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.
Small Duct System Benefits
In addition to their ability to fit into tight spaces, small ducts systems have the following advantages over conventional systems:
- 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.
About the Author
Scott Intagliata, a native of St. Louis, MO, graduated from Tulane University in 1983 with a degree in philosophy and then attended graduate school for English Literature at the University of MO, St. Louis. Mr. Intagliata has worked as a freelance journalist, spent 11 years consulting on political campaigns, and for the last 18 years has been one of the owners of Unico, Inc., a manufacturer of heating and air conditioning equipment located in St. Louis MO. He and his family live in a neighborhood on the National Historical Register in a home built for the 1904 World’s Fair and Olympics.