Optimum duct design delivers the maximum volume of cooled or heated air to all points of your house with the least energy loss. Conversely, poor design permanently builds inefficiencies and performance shortfalls that persist no matter what air conditioner or furnace is connected to the system. Many examples of bad duct design in existing ductwork are a matter of age. Residential construction from the 1980s and before, when energy conservation wasn’t a priority, didn’t stress proper ductwork layout or installation methods. Here are a few classic scenarios of bad duct design.
Uninsulated Ducts in Unconditioned Zones
As much of the ductwork as possible should be routed within the cooled and heated envelope of the home. When ducts must be run through zones of acute temperatures like an attic or crawl space, ductwork should be insulated to a level of R6 to prevent thermal loss or gain.
Stand-In Ducts
The only approved ductwork is made of sheet metal, fiberglass board or flexible duct material. Cost-cutting methods such as converting wooden structural voids—cavities inside walls or the channels between ceiling or floor joists—to use as substitute ductwork is not valid duct design. Wooden material shrinks, leaks air and may draw unfiltered contaminated air into the system.
No Return to the Return
While the ideal design incorporates a dedicated return duct in every room that has a supply duct, many houses are constructed with a single return located in a hallway, instead. Unfortunately, when room doors are closed, air can’t reach the return. To ensure that supply air in each room has an unobstructed path back to the return duct, pass-through grilles should be installed in doors or jumper ducts routed through ceilings to convey air to the central return.
Seal and Test
All joints in spans of new ductwork should be sealed with mastic and foil tape and permanently secured with sheet metal screws. After installation, new ducts should be pressure-tested to ensure leakage is within specifications of local codes.
For the professional approach to proper duct design in Yuma, contact the heating and cooling experts at Hansberger Refrigeration & Electric Company.
Our goal is to help educate our customers in Yuma, Arizona about energy and home comfort issues (specific to HVAC systems). For more information about duct design and other HVAC topics, download our free Home Comfort Resource guide.
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