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The furnace
must
also be elevated
a minimum
o['6
inches
to allow
clearance
for the condensate
drain
to
exit the cabinet
in the horizontal
position.
The horizontal
fllrnace
may also be suspended
from the joists
using 3/8" all-thread
rods with pieces of angle iron under-
neath the furnace
to lbrm a hanging
rack at both ends anti the
midpoint.
The rods need to be of sufficient
length to allow liar
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
W'T'"]
OLO,..S
"i;" "O"Y'"
UNCONFINED
AIR FOR COMBUSTION
AND VENTILATION
If these furnaces
are installed
in a nondirect
vent capacity
then the adequate
flow of combustion
anti ventilating
air
must not be obstructed
from reaching
the furnace.
Air open-
ings provided
lbr combustion
air must be kept free of obstruc-
tions which restrict
the flow of air. Airflow restrictions
aflect
the efficiency anti sale operation
of the furnace.
Keep this in
mind should you choose m remodel
or change the area which
contains your furnace.
Furnaces
must have a free flow of air
lbr proper performance.
Provisions
lbr combustion
anti ventilation
air shall be made
in accordance
with latest edition of Section 5.3, Air lbr
Combustion
anti Ventilation,
of the National
Fuel Gas Code,
ANSI Z223.1 -- CAN/CGA
B149.1 or applicable
provisions
of
the local btdlding
codes. Special conditions
created
by
mechanical
exhausting
of air anti fireplaces
must be con-
sidered to aw_id unsatisfactory
l_lrnace operation.
OUTSIDE AIR IS RECOMMENDED
The use of indoor air lbr 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 lot combustion.
The fl)llowing types of installations
will require
use of
OUTDOOR AIR lbr 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 lbllowing 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 sol_ening chemicals
* Deicing salts or chemicals
* Carbon Tetrachloride
* Halogen type reli'igerants
* Cleaning solvents (such as perchloroethylene)
* Printing inks, paint removers, varnish, etc.
* Hydrochloric acid
* Cements and glues
* Antistatic fabric softeners for clothes dryers
Installer's
Guide
* Masonry
acid washing
materials
Furnace locations may be in a "confined space" or an
"unconfined
space".
Unc'mlfined
space is defined in Figure 5. These spaces may
have adequate
air by infiltration
to provide
air lbr combustion
anti ventilation.
Buildings
with tight construction
(lbr
example,
weather
stripping,
heavily
insulated,
caulked,
vapor
barrier,
etc.), may need additional
air to be provided
as
described
lbr confinect space.
C'onf_ned spaces are installations
with less than 50 cu. ft. of
space per 1000 BTU/hr
input from all equipment
installed.
Air Áor combustion
and ventilation
requirements
can be
supplied
from inside the building as in Figure 8 or from the
outdoors,
as in Figure 9.
MINIMUM
AREA
IN SQUARE
FEET
(_FOR
UNCONFINED
SPACE
INSTALLATIONS
FURNACE
WITH 8 FT. CEILING
MAXIMUM BTUH
MINIMUM AREA IN SQUARE FEET
INPUT RATING
OF UNCONFINED
SPACE
60,000
375
80,000
500
100,000
625
120,000
875
Q
I
FURNACE
_'_1
m
CONFINED
SPACE
LESS THAN 50 CU. FT.
PER 1000 BTU/HR.
INPUT
ALL EQUIP. INSTALLED
1. All air from inside the building as in Figure 8: 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
lbr an unconfined
space.
The total input of all gas utilization
equipment
installed
in the combined
space shall be considered
in making
this
determination.
Reler to Table 2 for minimum
open areas
requirements.
2. All air from outdoors
as in Figure 9: The confined space
shall be provided
with two permanent
openings,
one
commencing
within
12 inches of the top anti one com-
mencing
within
12 inches of 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.
Reler to Table 2, for
minimum
open areas
requirements.
TABLE 2
MINIMUM FREE AREA IN SQUARE INCHES
EACH OPENING
FURNACE ONLY)
Furnace
Maximum
BTUH/INPUT
Rating
60,000
80,000
100,000
120,000
Air
From
Inside
100
100
100
120
Air From Outside
Vertical
Duct
15
20
25
30
Horizontal
Duct
30
40
50
60
18-CD19D6-27
7
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