 - 2

AABC - Associated Air Balance Council.

ASME - American Society of Mechanical Engineers.

ARI - Air Conditioning and Refrigeration Institute.

SMACNA - Sheet Metal and Air Conditioning Contractors National Association.

ANSI - American National Standards Institute.

NEMA - National Electrical Manufacturers Association UL - Underwriters Laboratories, Inc.

AWWA - American Water Works Association.

SCS - Soil Conservation Service.

1.05 Applicable Codes

A. The latest amended editions of the codes applicable to the work of the municipality having jurisdiction.

B. In the absence of any municipal adopted codes, the following shall apply:

1. International Building Code, 2018 Edition, with Georgia Amendments (2020)

2. International Fire Code, 2018 Edition

3. International Mechanical Code, 2018 Edition, with Georgia Amendments

(2020)

4. International Energy Conservation Code, 2015 Edition, with Georgia Supplements and Amendments (2020)

5. All City, County, State, Regional, and other ordinances applicable to the work shall apply.

1.06 Space Conditions

A. All work shall fit the spaces available. Verify all dimensions of the work before commencing fabrication and/or installation.

B. Minor deviations from the drawings required to conform to space conditions and to provide the required operation, service, or maintenance accessibility shall be made at no additional cost, and subject to approval.

C. Ductwork shall not be installed in electrical equipment rooms. Outside of electrical equipment rooms, do not run ductwork, or locate equipment, with respect to switchboards, panel boards, power panels, motor control centers, or dry type transformers:

Within 42" in front (and rear if free standing) of equipment;

or Within 36" of sides of equipment Clearances apply vertically from floor to ceiling structures.Record Drawings

General Provisions - HVAC 23 0010 - 3

D. Upon completion of the Project, the Contractor shall submit one set of contract prints with red marks indicating As-built conditions of all piping, ductwork, and equipment, and incorporating changes made during construction. A record of as-built conditions shall be kept throughout the Project and shall be used in the preparation of the final record drawings.

1.07 Guarantees

A. Furnish a written guarantee covering each category of work for a period of one year from date of legal acceptance for the project. Guarantee shall include prompt correction of all leaks.

B. Guarantee shall be furnished in exact conformity with the requirements of the

General Conditions.

1.08 Continuity of Service

A. All work shall be scheduled with that of other trades. The following conditions shall apply to all affected work.

B. Before disconnecting any existing systems for changes, the Contractor shall:

1. Have all materials needed stored at the job site.

2. Have assurance that all labor and skilled mechanics needed will be available at the proper time.

3. Estimate the time the system will be out of service and inform the Owner in writing.

4. Secure approval of the shutdown dates from the Owner in writing before disconnecting the system.

C. The operation of the cooling systems shall not be interrupted but one time and that period of shutdown shall be kept to a minimum.

D. No existing air conditioning system and/or equipment shall be shutdown for more than fifteen minutes without the approval of the Owner.

E. Work shall be done at such time and in such manner as to cause minimum inconvenience to the Owner and as approved by him or his representative. No allowance will be made for lack of knowledge of existing conditions.

1.09 Existing Conditions

A. Existing systems and equipment shall remain unchanged except where otherwise specified or shown on the drawings.

B. Where pipes, ducts, or controls that are to remain in service are disconnected for removal of equipment or because of building alterations, they shall be reconnected to match the existing installation.

General Provisions - HVAC 23 0010 - 4

C. The remodeling work to be done in the existing building shall be coordinated with work of other trades. New piping, ducts, or controls shall be run to point of connection to existing piping and tie-ins shall be made in such a manner as to afford minimum inconvenience to building occupants and operation.

D. All ductwork, dampers, etc., which are removed from the existing building shall become the property of the Contractor and shall be removed from the premises. Due allowances shall be made for this material in the bid.

E. Existing work shall be relocated as shown on the drawings.

F. Existing work shall be removed as shown on the drawings.

G. Work shall include the removal or extension of and connection to parts of the existing work, and all changes in the existing system to make it conform to changes in the building.

H. Piping rendered useless by the removal of walls, partitions, fixtures, etc., shall be removed and the outlets at the main plugged behind the finish surfaces.

