13
Fresh Air Duct Capacities For Ducts Supplying Fresh Air To Boiler In Tightly Constructed Houses
Table 3 - FRESH AIR DUCT CAPACITIES
THROUGH LOUVERS
Fresh Air
Duct Size
¼” Mesh
Screen
Wood
Louvers
Metal
Louvers
(Btuh)*
(Btuh)*
(Btuh)*
3 ½” x 12”
144,000
36,000
108,000
8” x 8”
256,000
64,000
192,000
8” x 12”
384,000
96,000
288,000
8” x 16”
512,000
128,000
384,000
*Btuh = British Thermal Units per hour based
on opening covered by ¼” mesh screen , wood
louvers, or metal louvers.
Figure 4 - Fresh Air Openings
7 - FRESH AIR FOR COMBUSTION
PN 240013278, Rev. A [12/31/2020]
