PAGE 9
ENTILATION & COMBUSTION CONTINUED
1. Ventilation of the boiler roo ust be adequate to provide sufficient air to properly
support co bustion per the latest revision of the National Fuel Gas Code, ANSI Z223.1
section 5.3.
2. When a boiler is located in an unconfined space in a building or conventional construction
fra e, asonry or etal building, infiltration nor ally is adequate to provide air for
co bustion and ventilation. However, if the equip ent is located in a building of unusually tight
construction (See the national Fuel Gas Code, Ansi Z223.1 section 1.7), the boiler area
should be considered as a confined space. In this case air for co bustion and ventilation shall
be provided according to part 5 on page 4. If there is any doubt, install air supply provisions
in accordance with the latest revision of the National Fuel Gas Code.
3. When a boiler is installed in an unconfined space, in a building of unusually tight
construction, air for co bustion and ventilation ust be obtained fro outdoors or fro
spaces freely co unicating with the outdoors. A per anent opening or openings having a
total free area of not less than 1 square inch per 5,000 BTU per hour of total input rating of
all appliances shall be provided. Ducts ay be used to convey akeup air fro the outdoors
and shall have the sa e cross-sectional area of the openings to which they are connected.
4. When air for co bustion and ventilation is fro inside buildings, the confined space shall
be provided with two per anent openings, one starting 12 inches fro the top and one 12
inches fro the botto of the enclosed space. Each opening shall have a ini u free area
of 1 square inch per one thousand (1000) BTU per hour of the total input rating of all appliances
in the enclosed space, but ust not be less than one hundred (100) square inches. These
openings ust freely co unicate directly with other spaces of sufficient volu e so that the
co bined volu e of all spaces eets the criteria for an unconfined space. See figure 1 on
page 8.
5. When the boiler is installed in a confined space and all air is provided fro the outdoors
the confined space shall be provided with one or two per anent openings according to
ethods A or B. When ducts are used, they shall be of the sa e cross sectional area as the
free area of the area of the openings to which they connect. The ini u di ension of
rectangular air ducts shall be not less than 3 x 3 inches or 9 square inches.
A. When installing two openings, one ust co ence within 12 inches fro the top and
the other within 12 inches fro the botto of the enclosure. The openings shall co unicate
directly, or by ducts, with the outdoors or spaces (crawl or attic) that freely co unicate with
the outdoors. One of the following ethods ust be used to provide adequate air for
ventilation and co bustion.
1. When directly co unicating with the outdoors, each opening shall have a
ini u free area of 1 square inch per 4,000 BTU per hour of total input rating of all
equip ent in the enclosure. See figure 2 on page 8.
2. When co unicating with the outdoors by eans of vertical ducts, each
opening shall have a ini u free area 1 square inch per 4,000 BTU per hour of total input
rating of all appliances in the enclosed space.
3. If horizontal ducts are used, each opening and duct shall have a ini u free
