Carrier WeatherExpert 48N2 Installation Instructions Manual

Also see for WeatherExpert 48N2: Controls, start-up, operation, service and troubleshooting instructions Installation instructions Controls, start-up, operation, service, and troubleshooting Installation instructions

Contents

2ACOUSTICAL CONSIDERATIONSIn order to minimize sound transmitted to the space, pleaseconform to the following recommendations (see Fig. 1):Location• Avoid locating the unit above sound-sensitive areas.Instead, locate the unit above restrooms, storage areas,corridors, or other noise-tolerant areas.• Avoid mounting the unit in the middle of large roofexpanses between vertical supports. This will minimizethe phenomenon known as roof bounce.• Install the units close to vertical roof supports (columnsor load bearing walls).• Locate the units at least 25 feet away from critical areas.If this is not possible, the ductwork and ceiling structureshould be acoustically treated.• Consider the use of vibration isolators or an acoustic curb.Ductwork• Utilize flexible connectors between the unit and the sup-ply and return ducts.• Supply and return air main trunk ducts should be locatedover hallways and/or public areas.• Provide trailing edge turning vanes in ductwork elbowsand tees to reduce air turbulence.• Make the ductwork as stiff as possible.• Use round duct wherever possible because it is less noisy.• Seal all penetrations around ductwork entering the space.• Make sure that ceiling and wall contractors do not attachhangers or supports to ductwork.• Provide as smooth and gradual transition as possible whenconnecting the rooftop unit discharge to the supply duct.• If a ceiling plenum return is utilized, provide a returnelbow or tee to eliminate line-of-sight noise to the space.Face the entrance of the return duct away from otheradjacent units.Acoustic Insulation• Provide acoustic interior lining for first 20 feet of supplyand return duct or until the first elbow is encountered.The elbow prevents line-of-sight transmission in the sup-ply and return ducts.• Install a double layer of 2-in. low density quilted fiber-glass acoustical pad with a 1/8-in. barium-loaded vinylfacing on top of the roof deck before building insulationand roofing installation occur. Place the material insidethe curb and for 4 to 8 ft beyond the unit perimeter,dependent upon unit size (larger units require a widerapron outside the curb). Openings in the pad should onlybe large enough for the supply and return ducts. An alter-nate approach is to use two layers of gypsum board withstaggered seams in addition to the acoustical pad.WARNINGDO NOT USE TORCH to remove any component. Systemcontains oil and refrigerant under pressure.To remove a component, wear protective gloves and gog-gles and proceed as follows:a. Shut off electrical power to unit.b. Recover refrigerant to relieve all pressure from sys-tem using both high-pressure and low pressure ports.c. Traces of vapor should be displaced with nitrogenand the work area should be well ventilated. Refrig-erant in contact with an open flame produces toxicgases.d. Cut component connection tubing with tubing cutterand remove component from unit. Use a pan to catchany oil that may come out of the lines and as a gagefor how much oil to add to the system.e. Carefully unsweat remaining tubing stubs when nec-essary. Oil can ignite when exposed to torch flame.Failure to follow these procedures may result in personalinjury or death.CAUTIONDO NOT re-use compressor oil or any oil that has beenexposed to the atmosphere. Dispose of oil per local codesand regulations. DO NOT leave refrigerant system open toair any longer than the actual time required to service theequipment. Seal circuits being serviced and charge withdry nitrogen to prevent oil contamination when timelyrepairs cannot be completed. Failure to follow these proce-dures may result in damage to equipment.