237339 SF - INDOOR DIRECT-FIRED HEATING AND VENTILATING UNITS.DOC

UNIT TRAININGEQUIPMENT SITE ADD/ALT

Copyright 2011 by The American Institute of Architects (AIA)

Exclusively published and distributed by Architectural Computer Services, Inc. (ARCOM) for the AIA

SECTION 237339 - INDOOR, DIRECT-FIRED HEATING AND VENTILATNG UNITS

This Section includes requirements for the LEED Rating System. However, equipment specified in this Section may not qualify for LEED Rating System prerequisites and credits. Verify, with manufacturers, that the requirements for prerequisites and credits can be met. To achieve prerequisites and obtain credits, HVAC system design alternatives that do not include gas-fired heating and ventilating units may be required.

Revise this Section by deleting and inserting text to meet Project-specific requirements.

Verify that Section titles referenced in this Section are correct for this Project's Specifications; Section titles may have changed.

PART 1 - GENERAL

1.1 SUMMARY

A. Section includes indoor, direct-fired heating and ventilating units.

1.2 ACTION SUBMITTALS

A. Product Data: For each type and configuration of indoor, direct--fired heating and ventilating unit.

B. Shop Drawings: For each type and configuration of indoor, direct-fired heating and ventilating unit.

1. Include plans, elevations, sections, and mounting details.

2. Include details of equipment assemblies. Indicate dimensions, weights, loads, required clearances, method of field assembly, components, and location and size of each field connection.

Retain "Design Calculations" Subparagraph below to delegate design responsibility to Contractor or to require structural data to be submitted for review as another way to verify compliance with requirements. Also retain below if retaining restrained spring isolators in "Installation" Article.

3. Design Calculations: Calculate requirements for selecting vibration isolators and seismic restraints and for designing vibration isolation bases.

1.3 INFORMATIONAL SUBMITTALS

A. Sample Warranty: For manufacturer's special warranty.

Retain "Seismic Qualification Certificates" Paragraph below if required by seismic criteria applicable to Project. Coordinate with Section 230548 "Vibration and Seismic Controls for HVAC Piping and Equipment."

B. Seismic Qualification Certificates: For indoor, direct-fired heating and ventilating units, accessories, and components, from manufacturer.

1.4 CLOSEOUT SUBMITTALS

A. Operation and maintenance data.

1.5 QUALITY ASSURANCE

A. Comply with NFPA 70.

One or both paragraphs below may be required to comply with Project requirements or authorities having jurisdiction. LEED Prerequisite IEQ 1 requires compliance with requirements in ASHRAE 62.1, including requirements for controls, surfaces in contact with the airstream, particulate and gaseous filtration, humidification and dehumidification, drain-pan construction and connection, finned-tube coil selection and cleaning, and equipment access. Verify, with manufacturers, availability of units with components and features that comply with these requirements.

B. ASHRAE Compliance: Applicable requirements in ASHRAE 62.1, Section 5 - "Systems and Equipment" and Section 7 - "Construction and Startup."

LEED Prerequisite EA 2 requires minimum efficiency equal to requirements in ASHRAE/IES 90.1.

C. ASHRAE/IES 90.1 Compliance: Applicable requirements in ASHRAE/IES 90.1, Section 6 - "Heating, Ventilating, and Air-Conditioning."

1.6 WARRANTY

A. Special Warranty: Manufacturer agrees to repair or replace components of direct-fired heating and ventilating units that fail in materials or workmanship within specified warranty period.

Verify available warranties and warranty periods for units and components. Warranty periods for similar equipment can vary among manufacturers and unit sizes.

1. Warranty Period for Heat Exchangers: Manufacturer's standard, but not less than five years from date of Substantial Completion.

PART 2 - PRODUCTS

See Editing Instruction No. 1 in the Evaluations for cautions about named manufacturers and products. For an explanation of options and Contractor's product selection procedures, see Section 016000 "Product Requirements."

2.1 MANUFACTURERS

Retain "Manufacturers" Paragraph and list of manufacturers below to require products from manufacturers listed or a comparable product from other manufacturers.

