What the heck is a small duct HVAC system?

Small duct HVAC systems, like The Unico System by NARI Platinum Partner Unico, are a space-saving way of adding modern indoor comfort to homes that simply don’t have the room for the bulky ductwork associated with traditional forced air central heating and cooling, and where adding such would significantly disrupt the home’s original design and aesthetics.

As defined by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), small duct high velocity (SDHV) systems are those that deliver conditioned air through smaller ductwork and flexible supply tubes at a higher static pressure (i.e. velocity) than conventional forced air equipment.

Because of their smaller size, small duct systems are popular with preservationists and owners for retrofitting older homes built before the advent of central heating and air conditioning; designers and builders of custom and log/timber homes for including central air that doesn’t require alterations to the original plans; and as a solution for easily providing standalone indoor comfort for room or wing additions.

In addition to their ability to fit into tight spaces, small ducts systems have the following advantages over conventional systems:

  • Quiet
  • Provide draft-free, even temperatures
  • Remove more moisture
  • Require little-to-no remodeling
  • Blend into any décor

Let’s take a quick look at the individual components of a small duct system:

Small and modular, SDHV system air handlers easily fit into tight spaces like attics, crawlspaces and mechanical closets.  Air handlers include a combination of blower and cooling and/or heating coils.


The plenum, or trunk line, attaches directly to the air handler and provides take-off points for the supply tubing. Plenums are available in round or rectangular configurations, and from 7” to 10” sizes. Plenums can be wrapped in an insulation sleeve to prevent thermal loss and stop condensation.  Small duct plenums take up one-third the space of conventional HVAC ducting.


The most unique aspect of small duct systems is the flexible supply tubing that snakes throughout small areas and delivers air via small, unobtrusive round or slotted outlets that can be painted, stained, or wallpapered to virtually disappear into the conditioned areas décor.


Whether your project is a high-end custom home or an older, historic gem a small duct system is the perfect solution for its HVAC needs.

How a small duct system fits into a typical home:

NARI Industry Partners provide new innovation in technology and products to help NARI members stay ahead of the curve and ensure Remodeling Done Right. Learn More >

| 5/18/2017 12:00:00 AM | 0 comments
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