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926TC: Installation, Start-up, Operating and Service and Maintenance Instructions
A
PLENUM
OPENING
B
D
FLOOR
OPENING
C
Fig. 25 – Installation on Combustible Flooring
Leveling Legs (If Desired)
In upflow position with side return inlet(s), leveling legs may be used.
See
Fig.
26. Install field-supplied, 5/16 x 1-1/2 in. (8 x 38 mm) (max)
corrosion-resistant machine bolts, washers and nuts.
NOTE: Bottom closure must be used when leveling legs are used. It
may be necessary to remove and reinstall bottom closure panel to install
leveling legs. To remove bottom closure panel, see
To install leveling legs:
1. Position furnace on its back. Locate and drill a hole in each bottom
corner of furnace.
2. For each leg, install nut on bolt and then install bolt with nut in
hole. (Install flat washer if desired.)
3. Install another nut on other side of furnace base. (Install flat washer
if desired.)
4. Adjust outside nut to provide desired height, and tighten inside nut
to secure arrangement.
5. Reinstall bottom closure panel if removed.
"
5/ 16
(8mm)
"
3
1
/
4
(44mm)
(8mm)
"
5
/
16
(44mm)
1
(44mm)
Fig. 26 – Leveling Legs
Location Relative to Cooling Equipment
The cooling coil must be installed parallel with, or on the downstream
side of the unit to avoid condensation in the heat exchangers. When
installed parallel with the furnace, dampers or other flow control must
prevent chilled air from entering the furnace. If the dampers are
manually operated, they must be equipped with means to prevent
operation of either unit unless the damper is in the full-heat or full-cool
position.
FILTER ARRANGEMENT
WARNING
!
FIRE, CARBON MONOXIDE AND POISONING HAZARD
Failure to follow this warning could result in fire, personal injury or death.
Never operate a furnace without a filter or filtration device installed. Never
operate a furnace with filter or filtration device access doors removed.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
FURNACE
FURNACE
(OR COIL CASING
WHEN USED)
APPROVED
COIL ASSEMBLY
OR
COIL BOX
COMBUSTIBLE
COMBUSTIBLE
FLOORING
FLOORING
DOWNFLOW
SUBBASE
SHEET METAL
PLENUM
SHEET METAL
PLENUM
FLOOR
FLOOR
OPENING
OPENING
Fig.
24.
(8mm)
"
5/ 16
"
1
3
/
4
(44mm)
(8mm)
"
5/ 16
"
3/ 4
"
3/ 4
1
There are no provisions for an internal filter rack in these furnaces. An
external filter is required.
This furnace may use an optional media filter cabinet. The optional
media filter cabinet uses either a standard 1-inch (25 mm) filter or 4-inch
(102 mm) wide media filter which can be purchased separately.
The optional media cabinet is sized for bottom return applications for
use in upflow, downflow and horizontal applications.
For upflow side return applications, the optional media cabinet (or field
supplied accessory air cleaner) can be installed on the side of the furnace
or side and bottom when a bottom plenum is used. See
A10491
Fig.
27.
For downflow applications, the Media Cabinet or field supplied
accessory air cleaner must only be connected to the bottom opening on
the furnace. See
Fig. 22
For horizontal applications, the Media Cabinet or field supplied
accessory air cleaner for all models can be connected to the bottom
opening on the furnace. For side return use in the horizontal position,
refer to
Fig.
23. If both side and bottom openings are used in
each opening used will require a filter.
The media cabinet or field supplied accessory air cleaner can also be
installed in the common return duct prior to entering the return air
opening in any orientation.
Refer to the instructions supplied with Media Cabinet or accessory air
filter for assembly and other details.
See
Table 9
for filter size details.
Filter and Return Duct Sizing
Pressure drop must be taken into account when sizing filters, filter racks,
IAQ devices, and associated system ductwork. See
comparison of Pressure Drop (initial/clean resistance to airflow) versus
Airflow for a variety of filter media types and sizes. These are
representative numbers. Consult the filter or IAQ device manufacturers'
specification sheet for performance data for a particular filter media or
IAQ device.
Design the filter and associated ductwork for the best match of pressure
drop versus filter size. Best practice usually chooses filter systems with
pressure drops under 0.2 in. w.c. (50 Pa), with the best blower electrical
efficiency and system airflow performance occurring with filter pressure
drops under 0.1 in. w.c. (25 Pa).
Design the duct system FIRST to determine how much pressure drop
may be allowed in the filter system. See the Air Ducts section.
Excessive filter pressure drop often compromises system airflow and
A89014
duct performance, causes inadequate airflow to the furthest ends of the
duct system, as well as causes excess noise and higher than anticipated
electrical consumption.
Provide duct transitions, as required, to smoothly transition airflow from
the return duct system to the filter (or IAQ device) to the furnace when
the dimensions of the ductwork or furnace return air opening do not
match the required filter or IAQ device dimensions. See the instructions
supplied with factory-accessory duct adapters.
19
and
Fig.
27.
NOTICE
!
Fig. 21
and
Fig.
23,
Table 7
for a
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