Nortek Air Solutions (NAS), the largest manufacturer of custom HVAC equipment in North America, received a Notice of Acceptance (NOA) Nov. 19 on its Welded Frame (WF-2) air handling unit (AHU) cabinet for compliance with Miami-Dade County’s (Fla.) High Velocity Hurricane Zone (MDC HVHZ) building code.

 The WF-2 was tested at 227 pounds per square foot (PSF), which more than doubles the nearest competitor’s AHU cabinet strength of 110-PSF. The PSF rating equates to approximately a 301-mph wind load rating, depending on equipment elevation and building importance (risk factor). The WF-2 NOA (No. 20-0630.02) lays testament that it’s the HVAC industry’s number one AHU cabinet for structural integrity against high wind events. The highest wind event recorded globally was the Oklahoma City, Okla., area’s 1999 Bridge Creek-Moore F5 tornado listed at 301-mph.

Nortek also claims the MDC list’s second and third positions with two Integrated Thermal Break Frames (ITF) that were passed at 135-PSF/230-mph and 125-PSF/221-mph for stainless steel and aluminum construction, respectively, (NOA No. 19-0227.05 attained for both in 2019).

The MDC HVHZ is considered the Gold Standard of national hurricane building codes. Engineers also refer to the code for other potential high wind events, such as tornados in the nation’s heartland. A NOA certification includes testing for lateral force, uniform static pressure, water resistance, cyclic wind pressure loading and large missile impact. These tests apply to all parts of an air handler’s infrastructure, such as unit base, floors, framework, access doors, handles and hinges, cabinet panels and other components susceptible to damage high wind events.

NAS, which markets the WF-2 and ITF AHUs under the Temtrol™ and Governair™ brands, builds the units with heavy gauge metal exterior panels and interior liners, and a structural integral or welded framework with a fully-welded structural unit base. All units are also voluntarily tested at NAS’ in-house factory test laboratory for performance, strength and durability.

“Engineers, contractors and building owners can be assured that an NAS air handler will give them the best cabinet performance in the industry whether it’s mounted on a roof in hurricane zones or any other high wind region of the nation,” said Joe Naccarello, Group Vice President–Sales and Customer Operations, NAS, St. Louis.

Knowing they had an incomparable design that hadn’t yet demonstrated its maximum test potential, Nortek engineers set out to push the WF-2 to its limit during MDC compliance testing. Consequently, the WF-2 was tested up to an unprecedented 340-PSF/369-mph maximum load pressure. However, MDC requires certification at 67-percent of maximum load pressure, which calculates to the WF-2’s new 227-PSF listing.