Ventilation & Combustion Air - Dunkirk XEB-4 Installation, Operation & Maintenance Manual

5�1 Requirements
!
WARNING
Asphyxiation Hazard! Provide enough air openings
to boiler/combustion area to dilute flue gases
and allow for consistent, quality combustion.
Do not obstruct air openings. Follow instructions
below, to maintain adequate combustion air.
Failure to follow these instructions could result in
ignition failure, overheating, carbon monoxide, and
accumulation of flue gases.
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 54Provide
make-up air where exhaust fans, clothes dryers, and
kitchen ventilation equipment interfere with proper
operation. If inadequate makeup air is suspected it is
always acceptable to add additional ventilation.
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 (Btu/hr)/1000 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
infiltration rate is 0.40 air changes per hour. See
Table 3 for space with boiler only. Use equation for
multiple appliances.
Volume ≥ 50 ft
3
B. Known Air Infiltration Rate. See Table 5-1 for
space with boiler only. Use equation for multiple
Input
(Btu/hr)
42,500
75,000
112,500
150,000
187,500
5 - VENTILATION & COMBUSTION AIR
x Total Input (Btu/hr)/1000
Table 3 - Air Infiltration
Known Air Infiltration Rate Method (ACH - Air Changes Per Hour)
Standard
Method
0�1
2125 6375
3750 11250
5625 16875
7500 22500
9375 28125
appliances. Do not use an air infiltration 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.
… Direct communication with outdoors or
communicating through vertical ducts. Provide
minimum free area of 1 in² per 4,000
total input rating of all appliances in enclosure.
… Communicating through horizontal ducts.
Provide minimum free area of 1 in² per 2,000
Btu/hr
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).
• 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.
National Gas and Propane Installation Code Requires
providing air supply in accordance with:
• Section 8.2 and 8.3 when combination of
appliances has a total input of up to and including
400,000 Btu/hr (120 kW).
• Section 8.4 when combination of appliances has total
input exceeding 400,000 Btu/hr (120 kW).
• Refer to Natural Gas and Propane Installation Code
for specific air supply requirements for enclosure
or structure where boiler is installed, including air
supply openings and ducts.
( ft3/h)
0�2 0�3
3188 2125
5625 3750
8438 5625
11250 7500
14063 9375
12
/ACH x Total Input (Btu/hr)/1000
3
of total input rating of all appliances in
0�4 0�5 0�6
1594 1275 1063
2813 2250 1875
4219 3375 2813
5625 4500 3750
7031 5625 4688
PN 240013099 Rev. A [08/15/2020]
of
Btu/hr