Form 433-CV/LN, Page 18
the original fan guard. These specially designed screws will cut
through the coating on the fan guard to provide a ground for the fan
motor.)
Rotate the fan blade to check for adequate clearance. If adjustment
is required, loosen the mounting screws, re-position the fan guard,
and tighten the screws. Rotate the fan blade and re-check for ad-
equate clearance. Repeat this procedure until the assembly is posi-
tioned properly.
5. Reconnect the fan motor wires and replace the access panel.
6. Restore power to the heater and turn on the gas. Light, following
the instructions on the lighting instruction plate. Check for proper
operation.
25. Venter Motor
Remove dirt and grease from the motor housing. Venter motor is
permanently lubricated.
The integrated circuit board controls and monitors operation of the
venter motor. If the contacts fail to close the venter motor will not
run. If the contacts fail to open, the venter motor will not shut off,
preventing the combustion air pressure switch from opening.
26. Operating Gas Valve
The gas valve requires no field maintenance except careful removal
of external dirt accumulation and checking of wiring connections.
Instructions for testing pressure settings are in Paragraph 12.
WARNING: The operating valve is the prime
safety shutoff. All gas supply lines must be free
of dirt or scale before connecting to the unit to
ensure positive closure. See Hazard Levels, page
1.
27. Limit Control
I
f it is determined that the limit control needs replacing, use only a
factory-authorized replacement part that is designed for the size of
heater. To access the limit control, remove the louver assembly from
the front of the heater.
For approximate limit location, see Figure 11.
28. Combustion Air Pressure
Switch
See Figure 12 for location. If it is determined that the pressure switch
needs replacing, use only the factory-authorized replacement part
that is designed for the size of heater being serviced.
29. Flame Rollout Switch
Models FT 30 and 45 are equipped with a flame rollout safety switch.
The flame rollout switch is a temperature activated manually reset,
limit switch. The switch is mounted on the side of the burner box
in a location that senses temperature in a central horizontal loca-
tion at the rear of the burner assembly.
If the flame rollout switch activates to shutdown the heater, the
cause must be corrected.
If it is determined that the flame rollout switch needs replacing,
use only the factory-authorized replacement part that is designed
for use on this heater.
30. Vent System
Check the vent system at least once a year. Inspection should in-
clude all joints, seams, and the vent cap. Replace any defective
parts.
Flame Sensor - Refer to Figure 10 and locate the flame sensor. Dis-
connect the wire; remove the screw and the flame sensor. Clean with
an emery cloth.
Ignition Control - The integrated circuit board monitors the operation
of the heater including ignition. Do not attempt to disassemble the cir-
cuit board. However, each heating season the lead wires should be
checked for insulation deterioration and good connections.
Proper operation of the direct spark ignition system requires a mini-
mum flame signal of 1.0 microamps as measured by a
microampmeter.
For further information and check out procedure on the direct spark
ignition system, refer to the manufacturer's control operating instruc-
tions supplied with the heater.
23. Heat Exchanger
The outside of the tubular heat exchanger can be cleaned from the
front of the heater with an air hose and/or a brush. Remove all accumu-
lated dust and grease deposits.
CAUTION: Eye protection is recommended.
The inner surfaces of the heat exchanger can be reached for cleaning
with the burner and venter assemblies removed (See Paragraph 21).
Clean with a long furnace brush or a heavy wire to which steel wool
has been attached. Brush inside each heat exchanger tube until all for-
eign material is removed. A flashlight is helpful in examining the in-
side of the tubes.
24. Fan
Remove dirt and grease from the motor. Remove dirt and grease from
the fan guard and blades. Use care when cleaning the fan blades to
prevent causing misalignment or imbalance. Check that the hub of the
fan blades is secure to the shaft.
Follow these instructions for replacement of the fan guard, fan motor
and/or fan blades.
1. If the heater is installed, turn off the gas and disconnect the electric
power.
2. Remove the access panel or 2x4 junction box cover. Disconnect the
fan motor wires.
3. Remove the assembled parts (the fan guard, the motor and the fan
blade).
4. Disassemble and replace whatever parts are needed and reassemble
using whatever part(s) are being replaced and the original parts. If
the fan guard is being replaced, it is important that the same hard-
ware be used for attaching the motor to the fan guard as was used
with the original guard. These screws are especially made to cut
through the coating on the fan guard to provide adequate ground-
ing for the motor.
Be sure the fan blade is in the proper position on the shaft; refer to
the illustration and table in Figure 12.
Position the assembly on the heater. Attach the fan guard.
(IMPORTANT: If replacing the fan guard, use the screws that held
Figure 12 - Proper
Position of the Fan
Blade on the
Motor Shaft
Model
S iz e
S et S crew
Torque
(Inch-Lbs)
"A" Hub
to Motor
30, 45
80 ± 10
1-1/8"
Fan
Hub
A
Fan
22. Ignition System (cont'd)
