Experimental Assessment of the Potential Demand and Energy Reduction by Retrofitting a Boiler With a Commercial Air Source Heat Pump at a Students’ Residence on University Campus

Abstract

Sanitary hot water consumption in the University residence contributes to a significant power and energy usage in relation to the energy consumed by other electrical devices. The study focused on retrofitting a 12kW boiler with two 1000 L storage tanks, with a 4.0 kW commercial air source heat pump (ASHP) unit to provide sanitary hot water at 55oC. A data acquisition system was built and employed in monitoring the operating performance of the electric boiler prior to intervention as well as operating performance of the ASHP water heater after the intervention. The results revealed that for the electric boiler, the average daily volume of hot water consumed was 1865 L, with an average power and energy consumption as well as load factor of 12.13 kW, 133.85 kWh and 0.464, respectively. In addition, the average daily volume of hot water consumed by the air source heat pump water heater was 1848 L while the average power, the average energy consumed and the load factor were 4.41 kW, 41.45 kWh and 0.370, respectively. We could conclude without reservation, that by retrofitting the electric boiler with a heat pump in a student residence (occupied by 75 female postgraduate students) on the University campus, an average daily energy saving of 94.40 kWh and a load factor reduction of 0.124 was realized while the average daily coefficient of performance was 3.10.