24
441 01 2613 06
Specifications are subject to change without notice.
close to a living area. It is often advisable to route the return air
ducts under the floor or through the attic.
•
Refer to
furnace
Technical Support Manual
(Blower Data)
for air flow information.
•
Size ductwork to handle air flow for heating (and air
conditioning if so equipped).
Duct Installation Requirements
•
When a furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside of the space
containing the furnace, the return air shall also be handled by
duct(s) sealed to the furnace casing and terminating outside
the space containing the furnace.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could
result in personal injury, death, and/or component
damage.
Install cooling coil on furnace discharge. Cool air
passing over heat exchanger could cause conden-
sate to form resulting in heat exchanger failure.
!
WARNING
•
When the furnace is used with a cooling unit , the furnace shall
be installed parallel with or on the upstream side of the cooling
unit to avoid condensation in the heating element.
•
With a parallel flow arrangement, the dampers or other means
used to control flow of air shall be adequate to prevent chilled
air from entering the furnace. Chilled air going through the
furnace could cause condensation and shorten furnace life.
Dampers (purchased locally) can be either automatic or
manual. Manually or automatically operated dampers
MUST
be equipped with a means to prevent furnace and air
conditioning operation, unless damper is in the full heat or
cool position.
•
Installation of locking-type dampers is recommended in all
branches, or in individual ducts to balance system’s air flows.
•
Non
−
combustible, flexible duct connectors are
recommended for return and supply connections to furnace.
•
If air return grille is located close to the fan inlet, install at least
one 90
°
air turn between fan and inlet grille to reduce noise.
•
Ductwork installed in attic or exposed to outside temperatures
requires a minimum of 2
″
(50.8mm) of insulation with outdoor
type vapor barrier.
•
Ductwork installed in an indoor unconditioned space requires
a minimum of 1
″
(25.4mm) of insulation with indoor type vapor
barrier.
Inspection Panel on some models
For a furnace not equipped with a cooling coil, the outlet duct shall
be provided with a removable access panel. This opening shall be
accessible when the furnace is installed and shall be of such a size
that the heat exchanger can be viewed for possible openings using
light assistance or a probe can be inserted for sampling the air
stream. This access cover shall be attached in such a manner as
to prevent air leaks.
Filters
A filter MUST be used.
Filters are not supplied with these furnaces, but can be purchased
from your distributor.
See
Table 4
for required high
−
velocity filter sizes.
Table 4
High
−
Velocity Air Filter Sizes
(max. 600 FPM/3.0 m/s)
Cabinet
Width
in (mm)
Internal
Filter
in(mm)
External Filter Rack
Bottom
Bottom
Side+
15
1
/
2
(393.7)
14 X 25
(355.6 x 635)
14 X 25
(355.6 x 635)
14 X 25 (355.6 x 635)
or 16 X 25 (508 x 635)*
19
1
/
8
(485.8)
16 X 25 *
(406.4 x 635) *
16 X 25
(406.4 x 635)*
16 X 25
(406.4 x 635)*
22
3
/
4
(577.9)
20 X 25
(508 x 635)*
20 X 25
(508 x 635)*
16 X 25
(508 x 635)*
* Greater than 1600 CFM with a maximum of 2000 CFM requires both (left and right)
side return filter racks or for single return in an upflow application, must use filter rack
NAHA001TK.
See
Figure 22
.
+ Side return air duct(s) is not permitted with horizontal or downflow furnace
installation.
Use either filter type:
•
Washable, high
−
velocity filters are based on a maximum air
flow rating of 600 FPM (3.0 m/s).
•
Disposable, low velocity filters are based on a maximum air
flow of 300 FPM (1.5 m/s) when used with external filter
grille.
!
RISK OF REDUCED FURNACE LIFE
F
ailure to follow this Caution may result in
premature furnace component failure.
Use of excessively dirty and/or restrictive air filters
may increase furnace operating temperatures and
shorten the life of the furnace.
Filters specified for the furnace are rated at a
maximum of 600 FPM air velocity and sized for the
furnace’s airflow rate. Replacement filters must be
of equivalent type, size, and rating except as
described below.
Disposable, low
−
velocity filters may be used to
replace washable, high
−
velocity filters, providing
they are sized for 300 FPM or less.
CAUTION
•
The furnaces with 1600 (755 L/s) or less CFM rating use a
16” x 25” (406.4 x 635mm) high
−
velocity filter and rack. On
these models the filter may be mounted internally for bottom
return or a filter and rack may be mounted externally for
bottom return.
•
The furnaces with 1600 CFM to 2000 CFM (755 L/s to 944
L/s) may require that both (left and right) side returns are
used or for single side return in upflow application, must use
filter rack NAHA001TK. Filter racks must be mounted
externally. See
Figure 24.
•
If return air must be on one side only, an optional 20
″
x 25
″
(508 x 635mm) filter standoff rack kit can be used. (See
Figure 22.)
For bottom return, an internal filter can be used
or a filter rack kit can be mounted externally.
•
See
Circulator Air Blower Data
for additional data.
NOTE:
The 20
″
x 25
″
(508 x 635mm) standoff side filter rack gives
more filter area but does not provide more air. See
Figure 22.
To
achieve 2000 CFM (944 L/s), two side returns may be required.
See
Figure 24.
NOTE:
Disposable low
−
velocity filters may be replaced with
washable, high
−
velocity filters. Washable, high
−
velocity filters can
be replaced
ONLY
with same type and size filter unless
low
−
velocity filters meet the minimum size areas for 300 FPM or
less.