AIR HANDLING. B. Section Building Automation and Control System Guidelines. C. Section Air Cleaning Devices and Filters

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1 AIR HANDLING PART 1: GENERAL 1.01 RELATED SECTIONS A. Section Clean Steam Generation B. Section Building Automation and Control System Guidelines C. Section Air Cleaning Devices and Filters D. Section Coils 1.02 SUMMARY COMMENTS A. Air handling units over 5,000 CFM shall be custom units with a guaranteed maximum leakage rate of less than 1/2% at 1-1/2 times the design static pressure. AMCA certified air handlers below 5,000 CFM shall typically be Factory Package (modular) units unless function and/or physical constraints require the use of a custom unit. B. With the advent of better digital controls, improved preventive maintenance and enhanced air handling system designs, it is now recommended to have all chilled water cooling coils protected against freezing without having to seasonally drain and refill cooling coils. The consultant shall carefully design the air handling system to avoid stratification in mixed-air systems, provide glycol preheat coils and adequate controls to monitor and prevent coil freezing. C. To reduce freeze-stat trips due to partial load-induced cold spots on preheat coils, circulation pump shall be provided at the coil. D. The potential for moisture carry-over shall be carefully considered for all air handling units provided with a cooling coil. Consultant shall design the equipment for a maximum coil face velocity of 475 fpm. E. Consultant shall size all air handler condensate traps (based on worst-case static pressure) and include a trap schedule in the construction documents. In addition, air handlers need to incorporate enough base rail height to allow for proper trap depth, or, the design needs to include a supplemental structural steel base rail under the air handler. F. Unit performance shall be certified in accordance with ANSI/AHRI Standard 430, Performance Rating of Central Station Air-Handling Units. DATE: 3/2/17 DATE: 3/2/17 Page 1 of 6

2 G. Air performance of all moving devices shall be rated in accordance with ANSI/AMCA 210, Laboratory Methods of Testing Fans for Aerodynamic Performance Rating and in accordance with AMCA 301 for sound, and shall be licensed to bear the AMCA certified rating. H. Engineer shall make it a priority to minimize air handler noise and vibration when designing an air handling system. Sound management features including (but not limited to) adequately sized cabinets (incorporating future anticipated capacity), large, lower speed, spring-isolated fans, minimal coil and filter static pressures, application of proper internal attenuation, and maximizing unit mass and stiffness all contribute to a quieter air handler. These features need to be analyzed critically by the consultant. I. The Consultant shall include in the specifications a requirement for equipment leakage testing by the air handling unit manufacturer once assembled on site with all penetrations in place and properly sealed. That means the leak test shall be performed only after all controls work has been completed. Providing any unit penetrations after the leak test will result in a re-test. This test shall also be witnessed by representatives from Cornell University and the Project Engineer of Record. PART 2: PRODUCTS 2.01 PREFERRED MANUFACTURERS A. Custom Air Handling Unit (aluminum) 1. Air Enterprise 2. Buffalo Air Handling 3. Environmental Air Systems B. Custom Air Handling Unit (Galvanized) 1. Buffalo Air Handling 2. HAAKON 3. MAFNA 4. SEMCO 5. Temtrol 6. TMI 7. Trane Custom 8. Ventrol C. Factory Package Air Handling Unit 1. AAON 2. Carrier DATE: 3/2/17 DATE: 3/2/17 Page 2 of 6

3 3. McQuay 4. Trane D. Deviations from these manufacturers will require approval by Facilities Engineering. Please be aware that in order to obtain approval for an air handler manufacturer not on the preferred list, the consultant will be responsible for providing Facilities Engineering with access to an installed unit (that s been in operation for at least five years) and to the facilities personnel responsible for maintaining the unit CONSTRUCTION A. The following criteria applies to both custom and factory package air handlers. B. Fan Section: 1. General: The fan, motor, and drive shall be internally spring isolated on a structural steel base complete with flex connections and lateral restraint. Direct drive self-supported fans (with variable speed drives {VSDs}) shall be provided in lieu of belt drive fans. The fan section shall have full size access door and adjacent removable panel for maintenance access. Fan sections typically have perforated inner walls for sound attenuation. Provide rigging beam for motor removal and maintenance purposes. 2. Draw-thru: Draw-thru units are preferred for most applications. The use of plenum fans negate system effect associated with insufficient discharge duct development length (typically associated with centrifugal utility set fans). 3. Blow-thru: The use of plenum fans in blow-thru applications promote a more even velocity profile across the coil face. Blow-thru units are also very effective at de-stratifying mixed air streams before the air enters the downstream preheat and cooling coils. This mixing effect eliminates the occurrence of a stratification-induced freeze-stat trips. Blow-thru air handlers shall not be specified when final filtration is required, due to the possibility of moisture coalescing on the filters. C. Fan Motors: An Electrically Commutated Motor (ECM or EC motor) is preferred because its use eliminates the need for a VSD and is more efficient at part-load than an AC induction motor with a VSD. Where an air handler application requires a motor size that isn t available in ECM, an AC motor with VSD is acceptable. DATE: 3/2/17 DATE: 3/2/17 Page 3 of 6

