Air Combustion And Ventilation - Smith 88 Installation And Operation Instructions Manual

E. AIR FOR COMBUSTION AND
VENTILATION
1. Adequate combustion air and ventilation air must be
provided for this appliance in accordance with the
section of the National Fuel Gas Code entitled, "Air
for Combustion and Ventilation" or applicable
provisions of the local building code. Subsections 2
through 8 as follows are based on the National Fuel
Gas Code requirements.
2. Required Combustion Air Volume: The total required
volume of indoor air is to be the sum of the required
volumes for all appliances located within the space.
Rooms communicating directly with the space in
which the appliances are installed and through
combustion air openings sized as indicated in
Subsection 3 are considered part of the required
volume. The required volume of indoor air is to be
determined by one of two methods.
a. Standard Method: The minimum required
volume of indoor air (room volume) shall be 50
cubic feet per 1000 BTU/Hr (4.8 m
method is to be used if the air infiltration rate is
unknown or if the rate of air infiltration is known
to be greater than 0.6 air changes per hour. As
an option, this method may be used if the air
infiltration rate is known to be between 0.6 and
0.4 air changes per hour. If the air infiltration rate
is known to be below 0.4 then the Known Air
Infiltration Rate Method must be used. If the
building in which this appliance is to be installed
is unusually tight, the manufacturer recommends
that the air infiltration rate be determined.
b. Known Air Infiltration Rate Method: Where
the air infiltration rate of a structure is known, the
minimum required volume of indoor air for
appliances other than fan assisted and for the
boiler shall be determined as follows:
Required Volume
where:
I
= Input of appliances other than fan
other
assisted in Btu/hr
ACH = air change per hour (percent of the
volume of the space exchanged per
hour, expressed as a decimal)
For fan assisted appliances, calculate the required
volume of air using the following equation:
Required Volume
I = Input of the fan assisted appliances in
fan
Btu/hr
Note: These calculations are not to be used for
infiltration rates greater than 0.60 ACH.
4
INSTALLATION AND OPERATING INSTRUCTIONS
3 /kW). This
[
I
21 ft 3
other
=
other Btu
ACH 1000 /
[
3 I
15 ft
fan
=
fan
Btu
ACH 1000 /
hr
3. Indoor Air Opening Size and Location: Openings
connecting indoor spaces shall be sized and located
as follows:
a. Combining spaces on the same floor:
Provide two permanent openings communicating
with additional spaces that have a minimum free
area of 1 in
of the total input rating of all gas fired equipment
but not less than 100 in
opening is to begin within 12 inches (305 mm)
from the top of the space and the other is to
begin within 12 inches (305 mm) from the floor.
The minimum dimension of either of these
openings shall be 3 inches (76 mm). See Figure
1.1 for an illustration of this arrangement.
Figure 1.1: Air Openings – All Air from Indoors
on the Same Floor
b. Combining spaces on different floors:
Provide one or more permanent openings
communicating with additional spaces that have
a total minimum free area of 2 in
]
Btu/hr (44 cm
of all equipment. See Figure 1.2 for an
hr
illustration of this arrangement.
]
Figure 1.2: Air Openings – All Air from Indoors
on Different Floors
2 2
per 1000 Btu/hr (22 cm per 1000 W)
2 (645 cm 2 ). One
2
per 1000
2
per 1000 W) of total input rating