1.10 Operating Instructions

A. Instructions: Instruct the Owner's representative in operation of the installed systems. The basis of these instructions shall be those written for inclusion in the maintenance and operating instruction data specified herein. Obtain certificates, signed by the Owner's representative, that these instructions have been received.

B. Notification: Notify the Owner at least five days before commencing operating period for refrigeration and heating equipment, as specified herein, in order that the Owner's representative may be present during that period.

1.11 Documentation

A. Documents to be submitted prior to request for final inspection:

1. Maintenance Manuals per Section 23 0100.

2. Test and Balance Reports.

3. Three copies of multi-year warranties bound in a brochure with index listing equipment.

B. Data to be Delivered at Final Inspection:

1. Record Drawings.

2. Certificate by Owner's representative confirming that operating instructions and training have been received.

General Provisions - HVAC 23 0010 - 5

1.12 Submittals

A. Procedure: Refer to the GENERAL CONDITIONS and SUPPLEMENTS thereto for submittal procedure of items called for in the Contract Documents.

B. Submittal data covering the work of this Division will be reviewed only after such items have been reviewed in detail and approved by the Contractor, such approval being indicated by suitable notations or stamp on the data.

C. Each submittal shall be clearly marked indicating Section and paragraph for which it is intended. Any deviations, exclusions or substitutions from specified material requirements shall be specifically identified in a summary sheet at the front of the submittal.

D. Where submittal sheets contain multiple products or selections, the specific item being submitted for review shall be clearly indicated with a red arrow (stamped or handwritten). “Catalog” submittals (multiple items contained in the submittal, specific items not identified) will be rejected and not reviewed.

E. Submit the requested submittals in sufficient quantity to provide two copies in addition to those required by Contractor.

F. All fan and pump submittals shall include performance curves indicating flow, pressure, efficiency, and power requirements. For pumps, adjacent impeller selections shall be included. For fans, alternate RPM curves shall be included.

G. Motor Tabulation on all motors furnished listing the following nameplate data:

Horsepower, voltage, phase and full load amps.

H. Submittal List: See the individual Mechanical Specification Sections for specific submittal requirements.

Part 2 Products (Not Used)

Part 3 Execution (Not Used)

END OF SECTION

Operation and Maintenance of HVAC Systems 23 0100 - 1

R- Section 23 0100 Operation and Maintenance of HVAC Systems

1.01 General

A. Provide manual in number of copies indicated under Section 23 0010 - General Provisions - HVAC.

B. Material submitted in the manuals shall represent the equipment manufacturer, model, and type installed on the project.

Part 2 Products

NOTE:

All references to vendors and "approved manufacturers" are included for description of quality and content of the designated equipment/materials. Equivalent items may be accepted if they meet all standards of quality and purpose for the intended use, as determined by Gwinnett County.

2.01 Maintenance and Operating Manuals

A. Maintenance and Operating Manuals shall consist of the following as a minimum:

1. Hardback three ring binders with job name and Owner's name on cover.

2. Typed index listing name, address, and phone number of the General Contractor, HVAC Subcontractor, Insulation Subcontractor, Sheetmetal Subcontractor, and Controls Subcontractor, and all major equipment suppliers.

3. Typed table of contents, listing each Section, title, and number.

4. All Sections shall be tabbed with plastic tabs listing Section numbers.

5. Each item of equipment requiring maintenance and operation data as noted in each specification section shall be provided with an index listing the types of equipment installed. Submittal data shall be included to the extent necessary to identify equipment, including summary sheet, such as model, size, air or water flow, pressure developed, speed, and motor size. Instructions shall include type and suggested frequency of maintenance, oiling, cleaning, disassembly, and reassembly directions, and wiring diagrams.

6. One section shall include a complete set of record control drawings, bound in a plastic insert, full size, complete with a written sequence of operation for all control systems.

Operation and Maintenance of HVAC Systems 23 0100 - 2

7. Letters, where factory startup or checking has been required, certifying completion of performance.

8. After the O&M manuals have been reviewed and approved by the Engineer and Owner, the contractor shall provide the Owner a digitized version of the manuals on a USB drive in addition to the hard copies provided.

