MN702GE 060320
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2. Pre-fire inspection • preparation
(continued)
Combustion air/ventilation openings
Sizing air openings
Follow all applicable codes and the appliance instruction manual (when available)
to size combustion air openings. Use the following guidelines when appliance
instructions are not available.
•
All air from inside building (building must be well-ventilated):
Size air openings for a free area (after louver deduction) of at least 1 square
inch per 1,000 Btuh input of all appliances in the space.
•
All air through openings directly from outside the building through an
adjacent outside wall:
If air openings connect directly to outside, provide two openings, one within
12 inches of the ceiling, the other within 12 inches of the floor. Each opening
must have a free area (after louver deduction) of:
•
If directly through side wall: 1 square inch for each 4,000 Btuh of all
appliances in the space.
•
If through vertical ducts: 1 square inch for each 4,000 Btuh of all
appliances in the space.
•
If through horizontal ducts: 1 square inch for each 2,000 Btuh of all
appliances in the space.
Locating air openings
Follow all applicable codes and the appliance instruction manual (when available)
to size combustion air openings. Refer to Figure 2 when appliance instructions
are not available.
Estimating free area
When specific information on the free area of louvers is not available, estimate
free area as follows:
1. Wood louvers — free area = area times 0.25.
2. Metal louvers or grilles — free area = area times 0.60.
3. Screens, when used must be no smaller than ¼ inch mesh.
Motorized vent dampers
Wire the vent damper end switch to prevent operation of the burner until the
air opening louvers are fully open.
Combustion air/ventilation opening checklist
•
Verify that air openings are unobstructed.
•
Verify that appliance space and air source spaces are free of:
•
Gasoline or other flammable liquids or vapors.
•
Combustible materials.
•
Air contaminants, such as laundry products, paint, thinner, varnish, etc.
•
Confirm with user that the area will be kept free of these materials at all
times.
Figure 2
Locating combustion air/ventilation openings
Installing the burner/appliance in a space that does not
provide enough air for combustion and ventilation can
result in severe personal injury, death or substantial
property damage. Follow all applicable codes and
guidelines below to ensure space has sufficient air
openings.
Exhaust fans and negative pressure conditions — Isolate
the boiler room from areas subject to negative pressure.
Size combustion air openings to ensure neutral air pres-
sure in the boiler room whenever the burner operates.
Make sure the space provides enough ventilation
to prevent overheating of the appliance, burner and
controls. If there is risk of overheating, you must install
ventilation air openings sized large enough to provide air
for cooling the equipment. Failure to provide ventilation
can result in severe personal injury, death or substantial
property damage.
The space and combustion air supply must not contain
corrosive contaminants, such as laundry products,
paints, varnishes or other chemicals.