remains a leader in the HVAC industry, continuing a tradition that is over a century old. We work with the owner, engineer, and contractor to create an efficient, reliable, andAllow us to meet, and exceed your expectations. 467 Zane Snead DriveSeismic Home > Products > ESR the BIG rooftop unit jobs! All rooftop air-handling units shall be supported by vibration isolation curbs as manufactured by Kinetics Noise Control. curbs shall be complete assemblies designed to resiliently support equipment at the specified elevation and shall constitute a fully enclosed air- and The isolation curb shall consist of an upper support rail with supply and return duct supports on which the equipment and duct openings rest and a lower support curb which is attached to the roof structure, separated by free-standing, unhoused, laterally stable steel springs. The upper support rail shall provide continuous structural support for the rooftop equipment and shall be designed to provide isolation against

casingradiated vibration in the rooftop equipment housing and structure borne vibration from rotating and mechanical equipment in the rooftop package. The upper support rail shall consist of a structural channel with sufficient elevation above the spring to preclude interference with the rooftop equipment and permit access to inspect the isolation system after placement of theSupport of the RTU by weather seal attachment bolt heads The lower support curb shall be a formed channel fabricated of heavy gauge galvanized steel with a continuous 1-1/2 inch x 1-1/2 inch (38 mm x 38 mm) nominal wood nailer attached to the isolation support pedestals. support pedestal, which includes the seismic and wind load restraints, shall be bolted or welded to the building support steel to suitably transfer seismic and wind load forces to the building structure. The lower support curb shall have a minimum elevation of 14 inches (356 mm) from the top of the wood

nailer to the base of the curb. Spring components shall be (1 inch/25 mm) (2 inch/51 mm) (4 inch/102 mm) deflection, free-standing, unhoused, laterally stable steel springs. window ac unit weight shall have a lateral stiffness greater than 1.2 times the rated verticalac motor control course stiffness and shall be designed for a typical 50% overload to solid. heat ac units wall springs shall have an polyester powder coated finish and be color coded to indicate load capacity. Spring coils shall rest on minimum 0.25 inch (6 mm) neoprene noise pads. Seismic and wind load restraints shall be designed to limit movement inRestraint components shall include neoprene snubbers at all contact points for energy absorption. There shall be no metal-to-metal

Standard units are designed to withstand a 43 psf horizontal and 25 psf vertical wind load. Resistance to higher loads or for ratings on extended height curbs or units attached to wood or concrete will require analysis by KNC, but can in most cases be met with only minor modification. The vibration isolation curb shall be air and weather tight using an elastomeric seal, which is attached to the upper support frame with a galvanized steelThe seal shall extend down past the wood nailer of the lower support assembly and flash over the roof material at the wood nailer on the lowerThe seal shall be Class A, as tested in accordance with approved Underwriter’s Laboratories, Inc., provisions. Metal or combination metal and elastomer seals are not permitted. The seal may not be penetrated for The isolation curb system shall be complete with cross-bracing as required as a part of the upper and lower assemblies. Supply and return flex connector support hardware shall be supplied for

installation by the contractor in the field. The supports will be clearly marked and dimensioned on the submittal and installation drawings. hardware shall be cut-to-length, galvanized steel channels supported and connected with stamped and punched galvanized steel duct support hangers. The support hangers shall allow the support elevation to be equal to or lower than the equipment rail elevation. Supply air and return duct shall be flexibly attached by the contractor to prevent transmission of vibration to the building structure. Airborne noise control packages, if required, shall be supported by the roof structure within the curb and shall have no rigid contact with the The isolation curb assemblies shall be shipped to the job site with the upper support rail, lower support curb, springs and restraints completelyThe contractor shall be required to assemble the four corners, attach the curb to the roof structure, install cross-bracing and flex connector

supports as necessary, and install and attach rooftop equipment. Vibration isolators shall be selected by the manufacturer for each specific application to comply with deflection requirements as shown on the Vibration Isolation Schedule or as indicated on the project documents. The manufacturer shall submit certified engineering drawings and calculations stamped by a licensed Professional Engineer demonstrating the isolation curb system has been designed (for a _____mph/_____km/h wind load), (for Seismic Zone____per code), (to withstand ___g horizontal force and_____g Roof curb shall be Model ESR as manufactured by Kinetics Noise Control,©2013 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 55, no. 9, September 2013. Barry Barnet, P.E., is a senior professional associate and senior mechanical engineer at HDR in Princeton, N.J. Energy recovery in laboratories has some special concerns because of the possibility of cross contamination between the supply and exhaust streams.

This article illustrates two methods of improving energy recovery in laboratory air-handling systems (with 100% outside air), where fume hoods and similar exhaust are considered to be hazardous (as defined by the International Mechanical Code [IMC]) and the energy recovery system is designed to preclude the possibility of cross-contamination between supply and exhaust. With both methods of recovery, the air-handling system supplies air at a neutral air temperature using dual energy recovery. For the purpose of revealing the improvement in energy recovery with the neutral air concept, both methods of recovery are also compared to a more traditional air-handling unit supplying air at a temperature of 55°F (13°C). The results show that with the neutral air approach it is possible to achieve efficient energy recovery even where the general exhaust used for recovery is only 40% of the total supply air, while still precluding the possibility of cross-contamination and complying with the IMC requirements for hazardous exhaust.

The first energy recovery method uses an energy wheel. The second recovery method uses glycol runaround. Under the first air-handling system, the traditional unit serves as a combined ventilating, makeup, humidity control, and cooling system (in a sense a “jack of all trades”), producing leaving air at a temperature of 55°F (13°C). Energy recovery in this case is single stage using only one energy wheel or a single glycol coil. With the second air-handling system (neutral air), the unit provides only ventilation, makeup air, and humidity control using dual-energy recovery, and produces a leaving-air temperature in the range of approximately 63°F to 70°F (17°C to 21°C). This system is combined with air recirculating supplemental cooling devices: typically fan coil units, chilled beams, or other similar devices. In hood intensive rooms care should be exercised to avoid interference between these devices and proper hood performance. Dual energy recovery consists of two energy wheels, one enthalpy and one sensible, for the first recovery method.

Under the second recovery method, two glycol coils are substituted for the wheels. The two glycol coils in this case can be described as a wraparound/runaround system.  The glycol flows in series from the second coil, where the supply air is heated up to neutral conditions, then wraps around the chilled water coil (providing dehumidification) to the first glycol coil (serving to precondition the outside air). Based on the previous variations, there are a total of four different combinations, with two energy recovery methods each applied to two different air-handling systems: Energy wheel method of recovery with a traditional system (Figure 1; with first wheel only); Energy wheel method of recovery with a neutral air system (Figure 1; with dual wheels); Glycol coil method of recovery with a traditional system (Figure 4; with first glycol coil only); Glycol coil method of recovery with a neutral air system (Figure 4; with dual coils). A method of recovery using heat pipes is not examined as this system is expected to have characteristics similar to glycol runaround but with slightly higher recovery effectiveness, due to the higher heat content of refrigerant verses a glycol solution.