Instruction manual

9
5.3.3 Equipment Located in Confined Spaces:
(a) All Air from Inside the Building: The confined space shall be pro-
vided with two permanent openings communicating directly with
an additional room(s) of sufficient volume so that the combined
volume of all spaces meets the criteria for an unconfined space.
The total input of all gas utilization equipment installed in the
combined space shall be considered in making this determina-
tion. Each opening shall have a minimum free area of 1 square
inch per 1,000 BTU per hour of the total input rating of all gas
utilization equipment in the confined space, but not less than 100
square inches. One opening shall be within 12 inches of the top
and one within 12 inches of the bottom of the enclosure.
Furnace
Water
Heater
Opening
Chimney or Gas Vent
Opening
NOTE: Each opening must have
a free area of not less than one
square inch per 1000 BTU of
the total input rating of all equip-
ment in the enclosure, but not
less than 100 square inches.
Equipment Located in Confined Spaces; All Air from Inside
Building. See 5.3.3-a.
(b) All Air from Outdoors: The confined space shall be provided with
two permanent openings, one commencing within 12 inches of
the top and one commencing within 12 inches of the bottom of
the enclosure. The openings shall communicate directly, or by
ducts, with the outdoors or spaces (crawl or attic) that freely com-
municate with the outdoors.
1. When directly communicating with the outdoors, each open-
ing shall have a minimum free area of 1 square inch per 4,000
BTU per hour of total input rating of all equipment in the
enclosure.
Furnace
Water
Heater
Outlet Air
Chimney or Gas Vent
NOTE: The inlet and outlet air
openings must each have a free
area of not less than one square
inch per 4000 BTU of the
total input rating of all equipment
in the enclosure.
Inlet Air
Ventilation louvers for
unheated crawl space
Alternate
air inlet
Ventilation louvers
(each end of attic)
Equipment Located in Confined Spaces; All Air from Outdoors—
Inlet Air from Ventilated Crawl Space and Outlet Air to Ventilated
Attic. See 5.3.3-b
Refer to the latest edition of the National Fuel Gas Code NFPA 54/
ANSI Z223.1 (Section 5.3), or CAN/CSA B149 Installation Codes
(Sections 7.2, 7.3, or 7.4), or applicable provisions of the local
building codes for determining the combustion air requirements
for the appliances.
This furnace must use indoor air for combustion. It cannot be in-
stalled as a direct vent (i.e., sealed combustion) furnace.
Most homes will require outside air be supplied to the furnace area
by means of ventilation grilles or ducts connecting directly to the
outdoors or spaces open to the outdoors such as attics or crawl
spaces.
The following information on air for combustion and ventilation is repro-
duced from the National Fuel Gas Code NFPA 54/ANSI Z223.1 Sec-
tion 5.3.
5.3.1 General:
(a) The provisions of 5.3 apply to gas utilization equipment installed
in buildings and which require air for combustion, ventilation
and dilution of flue gases from within the building. They do not
apply to (1) direct vent equipment which is constructed and in-
stalled so that all air for combustion is obtained from the outside
atmosphere and all flue gases are discharged to the outside atmo-
sphere, or (2) enclosed furnaces which incorporate an integral
total enclosure and use only outside air for combustion and dilu-
tion of flue gases.
(b) Equipment shall be installed in a location in which the facilities
for ventilation permit satisfactory combustion of gas, proper vent-
ing and the maintenance of ambient temperature at safe limits
under normal conditions of use. Equipment shall be located so as
not to interfere with proper circulation of air. When normal infil-
tration does not provide the necessary air, outside air shall be
introduced.
(c) In addition to air needed for combustion, process air shall be pro-
vided as required for: cooling of equipment or material, control-
ling dew point, heating, drying, oxidation or dilution, safety ex-
haust, odor control, and air for compressors.
(d) In addition to air needed for combustion, air shall be supplied for
ventilation, including all air required for comfort and proper work-
ing conditions for personnel.
(e) While all forms of building construction cannot be covered in
detail, air for combustion, ventilation and dilution of flue gases
for gas utilization equipment vented by natural draft normally
may be obtained by application of one of the methods covered in
5.3.3 and 5.3.4.
(f) Air requirements for the operation of exhaust fans, kitchen venti-
lation systems, clothes dryers, and fireplaces shall be considered
in determining the adequacy of a space to provide combustion air
requirements.
5.3.2 Equipment Located in Unconfined Spaces:
In unconfined spaces (see definition below) in buildings, infil-
tration may be adequate to provide air for combustion ventilation
and dilution of flue gases. However, in buildings of tight con-
struction (for example, weather stripping, heavily insulated,
caulked, vapor barrier, etc.), additional air may need to be pro-
vided using the methods described in 5.3.3-b or 5.3.4.
Space, Unconfined.
For purposes of this Code, a space whose volume is not less
than 50 cubic feet per 1,000 BTU per hour of the aggregate input
rating of all appliances installed in that space. Rooms communi-
cating directly with the space in which the appliances are installed
through openings not furnished with doors, are considered a part
of the unconfined space.