Understanding Small-Duct High-Velocity (SDHV)
Small-duct high-velocity HVAC systems (such as Unico System and SpacePak) use compact 2-inch flexible tubing to deliver air through specialized round nozzles, operating at static pressures of 1.2 to 1.5 in. w.g.—nearly triple standard residential ductwork. Installing the wrong air filter in an SDHV system can instantly trigger safety shutdowns.
Specialized Media Requirements
Because SDHV blowers operate at such intense static pressures, standard residential cardboard filters can buckle or collapse under the draw. Always use OEM-specified deep pleat media or commercial metal-framed filter cartridges rated for high-velocity return air plenum pressures.
About ClariSelect Editorial & Research Standards:
Sizing measurements, static pressure curves, and filtration ratings referenced across our educational guides are compiled from published ANSI/ASHRAE Standard 52.2 engineering data, AHAM AC-1 verified ratings, and manufacturer technical documentation. ClariSelect provides objective editorial research and analysis with zero sponsored placements.