Roger W. Griffith, P.E.

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Duct Smoke Detectors – Locate In Supply or Return Ducts?

May 8, 2015 by Roger Griffith 18 Comments

duct smoke detector

Duct smoke detectors, when installed in HVAC systems, automatically stop the system fans upon the detection of smoke. For HVAC systems with airflows exceeding 2,000 cfm, duct smoke detectors are required. This includes where multiple air handling systems utilize common ducts with a combined design capacity greater than 2,000 cfm.

But when duct smoke detectors are required, where should they be located? Let’s look at the requirements in two of the prominent codes and standards.

[Read more…]

Filed Under: HVAC Systems, International Mechanical Code Tagged With: NFPA 90A

Floor Registers in Commercial Buildings

May 29, 2014 by Roger Griffith Leave a Comment

HVAC floor register

Commercial buildings typically have ceiling diffusers or sidewall grilles, but occasionally there is a need to locate air supplies or returns on the floor of a facility. Floor registers are common in residential applications. Before locating them on the floor a commercial building, a careful review of the applicable codes is imperative.

Building codes typically do not prohibit floor registers in commercial buildings, however, the fire codes can restrict their usage. For example, NFPA 101: Life Safety Code, paragraph 9.2.1 states that “Air-conditioning, heating, ventilating ductwork, and related equipment shall be in accordance with NFPA 90A.” NFPA 90A: Standard for the Installation of Air-Conditioning and Ventilating Systems, paragraphs 4.3.7.3.1 and 4.3.8.3.1 state that “Air inlets/outlets shall be located at least 3 inches above the floor, unless provisions have been made to prevent dirt and dust accumulations from entering the system.”

[Read more…]

Filed Under: HVAC Systems Tagged With: NFPA 101, NFPA 90A

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Roger W. Griffith, P.E.
(865) 471-8142
RGriffith@GriffithEngineering.net

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Roger W. Griffith, P.E.
P.O. Box 702
Jefferson City, TN 37760
(865) 471-8142

Email: rgriffith@griffithengineering.net

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