Secondary Heat Exchanger - Navien NHB-055 Service Manual

4.9.11 Secondary Heat Exchanger

Part
Function
Failure Event
Effects
Error Code
Diagnostic
Version 1.0
1. Main part for heat transfer from the burner.
2. There are multiple paths of water pipes on the heat exchanger as well as inside the combustion
chamber which minimizes heat loss.
1. Water and/or exhaust gas leakage through a crack.
2. Improper heat transfer can cause the water in heat exchanger to boil.
1. Exhaust gas leakage.
2. Excessive heating of the water that produces boiling noises.
E016, E030, E047
1. Visual inspection: Check if there is a crack on the surface of heat exchanger.
2. Sound inspection: Check if boiling occurs.
Check Point
NHB Service Manual 75