Dunkirk EXCELSIOR EXB4075 Installation, Operation & Maintenance Manual page 12

Fresh Air Duct Capacities For Ducts Supplying Fresh Air To Boiler In Tightly Constructed Houses
Figure 4 - Fresh Air Openings
7 - FRESH AIR FOR COMBUSTION
Table 3 - FRESH AIR DUCT CAPACITIES
THROUGH LOUVERS
¼" Mesh
Fresh Air
Screen
Duct Size
(Btuh)*
3 ½" x 12" 144,000
8" x 8" 256,000
8" x 12" 384,000
8" x 16" 512,000
*Btuh = British Thermal Units per hour based on
opening covered by ¼" mesh screen , wood lou-
vers, or metal louvers.
Wood Metal
Louvers Louvers
(Btuh)* (Btuh)*
36,000 108,000
64,000 192,000
96,000 288,000
128,000 384,000
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