Hot water tanks provide storage for hot water that is used for space heating and domestic uses, such as laundry, bathing and washing dishes. There are various ways that hot water tanks heat water, including gas or oil burners, electric-immersion heaters or an external heat exchanger.
Two main types of hot water tanks are jacketed and unjacketed. Both come with features such as heating the water to 180 degrees Fahrenheit or lower, holding from 80 to 12,500 gallons of water and the customization of linings, heating coils and accessories. Jacketed hot water tanks are designed to control the temperature of the water by using a heating jacket around the vessel, through which a heating fluid is circulated. There are several different jacket designs. Another type is the solar-heated hot water tank. Solar hot water tanks heat water from solar thermal collectors. A built-in heat exchanger then heats the water.
The problems facing hot water storage tanks include limestone deposits and corrosion, which can inhibit the effectiveness of the heat exchanger. Proper installation, maintenance and warranties help protect against some of these problems. The typical lifespan of a water heater and tank is around 10 to 13 years. The cost of replacement is $500 to $1500, as of 2015. However, there are often hidden costs of mounts, vents, pipes and draining systems that may also need replaced.