Tonal noise characteristics from HVAC equipment and how to improve practically and technically

Abstract

All HVAC equipment has rotating components, such as compressors and fans. These critical components often exhibit annoying tonal characteristics. Although there are many engineering methods to improve the tonal characteristics, there exists no commonly accepted tonal metrics in HVAC equipment specifications, which typically only include sound power or sound pressure levels at few operating conditions. However, the equipment sound level can vary greatly by the operating conditions—the range may be as much as 10 dB or more, depending on compressor/fan types, sizes, and speed range. Although HVAC manufacturers understand the impact of the equipment tonal characteristics to the acoustical comfort of built environment, lack of customer requirement in the annoyance of the tonal characteristics makes it very challenging to be assessed and improved upon with the other competing functional requirements. This presentation will show typical tonal noise characteristics of chillers, air handlers, and transport HVAC equipment, and then propose methods to improve practically and technically from equipment manufacturer’s point of view.