ALL AIR FROM OUTDOORS:
1. If combustion air is taken from outdoors through vertical
ducts, the openings and ducts MUST have at least 1 sq in. of
free area per 4000 Btuh of the total input for all equipment
within the confined space.
2. If combustion air is taken from the outdoors through horizon-
tal ducts, the openings and ducts MUST have at least 1 sq in.
of free area per 2000 Btuh of the total input for all equipment
within the confined space.
When ducts are used, they must be of the same cross-sectional area
as the free area of the openings to which they connect. The
minimum dimension of rectangular ducts must not be less than 3
in.
Step 4—Contaminated Combustion Air
Contaminated combustion air must be avoided in order not to
adversely affect the long term life of furnace, especially heat
exchanger and burners.
The recommended source of combustion air is to use the outdoor
air supply. Use of indoor air in most applications is acceptable as
long as there is no exposure to the types of installation or
substances listed below and all provisions for indoor combustion
air meet the requirements for combustion air supply indicated in
the NFGC Z223.1, Section 5.3; CAN1-B149 Installation Codes;
and/or any applicable local codes.
INSTALLATIONS REQUIRING OUTDOOR COMBUSTION
AIR
1. The following types of installations require OUTDOOR AIR
for combustion due to chemical exposures:
a. Commercial buildings
b. Buildings with indoor pools
c. Furnaces installed in laundry rooms
d. Furnaces installed in hobby or craft rooms
e. Furnaces installed near chemical storage areas
2. Exposure to the following substances in the combustion air
supply also require OUTDOOR AIR for combustion:
a. Permanent wave solutions
b. Chlorinated waxes or cleaners
c. Chlorine based swimming pool chemicals
d. Water softening chemicals
e. De-icing salts or chemicals
f. Carbon tetrachloride
g. Halogen-type refrigerants
h. Cleaning solvents (such as perchloroethylene)
i. Printing inks, paint removers, varnishes, etc.
j. Hydrochloric acid
k. Cements and glues
l. Anti-static fabric softeners for clothes dryers
m. Masonry acid washing materials
INSTALLATION
Step 1—Duct Work Recommendations
IMPORTANT:
This furnace is equipped with a metal heat ex-
changer shipping bracket which must be removed before installing
furnace. The No. 10 screws which fasten bracket to furnace will
interfere with attachment of outlet duct if not removed. Remove
bracket by removing No. 10 screws located on bottom panel duct
supply flange, rotating bracket forward and lifting out.
The proper sizing of warm air ducts is necessary to ensure
satisfactory furnace operation. Duct work should be in accordance
with the latest editions of U.S. NFPA-90A (Air Conditioning
Systems) and NFPA-90B (Warm Air Heating and Air Condition-
ing Systems) or Canadian equivalent.
The following recommendations should be followed when install-
ing duct work:
1. Install locking type dampers in all branches of individual ducts
to balance out system. Dampers should be adjusted to impose
proper static at outlet of furnace.
2. Noncombustible flexible duct connectors are recommended to
connect both supply- and return-air ducts to furnace.
3. In cases where return-air grille is located close to fan inlet,
there should be at least one 90° air turn between fan and inlet
grille. Further reduction in sound can be accomplished by
installing acoustical air turning vanes and/or lining inside of
duct with acoustical material.
4. It is recommended that outlet duct be provided with a
removable access panel. The opening shall be accessible when
furnace is installed and shall be of such a size that heat
exchanger can be viewed for possible openings using light
assistance or so a probe can be inserted for sampling air
stream. The access panel shall be designed so as to prevent
leaks when locked in position. If an air conditioning coil is
installed, access panel to coil can be used for this purpose.
Air openings, intake and outlet pipes, return-air grilles, and
warm air registers must not be obstructed.
When supply ducts carry air circulated by furnace to areas
outside spaces containing furnace, return air shall also be
handled by a duct sealed to furnace casing and terminating
outside space containing furnace. Incorrect duct work termi-
nation and sealing will create a hazardous condition which
could lead to bodily harm.
5. When installing furnace with cooling equipment for year-
round operation, the following recommendations must be
followed for series or parallel airflow:
a. In series airflow applications, coil is mounted after furnace
in an enclosure in supply-air stream. The furnace blower is
used for both heating and cooling airflow.
For Example:
58EFB FURNACE
INPUT BTUH
FREE AREA PER
OPENING (SQ IN.)
ROUND PIPE
(IN. DIA)
50,000
12.5
4
75,000
18.8
5
100,000
25.0
6
125,000
31.3
7
For Example:
58EFB FURNACE
INPUT BTUH
FREE AREA PER
OPENING (SQ IN.)
ROUND PIPE
(IN. DIA)
50,000
25.0
6
75,000
37.5
7
100,000
50.0
8
125,000
62.5
9
5
