Fresh Air For Combustion - Dunkirk PSB-3D Installation, Operation & Maintenance Manual

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. Must be approved by
authority having jurisdiction.
• Mechanical Air Supply. Provide minimum of 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. Cannot be used if known air
infi ltration rate is 0.40 air changes per hour. See
Table 1 for space with natural gas boiler only. Use
equation for multiple appliances and/or propane.
Volume ≥ 50 ft
3
Table 3 - Minimum Room Volume, Indoor Air Only*
Standard
Input Mbh
Method
75 3750
112.5 5625
150 7500
187 9350
255 11250
262.5 13125
299 14950
* Table values based on boiler only. Add volume for any additional appliances.

FRESH AIR FOR COMBUSTION

WARNING
x Total Input [Mbh]
Known Air Infi ltration Rate Method (Air Changes Per Hour)
0.1
15750
23625
31500
39270
47250
55125
62790
B. Known Air Infi ltration Rate. See Table 1 for
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 for opening
requirements between connected indoor spaces.
• All Outdoor Air. Provide permanent opening(s)
communicating directly or by ducts with outdoors.
A. Two Permanent Opening Method. Provide opening
commencing within 12 inches of top and second
opening commencing within 12 inches of bottom of
enclosure.
B. One Permanent Opening Method. Provide 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 for additional
requirements for louvers, grilles, screens and air
ducts.
• Combination Indoor and Outdoor Air. Refer to National
Fuel Gas Code for application information.
0.2 0.3
7875 5250
11813 7875
15750 10500
19635 13090
23625 15750
27563 18375
31395 20930
6
⁄ACH x Total Input [Mbh]
3
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
3938 3150
5906 4725
7875 6300
9818 7854
11813 9450
13781 11025
15698 12558
0.6
2625
3938
5250
6545
7875
9188
10465