Effect of heat pump commissioning faults on energy use in a slab-on-grade residential house

This study seeks to develop an understanding of the effect of commissioning common faults on the energy consumption of an air-to-air heat pump installed in a single-family, slab-on-grade residential house. Through annual 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. Depending on the faults involved, the effects of simultaneous faults were found to be additive, little changed relative to the single fault condition, or well-beyond additive. A significant increase in annual energy use can be caused by lowering the thermostat setting in the cooling mode to improve indoor comfort in cases of excessive indoor humidity levels due to installation faults.