If you have an open office area with (2) AHUs, each AHU supply fan provides 1,500 cfm of supply air and return air that is fully ducted and has no common plenum.
Would duct detectors be provided on the supply side of each AHU? Do you combine the "CFM" since both units serve the same area? If not, would you ever cumulatively add multiple units of CFM? This has been an ongoing question as each of our AHJs sees it differently. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
5 Comments
J.H.
7/19/2024 09:08:02 am
Here is the latest guidance in NFPA 90A, 2024 Edition:
Reply
Chad
7/19/2024 09:41:28 am
That's a hard no, IMO. What is the justification he gives?
Reply
Chris
7/19/2024 12:36:27 pm
As an AHJ I would not require them based on what you've described above and agree as well with the other comments
Reply
Jack G
7/19/2024 01:24:45 pm
NFPA 90 a requires duct detectors in AHJ > 2000 ft3 per minute.
Reply
Scott McCormick
7/22/2024 08:37:00 am
IMC jurisdiction, not NFPA. It all comes down to smoke spread beyond the room or space.
Reply
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