Install Instructions

Table Of Contents
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I-UBX-UBZ-UDX-UDZ (04-21) 1034344-0
MAINTENANCE—CONTINUED
Maintenance Procedures—Continued
Burner Orifice Maintenance
The burner orifice usually needs to be replaced only when installing a gas conversion kit. When ordering a replacement
orifice only, provide BTUh content and specific gravity of gas as well as the model and serial number of the unit.
When removing or replacing the burner orifice, take care not to damage the venturi tube and/or the bracket.
Heat Exchanger Maintenance
NOTE: Inspection of the lower portion of the heat exchanger is done with the burner removed.
Refer to the Burner Maintenance section for information on inspecting the lower portion of the
heat exchanger.
1. Remove burner in accordance with Burner Maintenance section.
2. Remove any external dirt or dust accumulation.
3. Visually inspect heat exchanger for cracks and holes.
4. If crack or hole is found, replace heat exchanger.
5. Install burner in accordance with Burner Maintenance section.
Ignition System Maintenance
The DSI control module (circuit board, see Figure 11) monitors the operation of the heater including ignition. The
only replaceable component is the 3-amp Type ATC or ATO fuse (color code: violet, PN 201685). If the fuse is
blown, the problem is most likely an external overload. Correct the problem and replace the fuse.
Do not attempt to disassemble the control module. However, check the lead wires each heating season for insulation
deterioration and good connections.
For the flame sensor (see Figure 12 for location), disconnect the wire and remove the screw and the flame sensor.
Clean flame sensor with an emery cloth before reinstalling.
Proper operation of the direct spark ignition system requires a minimum flame signal of 1.0 microamps as measured
by a microampmeter.
For the ignitor (see Figure 12 for location), disconnect the wire and remove the screw and ignitor. Clean the ignitor
assembly with an emery cloth before reinstalling.
⚠ WARNING ⚠
Due to high voltage on the spark wire and electrode, do not touch when energized.
The spark gap (see Figure 17) must be maintained to 1/8 inch.
Figure 17. Ignitor Spark Gap