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   PART 1 - GENERAL

    01 WORK INCLUDED

    A. Provide roof mounted air handling units of the size, type and configuration as scheduled and shown on drawings.

    02 QUALITY ASSURANCE

    A. Certify unit components in accordance with ARI Standard 430 as applicable.

    B. Certify coils in accordance with ARI Standard 410. Substantiate performance by ARI computer generated output.

    C. ASHRAE Compliance: Construct and install refrigerant coils in accordance with ASHRAE 15 "Safety Code for Mechanical Refrigeration".

    D. NFPA Compliance: Provide air handling unit internal insulation having flame spread rating not over 25 and smoke developed rating no higher than 50; and complying with NFPA 90A "Standard for the Installation of Air Conditioning and Ventilating Systems".

    E. UL and NEMA Compliance: Provide electrical components required as part of air handling units, which have been listed and labeled by UL and comply with NEMA Standards.

    F. NEC Compliance: Comply with National Electrical Code (NFPA 70) as applicable to installation and electrical connections of ancillary electrical components of air handling units.

    03 SUBMITTALS

    A. Submit products to Architect for approval as required by Section 15010.

   PART 2 - PRODUCTS

    04 GENERAL

    A. Provide factory assembled modular roof mounted air handling unit to include fan section, coil section, filter section and accessory items as described on drawings or herein. Units designed for indoor use, modified and weatherproofed for outdoor use will not be acceptable.

    05 CASING

    A. Casing shall be designed specifically for outdoor installations and shall be leak tight against a 3" negative static pressure. Casing shall be fabricated of heavy gauge galvanized steel panel welded to 10 gauge, galvanized steel base channel, designed for curb mounting. All seams shall be welded or bolted and sealed to prevent leaks. Galvanized steel roof is flanged on all four sides and pitched for drainage.

    B. Access doors constructed of galvanized steel, and shall be gasketed, hinged, and furnished with latches. Access doors shall be provided for fan, coil, and filter sections as a minimum.

    C. Casing shall be internally insulated with 1" thick, 1-1/2 pound density neoprene coated fiberglass meeting UL181 erosion testing. Casing shall be insulated throughout.

    D. Casing shall be cleaned and phosphatized then finished with weather resistant baked on enamel paint.

    06 BLOWER SECTION

    A. Provide DWDI fan with galvanized or phosphatized painted steel scroll housing.

    B. Provide air foil, forward curve, or backward inclined fan wheel as scheduled, or as required by performance specifications. Statically and dynamically balance fan before and after installation in the cabinet section.

    C. Provide fan shaft keyed, set screwed or clamped to the wheel per the manufacturers standard design to meet the specified performance. Maximum fan rpm to be well below the first critical speed.

    D. Provide units with internally or externally mounted fan motors. Locate motors on factory slide rail base complete with adjustment nuts. Provide access to fans and internally mounted motors and all bearings. Units with internally mounted motors to have additional capacity to compensate for motor heat.

    E. Provide fan bearings of the ball, roller, or pillow block type, self-aligning and grease lubricated. Provide extended lubrication lines from fan bearing to unit casing. Connect lubrication lines to a Zerk fitting mounted on the casing. Select bearings for an average life of 200,000 hours at design operating conditions.

    F. Insulate fan section with 1" thick, neoprene coated, fiberglass, 1-1/2 pound density applied to internal surfaces with adhesive (100% coverage) and secured with weld pins, one for each 2 square foot of surface. Coat exposed edges of insulation with adhesive. Insulation and adhesive to meet NFPA-90A standards.

    G. Insulate divider plate between hot and cold deck.

    07 COIL SECTION

    A. Fabricate casings of continuous galvanized or phosphatized steel.

    B. Provide double constructed drain pan consisting of 1/2" urethane insulation covered with a sheet metal liner and mastic coating. Drain pan shall extend under both coil and fan sections.

    C. Completely enclose coil headers within the insulated casing with connections extended through cabinet.

    D. Insulate coil sections identically to fan section.

    08 HEATING COILS - HOT WATER

    A. Provide 1/2" or 5/8" outside diameter tubing with aluminum fins. Bond fins by mechanical expansion.

    B. Provide coils with a maximum working pressure of 175 psig at 400 degrees F.

    C. Test coils with air pressure of 350 psig submerged in water.

    09 FILTER SECTION

    A. Furnish factory built flat, medium capacity (v-arrangement), high capacity (z-arrangement) or high efficiency filter section complete with filters as specified herein. Filter area to be specified on unit schedule. Filter sections to have access doors on both ends. Refer to Section 15886 for filter specifications.

    010 INLET VANES

    A. Provide variable inlet vanes as scheduled on drawings, of the vane type, nested, suitable for shutoff pressures to 12" water gauge and temperatures to 200 degrees F., with vane shafts connected to control ring by crank arms integrated within inlet bell.

    011 ROOF CURBS

    A. Curbs shall be by equipment manufacturer, Custom Curb or a specifically approved curb manufacturer.

    B. Curbs shall be prefabricated and non-combustible. Curbs shall be full perimeter and a minimum of 12 inches in height unless otherwise specified. Sizes shall be as shown on drawings. Curb shall be designed to allow connection of field fabricated ductwork directly to curb.

    012 MANUFACTURERS

    A. Central station air handling units shall be manufactured by McQuay, Trane or approved equal.

   PART 3 - EXECUTION

    013 INSTALLATION

    A. Install each unit on a level, rigid and heavy concrete base.

    B. Mount each unit by spring or isolators (minimum 1-1/2" deflection) as set forth in the drawings to prevent transmission of vibration to the building and surrounding structure. Coordinate the selection of the isolators with manufacturer of the air handling units to assure compatibility of mounting details. Refer to other Division 15 sections for vibration isolation specification.

    C. Unit(s) mounted on inertia bases to require no vibration isolation by unit manufacturer.

    D. Provide clearance at each unit for routine service including the changing of filters, removal of coils, bearing greasing, opening of access doors, pulling of blower shaft and removal of motors.

    E. Ductwork: Duct connectors to each unit to allow for straight and smooth air flow. No turns are to be installed at the fan discharge which are in the opposite direction to fan wheel rotation.

    F. Provide flexible connections at duct connections to unit.

    G. Piping:

    1. Support piping independently of coils and with adequate flexibility to prevent undue stress at coil header connections.

    2. Install full size drain lines from the drain pan connection and include trap to permit condensate to drain freely.

    3. Install service valves on both supply and return lines to coils and install so valves can be shut off, a small section of pipe removed, and coil allowed to slide out. This condition applies to water and steam coils only.

    3.02 START-UP, TESTING, TRAINING

    A. Start-up unit, check for proper performance, motor rotation, air leakage, or infiltration, etc.

    B. Prepare unit for test and balance as required under Section 15030.

    C. Correct deficiencies found by Test and Balance Contractor.

    D. Demonstrate and instruct hospital engineering personnel in the operation of the system.

    END OF SECTION