Bradford White RG1PV50S6X19-264 Manual page 19

Combustion Air Supply continued-
Each opening must have a minimum free area of 1 in
/kW) of the total input rating of all gas utilization equipment in the confined
2
mm
space, but not less than 100 in
(31 cm) of the top and one within 12 in (31 cm) of the bottom of the enclosure.
All Air from Outdoors: Provide two permanent openings, one commencing
within 12 in (31 cm) of the top and one commencing within 12 in (31 cm) from
the bottom of the enclosure. The openings must communicate directly or by
ducts with the outdoors or spaces (crawl or attic) that freely communicate with
the outdoors.
1. When communicating with the outdoors through vertical ducts, each
opening must have a minimum free area of 1 in
/kW) of total input rating of all equipment in the enclosure.
2
mm
2. When communicating with the outdoors through horizontal ducts, each
opening must have a minimum free area of 1 in
/kW) of total input rating of all equipment in the enclosure.
2
mm
3. When ducts are used, they must be of the same cross-sectional area as the
free area of the openings to which they connect. The minimum dimension
of rectangular air ducts cannot be less than 3 in (8 cm).
Provide one permanent opening, commencing within 12 in (31 cm) of the top of
the enclosure. The appliance must have clearance of at least 1 in (3 cm) from
the sides and back and 6 in (16 cm) from the front of the appliance. The
opening must communicate directly or by ducts with the outdoors or spaces
(crawl or attic) that freely communicate with the outdoors and has a minimum
free area of the following:
2
1. 1 in /3000 BTU/hr (700 mm
located in the enclosure.
2. Not less than the sum of the areas of all vent connectors in the space.
Specially Engineered Installations
The requirements noted under CONFINED SPACES above will not necessarily
govern when special engineering, approved by the authority having jurisdiction,
provides an adequate supply of air for combustion, ventilation, and dilution of
flue gases.
2
). One opening must be within 12 in
2
(0.06 m
/kW) of the total input rating of all appliances
2
19
2
/1000 BTU/hr (2200
2
/4000 BTU/hr (550
2
/2000 BTU/hr (1100