Blower Adjustment; Lubrication Recommendations; Damper Linkage Adjustment; Control Operating Sequence - Modine Manufacturing DBP Installation And Service Manual

start- uP Procedure
Blower adjustments
If blower fan speed changes are required, adjust motor sheave
as follows:
1. Refer to page 34 to determine correct blower speed
according to job requirements, then proceed with steps 2
through 8.
2. Loosen motor base and take belt off of motor sheave.
3. Loosen set screw on outer side of adjustable motor sheave.
figure 15.1 - motor sheave adjustment
Toward Motor
4. Turn outer side of motor sheave clockwise until motor
sheave is fully closed.
5. From fully closed position, turn outer side of motor sheave
counterclockwise until the proper number of turns open are
achieved.
6. Retighten motor sheave set screw, replace belt and retighten
motor base. Motor base should be shifted for proper belt
tension which is 3/4" deflection with about 5 lbs. of force.
figure 15.2 - Belt tension adjustment
7. Recheck blower rpm after adjustment.
note: Do not fire unit until blower adjustment has been
made or unit may cycle on high limit control.
8. Check motor amps. Do not exceed nameplate amps shown
on motor nameplate.

lubrication recommendations

The blower can be provided with either spider or pillow block
bearings. Spider bearings are permanently lubricated and do not
require lubrication. Pillow block bearings are shipped greased
from the factory but will require lubrication. The bearings should
be checked and lubricated before each heating season but a
more frequent lubrication schedule may be required based on
the environment in which the unit is installed, and the frequency
of the equipment operation. Shell Alvania #2 lubricant is
recommended.
Set Screw
Adjustable Half
of Sheave
3/4" deflection
with 5 lbs. of force

damper linkage adjustment

If the unit is provided with a return air damper, to prevent
shipping damage, the return air damper linkage is disconnected
and the damper closed. Before operating the unit, the fresh and
return air dampers must be connected. This is accomplished by
the following:
1. The damper actuator should be de-energized and the fresh
air damper in a fully closed position.
2. Open the return air damper in a fully open position.
3. Slide the connecting rod into the ball joint on the blade arm
with the return air damper fully open. See Figure 15.3.
4. Tighten the 5/16" hex head screw on the ball joint.
figure 15.3 - damper linkage adjustment
BALL
JOINT
DAMPER BLADE

control operating sequence

IMPORTANT
To prevent premature heat exchanger failure, with all control
systems, a blower starting mechanism must be provided so
that the blower is running or energized within 45 seconds of
the gas control operation.
Indoor power vented duct furnaces are supplied with intermittent
pilot systems with continuous retry as standard. On mechanical
modulation systems the main burner is turned off 100%
when the thermostat is satisified, but the pilot remains lit. For
intermittent pilot systems, except mechanical modulation both
the main burner and pilot burner are turned off 100% when
the thermostat is satisfied. Intermittent pilot systems, for both
natural and propane gas, the ignition controller is 100% shut-off
with continuous retry. On a call for heat, the system will attempt
to light the pilot for 70 seconds. If the pilot is not sensed for
any reason, the ignition control will wait for approximately six
minutes with the combination gas control closed and no spark.
After six minutes, the cycle will begin again. After three cycles,
some ignition controllers lockout for approximately one hour
before the cycle begins again. This will continue indefinitely until
the pilot flame is sensed or power is interrupted to the system.
note: Gas Control Options (see page 16) could change the
listed sequence of operation based on their function.
The descriptions given are for the basic duct furnace.
5-565.1
CONNECTING
ROD
BLADE ARM
15