Residential heat pump heating performance with single faults imposed

A heat pump equipped with a thermostatic expansion valve (TXV) was tested in environmental chambers during steady-state no-fault and imposed-fault operation. The studied system was an R410A split residential heat pump with an 8.8 kW nominal cooling capacity, Seasonal Energy Efficiency Ratio (SEER) of 13, and Heating Seasonal Performance Factor (HSPF) of 7.8. The imposed faults were compressor valve leakage, outdoor improper air flow, indoor improper air flow, liquid line restriction, refrigerant undercharge, and refrigerant overcharge. Evaporator fouling, condenser fouling, and refrigerant overcharge caused the greatest performance degradation. We observed substantial commonality between sensitive features in the heating and cooling modes; however, several different features were identified for the heating mode as more sensitive.