High-Volume, Low-Speed (HVLS) Fans Part 4: How Sprinkler Systems Impact HVLS Installation

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By Gary Holder

Commercial and industrial sprinkler systems impact the location and installation of HVLS fans.

The National Fire Protection Association’s NFPA 13 Standard for the Installation of Sprinkler Systems requires new construction commercial and industrial buildings 5,000 sq ft or larger to have sprinkler systems. This same requirement applies to renovated buildings that are finished to a size of 12,000 sq ft or greater. NFPA 13 provides detailed guidelines for the design, installation, and maintenance of these sprinkler systems.

NFPA Guidelines for HVLS Fans

Amid the rising popularity of HVLS fans, the NFPA began to consider what impact these fans might have on sprinkler system fire suppression. In 2007, the NFPA and its Fire Protection Research Foundation (FPRF) initiated a series of test fires. The fires were part of an in-depth study to determine how much HVLS fans obstructed an active sprinkler system during a fire. The conclusions gathered from these tests formed the basis for the following guidelines, included in Section 11.1.7 of the 2013 Edition of NFPA 13:

  1. The maximum fan diameter shall be 24 ft.

  2. The HVLS fan shall be centered approximately between four adjacent sprinklers.

  3. The vertical clearance between the HVLS fan and the sprinkler deflector shall be a minimum of 3 feet.

  4. All HVLS fans shall be interlocked to shut down immediately upon receiving a water flow signal from the alarm system, in accordance with the requirements of NFPA 72.

Note that these guidelines only apply to fans that are 6 ft to 24 ft in diameter.

Number 4 is of particular importance because it requires HVLS fans to be wired to shut down immediately upon a waterflow signal from the fire alarm system. This is because the movement of air away from the fans (and, thus, sprinklers) may slow the rising heat from a fire, causing a delay in sprinkler activation. Number 2, however, may be the most challenging to implement, as it requires a bit more pre-planning and coordination—otherwise, sprinklers or fans may need to be relocated following inspections.