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1 Determine boiler location
Installation & Operation Manual
Combustion and ventilation air
requirements for appliances drawing air
from the equipment room
Provisions for combustion and ventilation air must be in
accordance with Air for Combustion and Ventilation, of the
latest edition of the National Fuel Gas Code, NFPA 54 / ANSI
Z223.1, in Canada, the latest edition of CGA Standard B149
Installation Code for Gas Burning Appliances and Equipment,
or applicable provisions of the local building codes.
The equipment room MUST be provided with properly sized
openings and/or be of sufficient volume to assure adequate
combustion air and proper ventilation for all gas fired appliances
in the equipment room to assure adequate combustion air and
proper ventilation.
The requirements shown are for the appliance only; additional
gas fired appliances in the equipment room will require an
increase in the net free area and/or volume to supply adequate
combustion air for all appliances.
No combustion air openings are needed when the appliance is
installed in a space with a volume NO LESS than 50 cubic feet
per 1,000 Btu/hr of all installed gas fired appliances and the
building MUST NOT be of “Tight Construction”
3
.
A combination of indoor and outdoor combustion air may
be utilized by applying a ratio of available volume to required
volume times the required outdoor air opening(s) size(s). This
must be done in accordance with the National Fuel Gas Code,
NFPA 54 / ANSI Z223.1.
Figure 1-5_Combustion Air Through Ducts
2. If combustion and ventilation air is taken from the
outdoors using a duct to deliver the air to the
equipment room, each of the two openings should be
sized based on a minimum free area of one square inch
per 2000 Btu/hr (11 cm
2
per kW) of input (see FIG. 1-5).
Figure 1-6_Combustion Air from Interior Space
3. If air is taken from another interior space combined with
the equipment room:
(a) Two spaces on same story: Each of the two openings
specified above should have a net free area of one square
inch for each 1000 Btu/hr (22 cm
2
per kW) of input, but
not less than 100 square inches (645 cm
2
) (see FIG. 1-6).
(b) Two spaces on different stories: One or more openings
should have a net free area of two square inches per 1000
Btu/hr (44 cm
2
per kW).
Figure 1-4_Combustion Air Direct from Outside
1. If air is taken directly from outside the building
with no duct, provide two permanent openings to
the equipment room each with a net free area of one square
inch per 4000 Btu/hr input (5.5 cm
2
per kW) (see FIG. 1-4).
Figure 1-7_Combustion Air from Outside - Single Opening
12