935SA: Installation, Start-up, Operating and Service Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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the heat exchanger can be viewed for possible openings using light
assistance or a probe can be inserted for sampling the air stream. The
cover attachment shall prevent leaks.
Connect supply-air duct to flanges on furnace supply-air outlet. Bend
flange upward to 90° with wide duct pliers (see
). The supply-air
duct must be connected to ONLY the furnace supply-outlet-air duct
flanges or air conditioning coil casing (when used). DO NOT cut main
furnace casing side to attach supply air duct, humidifier, or other
accessories. All supply-side accessories MUST be connected to duct
external to furnace main casing.
Return Air Connections
The return-air duct may be connected to bottom of the furnace. The side
of casing that faces downward may also be used for return air
connection. A combination of the bottom and downward facing side may
also be used. The upward facing side of the casing cannot be used as a
return air connection (see
).
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel installed in bottom
return-air opening. Remove and discard this panel when bottom return
air is used. To remove bottom closure panel (see
).
Side Return Air Inlet
These furnaces are shipped with bottom closure panel installed in bottom
return-air opening. This panel MUST be in place when side return air
inlet(s) are used without a bottom return air inlet.
Not all horizontal furnaces are approved for side return air connections
(see
). Where required by code, seal bottom closure to furnace
with tape, mastic, or other durable sealing method.
A170123
1. Lay furnace on the back or side
2. Remove the two (2) screws that secure the bottom closure panel to
the furnace casing and remove the panel
Fig. 34 – Removing Bottom Closure Panel (2 Screws)
Filter Arrangement
There are no provisions for an internal filter in these furnaces. An
external filter rack is required and is purchased separately. A field
supplied accessory air cleaner may also be used in place of the filter
rack.
For upflow applications, the filter can be installed on either side of the
furnace, the bottom of the furnace or any combination of side and
).
For horizontal applications, the filter rack (or field supplied accessory air
cleaner) can be connected to the bottom opening on the furnace. For side
return use in the horizontal position (see
). If both side and
), each opening used will require a
filter.
A filter rack or any field supplied accessory air cleaner can also be
installed in the common return duct prior to entering the return air
opening in any orientation.
The furnace may be used with an optional external media filter cabinet.
The optional media filter cabinet uses either a standard 1-in. (25 mm)
filter or 4-in. (102 mm) wide media filter which can be purchased
separately. A field supplied accessory air cleaner may also be used in
place of the media cabinet.
Filter and Return Duct Sizing
Pressure drop must be taken into account when sizing filters, filter racks,
IAQ devices, and associated system ductwork. For a 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).
Due to the relatively high pressure drops of 1-in. (25 mm) thick
after-market filter media, it is recommended that the filtration system be
designed for at least 2-in. (51 mm) thick media.
TIPS FROM CONTRACTORS: Install a media cabinet capable of
incorporating a 4-in. (102 mm) thick media filter. This allows room for
future upgrades to other IAQ devices.
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.
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.
1.
Lay furnace on the back or side
2.
Remove the two (2) screws that secure the bottom
closure panel to the furnace casing and remove the
panel
SCREWS (2)
BOTTOM
CLOSURE
Representative drawing. Models may vary.
NOTICE
!
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
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.
