Navien NCB-180, Service Manual

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66 NCB Service Manual Version 1.0
4.9.7 APS
Part Check Point
Function
Detecting the air pressure entering the burner system.
Failure Event
1. Combustion noise occurs.
2. Imperfect and/or abnormal flame occurs.
3. Occurs when APS does not detect proper voltage.
Effects
1. The boiler is not operating.
2. Produces excessive carbon monoxide emissions.
Error Code
E110
Diagnostic
1. Visual inspection: Connection and/or breakage of wires.
2. Voltage check: Check range of voltage shown below.
3. Check the exhaust duct for obstruction or blockages.
4. Check the condensate trap and drain piping for obstruction or blockages.
5. Check for decreased hot water output.
Color/Number of wires

RED-BLACK: DC 5 V

WHITE-BLACK: DC 0.3 ~ 4.5 V