Install Instructions

5
Type B Gas Vent - 3" to 12" Diameter
Installation Instructions
Fire-stopping
• In single-story,
slab-floor
houses having
an attic space,
a firestop must
be provided
where the vent
passes through
the ceiling,
unless an RSA
support is used
there. The
ceiling should
be cut away from the opening frame to PROVIDE
1-INCH MINIMUM CLEARANCE from the vent
pipe. A firestop consisting of a noncombustible
material, such as ¼-thick ceramic board or 26-
gauge galvanized sheet metal, should be cut to fit
the pipe and the framed opening. The firestop
should be fastened to the top of the joists and
framing members to
eliminate any pockets in which
combustible debris might collect. An RPC pipe collar
may be used on the underside of the ceiling to
finish off the opening. (See Figure 10.)
Framing to prevent contact with building
insulation
• In many instances, vents pass through ceilings that
are insulated. In 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 9.)
• 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.
• In single-story buildings with an attic space and with
the gas appliance located in a basement or crawl
space, firestops must be provided where the vent
passes through both the floor and the ceiling. This
can be done by cutting away and framing the floor
and ceiling construction and installing firestops of
noncombustible material as shown in Figure 10.
All combustible construction should be cut away
sufficiently to PROVIDE THE MINIMUM
CLEARANCE OF 1 INCH FROM THE VENT PIPE
SURFACE.
• In multi-story buildings, a firestop must be provided
at every point where the vent passes through a floor
or ceiling. These firestops may be provided as
indicated in the paragraph above.
• Four-inch round vent (4RPX) may be used in a
2" x 6" stud wall. The proper clearance in a 2" x 6"
wall is provided by the spacer on the pipe and by
the 4RFS firestop spacer. All other uses of a 4"
pipe require the normal 1-INCH CLEARANCE TO
COMBUSTIBLES.
Figure 10
Figure 11