Seasonal performance assessment of sanitary hot water production systems using propane and CO2 heat pumps

Heat pump water heaters can increase the energy efficiency in sanitary hot water produc-tion, which is a relevant share of the final energy consumption in multiresidential and tertiarybuildings. Refrigerants for these heat pumps are changing due to the F-Gas Regulation whichbans high-GWP fluids. While CO2is an established solution, propane is a promising low-GWP alternative for heat pump water heaters serving large users in the tertiary sector, whererefrigerant charge limits (due to propane’s flammability) can be bypassed by installing theheat pump outdoors. Here, the components of a CO2and a propane air-water heat pumpsystems of 40 kW are sized and their COPs are compared in different climates; then, the two heat pumps are coupled to a storage tank and a user demand profile (hospital and school). For three different locations, tank size necessary to maintain users’ comfort and seasonal performance factor are evaluated through simulation.