Analysis and survey of faults for air source heat pump water heater/chiller

Before developing an automated fault detection and diagnosis (FDD) system, it is important to identify the most important faults to consider. This paper firstly analyzes the common faults of air source heat pump water heater/chiller (ASHPWHC) units in heating mode on the basis of fault tree analysis (FTA). Then the results of the faults survey conducted among the major Chinese ASHPWHC unit users and service technicians are presented in terms of frequency Of Occurrence and relative cost to repair. Base on the analysis and survey, many of the important and difficult to diagnose ASHPWHC unit faults were identified. This will provide firm foundations to invest an automated fault FDD system of ASHPWHC units.