Catalogue

UV-PRC003-EN 13
Application Considerations
Acoustics
A growing population, and an increase in economic pressure to maximize building footprints have
resulted in higher building occupancies and less space to place the HVAC equipment. Often times
the close proximity of the equipment—such as a floor mounted unit ventilator—may cause noise
related complaints. Reducing the likelihood of these complaints requires careful planning:
• In the equipment sizing (under sizing and over sizing could increase noise level).
• And equipment placement (absorption and number of sound sources in the room greatly affect
noise).
Room NC is the sum of all sounds entering the room. Its value is based on assumptions about the
room’s characteristics. Given the complexity of various building systems, it is extremely important
to assure that the design goals (commissioning) for classroom acoustics, IAQ, and moisture control
are met through all aspects of the space.
For example, it is not uncommon for a school to install unit ventilators that are manufacturer-rated
for a specified airflow (cfm), but which are not AHRI-840 certified. These units may ship with a fan-
speed setting that delivers a lower than specified airflow, perhaps to reduce sound levels. Without
an overall building design goal, these units will be installed without delivering the specified airflow
needed to support the fresh air circulation, and possibly compromise IAQ.
Note: Unless the equipment is tested at the specified airflow, it is extremely difficult to determine
whether the unit meets the specified sound level.
Trane’s unit ventilator will not compromise air quality to support a minor reduction in airflow noise.
We encourage our engineers to specify their airflow needs at full building load requirements. Fine-
tuning of the speed setting may be interchanged through the unit’s 3-speed fan sensor quickly and
easily. This mechanical feature ensures that the equipment supplies proper cfm to support IAQ in
the classroom, while giving complete control of equipment noise to the administrative staff.
Technology that Supports Acoustic Enhancements
Another solution to airflow noise is through Trane direct digital controls (Tracer UC400). With the
Tracer UC400 controller, an infinitely variable speed fan control for the unit ventilator delivers the
airflow output customized to support the cfm space needs. When less cfm is necessary to meet the
Figure 8. Unit ventilator economizer
Acoustics
UV-PRC003-EN.book Page 13 Tuesday, June 4, 2013 8:59 PM