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5.3.4 Specially Engineered Installations:
The requirements of 5.3.3 shall not necessarily govern when
special engineering, approved by the authority having
jurisdiction, provides an adequate supply of air for combustion,
ventilation, and dilution of flue gases.
5.3.5 Louvers and Grilles:
In calculating free area in 5.3.3, consideration shall be given to
the blocking effect of louvers, grilles or screens protecting
openings. Screens used shall not be smaller than
¹⁄₄
" (6.4 mm)
mesh. If the area through a design of louver or grille is known, it
should be used in calculating the size of opening required to
provide the free area specified. If the design and free area is not
known, it may be assumed that wood louvers will have 20 to
25 percent free area and metal louvers and grilles will have 60 to
75 percent free area. Louvers and grilles shall be fixed in the open
position or interlocked with the equipment so that they are
opened automatically during equipment operation.
5.3.6 Special Conditions Created by Mechanical
Exhausting or Fireplaces:
Operation of exhaust fans, ventilation systems, clothes dryers or
fireplaces may create conditions requiring special attention to
avoid unsatisfactory operation of installed gas utilization
equipment. Air from Inside Building. See 5.3.3-a.
INSTALLATION POSITIONS
This furnace may be installed in an upright position or horizontal
on either the left or right side panel.
NOTE: Do not install this furnace on its back.
For upright upflow furnaces, the return air ductwork may be
attached to the side panel(s) and/or base pan.
For horizontal upflow furnaces, the return air ductwork must be
attached to the base pan.
For both the upright or horizontal counterflow furnaces, the
return air ductwork must be attached to the base pan (top end of
the blower compartment).
NOTE: Do not attach the ductwork to the back of the furnace.
For upflow installations requiring 1,800 CFM or more, use either
2 side returns or a bottom return or a combination of side and
bottom.
Contact your local distributor for the proper airflow requirements
and the number of required ductwork connections. See the
“Recommended Installation Positions” illustrations for the
appropriate installation positions, ductwork connections and the
resulting airflow
HORIZONTAL APPLICATIONS
AND CONSIDERATIONS
General
Horizontal applications, in particular, may dictate many of the
installation’s specifics such as airflow direction, ductwork
connections, flue and combustion air pipe connections, etc. The
basic application of this furnace as a horizontal furnace differs
only slightly from an upright installation.
When installing a furnace horizontally, additional consideration
must be given to the following:
■
Drain trap and lines
■
Leveling the furnace
■
Alternate vent/flue and combustion air connections
■
Alternate electrical and gas line connections
■
Drain pan
■
Freeze protection
■
Furnace suspension.
Horizontal Furnace
Drain Trap and Lines
In horizontal applications, the condensate drain trap is secured to
the furnace side panel, suspending it below the furnace. A
minimum clearance of 4
³⁄₄
" (12.1 cm) below the furnace must be
provided for the drain trap.
Additionally, the appropriate downward piping slope must be
maintained from the drain trap to the drain location.
Refer to “Condensate Drain Trap and Lines” for further details. If
the drain trap and drain line will be exposed to temperatures near
or below freezing, adequate measures must be taken to avoid
condensate from freezing.
Leveling
Leveling ensures proper condensate drainage from the heat
exchanger and induced draft blower. For proper flue pipe
drainage, the furnace must be level lengthwise from end to end.
The furnace should also be level from back to front, or have a
slight tilt with the access doors sloping downward
³⁄₄
" (1.9 cm)
lower than the back panel. The slight tilt allows the heat
exchanger condensate, generated in the recuperator coil, to flow
forward to the recuperator coil front cover.
Alternate Vent/Flue Connections
In horizontal installations, provisions for alternate vent/flue piping
are available for upflow furnaces with left discharge and
counterflow furnaces with right air discharge. This configuration
allows the vent/flue and combustion air piping to be run vertically
through the side of the furnace. Refer to the “Recommended
Installation Positions” illustrations for further details. The
standard piping connections may also be used in these positions.
See “Vent/Flue Pipe and Combustion Air Pipe” for details
concerning the conversion to the alternate vent/flue connections.
A. Alternate vent/flue location
B. Level end-to-end
C. Level side-to-side or slightly
tilted—doors 0" to
³⁄₄
" (1.9 cm)
below back panel
D. Drain line—
¹⁄₄
" (6.4 mm) per
foot downward slope
E. 36" (91.4 cm) minimum service
clearance
F. 4
³⁄₄
" (12.1 cm) minimum drain trap
clearance
G. Supports at both ends and middle
H. Drain pan
I. Gas line with 3" (7.6 cm) minimum
drip leg
F
A
B
C
D
E
G
H
I
