Product Manual ALR2-3
ALR 110F – 150F
19
Sound Pressure Levels, Multiple Units
Multiple air-cooled unit installations will have a higher sound level than a single unit on a
doubling basis. Two units will have approximately 3 dB higher sound level of one unit, 4 units
will be approximately 6 dB louder, and 8 units approximately 9 dB louder than one unit.
Sound Control
Walls adjacent to a unit
(20 feet {6.1 meters} or
less) will reflect sound
outwards, increasing the
sound pressure on the
side away from the wall.
This sound increase could
be as high as 3 dB for one
wall and as high as 6 dB
for a corner location. Unit
orientation and/or
distance as noted above
will decrease sound levels.
Sound levels can also be controlled by the installation of barrier walls. To be effective as sound
blockers, walls must be solid with no open penetrations. Sound tends to leak out of openings.
Block walls with filler material and slots on the side facing the unit are especially effective. The
wall should be about 10 feet high (two feet higher than the unit) and located at least 10 feet away
so as not to affect unit performance. A three-sided enclosure will be the most effective solution
and will reduce sound levels by about 10 dB. Remember that the wall will increase the sound
level on the side opposite it by 3 to 6 dB (one or three sided wall). Note: The effect of adjacent
walls on air recirculation and restriction must always be considered when employing sound
barrier walls.
