19
local codes. This wiring must have a minimum temperature
rating of 105°C and must be routed away from the burner
compartment. All line voltage wire splices must be made
inside the furnace junction box.
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Air Cleaner
Humidifier
Control Module
Hot 120 VAC
Neutral 120 VAC
Optional
Accessories
{
Figure 25
Line Voltage Connection for Accessories
Accessory Operation:
The furnace control module ener-
gizes the humidifier whenever the induced draft blower is
energized (when an air cleaner is installed on the system,
the humidifier is not energized until the air cleaner is
energized). The control module energizes the air cleaner
whenever the air circulation blower is energized.
VIlI. Circulating Air and Filters
DUCTWORK - AIR FLOW
Duct systems and register sizes must be properly designed
for the CFM and external static pressure rating of the
furnace. Ductwork should be designed in accordance with
the recommended methods of “Air Conditioning Contrac-
tors of America” Manual D.
A duct system must be installed in accordance with Stan-
dards of the National Board of Fire Underwriters for the
Installation of Air Conditioning, Warm Air Heating and
Ventilating Systems. Pamphlets No. 90A and 90B. NOTE:
Ductwork must never be attached to the back of the
furnace.
A closed return duct system must be used, with the return
duct connected to the furnace. Supply and return con-
nections to the furnace may be made with flexible joints to
reduce noise transmission. To prevent the blower from
interfering with combustion air or draft when a central return
is used, a connecting duct must be installed between the
unit and the utility room wall. A room, closet, or alcove must
not be used as a return air chamber.
When the furnace is used in connection with a cooling unit,
the furnace should be installed in 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 the flow of air must
be adequate to prevent chilled air from entering the furnace
and, if manually operated, must be equipped with means to
prevent operation of either unit unless the damper is in the
full heat or cool position.
When the furnace is installed without a cooling coil, it is
recommended that a removable access panel be provided
in the outlet air duct. 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 visual light inspection or
such that a sampling probe can be inserted into the air-
stream. The access panel must be made to prevent air
leaks when the furnace is in operation.
When the furnace is heating, the temperature of the return
air entering the furnace must be between 55°F and 100°F.
When a furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space con-
taining the furnace, the return air shall also be handled by
a duct sealed to the furnace casing and terminating outside
the space containing the furnace.
FILTERS - READ THIS SECTION BEFORE
INSTALLING THE RETURN AIR DUCTWORK
Filters must be used with this furnace. Discuss filter main-
tenance with the building owner. Filters do not ship with this
furnace, but must be provided by the installer. Filters must
comply with UL900 or CAN/ULCS111 standards. If the
furnace is installed without filters, the warranty will be
voided.
Guide dimples locate the side return cutout locations. Use
a straight edge to scribe lines connecting the dimples. Cut
an opening to match the dimensions of these lines.
NOTE:
An undersized opening will cause reduced airflow.
The bottom return is set up as a knock out.
For air delivery of less than 1800 CFM, use a one side or
bottom return.
For air delivery of 1800 CFM or higher, use either two-sided
returns or a one-sided return with a bottom return.
To ensure proper unit performance follow the filter sizes
given in the Specifications Sheet.
UPRIGHT INSTALLATIONS
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register, the bottom of the
blower compartment (upflows), a side panel external filter
rack kit (upflows), inside the side panel (upflows), or the
ductwork above a counterflow furnace. As an alternative a
media air filter (MAC1) or electronic air cleaner (EAC5) can
be used as the requested filter. Review and follow the filter
sizes given in the Specifications Sheet to ensure proper unit
performance. The following figures show possible filter
locations.
