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PROVISIONS FOR ADEQUATE COMBUSTION & VENTILATION AIR (continued)
actual BTU/Hr used is more than the maximum BTU/HR the space
can support. You must provide additional fresh air. Your options
are as follows:
A.
Rework worksheet, adding the space of an adjoining room. If
to adjoining room or add ventilation grills between rooms. See
B.
Vent room directly to the outdoors. See
Outdoors.
C. Install a lower BTU/Hr heater, if lower BTU/Hr size makes room
If the actual BTU/Hr used is less than the maximum BTU/Hr the
no additional fresh air ventilation.
space.
Ventilation Air
permanent openings: one within 12" of the ceiling and one within
1 and 2, Figure 5). You can also remove door into adjoining room
a minimum free area of one square inch per 1,000 BTUH of the total
Page 14
WARNING
Figure 5
WARNING
.
Provide extra fresh air by using ventilation grills or ducts. You must
provide two permanent openings: one within 12" of the ceiling and
or spaces open to the outdoors. These spaces include attics and
crawl spaces. In most cases for direct communication with the
outdoors or direct communication through a vertical duct a free
area opening of one square inch per 4,000 BTU/Hr of heater input
rating for each grill. If a horizontal duct is used, a grill free area or
duct opening shall have a free area opening of one square inch per
2,000 BTU/Hr for each grill. Follow the National Fuel Code ANSI
Z223.1/NFPA54, Air for Combustion and Ventilation for required
size of ventilation grills or ducts.
IMPORTANT: Do not provide openings for inlet or outlet air into attic
if attic has a thermostat-controlled power vent. Heated air entering
the attic will activate the power vent.
A1
B1
A1 x B1 = C1
A2 x B2 = C2
C1 + C2 = Sq. In. Required
For a 30,000 BTU Heater, 1 sq in per 1,000 BTU
equals 30 sq. in. of opening.
2
2
2
2
2
2
= 30in
A2
B2
2
2
2
Figure 7
26497-6-0511
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