Steffes DLF40B - Manual (Page 15)

For air delivery, the furnace is equipped with a 4­speed supply air blower which is factory wired to operate in
medium low speed for heating and in medium high speed for cooling and a fan only thermostat setting. The
blower speed may be adjusted for lower or higher output requirements. To do so, change the wiring on the
blower speed selection terminals located on the supply air blower. (See the Line Voltage Wiring Diagrams in this
manual for more information on the wiring and Table 3 for information on duct pressure with regard to blower
speed.)
TABLE 3
Attaching the Ducting
Step 1 Remove the supply air blower plenum assembly (60) and filter rack (18) from their boxes.
Step 2 To access the blower (56), remove the screws from the supply air blower plenum front access cover
(60) and detach it from the plenum.
Step 3 The supply air blower (56) is shipped banded to the plenum assembly (60). Cut the band to remove
the blower from the plenum and slide it into the plenum track through the front access.
Step 4 Attach the front access cover to the plenum.
Step 5 Attach the supply air blower plenum assembly (60) to the furnace by drilling two 1/8” holes per edge.
Attach to the furnace supply air side using the blunt tip screws supplied in the hardware package.
Step 6 Secure the filter rack assembly (18) on the return air side, again by drilling 1/8” holes per edge and
using the blunt tip screws supplied in the hardware package. A filter should already be included and
installed in the duct slot of the filter rack assembly.
Step 7 Connect both the return air and supply air house ducts to the furnace.
If the furnace is installed in a small enclosed area, a minimum of a 24" x 24" opening into
the area where the furnace is located must be installed if not already present. In addition, a
6" x 6" non­closing type register must be cut into the return air duct. (Refer to the Clear­
ance Requirements section of this manual for more information.)
STATIC PRESSURE (INCHES WATER)
SUPPLY AIR
BLOWER SPEED 0.10 0.25 0.50
HIGH Not Recommended 1850 CFM 1560 CFM
MEDIUM HIGH 1800 CFM 1780 CFM 1470 CFM
MEDIUM LOW 1610 CFM 1580 CFM 1420 CFM
LOW 1230 CFM 1205 CFM Not recommended
Installing The Furnace
(cont'd)
14
(.20 Static Maximum)
NOTE