Navien NCB-24LSWE, Service Manual

Page: 130 / 144

128 NCB Service Manual Version 1.0
6.2.9 Circulation Pump
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. Open the drain plug on the pump and Remove the 4
screws from circulation pump.
5. Replace with the new circulation pump
6. Place the new pump back into its original position
and ensure that all connections are tightly sealed.
7. Reinstall the pump drain plug at the bottom of the
unit.
8. Reconnect the wiring connector at the pump.
9. Install the Front panel back onto the unit by using
the four screws.
10. Turn on water supply, power supply, and gas supply
to the unit.
11. Open a hot water tap and ensure that there are no
leaks at the pump connections.
12. Open the air vent on top of pump to release air
within the system.
6.2.10 Flow Sensor
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. Drain all water
from the appliance.
4. Remove the Circulation Pump
5. Detach the 3 wire connectors that connect the flow
sensor.
Figure 22
6. Remove the flow sensor.
Figure 23
7. Replace with old flow sensor with the new part.
8. Turn on water supply, power supply, and gas supply
to the unit.
9. Carefully open a hot water tap and ensure there are
no leaks at the flow sensor connections.