Filter
Top Products
Date: 8-4-2010
Revision: 0
Form: 2396
interlocked with the boiler to prevent boiler
operation if the dampers are closed.
Combustion air openings must never be blocked
or obstructed in any manner.
The boiler room must be at a positive or neutral
pressure relative to the outdoors. A negative in
the boiler room will result in downdraft problems
and incomplete combustion due to the lack of
air.
WARNING!
Failure to provide an adequate air
supply will result in boiler damage and
hazardous conditions in the building
(fire and asphyxiation hazard as well
as equipment damage).
1.6.1 COMBUSTION AIR OPENINGS:
The design of combustion air openings MUST
comply with local and/or State codes or the
authority having jurisdiction. As a minimum,
combustion air openings to the boiler room shall
be provided as follows:
Note:
Combustion air provided solely from an indoor
source is discouraged. No dimension for a
round or rectangular opening shall be less than
3”.
Two Permanent Opening Method
One opening starting within 12” of the top of the
boiler room and one starting within 12” of the
bottom of the boiler room shall be provided. The
openings shall be open directly to the outside or
ducted directly to the outside.
When directly open to the outside or ducted to
the outside by
vertical ducts, each opening or
duct shall have a minimum fee open area of 1
in
2
per 4000 BTU total input rating of the
boiler(s) in the room.
If ducted to the outside through
horizontal
ducts, each opening or duct shall have a
minimum free area of 1 in
2
per 2000 BTU total
input rating of the boiler(s) in the room.
One Permanent Opening Method
One opening commencing within 12” of the top
of the room shall be provided. The opening
shall be directly to the outside or shall be ducted
to the outside with a horizontal or vertical duct.
The opening or duct shall have a minimum free
area of:
1 in
2
/ 3000 BTU /hour of the total input ratting of
all appliances (boilers) in the room.
Not less than the sum of the areas of all
vent
connectors in the room. A “vent connector” is
defined as the pipe or duct that connects a fuel
burning appliance to a vent or chimney.
Additional area must be provided for other air
consuming equipment in the room.
Mechanical Air Supply Systems
The combustion air supply may be provided by a
mechanical air supply system. If utilized, the
combustion air must be provided from the
outside at a minimum rate of 0.35 ft
3
/min. for
every 1000 Btu/hr. input for all appliances
located in the space.
If exhaust fans are utilized, additional air shall be
provided to replace the exhausted air.
Each boiler and other appliance must be
interlocked to prevent operation when the
mechanical air supply system is not in operation.
If the combustion air is provided by a buildings
mechanical ventilation system, the system shall
be sized to provide the specified combustion air
in addition to the ventilation air requirements.
1.6.2 LOUVERS, GRILLES, AND
SCREENS
Louvers and Grilles:
5
The required size of openings for combustion,
ventilation, and dilution air shall e based on the
net free area of each opening. Where the free
area through a design of louver, grille, or screen
is know, it shall be used in calculating the size
opening required to provide the free area