Part 3 Execution

3.01 Maintenance and Operating Manuals

A. All maintenance and operating manuals shall be complete and ready to turn over to Owner's representative at final inspection.

B. Incomplete manuals will be returned to the Contractor for complete resubmission.

Loose-leaf submittal of material at various stages of completion will not be acceptable.

Common Work Results for HVAC 23 0500 - 1

R- Section 23 0500 Common Work Results for HVAC

Description

A. This Section of specifications deals with materials and methods pertaining to all work specified under Division 23.

Related Sections

A. Section 23 0010 General Provisions Mechanical

B. Section 23 3100 Ductwork

Submittals

A. See General Conditions for submittal procedure.

B. Provide submittal data showing starter dimensions, weight, electrical requirements, and service access requirements.

C. Provide submittal data showing motor horsepower, electrical requirements, and efficiency.

D. Provide submittal data showing firestop systems, including details for penetrations and instructions for installation

E. Provide manufacturer’s instructions, indicate installation and support requirements.

Job Conditions

A. Install all apparatus so as to maintain maximum headroom and clearances consistent with requirements of the drawings and specifications.

B. All equipment requiring service shall be installed to permit access for servicing without damage to building structure or finishes.

be accepted if they meet all standards of quality and purpose for the intended use, as determined by Gwinnett County.

Common Work Results for HVAC 23 0500 - 2

Structural Attachments

A. Concrete Fasteners:

1. Fasteners shall be self-drilling type, Locke Mfg. Co. "Bull Dog", Phillips "Red Head", Diamond "Blue-Cut", or approved equal.

2. Fasteners shall be used in solid masonry walls and shall be used in solid concrete walls.

B. Toggle Bolts with not less than 1/4" diameter bolts shall be used in hollow type wall construction.

C. Clamps of configuration compatible with beams and steel members shall be used in steel construction. Clamps shall be Grinnell, Hilti, Michigan Hanger Company, Elcen, B-Line, or approved equal.

D. Hanger rods shall be selected to safely carry the load to be supported and shall not be less than the diameter listed by the hanger manufacturers for the specific size hanger used.

Painting

A. Primers shall be acrylic, corrosion resistant type, selected for the metal or other surface to be painted, with a maximum VOC emission of 150 grams per liter.

Sherwin-Williams Pro-Cryl Universal Primer, or approved equal.

B. Topcoats shall be acrylic latex base, selected for the material, surface and operating temperature of the equipment or apparatus to be painted, with a maximum VOC emission of 150 grams per liter for non-flat finishes and 50 grams per liter for flat finishes. Sherwin-Williams Pro-Mar 200 (interior metal, black-out), Sherwin-Williams SuperPaint (exterior metal), or approved equal.

Firestop Sealant

A. Firestop sealant shall be a synthetic elastomer caulk, strip, or sheet designed for use as a one part fire, smoke, and gas sealant. Material shall be intumescent and capable of being installed with caulk gun, shears, and putty knife. Material shall be UL classified and Factory Mutual approved for sealing in floors, walls, or partitions to 3 hour rating per ASTM E-814.

B. Fire barrier material shall be 3M Fire Barrier Sheet, Strip, and Caulk – or approved equal.

Asbestos

A. All materials used in this work shall be asbestos free.

Common Work Results for HVAC 23 0500 - 3

Installation

A. All work shall be installed plumb and square unless clearly indicated otherwise.

Installation shall be performed by competent persons, trained in their respective skills.

B. Furnish and install equipment complete, including connections, services and adjustments for systems to operate safely and in compliance with requirements of the contract.

C. Install each item in full compliance with current recommendations of the manufacturer. Equipment manufacturer or his authorized representative shall furnish services and/or supervision necessary to ensure compliance with this provision. Conflict between manufacturer's recommendation and other contract requirements shall be resolved before installation.

D. Requirements of the several acceptable manufacturers for each specified item of equipment may vary as to installation details, location and number of connections, dimensions and weight. Provide all drawings, services, material, and labor necessary for the installation and proper functioning of the equipment furnished.

