#### Question

The maximum flow rate of a standard shower head is about 3.5 gpm (13.3 L/min) and can be reduced to 2.75 gpm (10.5 L/min) by switching to a low-flow shower head that is equipped with flow controllers. Consider a family of four, with each person taking a 6-minute shower every morning. City water at 15$^\circ{}$C is heated to 55$^\circ{}$C in an oil water heater whose efficiency is 65 percent and then tempered to 42$^\circ{}$C by cold water at the T-elbow of the shower before being routed to the shower head. The price of heating oil is \$2.80/gal and its heating value is 146,300 kJ/gal. Assuming a constant specific heat of 4.18 kJ/kgK for water, determine the amount of oil and money saved per year by replacing the standard shower heads with the low-flow ones.