Practices

Effect of heat pump commissioning faults on annual energy use

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This slide presentation describes the main results of a study operated by the National Institute of Standards and Technology (NIST) in the USA, to understand the impact of commissioning common faults on the energy consumption of an air-to-air heat pump installed in a single-family house. Through annual simulations, the study found that duct leakage, refrigerant undercharge, oversizing of the heat pump with nominal ductwork, low indoor airflow due to undersized ductwork and refrigerant overcharge, have the largest 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 relatively to the single-fault condition, or well-beyond additive.