What is Hot water storage tank

Hot water storage tanks (also known in Afrikaans as hot water tanks,thermal storage tanks, hot water thermal storage units, thermal storage tanks,hot water tanks, and geysers) are tanks used to store hot water for space heating or home use.Water is a convenient heat storage medium because of its high specific heat capacity.This means that it can store more heat per unit weight than other substances.Water is non-toxic and low cost.An efficiently insulated tank can keep stored heat for days reducing fuel costs.Hot water tanks may have built-in gas or oil burner systems electric immersion heaters.Some types use an external heat exchanger, such as central heating systems, or use hot water from other sources of energy.Domestically, fossil fuel burners, immersion electric elements or district heating schemes are most typical.

Water heaters for washing, bathing or laundry have a thermostat control to adjust the temperature between 40 and 60 °C (104 and 140 °F) and are connected to a domestic cold water supply.Where the local water supply contains large amounts of dissolved minerals (such as limestone), heating the water can cause the minerals to precipitate (scale) in the tank. After only a few years, the tank may leak due to corrosion, the problem is exacerbated by dissolved oxygen in the water, which accelerates the corrosion of the tank and fittings.

Insulation 

Typically, hot water storage tanks are wrapped with insulation to reduce energy consumption, speed up the heating process, and maintain the desired operating temperature.Thicker insulation reduces standby heat loss.Water heaters come in different insulation grades, but extra insulation can be added to the outside of the water heater to reduce heat loss.In extreme conditions, the heater itself may be completely enclosed in a specially constructed insulating space.The most common type of water heater insulation is fiberglass, held in place with tape or straps or the outer jacket of the water heater.Where burners are used, the insulation must not block the air flow or the escape of combustion gases.Another common insulation used in storage tanks is polyurethane foam (PUF) insulation.If access to the inner tank is a priority (where the local water supply has particularly aggressive mineral or oxygen levels), the PUF may be applied in encapsulated form, allowing insulation to be removed for periodic integrity checks, and Repair tanks when needed.Very recently sensible storage systems has been commercialized using innovative supported vacuum insulation.This technology is now making it possible to store thermal energy is small to medium-sized systems for weeks without any significant heat losses. Where possible it has the potential to use affordable sensible thermal storage for medium-term energy storage.

Solar hot water storage tank

In a solar hot water system, a solar hot water storage tank stores heat from solar collectors.The tank has a built-in heat exchanger to heat the cold domestic water.In relatively temperate climates, such as the Mediterranean, (highly insulated but metal-clad) tanks are often mounted on the roof.All of these tanks suffer from the same problems as artificially heated tanks, including limestone deposits and corrosion, and experience a similar drop in overall efficiency unless rigorously maintained.