(1)
Air duct systems serving garages shall not be interconnected with other parts of the dwelling unit.
(2)
Trunk supply ducts shall not be nailed directly to wood members.
(3)
Branch ducts shall be supported at suitable spacings to maintain alignment and prevent sagging.
(4)
Ducts passing through unheated spaces shall have all joints taped or otherwise sealed to ensure that the ducts are airtight throughout their length.
(5)
Combustible ducts in concrete slabs-on-ground that are connected to a furnace supply plenum shall be located not closer than 600 mm to that plenum and not less than 600 mm from its connection to a riser or register.
(6)
Ducts in or beneath concrete slabs-on-ground shall be watertight and corrosion-, decay-, and mildew-resistant.
(7)
Underground ducts shall
(a)
be constructed to provide interior drainage from and access to all low points,
(b)
not be connected directly to a sewer, and
(c)
be installed and constructed of materials in conformance with ASHRAE Handbooks, SMACNA Manuals and the HRAI Digest.
(8)
Where a supply duct or return duct is not protected by an insulated exterior wall or where the duct is exposed to an unheated space it shall be insulated to provide a thermal resistance of not less than RSI 2.1.
(9)
Where a supply duct or return duct is located in an unconditioned space or outdoors, all joints of the ductwork shall be sealed to a Class A seal level in accordance with the SMACNA, “HVAC Duct Construction Standards – Metal and Flexible”.
(10)
Where a supply duct is located in a conditioned space, the ductwork shall be sealed to a Class C seal level in accordance with the SMACNA, “HVAC Duct Construction Standards – Metal and Flexible”.
(11)
A clean-out or pump-out connection shall be provided in an underground duct system at every low point of the duct system.