Lochinvar RESIDENTIAL GAS WATER HEATERS Instruction Manual page 9

A. ALL AIR FROM INSIDE BUILDINGS: (See Figures 4 and 5)
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 gas utilization 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 (22 cm
input rating of all gas utilization equipment in the confined space,
but not less than 100 square inches (645 cm
commence within 12" (30 cm) of the top and one commencing within
12" (30 cm) of the bottom of the enclosures.
FIGURE 5.
B. ALL AIR FROM OUTDOORS: (See Figures 6, 7 and 8)
The confined space shall be provided with two permanent openings,
one commencing within 12" (30 cm) of the top and one
commencing within 12" (30 cm) from the bottom of the enclosure.
The openings shall communicate directly, or by ducts, with the outdoors
or spaces (crawl or attic) that freely communicate with the outdoors.
1. When directly communicating with the outdoors, each opening shall
have a minimum free area of 1 square inch per 4,000 Btu per hour
2
(5.5 cm /kW) of total input rating of all equipment in the enclosure, see
Figure 6.
FIGURE 6.
2. When communicating with the outdoors through vertical ducts, each
opening must have a minimum free area of 1 square inch per 4,000
Btu per hour (5.5 cm 2 /kW) of total input rating of all equipment in
the enclosure, see Figure 7.
3. When communicating with the outdoors through horizontal ducts,
each opening shall have a minimum free area of 1 square inch
per 2,000 Btu per hour (11 cm
equipment in the enclosure, see Figure 8.
2
/kW) of the total
2
). One opening shall
2 /kW)) of total input rating of all
4. When ducts are used, they shall 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 shall
not be less than 3" (76.2 mm), see Figure 8.
5. 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 shall have a minimum
free area of 1 square inch per 3,000 BTU per hour (8.3 cm
total input rating of all equipment in enclosure. See Figure 8A.
6. Louvers and Grilles: In calculating free area, consideration shall be
given to the blocking effect of louvers, grilles or screens protecting
openings. Screens used shall not be smaller than 1/4 inch (6.4 mm)
mesh. If the free area 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
shall be fixed in the open position or interlocked with the equipment so
that they are opened automatically during equipment operation.
7. 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.
9
FIGURE 7.
FIGURE 8.
FIGURE 8A.
2 /kW) of