Protection of Materials and Equipment

A. Take precautions to protect all materials and equipment from damage during the construction process.

B. Do not store materials an equipment outdoors subject to weather without complete weather protection.

C. Do not install materials or equipment in a partially constructed structure exposed to weather, unless all material and equipment is continuously protected from damage by weather or the construction process.

D. Material and equipment damaged by improper protection during construction is subject to replacement based on the judgment of the Engineer at no cost to the Owner.

Cutting and Repairing

A. Cut and repair all walls, floors, and ceilings necessary for the installation of the mechanical work, but no cutting of work of other trades will be permitted without the consent of the Architect or his representative.

B. All cutting and repairing of walls, floors, and ceilings shall be subject to the supervision and approval of the Contractor.

Cleaning and Final Clean-Up

A. Keep the premises free of waste, debris and surplus materials.

Common Work Results for HVAC 23 0500 - 4

B. The installing contractors must take appropriate precautions during construction to prevent dust and debris from getting into air and water handling systems by covering equipment, controls, and open ended ducts and pipes while installation progresses.

C. After equipment has been installed, remove all extraneous materials, rust and stains; blow, vacuum or flush all foreign matter from all equipment.

D. Identification plates on equipment shall be free of paint and shall be polished.

Structural Attachments

A. Concrete fasteners may be used where approved in writing by Structural Engineer for individual loads of 150 lbs. or less.

B. Shooting of fasteners into the slab shall be allowed only in approved locations.

C. Devices for connection to the structure shall not be loaded more than 75% of the manufacturer's rated load.

Painting

A. Except where otherwise specified, painting shall be done under another Division.

Surfaces shall be left clean and free from oil.

B. Finishes of factory painted apparatus shall be touched up where finish is marred in installation.

C. Where galvanizing is broken during fabrication or installation, recoat exposed areas with cold galvanizing compound.

D. Interior ferrous pipe and supports exposed to view without removing ceilings or access panels shall be primed and topcoated with two coats of semi-gloss paint, color selected by Architect.

E. Exterior ferrous piping and supports shall be primed and topcoated with two coats exterior satin finish paint, color selected by Architect.

F. New HVAC equipment shall be identified as specified in Section 23 0553.

G. All ductwork, conduits, insulation, pipe and structure visible through grilles and diffusers shall be primed and topcoated with two coats of black egg-shell finish paint.

Firestop Sealing Floor and Wall Penetrations

A. Where ductwork, piping, control tubing, and conduit penetrate fire or smoke rated walls and floors, the penetration shall be sealed with fire barrier herein specified.

Common Work Results for HVAC 23 0500 - 5

B. Fire barrier shall be installed in strict accordance with manufacturer's printed instructions. Material shall be installed with sufficient depth to maintain a fire endurance rating equivalent to that of the adjacent wall or floor.

Testing, Balancing, and Adjusting 23 0593 - 1

R- Section 23 0593 Testing, Balancing, and Adjusting

A. This section specifies the requirements for testing and balancing the Heating, Ventilating, and Air Conditioning Systems.

1.02 Related Section

A. Section 23 0010 General Provisions HVAC

1.03 Qualifications

A. The test and balance work shall be performed by an independent firm certified by the Associated Air Balance Council (AABC), or National Environmental Balancing Bureau (NEBB). Acceptable Testing and Balancing agencies are Air Analysis of Atlanta, Test And Balancing Corporation, Air Data, or Research Air Flo. The test and balance firm shall be procured by the contractor.

1.04 Procedures

A. All air distribution systems and hydronic systems shall be tested, adjusted, and balanced to the conditions specified and/or shown on the drawings.

B. Performance of systems and components at specified conditions shall be verified by testing.

C. Before request for final inspection, calibrate, adjust, set, test and check all valves, dampers, temperatures, pressures, and flow rates of systems for operation and performance.

