Specifications

15
3.2 Gas Standards and Codes
Mechanical venting of gas-red appliances has
become an accepted standard. Many of today’s
heating appliances rely on mechanical venting to
perform and meet efciency and emission standards.
Despite the growing popularity, some appliance
manufacturers are still reluctant to allow the use of
mechanical venting to vent their appliances. Since
they don’t have any support from the standards and
codes, their reluctance is usually an indication of lack
of knowledge rather than a lack of adaptability.
If an appliance’s installation manual says that it must
be installed according to NFPA 54/ANSI Z223.1 or
similar this means a mechanical draft system can be
used. Only if the installation manual specically limits
its use by a statement like: “Mechanical venting is
not acceptable” should the use of a mechanical draft
system be avoided.
A manufacturer can not deny warranty coverage if
the conditions below are met.
Just as solid fuel-burning equipment, gas equipment
must meet minimum performance requirements:
804.3 Mechanical draft systems. Mechanical draft sys-
tems of either forced or induced draft design shall comply
with Sections 804.3.1 through 804.3.7.
804.3.1 Forced draft systems. Forced draft
systems and all portions of induced draft systems
under positive pressure during operation shall be
designed and installed so as to be gas tight to pre-
vent leakage of combustion products into a building.
804.3.2 Automatic shutoff. Power exhausters
serving automatically-red appliances shall be
electrically connected to each appliance to prevent
operation of the appliance when the power exhauster
is not in operation.
804.3.3 Termination. The termination of chimneys
or vents equipped with power exhausters shall be
located a minimum of 10 feet (3048 mm) from the
lot line or from adjacent buildings. The exhaust shall
be directed away from the building.
804.3.4 Horizontal terminations. Horizontal
terminations shall comply with the following
requirements:
1. Where located adjacent to walkways, the termina-
tion of mechanical draft systems shall
be not less than 7 feet (2134 mm) above the
level of the walkway.
2. Vents shall terminate at least 3 feet (914 mm)
above any forced air inlet located within 10 feet
(3048 mm).
3. The vent system shall terminate at least 4 feet
(1219 mm) below, 4 feet (1219 mm) horizon-
tally from or 1 foot (305 mm) above any door,
window or gravity air inlet into the building.
4. The vent termination point shall not be located
closer than 3 feet (914 mm) to an interior
corner formed by two walls perpendicular to
each other.
5. The vent termination shall not be mounted directly
above or within 3 feet (914 mm) horizontally
from an oil tank vent or gas meter.
6. The bottom of the vent termination shall be
located at least 12 inches (305 mm) above
nished grade.
804.3.5 Vertical terminations. Vertical terminations
shall comply with the following requirements:
1. Where located adjacent to walkways, the termina-
tion of mechanical draft systems shall be not
less than 7 feet (2134 mm) above the level of
the walkway.
2. Vents shall terminate at least 3 feet (914 mm)
above any forced air inlet located within 10 feet
(3048 mm).
3. Where the vent termination is located below an
adjacent roof structure, the termination point
shall be located at least 3 feet (914 mm) from
such structure.
4. The vent shall terminate at least 4 feet (1219 mm)
below, 4 feet (1219mm) horizontally from, or 1
foot (305 mm) above any door, window or grav-
ity air inlet for the building.
5. A vent cap shall be installed to prevent rain from
entering the vent system.
6. The vent termination shall be located at least 3
feet (914 mm) horizontally from any portion of
the roof structure.
804.3.6 Exhauster connections. An appliance
vented by natural draft shall not be connected into a
vent, chimney or vent connector on the discharge
side of a mechanical ue exhauster.
(IMC, 2009 Edition, pg. 72-73)
12.1 Minimum Safe Performance. A venting system
shall be designed and constructed so as to develop a
positive ow adequate to convey ue or vent gases to the
outdoors.
12.4.1 Appliance Draft Requirements. A venting system
shall satisfy the draft requirements of the appliance
in accordance with the manufacturer’s instructions.
(NFPA54/ANSI Z223.1, 2009 Edition, pg. 84)
503.3 Design and construction. A venting system shall
be designed and constructed so as to develop a
positive ow adequate to convey ue or vent gases to the
outdoors.
503.3.1 Appliance Draft Requirements. A venting
system shall satisfy the draft requirements of the
appliance in accordance with the manufacturer’s
instructions.
(IFGC, 2009 Edition, pg. 81)