Dunkirk DPFG Series, Supplemental Venting Instruction, Page: 3 / 11

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VENTING INSTRUCTIONS
P/N# 240005665, Rev. 1.1 [05/06]
FRESH AIR FOR COMBUSTION - CHIMNEY VENTED BOILERS
WARNING
Be sure to provide enough fresh air for
combustion. Enough air ensures proper
combustion and assures that no hazard will
develop due to the lack of oxygen.
Ventilation of the boiler room must be adequate to
provide sufficient air to properly support combustion
per the latest revision of the National Fuel Gas Code,
ANSI Z223.1, Section 5.3.
When a boiler is located in an unconfined space in a
building or conventional construction frame, masonry
or metal building, infiltration normally is adequate to
provide air for combustion and ventilation. However,
if the equipment is located in a building of unusually
tight construction (See the National Fuel Gas Code,
ANSI Z223.1, Section 1.7), the boiler area should be
considered as a confined space. In this case air for
combustion and ventilation shall be provided according
to Part 5. If there is any doubt, install air supply
provisions in accordance with the latest revision of the
National Fuel Gas Code.
You must provide for enough fresh air to assure proper
combustion. The fire in the boiler uses oxygen. It must
have a continuous supply. The air in a house contains
only enough oxygen to supply the burner for a short
time. Outside air must enter the house to replace that
used by the burner. Study following two examples to
determine your fresh air requirements.
BOILER IN UNCONFINED SPACE
If your boiler is in an open area (unpartitioned basement)
in a conventional house, the air that leaks through
the cracks around doors and windows will usually be
adequate to provide air for combustion. The doors
should not fit tightly. Do not caulk the cracks around
the windows.
An unconfined space is defined as a space whose
volume is not less than 50 cubic feet per 1,000 Btu per
hour of the total input rating of all appliances installed
in the space.
BOILER IN CONFINED SPACE
ALL AIR FROM INSIDE BUILDING: The confined
space shall be provided with two permanent openings
communicating directly with an additional room(s)
of sufficient volume so that the combined volume
of all spaces meets the criteria for an unconfined
space. The total input of all combustion equipment
installed in the combined space shall be considered
in making this determination. Each opening shall
have a minimum free area of one square inch per
1,000 Btu per hour of the total input rating of all
combustion equipment in the confined space but not
less than 100 square inches. One opening shall be
within 12 inches of the top and one within 12 inches
of the bottom of the enclosure. See Figure #1 .
Example: Your boiler is rated at 100,000 Btu per
hour. The water heater is rated at 30,000 Btu per
hour. The total is 130,000 Btu per hour. You need
two grilles, each with 130 square inches of FREE
opening. Metal grilles have about 60% FREE
area. To find the louvered area needed, multiply
the FREE area required by 1.7 (130 x 1.7 = 221.0
sq. in. louvered area). In this example, two grilles,
each having an 8” x 30” (240 sq. in.) louvered
area would be used. Figure 1 shows the grille
locations.
ALL AIR FROM OUTDOORS: The confined space
shall be provided with two permanent openings, one
commencing within 12 inches of the top and one
commencing within 12 inches of the bottom of the
enclosure. The openings shall communicate directly,
FIG. 1 – AIR OPENINGS FOR CLOSET OR UTILITY
ROOM INSTALLATIONS