Circulation Pump ("A" Models Only) - Navien NPE-180A Service Manual

4.11.15 Circulation Pump ("A" models only)

Part
1. Pump operates when using internal or external hot water circulation.
Function
2. Internal circulation will minimize the effect of temperature fluctuations and external circulation delivers hot
Failure Event Unable to detect or measure water flow rate when the pump is called to operate.
1. The water heater freezes.
Effects 2. Temperature fluctuations when the water heater is set to internal recirculation.
3. Hot water is not quickly available at fixtures when the water heater is set to external recirculation.
Error Code E438
1. Visual inspection: Check the circulation pump connection wire.
Diagnostic
2. Voltage check: Check range of voltage shown below.
YELLOW-WHITE
Color/Number
●
of wires
●
72 NPE Service Manual
water to fixtures quickly resulting in water conservation.
* Check for blocked/clogged water filter.
ON : AC 96 ~138 V
OFF : 0V
Check Point
Version 2.21