Install Instructions

Type B Gas Vent - 3” to 12” Diameter
Installation Instructions
7
of the vertical vent. The horizont al length of
this vent connector should not exceed 1½ feet
for each inch of connector diameter. If it is nec-
essary for B-vent connector to pass through a
partition, an RWT thimble may be used, or the
wall framed to allow 1-INCH CLEARANCE and
an RPC collar used on each side of the parti-
tion. When a vent connector is used, it should
have as much vertical rise as possible BEFORE
the horizontal run. Vent connectors attached
directly to side out-
let draft hoods,
shuch as floor fur-
naces, shall be
pitched upward at
least 1/4 inch per
foot. The lateral
run of vent connec-
tors attached to top
outlet draft hoods
may be either horizontal or pitched upward.
(B) The necessary straight lengths of pipe should
be connected to the elbow, tee, or the draft hood
connector, and all joints should be securely
locked together as indicated above.
(C) Floors, ceilings, a nd other combustible
construction should be cut away or framed a s
necessary to provide a MINIMUM OF 1-INCH
CLEARANCE from the surface of the vent pipe.
Metal straps should be used to maintain the vent
pipe in position to ensure that the 1-INCH
CLEARANCE to combustibles is maintained
after the walls are closed. (See Figure 16.) DO
NOT SCREW INTO THE VENT.
CAUTION
Do not allow the offset pipe to put pressure
on the elbow. Use pipe strap for support.
(D) Whenever possible, the vent should be contin-
ued straight out through the roof. If it is neces-
sary to make offsets in the attic space, the lat-
eral run should be sloped upward as sharply
as possible, using elbows to minimize resis-
tance. The lateral run should be supported
using metal straps, and again maintaining the
MINIMUM CLEARANCE OF 1 INCH from com-
bustibles. (See Figure 9.)
CAUTION
Laterals in common vents are limited to
1½ feet for each inch of vent diameter .
(E) Laterals must be supported at 5-foot maximum
intervals. Where vertical vents are spaced by
firestops between floors, they need only be sup-
ported at the bottom.
Framing to prevent contact with building
insulation
• In many instances, vents pass through ceilings
that are insulated. I n these cases, it is
necessary to frame around the opening cut in
the ceiling for passage of the vent pipe so that
building insulation or other combustible material
will not come in contact with the surface of the
vent. This framing should, of course, be
arranged to PROVIDE 1-INCH MINIMUM
CLEARANCE from the surface of the vent.
(See Figure 16).
• Occasionally Type B vent connectors must pass
through partitions that are insulated. The
simplest means of preventing contact with the
insulation in these cases is to use an RWT wall
thimble.
DO NOT USE SCREWS
IN B-VENT UNLESS
LINING A MASONRY
CHIMNE Y. SCREWS
ARE NOT NECESSARY
AND CAUSE NOISE.
For
For Caps see
Figure 20 and Table 3
Figure 16