8 18-CD35D1-1
INSTALLER’S GUIDE
5
U P F L O W /
HORIZONTAL
SHOWN
6" Minimum
The furnace may be placed horizontally in a crawl space on a
pad or other noncombustible material which will raise the unit
for sufficient protection from moisture. The furnace must be
supported at both ends and the middle when installed horizontally.
The furnace must also be elevated a minimum of 6 inches to
allow clearance for the condensate drain to exit the cabinet in the
horizontal position.
The horizontal furnace may also be suspended from the joists
using 3/8" all-thread rods with pieces of angle iron underneath
the furnace to form a hanging rack at both ends and the midpoint.
The rods need to be of sufficient length to allow for proper
clearances from combustible materials. The angle iron needs to
be at least 32" in length to allow for access to service panels.
50 CU. FT. OR MORE
PER 1000 BTU/HR. INPUT
ALL EQUIP. INSTALLED
UNCONFINED
6
AIR FOR COMBUSTION AND
VENTILATION
If these furnaces are installed in a non-direct vent capacity then
the adequate flow of combustion and ventilating air must not be
obstructed from reaching the furnace. Air openings provided for
combustion air must be kept free of obstructions which restrict
the flow of air. Airflow restrictions affect the efficiency and safe
operation of the furnace. Keep this in mind should you choose
to remodel or change the area which contains your furnace.
Furnaces must have a free flow of air for proper performance.
Provisions for combustion and ventilation air shall be made in
accordance with latest edition of Section 5.3, Air for Combustion
and Ventilation, of the National Fuel Gas Code, ANSI Z223.1 —
CAN/CGA B149.1 or applicable provisions of the local building
codes. Special conditions created by mechanical exhausting of
air and fireplaces must be considered to avoid unsatisfactory
furnace operation.
OUTSIDE AIR IS RECOMMENDED
The use of indoor air for most applications is acceptable, unless
there is the presence of corrosive chemicals or contamination.
Certain types of installation will require the use of outside air for
combustion.
The following types of installations will
require
use of
OUTDOOR AIR for combustion, due to chemical exposures:
• Commercial buildings
• Buildings with indoor pools
• Furnaces installed in “confined” laundry rooms
• Furnaces installed in “confined” hobby or craft rooms
• Furnaces installed near chemical storage areas.
Exposure to the following substances in the combustion air
supply will also require OUTDOOR AIR for combustion:
• Permanent wave solutions
• Chlorinated waxes and cleaners
• Chlorine based swimming pool chemicals
• Water softening chemicals
• Deicing salts or chemicals
• Carbon Tetrachloride
• Halogen type refrigerants
• Cleaning solvents (such as perchloroethylene)
• Printing inks, paint removers, varnish, etc.
• Hydrochloric acid
• Cements and glues
• Antistatic fabric softeners for clothes dryers
• Masonry acid washing materials
Furnace locations may be in a “
confined space
” or an
“
unconfined space
”.
Unconfined space is defined in Figure 6. These spaces may
have adequate air by infiltration to provide air for combustion
and ventilation. Buildings with tight construction (for example,
weather stripping, heavily insulated, caulked, vapor barrier, etc.)
may need additional air to be provided as described for confined
space.
Confined spaces are installations with less than 50 cu. ft. of
space per 1000 BTU/hr input from all equipment installed, as in
Figure 7. Air for combustion and ventilation requirements can
be supplied from inside the building as in Figure 8 or from the
outdoors, as in Figure 9.
