Instructions / Assembly
Heating and Cooling Essentials
Floor opening
to joist spaces
Temporary
support wire
Floor opening
B
Figure 28-50. A—If a large baseboard grille is used, double
stud and joist spaces should be prepared. B—Floor type
grilles are commonly used when the furnace is located in the
basement.
come loose and leak air. Air leaks from poorly sealed
ducts can be one of the biggest energy and money
losers in a home. The California Energy Commission
has ruled that fabric-based duct tape can no longer be
used for sealing ductwork, and other states are consid-
ering a similar ban.
Tape
Insulation
Figure 28-52. Use tape or sealant to close insulation on
round pipe. Remove temporary support wires and replace
them with strapping.
Ducts in homes with high energy-efficiency ratings
are usually sealed with mastic and fiberglass rein-
forcing membrane, Figure 28-53. Mastic is a nontoxic
adhesive-material used for permanently sealing joints
and seams for all types of air duct materials. Most
Figure 28-53. A—Mastic is available in 1, 2, and 5 gallon
recyclable plastic pails. B—Fiberglass reinforcing membrane
is designed for use with mastic. A roll is 3" x 50' or
3"x 150'. (Courtesy of RCD Corporation)
Return air grille
Return air
Wood or
metal air stop
Sheeted joist space
Duct opening
Figure 28-51. Sheeting, or panning, is easier to install than duct and just as efficient.