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Installation & Service Manual
10
Figure 1-3_Combustion Air Direct from Outside
Combustion and ventilation air
requirements for conventionally vented
appliances
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, 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 room where the appliance is installed MUST be provided
with properly sized openings to assure adequate combustion
air and proper ventilation when the appliance is installed with
conventional venting.
1. If air is taken directly from outside the building
with no duct, provide two permanent openings (see
FIG. 1-3):
(a) Combustion air opening, with a minimum free
area of one square inch per 4000 Btu/hr input
(5.5 cm
2
per kW). This opening must be
located within 12" (30 cm) of the floor.
(b) Ventilation air opening, with a minimum free
area of one square inch per 4000 Btu/hr input
(5.5 cm
2
per kW). This opening must be
located within 12" (30 cm) of the ceiling.
Figure 1-4_Combustion Air Through Ducts
2. If combustion and ventilation air is taken from the
outdoors using a duct to deliver the air to the room where
the appliance is installed, each of the two openings should
be sized based on a minimum free area of one square inch
per 2000 Btu/hr (11cm
2
per kW) (see FIG. 1-4).
Figure 1-5_Combustion Air from Interior Space
3. If air is taken from another interior space that is adequately
ventilated, each of the two openings specified above should
have a net free area of one square inch for each 1000 Btu/hr
(22cm
2
per kW) of input, but not less than 100 square
inches (645cm
2
) (see FIG. 1-5).
1 Determine boiler location