How Do You Size Hot Water Storage Tanks?

A hot water storage tank holds the water that the heat pump water heater heats up. The capacity of the tank is the amount of water it holds in gallons. Its rating is the amount of that water, in gallons, the heater can supply per hour. How much the heater can heat depends on the source of heat--burner or element--and the size of the burner or element. Properly sizing/choosing the correct hot water storage tank for your home depends on how many gallons of hot water you use. Estimate your peak hour demand. The peak hour is the hour your household uses the most hot water. When totaling the peak hour demand, make sure you total the number of gallons of hot water used by all persons in your household in that hour. The Encyclopedia of Alternative Energy and Sustainable Living provides a worksheet that gives the average number of gallons used per task such as shaving, hand dish washing, food preparation and automatic dishwasher use, among others (see References). Multiply the average ...  more