Independence Installation, Operating, and Service Instructions

9
103538-08 - 3/18
I. Pre-Installation (continued)
4. Combination indoor and outdoor combustion air.
a. Indoor openings, when used, must comply with
paragraph 2c above.
b. Outdoor opening(s) location must comply with
paragraph 3 above.
c. Calculate outdoor opening size per the following:
i. Determine ratio of interior spaces: available
volume of all communicating spaces divided
by required volume.
ii. Determine outdoor size reduction factor: 1
minus ratio of interior spaces
iii. Minimum size of outdoor opening is full
size of outdoor air opening(s) per paragraph
3 multiplied by outdoor size reduction
factor.
iv. Minimum dimension of air openings not less
than 3 in.
5. Engineered installations. Provide adequate supply
of combustion, ventilation, and dilution air using
engineered methods as approved by local authority
having jurisdiction.
6. Mechanical combustion air supply. Provide outdoor
air at minimum rate of 0.35 cfm per Mbh for all
appliances located within space.
a. Provide additional air where exhaust fans
installed to replace exhausted air.
b. Interlock each appliance to mechanical
combustion air supply to prevent main burner
operation when mechanical combustion air
supply system not in operation.
c. Provide specied combustion air plus ventilation
air when combustion air provided by building’s
mechanical ventilation system.
7. Ventilation Duct Louvers and Grilles. Equip outside
openings with louvers to prevent entrance of rain
and snow, and screens to prevent entrance of insects
and rodents. Louvers and grilles must be xed in
open position or interlocked with equipment to open
automatically before burner operation and to shut
down burner operation if louvers close during
burner operation. Screens must not be smaller than
¼ inch mesh.
Consider the blocking effect of louvers, grilles and
screens when calculating the opening size to provide
the required free area. If free area of louver or grille
is not known, assume wood louvers have 25 percent
free area and metal louvers and grilles have 75
percent free area.
8. Combustion air ducts shall comply with following:
a. Constructed of galvanized steel or material
having equivalent corrosion resistance, strength,
and rigidity.
Exception for dwelling units. Unobstructed stud
and joist spaces are not prohibited from
conveying combustion air provided not more
than one re block is removed.
b. Terminate in unobstructed space, allowing free
movement of combustion air to appliance(s).
c. Serve single space.
d. Two permanent openings method. Single duct
cannot serve both upper and lower openings.
Maintain separation between ducts serving upper
and lower openings to source of combustion air.
3. Do not screen where terminating in attic spaces.
f. Horizontal ducts cannot slope downward toward
combustion air source.
g. Do not use space surrounding chimney liner, gas
vent, special gas vent, or plastic piping installed
within masonry, metal, or factory built chimeny.
h. Combustion air intake located on building
exterior shall have lowest side of intake located
at least 12 in. vertically from adjoining nish
ground level.
H. Do not install boiler where gasoline or other ammable
vapors or liquids, or sources of hydrocarbons (i.e.
bleaches, cleaners, chemicals, sprays, paint removers,
fabric softeners, etc.) are used or stored.