NIST Technical Note 1848: Sensitivity Analysis of Installation Faults on Heat Pump Performance
In this technical note, the National Institute of Standards and Technology (NIST) analyses the impact of different faults on heat pump performance installed in a single-family residential house. It combines building effects, equipment effects, and climate effects to assess the impact of installation faults on a heat pump’s seasonal energy consumption through simulations of the house/heat pump system. The study found that duct leakage, refrigerant undercharge, oversized heat pump with nominal ductwork, low indoor airflow due to undersized ductwork, and refrigerant overcharge have the most potential for causing significant performance degradation and increased annual energy consumption. The effect of simultaneous faults was found to be additive (e.g., duct leakage and non-condensable gases), little changed relatively to the single fault condition (e.g., low indoor airflow and refrigerant undercharge), or well-beyond additive (duct leakage and refrigerant undercharge).