A. Manufacturers: Subject to compliance with requirements, provide products by one of the following:

Retain "Basis-of-Design Product" Paragraph and list of manufacturers below to identify a specific product or a comparable product from manufacturers listed. Retain option and delete insert note if manufacturer's name and model number are indicated on Drawings.

1. Rupp Air Management Stystems

2. Greenheck.

2.2 SYSTEM DESCRIPTION

A. Factory-assembled, prewired, self-contained unit consisting of cabinet, supply fan, controls, filters, and direct-fired gas burner to be installed exterior to the building.

B. Electrical Components, Devices, and Accessories: Listed and labeled as defined in NFPA 70, by a qualified testing agency, and marked for intended location and application.

2.3 UNIT CASINGS

Air-handling-unit configuration, casing materials, and thicknesses may be scheduled. If so, scheduled information may be deleted from this article.

A. General Fabrication Requirements for Casings:

1. Forming: Form walls, roofs, and floors with at least two breaks at each joint.

2. Casing Joints: Sheet metal screws or pop rivets, factory sealed with water-resistant sealant.

3. Factory Finish for Steel and Galvanized-Steel Casings: Apply manufacturer's standard primer immediately after cleaning and pretreating.

4. Air-Handling-Unit Mounting Frame: Formed galvanized-steel channel or structural channel supports, designed for low deflection, welded with integral lifting lugs.

Retain "Seismic Fabrication Requirements" Subparagraph below for projects in seismic areas. If retaining, also retain "Seismic Qualification Certificates" Paragraph in "Informational Submittals" Article.

a. Seismic Fabrication Requirements: Fabricate mounting base and attachment to air-handling-unit sections, accessories, and components with reinforcement strong enough to withstand seismic forces defined in Section 230548 "Vibration and Seismic Controls for HVAC Piping and Equipment" when air-handling-unit frame is anchored to building structure.

"Airstream Surfaces" Subparagraph below may be required to comply with Project requirements or authorities having jurisdiction. Retain subparagraph to comply with LEED Prerequisite IEQ 1.

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

Retain one of first three options in "Configuration" Paragraph below, plus fourth or fifth option.

B. Configuration: Horizontal unit with horizontal discharge for suspended installation.

"Inspection and Access Panels and Access Doors" Paragraph below may be required to comply with Project requirements or authorities having jurisdiction. LEED Prerequisite IEQ 1 requires compliance with ASHRAE 62.1, in which Section 5.14 - "Access for Inspection, Cleaning, and Maintenance" sets requirements for equipment access. If applying for LEED certification, comply with requirements in ASHRAE 62.1.

C. Inspection and Access Panels and Access Doors: Formed and reinforced, single- or double-wall and insulated panels of same materials and thicknesses as casing and complying with ASHRAE 62.1.

2.4 SUPPLY-AIR FAN

A. Fan Type: Centrifugal, rated according to AMCA 210; statically and dynamically balanced, galvanized steel; mounted on solid-steel shaft with heavy-duty, self-aligning, permanently lubricated ball bearings or pillow-block bearings.

B. Drive: V-belt drive with matching fan pulley and adjustable motor sheaves and belt assembly.

Retain first option in "Mounting" Paragraph below for units installed in seismic areas, and retain second or third option.

C. Mounting: Fan wheel, motor, and drives shall be mounted in fan casing with vibration isolators.

D. Fan-Shaft Lubrication Lines: Extended to a location outside the casing.

2.5 AIR FILTERS

Retain this article for units that circulate some return air. Filters are not often used for 100 percent outdoor-air, direct-fired, heating-only units. For units that circulate some return air, filters can be added for return air. Standard filters are 1-inch- (25-mm-) thick, low-efficiency, washable media and replaceable glass-fiber media. Optional, 2-inch- (50-mm-) thick, low-efficiency, glass-fiber or polyester filters, and medium-efficiency filters, are available from most manufacturers.