D. All test and balance work shall be performed in accordance with AABC or NEBB procedures.

1.05 Reports

A. Submit completed and certified report to Prime Consultant in triplicate.

Testing, Balancing, and Adjusting 23 0593 - 2

2.01 General

A. Provide all instruments, charts, materials, and equipment required to develop a complete test and balance report.

3.01 Test and Balance Report

A. Test and balance report shall be a complete document, not limited to, but including at least the following:

1. Air side of systems:

a. Coil entering and leaving temperatures.

b. All air unit component pressure drops.

c. Fan RPM and entering and leaving static pressure.

d. Space temperatures at thermostats.

e. Outlet temperatures of selected diffusers.

3.02 Balancing and Adjustment After Final Inspection

A. After building is accepted and occupied, and after testing and preliminary balancing are completed, send qualified personnel to building for not less than one period during summer and one period during winter, observe temperatures throughout conditioned spaces, consult with Owner's representative as to need for additional balancing or adjustment, then perform such work as is indicated.

B. Schedule these visits, at a time agreeable to Owner, during December through

February for heating, and July through August for cooling.

Ductwork 23 3100 - 1

R- Section 23 3100 Ductwork

A. This section specifies the sheetmetal requirements for Division 23 ductwork.

1.02 Related Sections

A. Section 23 0500 Common Work Results for HVAC

B. Section 23 0700 Mechanical Systems Insulation

C. Section 23 0593 Testing, Balancing and Adjusting

D. Section 23 3713 Grilles, Registers, and Diffusers

1.03 Submittals

B. Provide data on damper performance including, but not limited to, total static pressure drop verses airflow shown for all multi-blade dampers, size and quantity of dampers required.

C. Provide shop drawing showing multi-blade damper dimensions, construction, duct connection sizes and electrical requirements.

D. Provide manufacturer’s instructions, indicate installation and support requirements.

1.04 Standards

A. Refer to the SMACNA "HVAC Duct Construction Standards, Metal and Flexible", latest edition.

B. Refer to the SMACNA “Duct Cleanliness for New Construction Guidelines”, latest printing.

C. Unless noted otherwise herein, all ductwork shall be constructed, sealed, and supported in strict compliance with the SMACNA standards referenced above.

D. UL 181A Closure Systems for Use with Rigid Air Ducts.

E. UL 181B Closure Systems for Use with Flexible Air Ducts and Air Connectors.

Ductwork 23 3100 - 2

1.05 Pressure and Velocity Ratings

A. Ductwork, unless otherwise noted, shall be constructed and reinforced for 2000 FPM velocity and 2" static positive or negative, unless otherwise noted. This construction shall be referred to as "low pressure".

B. For all ductwork required to be constructed and reinforced for over 2” positive or negative pressure, submit a Ductwork Reinforcing Schedule. This schedule shall indicate size, metal gauge, and reinforcement size and spacing, for all ductwork over 2” pressure class.

1.06 Duct Dimensions

A. Dimensions shown on the drawings are metal-to-metal size, unless noted otherwise.

be accepted if they meet all standards of quality and purpose for the intended use, as determined by Gwinnett County.

2.01 Metal Materials

A. Ductwork in natatoriums shall be constructed from aluminum flat sheet, type 3003- H14.

B. Formed reinforcing drives, slips, pocket locks, and standing seams shall be constructed from sheet metal stock of the same material as the associated ductwork. Intermediate reinforcing angles may be uncoated steel painted with two coats of primer.

C. Round and flat oval ductwork shall be factory fabricated low-pressure spiral lock seam type constructed in accordance with the above-referenced SMACNA standards. Round snap-lock type ductwork shall not be installed on project. All fittings shall be factory fabricated by same manufacturer as ductwork. Round duct below grade shall be minimum 20 gauge. Manufacturers shall be Semco, Monroe Metals, United Sheet Metal, or Lindab, or approved equal.

2.02 Plenums and Casings

A. Field fabricated plenums and casings shall be constructed per referenced SMACNA standards, except minimum steel gauge shall be 18 and minimum angle size 1" x 1" x 1/8". Angles shall be galvanized. Access doors shall be hinged, gasketed, and latched. Minimum size shall be 20" width by 48" high unless casing is 60" or less high. Door height shall be adjusted to 12" less than casing height for casings less than 60" high.

