The energy consumption associated with a home water heater has two components: (i) the energy that must be supplied to bring the temperature of groundwater to the heater storage temperature, as it is introduced to replace hot water that has been used; (ii) the energy needed to compensate for heat losses incurred while the water is stored at the prescribed temperature. In this problem, we will evaluate the first of these components for a family of four, whose daily hot water consumption is approximately 100 gal. If groundwater is available at 15°C, what is the annual energy consumption associ- ated with heating the water to a storage temperature of 55°C? For a unit electrical power cost of $0.18/kW · h, what is the annual cost associated with supplying hot water by means of
(a) electric resistance heating or
(b) a heat pump having a COP of 3.