Ignition system (cont’d) – Thomas & Betts UDAP User Manual
Page 32
Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 32
31. Venter Motor
and Wheel
30. Fan Motor,
Fan Blades,
and Guard
Remove dirt and grease from the motor, 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.
FIGURE 21 - Fan Blade
Position on the Shaft
29. Ignition
System
(cont’d)
FIGURE 20 - Ignitor
showing required
Spark Gap
measurement
1/8 inch
(3.2mm)
IMPORTANT: When re-assembling, the brown ground wire must remain attached
to the ignitor.
CAUTION: Due to high voltage on the spark wire and electrode,
do not touch when energized. See Hazard Levels, page 2.
Flame Sensor - Refer to FIGURE 18 and locate the flame sensor. Disconnect the
wire; remove the screw and the flame sensor. Clean with an emery cloth.
Flame Sensor
Replacement Instructions
Ignitor - Refer to FIGURE 18 and locate the ignitor. Disconnect the wire; re-
move the screw and the ignitor. Clean the ignitor assembly with an emery cloth.
Spark gap must be maintained to 1/8". See FIGURE 20.
Ignitor
1. If the heater is installed, turn off the gas and disconnect the electric power.
2. Open the access door and disconnect the fan motor wires, capacitor wires at the
capacitor, and ground screw.
3. Remove the assembled parts (the fan guard, the motor and the fan blade).
4. Disassemble and replace whatever parts are needed and reas-
semble using whatever part(s) are being replaced and the original
parts.
Be sure the fan blade is in the proper position on the shaft; refer to
the illustration and table in FIGURE 21.
Position the assembly on the heater. Attach the fan guard.
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 according to the wiring diagram and close 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.
Remove dirt and grease from the motor casing, the venter housing, and the venter
wheel. Venter motor bearings are permanently lubricated. Follow these instruc-
tions for replacement of the venter motor and wheel assembly. Keep all hardware
removed to be used in re-assembling and installing the replacement parts.
1. Turn off the gas and disconnect the electric power.
2. Open the burner/control compartment access panel.
3. Disconnect the three venter motor wires at the DSI control, capacitor wires at
the capacitor (if applicable), and ground screw (located on the control panel).
4. Sizes 30 and 45 - Disconnect the gas train and move it out of the way. Discon-
nect the gas supply at the union outside of the cabinet. At the gas valve, mark
and disconnect the wires. Carefully remove the burner orifice and orifice adapter
locking nut. Slide the orifice adapter out through the bracket on the burner push-
ing the gas train to the right. This will move the gas train out of the way.
Dimension A
Size
inches mm
30
1
25
45
9/16
14
60
1-1/2
38
75
2-1/8
54
100
2-3/8
60
125 2-5/16 59
150
2-3/8
60
175
2-1/8
54
200
1-5/8
67
225,
250,
300
2
51
350
1-7/8
48
400
1-3/8
35
A
Fan
Motor
Fan
Blade