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UEZ-IOM (07-23) 1034347-I
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
NOTES:
• The unit is equipped with a TCORE
3
® heat exchanger.
• Inspection of the lower portion of the heat exchanger is done with the burner removed. Refer
to the Burner Maintenance (Unit Sizes 130–310) section for information on inspecting the lower
portion of the heat exchanger.
1. Remove burner in accordance with Burner Maintenance (Unit Sizes 055–110) or Burner Maintenance (Unit
Sizes 130–310) 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 (Unit Sizes 055–110) or Burner Maintenance (Unit
Sizes 130–310) section.
Ignition System Maintenance
• The DSI control module (circuit board, see Figure 26) 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 27 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.
⚠ CAUTION ⚠
When reassembling, the brown ground wire must remain attached to the ignitor for unit sizes 055,
085, and 110.
• For the ignitor (see Figure 27 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 33) must be maintained to 1/8 inch.
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