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Venting
A-General Recommendations and Requirements
NOTE - The vent is a passageway, vertical or nearly so,
used to convey flue gases from an appliance, or its vent
connector, to the outside atmosphere. The vent
connector is the pipe or duct that connects a fuel-gas
burning appliance to a vent or chimney.
Unit heaters must be vented in compliance with all local
codes or requirements of the local utility, the current
standards of the (American) National Fuel Gas Code,
ANSI Z223.1 or (Canada) CAN/CGA-B149 Installation
Codes, and the following instructions.
A metal stamped/extruded transition is supplied with this
certified unit. It must not be modified or altered and must
be installed on the outlet of the induced draft blower
assembly prior to the installation of the vent or vent
connector. Failure to comply with this requirement will
void the certification of the unit by the approval agencies.
Single wall vent material shall have all seams and joints
sealed with pressure sensitive aluminum tape or silicone
rubber sealant. Aluminum tape must meet the provisions
of SMACNA AFTS-100-73 Standards. The aluminum
tape has a temperature rating of 400°F (204°C). Silicone
rubber sealant must have a temperature rating of 482°F
(250°C), i.e., Dow Corning RTV-736 or equivalent. All
joints shall be secured with at least two corrosion
resistant screws. All joints must be checked for gas
tightness after installation.
Single wall vent shall not pass through any attic, interior
wall, concealed space, or floor.
1-
These unit heaters are to be used with NFPA- or
ANSI- approved chimneys, U.L. listed type B-1 gas
vents, single wall metal pipe, or listed chimney-lining
system for gas venting where applicable, as well as
the modifications and limitations listed in Figure 2.
Seal single wall vent material according to the
section
A-General Recommendations and
Requirements.
B-Vertical Vents Using Metal Vent Pipe- Commercial
and Residential Installations
These compact unit heaters are listed as Category I
appliances for vertical vent installations.
2- The vent connector shall be 3" (76mm) diameter on
30/45 units and 4" (100mm) diameter on 60/75
units. In all cases, a flue transition piece (supplied)
is required to fit over the outlet of the induced draft
assembly on the appliance.
3- Keep the vent connector runs as short as possible
with a minimum number of elbows. Refer to the
(American) National Fuel Gas Code ANSI Z223.1 or
(Canada) CAN/CGA-B149 Installation Code for
maximum vent and vent connector lengths.
Horizontal run of the vent connector from the
induced draft blower to the chimney/vent cannot
exceed the values in Table 2. Single wall vent
connector shall not be insulated.
4- When the length of a single wall vent, including
elbows, exceeds 5 feet (1.5 m), the vent shall be
insulated along its entire length with a minimum of
1/2" thick foil faced fiberglass 1-1/2 pound density
insulation. If a single wall vent is used in an
unheated area it shall be insulated. Failure to do so
will result in condensation of flue gases.
5- The unit may be vented vertically as a single
appliance or as a common vent with other gas-fired
appliances. In common venting situations, vent
connectors for other appliances must maintain a 4"
(100mm) vertical separation between the vent
connectors. Refer to common venting Tables in the
(American) National Fuel Gas Code ANSI Z223.1 or
(Canada) CAN/CGA-B149 Installation Code for
proper vent size.
FIGURE 2
VENT TERMINATION ON SINGLE WALL VENT
SINGLE WALL TERMINATION
DOUBLE WALL (TYPE B-1) TERMINATION
ROOF FLASHING
ROOF PITCHED
FROM 0" TO 45"
2" CLEARANCE
THIMBLE
SEAL JOINT BETWEEN SINGLE WALL VENT AND “B"
VENT AND THE ANNULAR SPACE OF THE “B" VENT.
CLEARANCE TO BE
AS SPECIFIED ON
TYPE “B" VENT PIPE.
12" MAX
ROOF FLASHING
ROOF PITCHED
FROM 0" TO 45"
SHALL NOT BE A
CONCEALED SPACE
