The efficiency at which ducts convey heated and cooled airflow can impact a home’s comfort and energy bills. If you’re upgrading your HVAC system or are designing a new home, it’s essential your HVAC contractor adheres to the following industry-standard HVAC air duct principles.
The typical home may be divided into two sections — conditioned and unconditioned. Sheet metal can easily transfer heat energy (i.e. heat gain/loss) between conditioned airflow and unconditioned airflow with acute temperatures. If your retrofitted or new ductwork system is constructed of sheet metal, it’s vital to locate as much of the ductwork in the conditioned area as possible. You should insulate ductwork in unconditioned areas to R-8.
Building contractors sometimes take shortcuts by using cavities in walls, floors and the attic. This is an unacceptable ductwork design practice, as all ductwork should be constructed of genuine materials, which are generally sheet metal or fiberglass.
Damper doors should be installed at the duct trunk, so the contractor can balance airflow to each zone just right. Air pressure in the supply and return sides should be as close to neutral as possible. This is because unbalanced air pressure can impact comfort, energy bills and cause excessive wear on your furnace and A/C.
Free airflow through your living space is a sign of balanced airflow. Each room with a supply register should also contain a return grill. If this isn’t practical, ensure your contractor is willing to design transfer grills and jumper ducts between rooms. This way, airflow can recirculate freely to return grills when doors to rooms are closed.
Duct Sealing and Testing
Acceptable duct sealing materials include foil-backed tape, sheet metal screws and mastic paste. Sheet metal screws mechanically hold duct seams together, while mastic paste can keep ducts air-tight. Seams may then be wrapped with foil-backed tape to ensure a long-lasting bond. Leakage rate should be tested using a duct blaster or blower door test.
Strictly following these HVAC air duct principles can help ensure long-lasting comfort and lower energy bills. For more information, please contact Donald P. Dick Air Conditioning in Fresno.
Our goal is to help educate our customers in the greater Fresno, California area about energy and home comfort issues (specific to HVAC systems). For more information about air ducts and other HVAC topics, download our free Home Comfort Resource guide.
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