Ductwork 23 3100 - 3

2.03 Accessories

A. Low pressure single blade manual dampers shall be constructed in accordance with Figure 2.12 of referenced SMACNA standards, except as noted. Provide end bearings and continuous rods on all dampers except those 10” round and smaller in 1” pressure class ductwork. Single blade dampers shall not be used in ducts over 30" in one dimension.

B. Access doors shall be galvanized steel hinged and latched insulated type, minimum

8" x 8" size, manufactured per referenced SMACNA standards. Where access to equipment requires a larger door, size shall be increased to allow full accessibility.

Hinges shall be furnished with brass pins. Where hinges do not allow for access, latches shall be provided on all sides. Manufacturers shall be Air Balance, Krueger, Nailor Ind., Phillips Aire, Ruskin, or Ventlok, or approved equal.

C. Flexible duct connectors shall be non-combustible glass fabric of 30 oz. per square yard minimum weight fabric, coated on each side with fire-retardant Neoprene for indoor applications and Hypalon on exterior or corrosive airstream applications.

Fabric shall be 3" wide and attached at each edge with a strip of 24-gauge galvanized steel. Material shall be tested in accordance with UL 181 and shall be suitable for contained exposure 200F continuously.

D. Low VOC water based duct sealing compounds shall be manufactured to comply with NFPA 90A, UL listed and complying with ASTM E84. The sealants must be rated for high pressure applications, both indoor and outdoor, and also comply with the current VOC limits of the Bay Area Air Quality Management District Regulation 8, Rule 51, with a maximum VOC emission of 250 grams per liter. Sealants shall be by Ductmate, Foster, Hardcast or United Sheet Metal, or approved equal. Pressure sensitive tape is not acceptable.

3.01 General Ductwork Installation

A. All ductwork shall be fabricated, stored and installed per the SMACNA Duct Cleanliness Guidelines for Intermediate Level Cleanliness. This guide includes the requirement for ducts to be stored in a clean, dry area, the installation area shall be protected from the elements, and temporary closure of open ends on completed ducts, and other measures intended to minimize contamination of the circulating air.

B. Provide offsets, elbows, and transitions to coordinate with other work. Changes in shape or dimension shall be made with a maximum slope as noted in SMACNA Duct Construction Standards.

C. Ducts over 12" in either dimension, except those to be externally insulated with rigid board or internally insulated, shall have all sides cross.

D. Leave system clean from dust, trash and foreign matter

Ductwork 23 3100 - 4

E. Installation shall be air tight and free from rattles, vibration and movement.

F. Provide access doors for access to fire dampers, controls, coils, duct smoke detectors, humidifiers, and where required for cleaning, oiling, inspection and maintenance.

G. Install flexible connections at each air handling unit connection and each fan connection, unless air handling units are internally isolated.

H. Paint interior ductwork visible behind grilles or register flat black.

3.02 Ductwork Support

A. Ductwork shall be supported per SMACNA standards except hanger spacing shall not exceed 8' for rectangular duct and 10' for round rigid ductwork.

B. Ductwork penetrating floors in equipment rooms shall be provided with a 4" high concrete curb around the duct.

C. Support vertical risers at each floor.

3.03 Low Pressure Ductwork

A. Squared and radiused elbows shall be constructed as per figure 2-2, except no mitered elbows or square elbows without vanes are allowed. Turning vanes shall be constructed as per figures 2-3 and 2-4.

B. Divided flow branches shall be constructed as per figure 2-5, always with splitter damper.

C. TDC and TDF duct joint systems may be used as outlined in SMACNA standards, provided corner pieces are used and bolted at all locations.

3.04 Duct Sealing

A. Seal Levels:

1. Seal level A - Seal all transverse joints, longitudinal seams, and all duct wall penetrations.

2. Seal Level B – Seal all transverse joints and longitudinal seams.

3. Seal Level C – Seal all transverse joints.

B. Seal Procedures:

1. All longitudinal and transverse joints, seams and connections in and between metallic and non-metallic ducts shall be constructed as specified in SMACNA HVAC Duct Construction Standards.

