Central AC System GuideSmall-duct high-velocity (SDHV) central air conditioning, made by manufacturers such as Unico and SpacePak, delivers whole-home cooling through compact flexible tubing instead of the bulky sheet-metal ducts used in conventional systems. This guide explains how the small tubing and high-velocity air delivery work, why the approach suits homes that cannot accommodate traditional ductwork, and what comfort characteristics owners can expect.
Small ducts and high-velocity delivery
Unico describes its product as a Small-Duct High-Velocity heating and cooling system that uses small-diameter supply tubing rather than large rectangular ducts. Unico states the supply ducts have a 2 and 2.5 inch inside diameter and are flexible with sound-deadening properties.
The air enters the room through small jets that actively mix the room air. Unico states these small jets of air mix the room air for even temperature in the space.
Fitting cooling into homes without conventional ducts
The compact tubing is the main reason these systems suit older or architecturally sensitive homes. Unico states that its system can be discreetly retrofitted into vintage homes and works whether a home has pre-existing ductwork or none.
Unico states the tubing fits within wall cavities, in-floor spaces, or within old conventional ductwork, so installation avoids the extensive remodeling that large ducts would require.
Comfort characteristics: even temperatures and low drafts
Because the high-velocity jets continuously mix room air, SDHV systems are marketed for even, draft-free comfort. SpacePak describes itself as the original Small Duct High Velocity central heating and cooling system that provides true central air without bulky ducts or unsightly wall units.
SpacePak states its system eliminates dead zones and cold spots to keep a home at an even temperature and uses a unique draft-free delivery. SpacePak also states its system is designed to pull humidity from the air, making a home feel cooler.