Service manual

FIGURE 2
For installation on combustible flooring, the tank leg thermal
break piece identified as part No. 25 on the replacement parts
illustration must be installed under each leg.
Combustion and Ventilation Air - Provisions must be
made for adequate combustion and ventilation air. Details
outlining proper air supply for various types of installation are
prescribed by the National Fuel Gas Code (ANSI Z-223.1 /
NFPA 54) latest edition. If the water heater is installed in
unconfined space
within the building, infiltration air may be
adequate for proper combustion and ventilation. Buildings of
tight construction (weather stripping, caulked, etc.) require
additional air from outdoors.
If the water heater is installed in a confined space
(volume is
less than 50 cu. ft. per 1000 BTUH of the total input rating
of all gas appliances in that space), air must be supplied
through two permanent openings. One opening shall be
within 12 inches from the top of the enclosure and one within
3
12 inches of the bottom. The openings must be protected by
metal louvers or 1/4” min. mesh metal screen. The size of the
openings are as follows:
1. If the openings communicate directly with an additional
room(s) of sufficient volume, each opening shall have a
minimum free area opening of 1 sq. in. per 1000 BTUH of
the total input rating of all gas appliances in the confined
space, but not less than 100 sq. inches.
2. If the openings communicate directly with the outdoors or
through vertical ducts with the outdoors, each opening
shall have a minimum free area of 1 sq. in. per 4000 of the
total rating of all gas appliances in the enclosure.
3. If the openings communicate with the outdoors through
horizontal ducts, each opening shall have a minimum free
area of 1 sq. in. per 2000 BTUH of the total rating of all
gas appliances.
CLEARANCES FROM
COMBUSTIBLE CONSTRUCTION
ABCD
D80-125 24” 2” 6” 6”
D80-165 24” 2” 6” 6”
D80-180 24” 2” 6” 6”
D80-199 24” 2” 6” 6”
D100T-199 24” 2” 6” 6”
D100-199 18” 2” 6” 6”
D100-250 18” 2” 6” 6”
D100-270 18” 2” 6” 6”
D100-300 18” 4” 6” 6”
D75-365 24” 2” 6” 6”
D75-399 24” 2” 6” 6”
D80-512 18” 4” 6” 6”
FIGURE 1
REMEMBER: Flammable vapors may be drawn to
this water heater from other areas of the structure by
air currents.
NOTE: HEATER SHALL BE LOCATED OR PROTECTED
SO IT IS NOT SUBJECT TO PHYSICAL DAMAGE BY
MOVING VEHICLES OR AREA FLOODING.
FIGURE 3 Typical Installation in Residential Garages (IIlustration
copyright by the American Gas Association. Used by
permission of the copyright holder)
150158 Rev. 2 August - 2010