SUPPLY & RETURN: In order to effectively move the air through
the occupied space, you will require some form of air duct system
to both bring the warm/moist or cold air back to the HVAC system
or Air Handler (thru return air ducts) to be properly cooled or
heated. And you will require a system of supply ducts to take
the cooled or heated air back to the occupied space. These systems
of return and supply ducts are absolutely necessary for proper
conditioning of the entire occupied area. For more information
on supply & return ducts, click here.
The number of supply and return ducts is also a factor in proper
heating and cooling. Having ample return ducts in any home or
commercial facility increases the ability to more rapidly cool
and/or heat the air. The faster you can cool or heat all the air,
the less energy is used and a higher degree of comfort is achieved.
Conversely, having too few returns or supply ducts will create
cold or warm spots or areas in the occupied space. In addition,
the ability for the HVAC system to filter the air through the
air filter will be reduced significantly when the number of return
air ducts is reduced. For more information on supply & return
ducts, click here.
Duct Construction and Leakage
Selecting appropriate duct construction is an important part of
minimizing duct leakage. A specification for duct construction
and sealing needs to be determined early in the duct design process.
The engineer should specify a leakage class [ASHRAE, 1997] to
meet the requirements of the system application and local energy
conservation code. Project specification should allow appropriate
duct leakage and leakage testing following the "HVAC Air
Duct Leakage Test Manual" [SMACNA, 1985]. Random testing
should always be required as part of air balancing
Hvac Duct Design Software