8
18-CD33D1-4
Installer’s Guide
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 suf-
ficient length to allow for proper clearances from combus-
tible materials. The angle iron needs to be at least 32" in
length to allow for access to service panels.
AIR FOR COMBUSTION AND VENTILATION
If these furnaces are installed in a nondirect vent capac-
ity 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 restric-
tions affect the efficiency and safe operation of the fur-
nace. 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
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 mid-
dle when installed horizontally.
4
UPFLOW/
HORIZONTAL
SHOWN
50 CU. FT. OR MORE
PER 1000 BTU/HR. INPUT
ALL EQUIP. INSTALLED
UNCONFINED
5
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 con sidered to avoid unsatisfactory furnace op-
eration.
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
re-
quire
the use of outside air for combustion.
The following types of installations will
require
use of
OUTDOOR AIR for combustion, due to chemical expo-
sures:
* 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 combus-
tion:
* 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 5. These spac-
es 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 addi-
tional 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 in-
stalled. 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.
