American Standard PFWF071A93ABA Installation Manual page 23

Figure 17
Suggested method to acommodate vent
connector passage through a wall
composed of combustible material.
The vent connector pipe between the boiler and chim-
ney shall be of equal diameter as the fl ue outlet of the
boiler.
The vent connector pipe must be made of 24 gauge (or
thicker) corrosion-resistant steel.
The vent connector pipe should be as short as possi-
ble and installed so that it has a continuous rise from
the boiler to the chimney. The horizontal length of a
connector to a natural draft chimney or vent serving
a single appliance shall not be more than 75 percent
of the height of the vertical portion of the chimney or
vent above the connector. Elbows should be minimi-
zed and the pipe should be joined with metal screws
and supported by straps. All horizontal runs of vent
connector pipe should be pitched upward a minimum
of 1/4 inch per foot of run.
A thimble should be used to connect the vent con-
nector pipe to the chimney so the pipe may be readily
removed in case of inspection or replacement. See
Fig. 17.
Figure 18
Alternate construction that allows reduced
clearances to combustible materials.
Table 5
Reduction of Clearances with Specifi ed Forms of Pro-
tection
Type of Protection
Applied to and covering all sur-
faces of combustible material
within the distance specifi ed as
the required clearance with no
protection. See Figure 11.
a. 3 -1/2" thick masonry wall
without ventilation air space.....
b. 1/2" insulation board over
1" glass fi ber or mineral wool
batts.....
c. 0.024 (24 gauge) sheet metal
over 1" glass fi ber or mineral
wool batts reinforced with wire
on rear face with ventilated air
space.....
d. 3 - 1/2" thick masonry wall
with ventilation air space.....
e. 0.024 (24 gauge) sheet metal
with ventilated air space.....
f. /2" insulation board with
ventilated air space....
g. 0.024 (24 gauge) sheet metal
with ventilated air space over
0.024 (24 gauge) sheet metal
with ventilated air space.....
h. 1" glass fi ber or mineral wool
batts sandwiched between two
sheets 0.024 (24 gauge) sheet
metal with ventilated air space
A. Equal the required clearance with no protection.
B. Equals the reduced clearance permitted in accordance with
the preceeding clearance chart.
C. The protection applied to the construction that covers the
combustible material should extend far enough in each direc-
tion to make C equal to A.
Allowable Clearance
with Specifi ed Protec-
tion (in.)
Where the required clear-
ance with no protection
from the appliance or
chimney connector is: 9
inches
Above Sides & Rear
--- 6
6 5
5 3
--- 6
5 3
5 3
5 3
5 3
18-CG03D1-4
23