FORM 100.50-EG5 (108)
11
JOHNSON CONTROLS
In the non-modulating exhaust system, the exhaust air-
fl ow is constant whenever the exhaust fan is operating.
This type of control should only be used to either assist
a smoke purge system or when a system requires a
constant volume of exhaust airfl ow.
ACOUSTICAL CONSIDERATIONS
The Eco
2
unit is designed for lower sound levels than
competitive units by using fl exible fan connections, fan
spring isolators, double-wall construction, multiple fan
options, and lower speed and horsepower fans. For
VAV applications, VFDs are used instead of inlet guide
vanes. Additional sound attenuation can be obtained
using compressor sound blankets and fi eld-supplied
sound attenuators when necessary.
Even with these equipment design features, the acousti-
cal characteristics of the entire installation must never be
overlooked. Additional steps for the acoustical character-
istics of a rooftop installation should be addressed during
the design phase of a project to avoid costly alterations
after the installation of the equipment. During the design
phase of a project, the designing engineer should con-
sider, at a minimum, the impact of the equipment location,
rooftop installation, building structure, and duct work.
