Seminar 73. AHR Expo Session: Basics of HVAC Noise Control
ASHRAE 2013 Winter Conference
Designing HVAC systems with good acoustic performance can be a challenge: this session addresses three common issues to improve acumen for sound and vibration. Explore the idiosyncrasies of selecting fans that optimize acoustic and energy performance for improved system design. Learn about the physics of sound that explains the performance and limitations of silencers and acoustic louvers. Fine tune the most valuable and effective tool for acoustics: your ears. This session also provides audio examples to connect you with the fundamental aural experience.
What Does That Sound Like and Mean? (Ear Training)
The two most common complaints for HVAC systems is thermal comfort and noise. Understanding how noise can be an annoyance and what the goal criteria sounds like gives you the designer and contractor the tools to be successful on the acoustic front. Explore the aural landscape of HVAC acoustics with your ears as we navigate successful projects and common issues, and how to troubleshoot problems. Make the connection between the perceived sound level and the criteria values stated in the ASHRAE handbook. Don't let your ears fool you, but use them as a powerful tool in your toolbox.
Fan Selection Impact on Noise
The noise produced by a fan depends not only on its duty point, i.e., airflow CFM and total fan pressure, but also on its type & size. For a given duty point a fan that is the wrong type and/or the wrong size can be as much as 30 dB louder than the optimum selection. This presentation will show examples of quiet and noisy fan selections, and offer simple guidelines for selecting fans to minimize excessive fan noise.
Understanding the Physics of Silencers
HVAC Silencers or sound attenuators are used on many different types of HVAC equipment. Silencer manufacturers have various models designed to meet specific DIL (Dynamic Insertion Loss) and static pressure drop requirements. A properly selected silencer can reduce noise levels significantly across the entire frequency spectrum. However, if a silencer is improperly selected, issues in acoustic performance, pressure drop, and self-noise may arise. The silencer itself may even become another noise source! This presentation will explain silencer definitions, testing procedures, and how to properly select silencers to ensure the maximum performance is gained without disrupting the HVAC system.