Water Heater Facts
Water heating is a method of heat transfer using an energy source to heat water above its initial temperature. Typical hot water domestic uses include cooking, washing, bathing and heating up space. Hot water and water heated to steam have various applications in the industry.
Water is traditionally heated domestically in vessels known as water heaters, kettles, cauldrons, pots, or coppers. Such metal vessels heating a batch of water do not deliver continuous heated water supply at a preset temperature. Hot water rarely occurs naturally, usually from natural hot springs. The temperature varies with the rate of consumption, getting cooler as the flow rises.
Appliances that provide continuous hot water supply are referred to as water heaters, hot water heaters, hot water tanks, boilers, heat exchangers, geysers (only in Southern Africa), or calorifiers. These names depend on the region, and whether they heat drinking or non-drinking water is in domestic or industrial use, as well as their source of energy. For residential systems, domestic hot water (DHW) is also called potable water heated for use other than space heating.
Commonly used for heating water are fossil fuels (natural gas, liquefied petroleum gas, oil), or solid fuels. These can be consumed directly or can generate electricity which, in effect, heats the water. Heat water electricity may also come from any other electrical source, such as nuclear or renewable energy. Alternative energy such as solar energy, heat pumps, recycling of hot water heat, and geothermal heating can also heat water, often in combination with fossil-fuel or electric-powered backup systems.
In some countries, densely populated urban areas provide hot water district heating. In Scandinavia, Finland and Poland, in particular, that is the case. District heating systems draw electricity from combined heat and power (CHP) plants for water heating and space heating, industrial waste heat, incinerators, geothermal heating, and central solar heating. Actual heating of tap water takes place at the premises of the customers in heat exchangers. Given the expected high availability of district heating systems, the consumer generally does not have an in-building backup system.
Domestic hot water used in households in the United States today is most commonly heated with natural gas, electric resistance, or a heat pump. Hot water heaters with electric heat pumps are significantly more efficient than hot water heaters with electrical resistance but also more expensive to buy. Some power utilities offer funding to their customers to help offset the higher first cost of energy-efficient hot water heaters.
Hot water storage tank
A hot water storage tank (also known as a hot water tank, thermal storage tank, hot water thermal storage container, heat storage tank, and hot water cylinder) is a water tank used to store hot water for heating space or domestic use.
Water is a versatile medium for heat storage since it has a high specific heat capacity. It means it can retain more heat per unit of weight, relative to other substances. Water is non-toxic and it costs nothing.
An effectively insulated tank can hold the stored heat for days, reducing the cost of fuel. Hot water tanks may have an integrated gas or an oil burner system, heaters for electrical immersion. Some types use an external heat exchanger like a central heating system or heated water from a different source of energy. A fossil-fuel burner, electrical immersion components, or a district heating scheme is the most common in the domestic sense.
Water heaters for cooking, bathing or laundry have thermostat controls in the range of 40 to 60 ° C (104 to 140 ° F) to regulate the temperature and are connected to the domestic cold water.
Where the local water source has a high content of dissolved minerals such as calcareous, water heating allows the minerals to precipitate (scaling) into the tank. After only a few years, a tank may develop leaks due to corrosion, an issue exacerbated by dissolved oxygen in the water that accelerates corrosion of both tank and fittings.