Table of Contents
Advertisement
3.4 Combustion Air
Air Inlet Requirements – United States
Air inlet requirements for the United States are established by NFPA 54/ANSI Z223.1 & NFPA/ANSI
211. When air is supplied from inside the building, the total required volume shall be the sum of the
required volume for all the appliances located in the mechanical room. Adjacent rooms furnished with
fixed openings communicating directly with the mechanical room are considered part of the required
volume. The minimum volume is 50 ft
capacity.
Openings used to connect indoor spaces to obtain the required minimum volume shall be sized as
When rooms are on the same floor, each opening shall have an area equal to 1 square inch for
each 1,000 Btu/Hr (2,200 mm
square inches. One opening should commence less than 12 inches above the floor and the other
less than 12 inches below the ceiling. The minimum dimension of air openings shall be 3
When rooms are on different floors, each opening shall have an area equal to 2 square inches for
each 1,000 Btu/Hr (4,400 mm
When combustion air is supplied from outside the building, the boiler room shall be provided with one or two
openings to ensure adequate combustion air and proper
When using one permanent opening, the opening shall commence within 12 inches of the ceiling and shall
Under no circumstances
shall the boiler room ever be
under a negative pressure.
Particular care should be
taken when exhaust fans,
compressors, air-handling
units, or other equipment
may rob air from the boiler.
Note that this equipment
might be in rooms other
than the boiler room. This
applies to both sealed
combustion and
atmospheric room
combustion air applications.
2
mm
/kW) of total boiler input is required.
Revised: February 2, 2024
Released: February 2, 2024
3
per 1,000 Btu/Hr (4.8 m
2
/kW) of installed appliance input capacity, but not less than 100
2
/kW) of installed appliance input
ventilation.
communicate directly with the outdoors or through a vertical or
horizontal duct that communicates to the
of the opening is 1 square inch for each 3,000 Btu/Hr (700 mm
installed appliance input capacity, and not less than the sum of the
areas of all vent connectors in the room.
When using two permanent openings, one opening shall commence
within 12 inches above the floor and the other within 12 inches below
the ceiling, preferably on opposite walls. The openings shall
communicate directly, or by way of ducts, with free outdoor air. The
minimum net free area of the openings shall be calculated in
accordance with the
following:
When air is taken directly from outside the building, each opening
(minimum of two, as outlined above), 1 square inch for each 4,000
2
Btu per hour (550 mm
When air is taken from the outdoors through a vertical duct into
the mechanical room, 1 square inch per 4,000 Btu per hour (550
2
mm
/kW) of total boiler input is required.
When air is taken from the outdoors through a horizontal duct into
the mechanical room, 1 square inch per 2,000 Btu per hour (1,100
Patterson-Kelley 2024
All Rights Reserved.
P-K Storm
Technical Service 1.877.728.5351
3
/kW) of installed appliance input
capacity.
outdoors.
/kW) of total boiler input is
2691000403 P-K Storm ST2500-ST8000
Installation and Owners Manual Rev G.docx
®
Gas Fired Boiler
follows:
inches.
Minimum free area
/kW) of
2
required.
Page 25
Advertisement
Table of Contents
