3-Way Valve; Water Pressure Sensor - Navien NCB300-28K Service Manual

6.2.10 3-way Valve

1. Turn off the gas supply to the unit.
2. Turn off the 230V power supply to the unit.
3. Turn off the water supply to the unit. Drain all water from
the appliance.
4. Detach the wire connector that connects the 3-way valve.
5. Remove the clip on the back of the 3-way valve.
Figure 17
6. Replace it with the new 3-way valve.
7. Connect the 3-way valve wire housing.
8. Turn on water supply, power supply, and gas supply to the
unit.

6.2.11 Water Pressure Sensor

1. Turn off the gas supply to the unit.
2. Turn off the 230V power supply to the unit.
3. Turn off the water supply to the unit. Drain all water from
the appliance.
4. Remove the wire connectors from the water pressure sensor.
Figure 18
Replacement of Parts 91