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Air openings to combustion area must not
!
be obstructed. Following instructions below,
adequate combustion air can be maintained.
Provide combustion air and ventilation air in accordance
with the section "Air for Combustion and Ventilation," of
the National Fuel Gas Code, ANSI Z223.1 / NFPA 54, or
applicable provisions of local building codes.
Provide make-up air where exhaust fans, clothes dryers,
and kitchen ventilation equipment interfere with proper
operation.
National Fuel Gas Code recognizes several methods
of obtaining adequate ventilation and combustion air.
Requirements of the authority having jurisdiction may
override these methods.
•
Engineered Installations
authority having jurisdiction.
•
Mechanical Air Supply
0.35 cfm per Mbh for all appliances located within
space. Additional requirements where exhaust fans
installed. Interlock each appliance to mechanical air
supply system to prevent main burner operation when
mechanical air supply system not operating.
•
All Indoor Air
. Calculate minimum volume for
all appliances in space. Use a different method if
minimum volume not available.
A.
Standard Method.
infi ltration rate is less than 0.40 air changes per
hour. See Table 1 for space with boiler only. Use
equation for multiple appliances.
Volume ≥ 50 ft
3
Table 1 - Minimum Room Volume, Indoor Air Only*
Standard
Input Mbh
Method
45
2250
70
3500
96
4800
120
6000
145
7250
175
8750
195
9750
245
12250
295
14750
* Table values based on boiler only. Add volume for any additional appliances.
VENTILATION & COMBUSTION AIR
WARNING
. Must be approved by
. Provide minimum of
Cannot be used if known air
x Total Input [Mbh]
Known Air Infi ltration Rate Method (Air Changes Per Hour)
0.1
9450
14700
20160
25200
30450
36750
40950
51450
61950
B.
Known Air Infi ltration Rate.
space with boiler only. Use equation for multiple
appliances. Do not use an air infi ltration rate
(ACH) greater than 0.60.
Volume ≥ 21 ft
C.
Refer to National Fuel Gas Code
requirements between connected indoor spaces.
•
All Outdoor Air.
communicating directly or by ducts with outdoors.
A.
Two Permanent Opening Method
opening commencing within 12 inches of top and
second opening commencing within 12 inches of
bottom of enclosure.
B.
One Permanent Opening Method
opening commencing within 12 inches of top of
enclosure. Provide minimum clearance of 1 inch on
sides/back and 6 inches on front of boiler (does not
supersede clearance to combustible materials).
C.
Refer to National Fuel Gas Code
requirements for louvers, grilles, screens and air
ducts.
•
Combination Indoor and Outdoor Air.
National Fuel Gas Code for application information.
0.2
0.3
4725
3150
7350
4900
10080
6720
12600
8400
15225
10150
18375
12250
20475
13650
25725
17150
30975
20650
5
⁄ACH x Total Input [Mbh]
3
Provide permanent opening(s)
Direct communication with outdoors or
communicating through vertical ducts. Provide
minimum free area of 1 in² per 4 Mbh of total
input rating of all appliances in enclosure.
Communicating through horizontal ducts.
Provide minimum free area of 1 in² per 2
Mbh of total input rating of all appliances in
enclosure.
0.4
0.5
2363
1890
3675
2940
5040
4032
6300
5040
7613
6090
9188
7350
10238
8190
12863
10290
15488
12390
See Table 1 for
for opening
. Provide
. Provide
for additional
Refer to
0.6
1575
2450
3360
4200
5075
6125
6825
8575
10325
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