Circulation Pump - Navien NCB-180 Service Manual

4.9.14 Circulation Pump

Part
Function
Failure Event
Effects
Error Code
Diagnostic
Color/Number of wires
1. Pump operates when using internal or external hot water circulation.
2. Internal circulation will minimize the effect of temperature fluctuations and external circulation
delivers hot water to fixtures quickly resulting in water conservation.
Unable to detect or measure water flow rate when the pump is called to operate.
1. The boiler freezes.
2. Temperature fluctuations when the boiler is set to internal recirculation.
3. Hot water is not quickly available at fixtures when the boiler is set to external recirculation.
-
1. Visual inspection: Check the circulation pump connection wire.
2. * Check for blocked/clogged water filter.
3. Voltage check: Check range of voltage shown below.
YELLOW-WHITE
ON : AC 96 ~138 V

OFF : 0V

<Circulation Pump>
Check Point
<Air Vent>