13
STEP 3: BREACHING RUNS
1. Breaching can be full size for an entire bank of boil-
ers (Figure 4.5 left) or may be tapered (Figure 4.5
right), using one tapered division within a bank of six
modules.
2. For tapered breaching, the smallest sized breaching
division is always the furthest from the chimney with
transition to the larger division leading toward the chim-
ney (see Figure 4.5 right). All increaser fittings must be
tapered to assure proper flue gas flow.
3. Remember, for rectangular breaching, the larger di-
mension of the rectangle must be in the vertical.
4. ALL BREACHING RUNS MUST BE PITCHED 1/4”
PER FOOT OF LENGTH UPWARDS TOWARD THE
CHIMNEY.
5. Where breaching runs connect into another breach-
ing run, they must be connected so the flow-streams
from each breaching run do not face or oppose each
other, but rather, mix together in the same general di-
rection (see Figure 4.6). Construction involves using
Wye-fittings and rounded 45
0
elbows angled towards
the chimney to assure proper flue gas flow.
TAPERED
PITCH 1/4" PER RUNNING FOOT
UPWARD TOWARD CHIMNEY
C
H
I
M
N
E
Y
C
H
I
M
N
E
Y
FULL SIZE
PITCH 1/4" PER RUNNING FOOT
UPWARD TOWARD CHIMNEY
FIGURE 4.5
PREFERRED
DOUBLE WYE FITTING
WYE FITTING
45 ELBOW
0
ACCEPTABLE
FIGURE 4.6
6. Where two or more breaching runs connect into the
same chimney, make sure the openings into the chim-
ney do not face or oppose each other.
7. At the breaching-chimney connection, breaching
must be flush with the inside of the chimney liner and
sealed.
CHIMNEY
BREECHING
RUN
BREECHING
RUN
FIGURE 4.7