4 D. Base Construction: 1. General: Floors shall be double bottom construction with a minimum R-12 (indoor unit) or R-24 (outdoor unit) closed-cell foam insulation between. The base frame assembly shall have a minimum of four lifting lugs per shipped section. The structural base frame shall be fitted with cross-members to prevent floor oil-canning and to support all interior components. Floor material shall have safety-tread surface, and shall have continuously-welded seams. All unit base service openings shall be framed with a minimum 2-inch high water dam continuously welded to the floor. All pipe and electric conduit chases with openings to building or elements shall be covered with thin gage aluminum or 304 stainless steel. Refer to Section 1.02.E for condensate trap requirements. 2. Aluminum Construction: Base frame assembly shall be fabricated from a minimum of 3/16-inch thick aluminum plate welded at all joints and to structural members, designed for a minimum live load of 100 pounds per square foot. 3. Galvanized Construction: Base frame assembly shall be fabricated from a minimum of 8 ga. galvanized steel. The floor shall employ a 16 ga. galvanized steel outer panel, and a 3/16-inch thick aluminum or 10 ga. stainless steel inner panel. E. Cabinet Construction: 1. General: Roof and walls shall be double wall with a minimum R-12 (indoor unit) or R-24 (outdoor unit) insulation between. The panels shall be unitized in such a manner as not to disturb the insulation if panels are removed. Unit construction shall incorporate thermal breaks between the inner and outer wall panels, as well as between the walls and structure. Perforated inner walls are acceptable for use in all sections except in outside air intake, cooling coil, humidifier sections and any sections after the humidifier. Both galvanized and aluminum constructions are acceptable. Panel deflection shall not exceed a maximum of 1/200 of any span at 1-1/2 times the design positive or negative pressure (plus snow and wind loading for outside units). 2. Aluminum Construction: The outer panels shall be fabricated of minimum inch thick aluminum. Inner panels shall be fabricated of inch thick aluminum. Interior finish shall be smooth mill. 3. Galvanized Construction: The outer panels shall be fabricated of 16 ga. steel. Inner panels shall be fabricated of 16 ga. galvanized steel. DATE: 3/2/17 DATE: 3/2/17 Page 4 of 6

5 F. Cabinet Insulation: Use of closed cell polyisocyanurate foam insulation is preferred. Insulation shall be ASTM-84 and UL 723 fire and smoke rated to a fire hazard classification of 25/50. Insulation shall meet or exceed a 3.0 pounds per cubic foot (pcf) density material rating. The insulation shall meet the erosion requirement of UL 181 facing the air stream. G. Humidifier Section: Humidifier section shall incorporate stainless steel or aluminum inner panels, structural components and hardware. Carbon steel is not acceptable. See Section for specifics related to the humidification system. H. Coil Sections: Coil sections shall be separated by a minimum space of 18-inches. Each coil section shall have a full size access door. Coil casings shall be fabricated from 16 ga. 304 stainless steel. Removable panels shall be located on both sides of the air handler unit, not just on the coil removal side. See Section for more specifics on coil construction. I. Drain Pans: Double-pitched drain pans shall be fabricated from 18 ga. 304 stainless steel and shall extend the entire length of the coil section, and extend as far as possible in the direction of airflow, far enough to catch condensate at the maximum recommended coil air velocity. Each tier of coils in a stacked configuration shall employ a dedicated drain pan. Intermediate drain pans shall extend at least 3-inches upstream and at least 12-inches downstream of the coil face. Each drain pan shall be individually piped down to the bottom pan; lower drain pan to be provided with a drain connection of sufficient size to remove condensate, and extended to the unit exterior for connection by others. Drain pans recessed into the floor shall be insulated. J. Access Doors: Access doors shall be included between each air handler component, and shall be of the same construction as the panels described above. The doors shall have two continuous neoprene gasket seals around the entire periphery of the door. Each access door shall have a minimum of two non-corrosive securing latches which are also operable from inside the unit. Provide 1-inch dia. test ports with screwed caps on casing upstream and downstream of all coils and filters for pressure and temperature measurement. Positively pressurized sections shall have inwardly swinging doors, while negatively pressurized doors shall swing outward. Doors shall incorporate thermopane safety glass windows for every section. K. Lights: Water-tight marine lights with LED lamps and wire guards shall be provided in each section that provides service access. A single externally wall-mounted switch shall be provided to control all interior lights. Switch shall have pilot light in handle. DATE: 3/2/17 DATE: 3/2/17 Page 5 of 6

6 L. Filter Section: Filter sections shall be deep enough to allow for deep-pocket or cartridge filters (See Section for acceptable filtration applications). Filter sections shall also be equipped with access doors of adequate size to remove and replace the filters. Filter frames shall employ factory-applied gaskets between frame and filter. For filters installed upstream or downstream of the fan, the filter frame shall allow filters to be installed only on the upstream side of the frame. This configuration will help push the filter against the filter frame, thus providing a better seal between the filter and frame. The use of slide filter frames should only be considered as a last-resort. Two access doors are required for slide filter applications. A Dwyer Photohelic gauge shall be mounted on the outside of the cabinet with copper probes measuring the pressure drop across the filter section. The purpose of the analogue output is for filter load trending over the life of the filter. M. Controls: Generally, controls shall be field mounted. See Section for specifics on recommended building and automated controls systems required for air handling units EXECUTION A. Shipping: Air handlers shall be properly protected during shipment. Units shipped on unprotected flat-bed trailers shall be made all-weather-tight. B. Storage: If air handlers need to be stored on site before installation within an enclosed building, all-weather-tight protection shall be maintained until the units are within an enclosed space. DATE: 3/2/17 DATE: 3/2/17 Page 6 of 6