End reflection is the sound energy that is reflected back into the duct during testing instead of entering the test reverberation room. It occurs due to the test setup. The revised standard is now being used in test procedures for the variable air volume terminals certification program.

“The updated standard makes testing procedures consistent with AHRI products,” said Stephen Yurek, president and CEO, AHRI. “It will allow for greater accuracy when measuring the noise levels of the units, and improves testing procedures overall.”

Actual room noise levels measured in the field are not affected by this change. This change in the rating procedure and subsequent reporting may increase the resultant discharge noise criteria (NC) level in some cases with duct end reflection corrections applied. Certification ratings can be viewed in by visiting http://bit.ly/MR5nNG.

Publication date: 9/3/2012