SYSTEM OPERATION
27
8. Heating input (W1/ W2) always has priority over all
other thermostat input.
9. Cooling input (YLo/ Y) has priority over continuous fan
input.
10. Continuous fan input (G) has lowest priority.
*The blower speed wiring connections must remain in
factory position
.
1. Refer to the air flow table for your specific model
furnace
2. If a cooling or heat pump condensing unit is being
used in conjunction with this furnace, the three DIP
switches in
S2 are used to select the proper
cooling speeds to match the outdoor unit size. Typical
CFM requirements are 400
CFM / Ton.
1. Turn OFF power to the furnace.
2. Select the heating and cooling blower speeds that match
the installation requirements from the airflow table in
this manual or the Service Manual, If factory cooling
speeds do not match the installation requirements, the
dip switch settings must be changed from factory posi-
tion
3. Turn ON power to furnace.
4. Verify proper temperature rise in heat modes and CFM
in cooling modes
In general lower heating speeds will: reduce electrical consump-
tion, lower operating sound levels of the blower, and increase
the outlet air temperature delivered to the home. The speeds
available allow the blower performance to be optimized for the
particular homeowner’s needs.
CIRCULATING AIR AND FILTERS
DUCTWORK - AIR FLOW
Duct systems and register sizes must be properly designed
for the C.F.M. 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 should be installed in accordance with Stan-
dards of the National Board of Fire Underwriters for the In-
stallation of Air Conditioning, Warm Air Heating and Venti-
lating Systems, Pamphlets No. 90A and 90B.
A return air filter is not supplied with the furnace. The in-
staller must supply a means of filtering all of the return air.
Filter(s) shall comply with UL900 or CAN/ULC-S111 Stan-
dards. If the furnace is installed without filters, the warranty
will be voided.
Upflow furnaces with air delivery of less than 1800 CFM:
Use one side return or one bottom return ductwork connec-
tion.
Upflow furnaces with air delivery of 1800 CFM or higher:
Use two side returns or one side return and one bottom
return connection.
Guide dimples locate the side and bottom return cutout lo-
cations. Use a straight edge to scribe lines connecting the
dimples. Cut out the opening on these lines. An undersized
opening will cause reduced airflow. For bottom return con-
nection, remove the bottom of the cabinet before setting the
furnace on the raised platform or return air duct.
A closed return duct system must be used, with the return
duct connected to the furnace.
NOTE:
Ductwork must never
be attached to the back of the furnace.
Supply and return
connections to the furnace may be made with flexible joints
to reduce noise transmission, if desired. If a central return
is used, a connecting duct must be installed between the
unit and the utility room wall so the blower will not interfere
with combustion air or draft. The 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 heating, the temperature of the return
air entering the furnace must be between
55°F
and
100°F
.
