New Construction (§140.4(l)): Only required for single zone units (heating only, cooling only or heating and cooling) serving 5,000 ft² of space or less where 25 percent or more of the duct surface area is in one of the following spaces:
•Outdoors, or
•In a space directly under a roof that has a U-factor greater than the U-factor of the ceiling, or if the roof does not meet the requirements of Section 140.3(a)1B; or
•Has fixed vents or openings to the outside or unconditioned spaces; or
•In an unconditioned crawlspace; or
•In other unconditioned spaces.
Downshot units with ducts in spaces with insulation on the walls and roof need not be sealed. Units with extensive ductwork on the roof or in an un-insulated attic may need to be sealed depending on the surface area ratio.
Retrofit (§141.0): The same scope limitations for zone size, unit type and ductwork location apply as in new construction. With these constraints, requirements for sealing and testing apply to:
•New ductwork serving either new or existing single-zone units (§141.0(b)2D)
•New ductwork as an extension of existing ductwork with either new or existing single-zone units
•Existing ductwork where the single-zone unit is being replaced or having a major component replaced (§141.0(b)2E), including:
o Air handler
o Cooling coil
o Heating coil
o Condenser coil (split system)
o Condensing unit (split system)
o Different levels of leakage requirements apply to new and existing ductwork (see §141.0(b)2D).