Instructions / Assembly

Heating and Cooling Essentials
4" metal sleeve
D
Figure 28-39. Connecting lengths of insulated flexible duct. A—Cut completely around and through duct with knife or scissors.
Cut wire helix with heavy-duty snips or side cutters. B—Peel back the jacket and insulation from core. Butt two cores together
on a standard 4" metal sleeve . C—Tape core together with at least two wraps of duct tape. Secure with two approved clamps.
D—Pull jacket and insulation back over cores. Tape jackets together with two wraps of tape, then mastic sealant.
28.14 Registers and Diffusers
Figure 28-40. Rectangular duct is used to provide vertical
passages (wall stacks) that carry treated air from floor-to-
floor of a building. This stack is being fabricated for use in an
office building. Note: The worker should be wearing safety
glasses.
length of last section as required. When stack must be
lowered from above, enlarge openings as necessary
and lower stack into the stud space as it is assembled
section by section.
To join two sections of stack (or "riser") duct
together, "S" cleats can be used to secure the long
sides of the duct. Sheet metal screws should be applied
on the shorter sides of the ducting, and if needed, can be
used on the longer dimension. The seams are then sealed
with mastic. The same care should be taken when
connecting with the stack heads or boots, Figure 28-42.
The final fitting in the duct system used to move air
to its destination is the register box, or "boot." Due to
the numerous locations and difficult areas registers
must fit, boots are available in a variety of shapes and
sizes, Figure 28-43. Supply air is released into a room
Wall studs
Drywall
Floor joists
Floor
Figure 28-41. In residential installations, wall stack is gener-
ally pushed up into the wall from the basement. When
cutting openings for a stack, use a flashlight and mirror to
check for obstructions between studs.