The Information contained on this web page has been collected and presented as a guide. It should be used as a guide only and should not be relied upon as the sole source of information relating to ventilation requirements or legal requirements in any state or municipality. No warranty, either express or implied, is made with respect to the information contained herein. For additional information contact the specific state or municipality to obtain specific technical or legal ventilating requirements that may apply. Empire Ventilation Equipment Co., Inc. is not responsible for any loss, inconvenience, damage (whether special or consequential) or claims arising out of the use of the information contained on this page.
1203.1 General. Buildings shall be provided
with natural ventilation in accordance with
Section 1203.4 or mechanical ventilation in
accordance with Minnesota Rules, chapter
1. Buildings or portions thereof that are
not intended for normal human
occupancy, or where the primary purpose
is not associated with human comfort.
304.7 Louvers and grilles. The required size
of openings for combustion, ventilation, and
dilution air shall be based on the net free area
of each opening. Where the free area through
a design of louver or grille is known, it shall
be used in calculating the size opening
required to provide the free area specified.
Where the design and free area are not
known, it shall be assumed that wood louvers
will have 25 percent free area and metal
louvers and grilles will have 75 percent free
area. Nonmotorized louvers and grilles shall
be fixed in the open position.
304.7.1 Motorized louvers. Motorized
louvers shall be interlocked with the
equipment so they are proven in the full open
position prior to main burner ignition and
during main burner operation. Means shall be
provided to prevent the main burner from
igniting should the louver fail to open during
burner startup and to shut down the main
burner if the louvers close during burner
304.8 Combustion air ducts. Combustion
air ducts shall comply with the following:
1. Ducts shall be of galvanized steel or an
equivalent corrosion-resistant material. If
flexible duct is used, increase the duct
diameter by one inch. Flexible duct shall be
stretched with minimal sags.
2. Ducts shall terminate in an unobstructed
space, allowing free movement of combustion
air to the appliances.
3. Ducts shall serve a single space.
4. Ducts shall not service both upper and
lower combustion air openings where both
such openings are used. The separation
between ducts serving upper and lower
combustion air openings shall be maintained
to the source of combustion air.
5. Ducts shall not terminate in an attic space.
6. The remaining space surrounding a
chimney liner, gas vent, special gas vent, or
plastic piping installed within a masonry,
metal or factory-built chimney shall not be
used to supply combustion air.
Exception: Direct ventilator gas-fired appliances
designed for installation in a solid fuelburning
fireplace where installed in
accordance with the listing and the
7. Vertical ducts shall not extend through two
or more stories without prior approval from
the building official.
8. Ducts shall not terminate in the return air
plenum of a forced air heating system unless
installed in accordance with the heating
equipment manufacturer's installation
9. Combustion air intake openings shall be
located to avoid intake of exhaust air in
accordance with IMC Section 401.5.2 and
IFGC Section 503.8 and shall be covered with
corrosion resistant screen of not less than 1/4
inch (6.4 mm) mesh.
10. Combustion air intake openings shall be
located at least 12 inches (305 mm) above
adjoining grade level.
11. When both makeup air and combustion
air openings are required, they shall be
provided through separate openings to the
outdoors. Refer to IMC Section 501.4 to
determine requirements for makeup air.
Exception: Combination makeup air and
combustion air systems may be approved by
the building official where they are
reasonably equivalent in terms of health,
safety, and durability.