Acoustical Considerations; Location; Ductwork; Acoustic Insulation - Carrier WeatherMaker 48A020 Installation Instructions Manual

AVERTISSEMENT
RISQUE D´INCENDIE OU D´EXPLOSION
Si les consignes de sécurité ne sont pas suivies à la lettre,
cela peut entraîner la mort, de graves blessures ou des
dommages matériels.
Ne pas entreposer ni utiliser d´essence ni autres vapeurs ou
liquides inflammables à proximité de cet appareil ou de tout
autre appareil.
QUE FAIRE SI UNE ODEUR DE GAZ EST DÉTECTÉE
• Ne mettre en marche aucun appareil.
• Ne toucher aucun interrupteur électrique; ne pas
utiliser de téléphone dans le bâtiment.
• Quitter le bâtiment immédiatement.
• Appeler immédiatement le fournisseur de gaz en
utilisant le téléphone d´un voisin. Suivre les
instructions du fournisseur de gaz.
• Si le fournisseur de gaz n´est pas accessible, appeler le
service d´incendie.
L´installation et l´entretien doivent être effectués par un
installateur ou une entreprise d´entretien qualifié, ou le
fournisseur de gaz.

ACOUSTICAL CONSIDERATIONS

In order to minimize sound transmitted to the space, please
conform 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 roof
expanses between vertical supports. This will minimize
the phenomenon known as roof bounce.
FLEXIBLE
CONNECTORS
SUPPLY AND
RETURN
VIBRATION
ISOLATORS
IN ROOF
CURB
INTAKE
SUPPLY
PLENUM
FAN
SUPPLY AND RETURN
DUCTS LINED WITH
ACOUSTICAL DUCT LINER
Fig. 1 — Acoustical Considerations
3
• Install the units close to vertical roof supports (columns
or load bearing walls).
• Locate the units at least 25 ft away from critical areas. If
this is not possible, the ductwork and ceiling structure
should 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 located
over hallways and/or public areas.
• Provide trailing edge turning vanes in ductwork elbows
and 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 attach
hangers or supports to ductwork.
• Provide as smooth and gradual transition as possible when
connecting the rooftop unit discharge to the supply duct.
• If a ceiling plenum return is utilized, provide a return
elbow or tee to eliminate line-of-sight noise to the space.
Face the entrance of the return duct away from other
adjacent units.

Acoustic Insulation

• Provide acoustic interior lining for first 20 ft of supply
and 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 fiberglass
acoustical pad with a 1 / -in. barium-loaded vinyl facing on
8
top of the roof deck before building insulation and roofing
installation occur. Place the material inside the curb and
for 4 to 8 ft beyond the unit perimeter, dependent upon
unit size (larger units require a wider apron outside the
curb). Openings in the pad should only be large enough for
the supply and return ducts. An alternate approach is to
use two layers of gypsum board with staggered seams in
addition to the acoustical pad.
DISCHARGE
PLENUM
COMPRESSOR/
CONDENSING
SECTION
ROUND DUCT CONTROLS
RUMBLE BEST
ALL ROOF
PENETRATIONS
SHOULD BE
SEALED
AIR TIGHT