Kenmore 153.331762 Use & Care Manual page 13

FIGURE 12.
• When communicating with the outdoors through vertical
ducts, each opening should have a minimum free area of
1 square inch per 4,000 BTU per hour (5.5 cm
total input rating of all equipment in the enclosure, see
Figure 12 on page 11.
• When communicating with the outdoors through horizontal
ducts, each opening should have a minimum free area
of 1 square inch per 2,000 BTU per hour (11 cm
total input rating of all equipment in the enclosure, see
Figure 14.
• Alternatively a single permanent opening may be used when
communicating directly with the outdoors, or with spaces that
freely communicate with the outdoors. The opening should
have a minimum free area of 1 square inch per 3,000 BTU
per hour (8.3 cm /kW) of total input rating of all equipment in
2
enclosure. See Figure 13.
FIGURE 13
• When ducts are used, they should be of the same cross-
sectional area as the free area of the openings to which they
connect. The minimum short side dimension of rectangular
air ducts should not be less than 3 inches (76.2 mm), see
Figure 14.
/kW) of
2
• Louvers and Grilles: In calculating free area, consideration
should be given to the blocking effect of louvers, grilles or
screens protecting openings. Screens used should not
be smaller than 1/4 inch (6.4 mm) mesh. If the free area
/kW) of
2
through a design of louver or grille is known, it should be
used in calculating the size opening required to provide
the free area specified. If the design and free area is not
known, it may be assumed that wood louvers will be 20-25
percent free area and metal louvers and grilles will have
60-75 percent free area. Louvers and grilles should be
fixed in the open position or interlocked with the equipment
so that they are opened automatically during equipment
operation.
• Special Conditions Created by Mechanical Exhausting or
Fireplaces: operation of exhaust fans, ventilation systems,
clothes dryers or fireplaces may create conditions requiring
special attention to avoid unsatisfactory operation of
installed gas utilization equipment.
13
FIGURE 14.