LEED Prerequisite IEQ 1 requires compliance with ASHRAE 62.1, which requires a MERV 6 or higher.

A. Comply with NFPA 90B.

Retain "Cleanable Filters" or "Disposable Panel Filters" Paragraph below.

B. Disposable Panel Filters: Factory-fabricated, flat-panel-type, disposable air filters; 2 inch.

2.6 DAMPERS

Low-leak dampers can be furnished for return air. Retain option in "Outdoor-Air (and Return-Air )Damper" Paragraph below for units that circulate varying amounts of return air. Return-air dampers modulate proportionally with outdoor-air dampers to vary the amount of return and outdoor air delivered to the space.

A. Outdoor-AirDamper: Galvanized-steel, opposed-blade dampers with vinyl blade seals and stainless-steel jamb seals, having a maximum leakage of 10 cfm/sq. ft. of damper area, at a differential pressure of 2-inch wg.

B. Damper Operator: Direct coupled, electronic with spring return or fully modulating as required by the control sequence.

2.7 DIRECT-FIRED GAS BURNER

A. Description: Factory assembled, piped, and wired; and complying with ANSI Z21.47, "Gas-Fired Central Furnaces," and with NFPA 54, "National Fuel Gas Code."

1. CSA Approval: Designed and certified by and bearing label of CSA.

2. Burners: Stainless steel.

a. Gas Control Valve: Modulating.

b. Rated maximum turndown ratio of 16 to 1.

c. Fuel: Natural gas.

d. Minimum Combustion Efficiency: 91 percent.

e. Ignition: Electronically controlled electric spark with flame sensor.

High-altitude feature in subparagraph below is available from some manufacturers.

B. Safety Controls:

1. Vent Flow Verification: Differential pressure switch to verify open vent.

2. Control Transformer: 24-V ac.

3. High Limit: Thermal switch or fuse to stop burner.

4. Gas Train: Regulated, redundant, 24-V ac gas valve assembly containing pilot solenoid valve, electronic-modulating temperature control valve, pilot filter, pressure regulator, pilot shutoff, and manual shutoff all in one body.

5. Purge-period timer shall automatically delay burner ignition and bypass low-limit control.

Owner's insurance underwriter may require gas train by FM Global or XL Insurance.

6. Gas Manifold: Safety switches and controls complying with ANSI standards and ETL, IRI and FM Global.

Airflow proving switch feature in "Airflow Proving Switch" Subparagraph below is provided by some manufacturers.

7. Airflow Proving Switch: Differential pressure switch senses correct airflow before energizing pilot.

8. Automatic-Reset, High-Limit Control Device: Stops burner and closes main gas valve if high-limit temperature is exceeded.

9. Safety Lockout Switch: Locks out ignition sequence if burner fails to light after three tries. Controls are reset manually by turning the unit off and on.

2.8 UNIT CONTROL PANEL

A. Factory-wired, fuse-protected control transformer, connection for power supply and field-wired unit to remote control panel.

B. Control Panel: Surface-mounted remote panel, with engraved plastic cover and the following lights and switches:

1. On-off-auto fan switch.

2. Heat-vent-off switch.

3. Supply-fan operation indicating light.

4. Heating operation indicating light.

5. Thermostat.

6. Damper position potentiometer.

7. Dirty-filter indicating light operated by unit-mounted differential pressure switch.

8. Safety-lockout indicating light.

9. Enclosure: minimum NEMA 250, Type 12.

2.9 CONTROLS

A. Control Devices:

1. Remote Thermostat: Adjustable room thermostat with temperature readout.

2. Remote Setback Thermostat: Adjustable room thermostat without temperature readout.

3. Static-Pressure Transmitter: Nondirectional sensor with suitable range for expected input, and temperature compensated.

4. Timers: Seven-day, programming-switch timer with synchronous-timing motor and seven-day dial; continuously charged, nickel-cadmium-battery-driven, eight-hour, power-failure carryover; multiple-switch trippers; minimum of two and maximum of eight signals per day with two normally open and two normally closed output contacts.

