Specifications
14
The termination of a venting system including a me-
chanical draft system follows other requirements as
described in the following:
IMC
The International Mechanical Code is virtually in full
agreement with NFPA 211:
Just as the NFPA 211 describes termination
requirements, almost identical requirements can be
found in the IMC:
(b) The mechanical draft system shall be listed in
accordance with UL 378, Standard for Draft
Equipment, for use with the type of appliance
and range of chimney service appropriate for
the application. The mechanical draft system
shall not cause or permit blockage of the ue
or electrical hazard after exposure to a
chimney re or over re conditions. The
mechanical draft system shall be installed in
accordance with the terms of the listing and
the manufacturers’ instructions.
(c) The mechanical draft system shall be sized
to maintain draft within the range specied by
the appliance manufacturer.
(NFPA 211, 2006 Edition, pg. 211-13 and 211-14)
c. Not less than 2 ft (0.61 m) from an
adjacent building and not less than
7 ft (2.1 m) above grade where located
adjacent to public walkways
(2) The exit terminal shall be so arranged that
ue gases are not directed so that they
jeopardize people, overheat combustible
structures, or enter buildings.
(3) Forced draft systems and all portions of
induced draft systems under positive
pressure during operation shall be
designed and installed to be gastight or to
prevent leakage of combustion products
into a building.
(4) Through-the-wall vents for gas appliances
shall not terminate over public walkways or
over an area where condensate or vapor
could create a nuisance or hazard or could
be detrimental to the operation of
regulators, relief valves, or other
equipment.
(NFPA 211, 2006 Edition, pg. 211-31 and 211-32)
804.3.7 Exhauster sizing. Mechanical ue exhausters
and the vent system served shall be sized and installed in
accordance with the manufacturer’s installation
instructions.
804.3.8 Mechanical draft systems for manually red
appliances and replaces. A mechanical draft system
shall be permitted to be used with manually red
appliances and replaces where such system complies
with all of the following requirements:
1. The mechanical draft device shall be listed and
installed in accordance with the manufacturer’s
installation instructions.
2. A device shall be installed that produces
visible and audible warning upon failure of the
mechanical draft device or loss of electrical
power, at any time that the mechanical draft
device is turned on. This device shall be
equipped with a battery backup if it receives
power from the building wiring.
3. A smoke detector shall be installed in the room
with the appliance or replace. This device
shall be equipped with a battery backup if it
receives power from the building wiring.
(IMC, 2009 Edition, pg. 73)
10.4 Termination (Height).
10.4.1 All vents shall terminate above the roof surface.
Exception: Pellet vents and other vents as provided in
10.4.5 and Section 10.7.
10.4.1.1 Vents installed with mechanical exhausters shall
terminate not less than 12 in. (305 mm) above the highest
point where they pass through the roof surface.
10.4.1.2 Vents installed with a listed cap shall
terminate in accordance with the terms of the cap’s listing.
10.4.1.3 Vents installed without listed caps or
mechanical exhausters shall extend 2 ft (0.61 m) above
the highest point where they pass through the roof
surface of a building and at least 2 ft (0.61 m) higher than
any portion of a building within
10 ft (3.1 m). [See Figure 4.2(a) and 4.2(b).]
10.4.2 Natural draft vents for gas appliances shall
terminate at an elevation not less than 5 ft (1.53 m) above
the highest connected appliance outlet.
Exception: As provided in 10.4.3 and 10.7.2.
10.4.3 Natural draft gas vents serving vented wall
furnaces shall terminate at an elevation not less than 12 ft
(3.7 m) above the bottom of the furnace.
10.4.4 Vents passing through roofs shall extend through
the roof ashing.
10.4.5 Mechanical draft systems shall not be required to
comply with 10.4.1 and 10.4.3, provided they comply with
the following:
(1) The exit terminal of a mechanical draft
system other than a direct vent appliance
(sealed combustion system appliance)
shall be located in accordance with the
following:
a. Not less than 3 ft (0.92 m) above any
forced air inlet located within 10 ft
(3.1 m)
b. Not less than 4 ft (1.2 m) below, 4 ft
(1.2 m) horizontally from, or 1 ft
(305 mm) above any door, window, or
gravity air inlet into any building