Steffes DLF40B - Manual (Page 21)

Outdoor Temperature Sensor
The outdoor temperature sensor provides outdoor temperature information for automatic charge regulation of the
furnace. In standard configuration from the factory, the outdoor sensor is calibrated at 55
o F, 35 o F, and 15 o F for
initiating the level, 1 (1/3), 2 (2/3) and 3 (maximum) brick core charges. If outdoor temperature charging set
points other than the standard configuration are preferred, the sensor must be specially ordered from the factory.
Outdoor Sensor Placement:
The outdoor sensor is shipped inside the supply air blower plenum assembly. When installing the sensor, please
follow these recommended guidelines in relation to placement and wiring:
Ø Optimal placement of the outdoor temperature sensor is on an outdoor surface in a location above ground
level where it will not be affected by direct sunlight or other sources of heat or cold.
Ø The outdoor sensor has an 8­foot, 4­conductor, 300V insulated cable (18AWG). If this is not long enough
for the installation, additional wire can be spliced to this wire. Since this is a low voltage circuit, standard
Class II (thermostat) wire can be used as extension wire provided it does not enter the line voltage areas
of the furnace.
Outdoor Sensor Mounting and Wiring Connections:
Step 1
Attach the outdoor temperature sensor (64) to an outdoor surface using its four mounting flanges.
Step 2 Disconnect power to the furnace and route the low voltage wire from the sensor to the furnace.
Step 3 Route the wire into the furnace’s electrical compartment and up to the charge control circuit board
(30).
Never install any wiring in the line voltage compartment of the furnace unless it
is rated for line voltage.
Step 4 Connect the sensor to the 4 position terminal strip on the bottom front of the charge control circuit
board (30). The wire is color coded to match the terminal position in which it should be connected:
White (W), Green (G), Black (B), and Red (R). (See the Low Voltage Wiring Diagram in this
manual for a depiction of the location of these terminals.)
Room Thermostat
A low voltage thermostat is required for room temperature control with the furnace. Steffes has both mechani­
cal and digital configurations with a heating and cooling sub base available for use with this system. Some also
provide a room temperature set back option. Any thermostat used with this system must be 24 VAC and have
the ability to switch 1/2 amp minimum at a .5 anticipator setting. (Contact the factory for more information on
the thermostats available from Steffes.)
In applications where an air conditioning system will be used in conjunction with the furnace, the furnace can
also be used to control the air conditioning system through the wall thermostat during the cooling months. (See
Figure 13 for information as to how to make room thermostat connections.)
Placement:
Optimal placement of the room thermostat is on an interior wall where it will not be affected by direct sunlight or
other sources of heat or cold.
Installing The Furnace
(cont'd)
20
NOTE