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035-15241-003 Rev. A (201)
INSTALLATIONS ON COMBUSTIBLE FLOORING
(50-125 MBH MODELS)
This furnace may not be installed directly on combustible
materials in the downflow position. It may be installed directly
on floors made of concrete or other-non-combustible materi-
als. If it is necessary to install the furnace in the downflow
position on a combustible floor, it is required that a combusti-
ble sub-base be used. The part number of the correct sub-
base accessory is shown in the specification Table on Page
3.
COMBUSTION AND VENTILATION AIR
Provide ventilation and combustion air in accordance with
section 5.3, Air for Combustion and Ventilation, of the
NATIONAL FUEL GAS CODE, ANSI Z223.1, or applicable
provisions of the local building codes. In Canada, refer to the
latest edition of the CAN/CGA-B149 Installation Code and
local codes for specifics.
Adequate ventilation and combustion air must be
provided to insure satisfactory and safe operation
of the furnace. Air openings in front panel and top
panel must not be obstructed. Failure to observe
this recommendation could result in asphyxiation.
Do not store or use halogen emitting substances
in the vicinity of this appliance. Such substances
include chlorine based cleaners and swimming
pool chemicals, water softening chemicals, de-ic-
ing salts and chemicals, cleaning solvents such
as carbon tetrachloride or perchloroethylene,
halogen type refrigerants, printing inks, paint and
paint removers, varnishes, hydrochloric acid, ce-
ments and glues, and masonry acid washing ma-
terials. The air used by the burner for combustion
must be free of halogens to avoid possible corro-
sion to the heating surfaces, which could result in
asphyxiation.
IMPORTANT -
This furnace is not to be used as a construc-
tion heater to supply heat to an unfinished building during the
finishing phases of construction. This practice exposes the
furnace to abnormally low return air temperatures, which can
cause condensation in the furnace or vent leading to prema-
ture failure. This practice also exposes the furnace to an
abnormally corrosive atmosphere from sources such as
paint, varnish and adhesives, which can lead to premature
heat exchanger or vent failure. The practice also allows for-
eign materials such as sawdust or sheet rock dust to enter
the furnace blower, burner, heat exchanger, motors, and vent
system resulting in shorter life of the furnace. Use of this fur-
nace as a construction heater will void the warranty.
Unitary Products Group
INSTALLATIONS IN A CONFINED SPACE
A confined space is defined as a space whose volume is less
than 50 cubic feet per 1000 BTUH of the total input ratings of
all appliances installed in the space. If the furnace is to be
installed in a confined space such as a small closet or room,
provisions must be made for supplying combustion and venti-
lation air to the space surrounding the furnace. (See Figure
6). This air must come from the outside or from some larger
area in the building which meets the requirements of an
unconfined space.
Two openings of equal area must be provided; one starting
within twelve inches of the ceiling and one starting within
twelve inches of the floor of the confined space. The upper
opening must always be above the top of the furnace casing.
The lower opening, if in the sidewall, floor or door, shall be
located below the level of the burner in the furnace.
If all air is from inside building, the total free area of each
opening must be at least one square inch for each 1,000
BTUH of furnace input but not less than 100 square inches.
If all air is from outdoors, when communicating directly with
the outdoors through vertical ducts, the total free area of each
opening must be at least one square inch for each 4,000
BTUH of furnace input. When communicating directly with the
outdoors through horizontal ducts, the total free area of each
duct must be at least one square inch for each 2,000 BTUH
of furnace input.
When ducts are used, they must be of the same cross-sec-
tional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
must not be less than three inches.
INSTALLATIONS IN AN UNCONFINED SPACE
An unconfined space is defined as a space whose volume is
more than 50 cubic feet per 1000 BTUH of the total input rat-
ings of all appliances installed in the space. In unconfined
spaces in a building of conventional frame, masonry, or metal
construction, infiltration is normally adequate to provide air for
combustion and ventilation.
In buildings of tight construction, all air must be obtained from
outdoors or from spaces communicating freely with outdoors.
A permanent opening or openings having a total free area of
not less than one square inch for each 5000 BTUH of furnace
input must be provided.
If the furnace is to be installed in a commercial building, a
building with an indoor pool, a laundry room, hobby or craft
room, or chemical storage area, all air must be brought in
from outside as described above.
Further details on supplying outdoor air for combustion may
be obtained from Section 5.3 of the National Fuel Gas Code
ANSI Z223.1. In Canada, refer to the latest edition of the
CAN/CGA-B149 Installation Code and local codes for specif-
ics.
7
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