64 Venting for Combustion Air
2. Provide two openings to allow for circulation of combustion air as specified by ANSI Z223.1/NFPA 54 or check
local codes for the proper combustion air requirements in your region.
Maximum
Input (BTU/H)
Outdoor make up air is provided, a
minimum free area of 1 in
2
,
per 4,000 BTU/H
Indoor make up air is provided, a
minimum free area of 1 in
2
,
per 1,000 BTU/H
NCB-
250/150H
210,000
53 in
2
10 in (W) x 6 in (H) or 9 in round 210 in
2
14
1
/
2
in (W) x 14
1
/
2
in (H)
NCB-
240/130H
199,900
50 in
2
10 in (W) x 5 in (H) or 8 in round 199 in
2
14
1
/
4
in (W) x 14
1
/
4
in (H)
NCB-
240/110H
199,900
50 in
2
10 in (W) x 5 in (H) or 8 in round 199 in
2
14
1
/
4
in (W) x 14
1
/
4
in (H)
NCB-
190/080H
160,000
40 in
2
10 in (W) x 4 in (H) or 8 in round 160 in
2
12
3
/
4
in (W) x 12
3
/
4
in (H)
NCB-
190/060H
160,000
40 in
2
10 in (W) x 4 in (H) or 8 in round 160 in
2
12
3
/
4
in (W) x 12
3
/
4
in (H)
Ref
Description
Canadian Non-
Direct Vent
Installations
1
US Non-Direct Vent
Installations
2
A
Clearance above grade, veranda, porch, deck, or
balcony
12 in (30 cm)
12 in (30 cm)
B
Clearance to window or door that may be opened
36 in (91 cm)
48 in (120 cm) below
or to side of opening;
12 in (30 cm) above
opening
C
Clearance to permanently closed window
*
*
D
Vertical clearance to ventilated soffit located above
the terminal within a horizontal distance of 2 feet
(61 cm) from the center line of the terminal
*
*
Summary of Contents for NCB-190/060H
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