B. Fan Control: Interlock fan to start with exhaust fans to which this heating and ventilating unit is associated for makeup air.

Retain "Outdoor-Air Damper Control, 100 Percent Outdoor-Air Units" or "Mixed Outdoor- and Return-Air Damper Control" Paragraph below. Retain first paragraph for units that supply 100 percent outdoor air.

C. Outdoor-Air Damper Control, 100 Percent Outdoor-Air Units: Outdoor-air damper shall open when supply fan starts, and close when fan stops.

Retain "Mixed Outdoor- and Return-Air Damper Control" Paragraph below for units that circulate varying amounts of outdoor and return air.

D. Temperature Control: Operates gas valve to maintain supply-air temperature.

1. Operates gas valve to maintain discharge-air temperature with factory-mounted sensor in blower outlet.

PART 3 - EXECUTION

3.1 INSTALLATION

Retain one of two "Equipment Mounting" or "Unit Support" paragraphs below. Coordinate with Drawings and Sections specifying vibration and seismic controls.

Retain first "Equipment Mounting" Paragraph to require equipment to be installed on cast-in-place concrete bases with vibration isolation devices.

Retain "Equipment Mounting" Paragraph below to require equipment to be installed on vibration isolation devices without cast-in-place concrete bases or "Unit Support" Paragraph for installation without vibration isolation devices.

A. Equipment Mounting: Install heating and ventilating unit using elastomeric mounts or restrained spring isolators. Comply with requirements for isolation devices specified in Section 230548 "Vibration and Seismic Controls for HVAC Piping and Equipment."

Retain or insert amount of required deflection in "Minimum Deflection for Vibration Isolation Devices" Subparagraph below.

1. Minimum Deflection for Vibration Isolation Devices: 1/4 inch.

B. Unit Support: Install heating and ventilating unit level on structural frames. Coordinate wall penetrations and flashing with wall construction. Secure units to structural support with anchor bolts.

C. Install gas-fired units according to NFPA 54, "National Fuel Gas Code."

D. Install controls and equipment shipped by manufacturer for field installation with direct-fired heating and ventilating units.

Retain paragraph below for units requiring seismic restraints.

E. Install seismic restraints according to manufacturer's written instructions.

3.2 CONNECTIONS

Coordinate installations and specialty arrangements with Drawings and with requirements specified in individual piping, duct, and electrical Sections. If Drawings are explicit enough, these requirements may be reduced or omitted.

A. Drawings indicate general arrangement of piping, fittings, and specialties.

1. Gas Piping: Comply with requirements in Section 231123 "Facility Natural-Gas Piping." Connect gas piping with shutoff valve and union, and with sufficient clearance for burner removal and service. Make final connections of gas piping to unit with corrugated, stainless-steel tubing flexible connectors complying with ANSI LC 1/CSA 6.26 equipment connections.

B. Duct Connections: Connect supply ducts to direct-fired heating and ventilating units with flexible duct connectors. Comply with requirements in Section 233300 "Air Duct Accessories" for flexible duct connectors.

C. Ground equipment according to Section 26.

D. Connect wiring according to Section 26.

3.3 FIELD QUALITY CONTROL

Retain "Perform tests and inspections" Paragraph below to require Contractor to perform tests and inspections.

A. Perform tests and inspections with the assistance of a factory-authorized service representative.

See Section 014000 "Quality Requirements" for retesting and reinspecting requirements and Section 017300 "Execution" for requirements for correcting the Work.

B. Units will be considered defective if they do not pass tests and inspections.

C. Prepare test and inspection reports.

3.4 ADJUSTING

A. Adjust initial temperature set points.

B. Set field-adjustable switches and circuit-breaker trip ranges as indicated.

3.5 DEMONSTRATION

A. Engage a factory-authorized service representative to train Owner's maintenance personnel to adjust, operate, and maintain heating and ventilating units.

END OF SECTION 237339

Project No: 390265

INDOOR, DIRECT-FIRED HEATING

237339 - 1

AND VENTILATNG UNITS