Consider Various Pressure Control Methods in a VAV System
All diffusers become noisier with higher pressures at their inlet and this is true for VAV diffusers. Pressure is often reduced by the use of a balancing damper or terminal unit, but VAV diffusers are unique as they have a built in VAV damper that can close down to a minimum flow.
ASHRAE Standard 70
guidelines are in place so that ideal conditions are present during GRD testing
and to ensure the testing is repeatable. It is important to note that the performance
published in the
is based on these ideal conditions outlined in ASHRAE 70 and that
any field modifications can affect the performance of the outlet. There are five common field conditions and their influence on the air pattern of a given diffuser:
ACTIVE CHILLED BEAMS
In a chilled beam, the term “induction” is used to describe the process of injecting primary air under pressure through a nozzle, which in turn entrains return or plenum air at the discharge of the nozzle.
In the HVAC design world, there is some uncertainty about the application of new and existing air distribution technologies since codes change so quickly and sometimes drastically. Customer mock-ups of the proposed HVAC design for a specific space are a great way to help resolve design uncertainty.
Atlanta’s In-Situ Acoustical Test Chamber