Navien Condensing Water Heater NPE-180A

Turn off the gas supply to the unit

Disconnect the unit from the power supply

Turn off the water supply to the unit

Removal of Old Air Pressure Sensor

Remove the air pressure sensor wiring connector (Figure 11)

Remove the hose from the air pressure sensor

Remove the 2 screws that attach the air pressure sensor to the burner assembly

Pull out the air pressure sensor

Turn off the gas supply to the unit

Disconnect the unit from the power supply

Turn off the water supply to the unit

Remove the mounting screw from the fan assembly

Remove the fan assembly bracket with the attached intake port

Disconnect the wiring connector from the fan assembly

Remove the 4 screws from the gas valve connection

Turn off the gas supply to the unit

Disconnect the unit from the power supply

Turn off the water supply to the unit

Remove the Ignition Transformer insulated cables from the flame rod

Disconnect the wiring connector from the Ignition Transformer

Remove the 2 screws from the Ignitor Transformer

Pull out the Ignition Transformer

Replace the old Ignition Transformer with the new part, and then use the 2 screws to secure the part

Reconnect the Ignition Transformer insulated cables to the flame rod

Turn off the gas supply to the unit

Disconnect the unit from the power supply

Turn off the water supply to the unit and drain all water from the appliance

Remove the stainless clip and four screws at the flow sensor

Detach the 2 wire connectors that connect the flow sensor to the PCB

Replace the old flow sensor with the new part

Reinstall the flow sensor into the cold water inlet pipe and reattach the stainless clip

Ensure that the flow sensor is properly connected to the cold water inlet pipe and that the clip is tightly holding the two parts together

CAUTION: Servicing must be performed by a qualified service agency or gas supplier

Inspect for general signs of corrosion

Check and adjust the gas/air ratio

Carry out a water leak test in operation