Interpretation #7837
Published September 30, 2016
Original Request
- Code Version
- 2014
- Code
- MECHANIC
- Code Description
- Chapter
- Section
- 601.5
- Topic
- Dampers in return grills for T&B
Question
Is it the intent of 601.50 to disallow the use of dampers in return grills for the purpose of test and balance?
Answer Published 09/30/2016 at 1:55 PM
No
Commentary
FBC Mechanical 601.5 requires only balanced return air and
constrains the design to ensure that pressure differentials
across closed doors are no greater than 0.01 inches of water
column. If the design includes return grilles that are
properly sized, with dampers, so as to limit the pressure
differential to the Code-mandated 0.01 inches of water column,
dampers are, of course, allowed.