CHIMNEY TERMINATIONS
STACK CLOSURE RING (CR)
The stack closure ring (
FIG. 47
) is the simplest method of
terminating a chimney. It provides protection of the annular
space between the inner and outer walls and leaves the top of
the chimney open to the elements. A drain section (or tee with
drain tee cap) should always be installed when a closure ring is
used as a termination. The closure ring is installed on the inner
wall and overlaps the outer wall. The joint at the inner wall should
be sealed with chimney sealant. A closure ring may be used for
either vertical or horizontal discharge.
FIG. 47 – STACK CLOSURE RING
STACK CAP (C)
The stack cap (
FIG. 48
) is designed to offer partial protection
from rain entering the chimney. It is equipped with an inverted
cone to divert flue gases upward to avoid contamination of the
surrounding roof area. The cap may be equipped with a birdscreen
if desired. The stack cap is intended for use as a termination only
for a vertical discharge.
A cap is attached to the top section of pipe with a flange band
and sealant. The annular opening between the inner and outer
walls of the pipe is protected with a closure ring provided with
the cap. When the chimney is terminated with a stack cap, it is
recommended that provisions be made for drainage of rain from
the base of the stack.
EXIT CONE (EC)
The exit cone (
FIG. 49
) is designed to produce additional gas
velocity at the chimney exit to help disperse the effluent. The
opening of the cone is based on a ratio of 0.8 times the nominal
pipe diameter. Since the exit cone is an open top termination,
provision for drainage is recommended. An exit cone may be
used for either vertical or horizontal discharge.
FIG. 49 – EXIT CONE
STACK HEAD ASSEMBLY (SHA)
The stack head assembly is designed for free, unobstructed
venting of the chimney while providing maximal protection
from rain entering the chimney. The stack head is a “low loss”
termination and is recommended by the Industrial Ventilation
Manual, 20
th
Edition, American Conference of Industrial
Hygienists, FIG. 8-6.
For diameters 6” – 24”, the stack head adapter section is an integral
component that attaches to the chimney flue using a flange band
and sealant. PSW sections are added to the desired height. A
closure ring is attached to the flue to protect the annular space
between the inner and outer walls from rain (See
FIG. 50A
). The
maximum free standing height of the stack head assembly is 60”
(1524). Heights above 60” (1524) will require guying.
FIG. 48 - STACK CAP
APPLY SEALANT
OPTIONAL BIRD SCREEN
CAP
CLOSURE RING
(INCLUDED)
FLANGE BAND
CLOSURE BAND
APPLY SEALANT
0.8 D
PIPE I.D.
18
FIG. 46 – INSTALLATION OF FLASHING AND STORM
COLLAR
With the flashing in place, the storm collar is placed around the
chimney and sealed to the casing with silicone sealer. The storm
collar should not quite rest on the flashing when the chimney is
cold (1/4” gap between the collar and the top of the flashing).
When a chimney is installed with a flashing and collar rather than
a ventilated thimble, the chimney must be stabilized by installing
either a full angle ring or a plate support just below the roof. If the
chimney height above the plate support or full angle ring exceeds
the “B” dimension in
TABLE 7 on PAGE 5
, it must be guyed to
avoid wind damage.
FLANGE BAND
STORM COLLAR
TALL CONE FLASHING
16 GA. PAN
PLATE
STRUCTURAL FRAME
MAINTAIN
ADEQUATE
EXPANSION
CURB
DO NOT RESTRICT
VERTICAL MOVEMENT
OF FLANGE BAND
SEALANT