Ignition Transformer; Aps - Navien NCB-150E Service Manual

6.2.5 Ignition Transformer

1. Turn off the gas supply to the unit.
2. Disconnect the unit from the power supply.
3. Turn off the water supply to the unit.
4. Remove the Ignition Transformer insulated cables from the
flame rod.
5. Disconnect the wiring connector from the Ignition Transformer
(Figure 9).
Figure 9
6. Remove the 2 screws from the Igniter Transformer.
Figure 10
7. Pull out the Ignition Transformer.
8. Replace the old Ignition Transformer with the new part, and
then use the 2 screws to secure the part.
9. Reconnect the Ignition Transformer insulated cables to the
flame rod.
10. Reattach the wiring connectors from the Ignition Transformer.
11. Turn on water supply, power supply, and gas supply to the
unit.
NOTE
Verify that the Ignition Transformer insulated cables are firmly
connected to the flame rod.

6.2.6 APS

1. Turn off the gas supply to the unit.
2. Disconnect the unit from the power supply.
3. Turn off the water supply to the unit.
4. Remove the air pressure sensor wiring connector (Figure 11).
Figure 11
5. Remove the hose from the air pressure sensor.
Figure 12
Replacement of Parts 137