Navien NHB-055 Service Manual page 4

5.2.15 278Error
5.2.16 279Error
5.2.17 291Error
5.2.18 302Error
5.2.19 352Error
5.2.20 353Error
5.2.21 515Error
5.2.22 517Error
5.2.23 594Error
5.2.24 615Error
5.2.25 740Error
5.2.26 777Error
5.2.27 782Error
5.2.28 784Error
5.3 Troubleshooting guide by symptom
5.3.1 Noise
5.3.2 Water Temperature Issue
5.3.3 Circuit breaker operation
6. Replacement of Parts
6.1 Replacement Procedure
6.2 Components Replacement Instructions
6.2.1 PCB
6.2.2 Fuse
6.2.3 Fan (Combustion Air)
6.2.4 Flame Rod
6.2.5 Ignition Transformer
6.2.6 APS
6.2.7 Main Gas Valve
6.2.8 Condensate Trap
6.2.9 Water Pressure Sensor
4 NHB Service Manual
7. Components Diagram and Part List
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7.1 Case Assembly
114
7.2 Heat Exchanger and Waterway Assembly
115
7.3 Combustion Parts Assembly
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8. Inspection and Maintenance Schedule
118
8.1 Annual Servicing
119
8.2 Maintenance Report
119
8.3 Maintenance Schedules
120
8.4 Inspection Report
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Version 1.0