Ductwork 23 3100 - 5

2. Seal joints per SMACNA procedures with duct sealer as duct is erected.

Sealing ductwork after erection is complete will not be accepted. Cover all joints to be sealed with sealer and assemble in normal fashion. Duct Seal Levels are as follows:

3. For Seal Level A and B: Pressure sensitive tape shall not be used as the primary sealant, unless it has been certified to comply with UL-181A or UL- 181B by and independent testing laboratory and the tape is used in accordance with that certification.

4. Where ductwork is bolted together, provide 1/8" thick gaskets at each bolted joint.

5. Spiral lock seams in a round or flat oval duct need not be sealed. All other connections are considered transverse joints, including but not limited to spin-ins, taps, and other branch connections, access door frames and jambs, duct connections to equipment, etc...

6. Closure systems used to seal factory-made rigid air ducts or air connectors shall comply with UL 181A and shall be marked "181A-P" for pressure-sensitive tape, "181A-M" for mastic or "181A-H" for heat-sensitive tape.

7. Closure systems used to seal flexible air ducts and flexible air connectors shall comply with UL 181B and shall be marked "181B-FX" for pressure-sensitive tape or "181B-M" for mastic.

8. Duct connections to flanges of air distribution system equipment shall be sealed and mechanically fastened. Mechanical fasteners for use with flexible nonmetallic air ducts shall comply UL-181B and shall be marked "!181B-C".

9. Openings for rotating shafts shall be sealed with bushings or other devices that seal off air leakage.

10. Unlisted duct tape is not permitted as a sealant on any duct.

C. All low pressure ductwork shall be sealed as follows:

1. Exterior – Seal Level A.

2. Unconditioned Interior Space – Seal Level A except for exhaust ducts, which shall be Seal Level B.

3. Plenums or Conditioned Space – Seal Level B.

3.05 Ducts through Fire Rated Walls and Floors

A. Ducts through fire rated walls and floors shall have areas around exterior of duct or insulation sealed with fire barrier material. See Section 23 0500.

Ductwork 23 3100 - 6

3.06 Field-Fabricated Plenums

A. Reinforcing frame shall consist of base angles set on gasket and bolted to foundations. Horizontal and vertical frame angles shall be spaced as per SMACNA requirements. Angles shall be bolted or welded together. Access door openings shall be framed on four sides. Plenum casings shall be bolted, riveted or spot welded to inside surface of angle frame. Seal all joints with gaskets.

B. Plenum doors shall be installed to close with plenum pressure. Install doors on sills, minimum 6" for 60" high casing, otherwise 8".

3.07 Aluminum Ductwork

A. All aluminum exhaust ductwork shall be watertight using silicon sealed joints. Slope ductwork back to grilles 1/32”/ft. No traps allowed in aluminum exhaust duct systems.

Grilles, Registers, and Diffusers 23 3713 - 1

R- Section 23 3713 Grilles, Registers, and Diffusers

A. This section specifies grilles, registers, and diffusers furnished and installed under Division 23.

1.02 Related Section

A. Section 23 3100 Ductwork

1.03 Submittals

B. Provide data on air distribution performance including, but not limited to, total static pressure drop and sound generation (NC) verses airflow shown for each supply and return grille, size and quantity of grilles required.

C. Provide shop drawing showing catalog illustrations, dimensions, duct connection sizes and accessories.

D. Provide manufacturer’s instructions, indicate installation and support requirements.

1.04 Quality Assurance

A. Performance of grilles, registers, and diffusers shall be tested in accordance with ANSI/ASHRAE Standard 70 -1991.

B. All grilles, registers, and diffusers shall be selected and furnished by one manufacturer.

2.01 General

A. Grilles, registers, and diffusers have been selected from one manufacturer's catalog. Alternate manufacturers shall be Titus, Metalaire, Price, Krueger, Tuttle & Bailey, or Nailor Industries, or approved equal..

Grilles, Registers, and Diffusers 23 3713 - 2

B. All grilles and registers with borders shall be furnished with gasketed seals around the perimeter. All grilles, registers, and diffusers shall be aluminum or steel as scheduled.

3.01 Installation

A. Install offset return grilles so that blade offset is angled down towards the floor.