The energy boost from the water is 351.6 joules. The average power utilized to heat this water is 0.023 watts because it took 252 minutes (5,120 seconds). This means that it takes about 2.3 hours for one watt of power to heat one liter of water in our example.
Heating water is an important application of electricity because it is easy to do and can be done with simple equipment. Heating water is needed in homes when there is no hot water available or when using very little heat to bathe or wash clothes is more cost-effective than buying extra hot water. In factories, heating water is used in processes where it is not convenient or possible to use a boiler; examples include small batches of hot water for steaming vegetables or making tea. Electricity is always useful if you want to work or play while your hands are warm, so heating water is another application that fits in well with solar power.
There are two main types of devices used for heating water: resistive heaters and electronic heaters. Resistive heaters consist of a metal rod that passes through the water and heats it by contact. The water is then heated by radiation and conduction. Electronic heaters use an electric current to heat a metal element that in turn heats the water.
Watts = 3.1 x Gallons x DT (in degrees Fahrenheit)/Heat-Up Time (in hrs) Example: To heat 20 gallons of water by 100 degrees Fahrenheit in 30 minutes (0.5 hours), multiply 3.1 x 20 x 100/0.5 = 12,400 Watts. To determine the watts required to heat flowing water, use the following equation: Watts = 165 x Gallons Per Minute x Degrees Celsius (in degrees Fahrenheit) / 10.56 Example: To find the watts required to heat 20 gallons per minute at 100 degrees Fahrenheit, use this equation: 165 x 20 x 100/10.56 = 11,620 Watts.
A heating system can be divided into two parts: the heater and the ducting. The ducting is the piping that carries heat from the heater to various points in the house. Ducts are usually made of metal, although fiberglass or plastic ducting is now being used instead. Heaters come in a variety of types. If you need heat only for a few rooms, an electric blanket or space heater will do the job nicely. If you need to provide heat for a large area, such as all floor space in a home, then consider a hydronic heating system. Hydronic systems use a boiler that produces steam that flows through tubing installed under floors and up into radiant heating elements that emit heat when water reaches their hot side.
The amount of heat needed for home heating depends on the temperature difference between the inside and outside temperatures.
In our kitchen, we need to add energy—165,000 joules (or 0.046 kilowatt hours) in the form of heat to bring that 500 mL of water from room temperature (21C) to boiling (100C). That's not a lot of energy compared with other processes such as melting ice or burning fossil fuels. But it is enough to be noticeable at home and over time could amount to something significant if all your water heating is done by boiling.
If you count only the electricity used for hot water production but not other household uses such as lighting, washing machines, etc., then the amount of energy needed to produce 1 kg of hot water is about 17 watt-hours (the term "watt hour" refers to the energy content of one watt of electrical power applied for one hour). This means that to produce 1 kg of hot water, you would need about 17 watts of power for one hour. Multiply this by the total number of kilograms of water heated each day and you arrive at an estimate of how much electricity is used by domestic hot water systems around the world. It is usually less than 1 kilowatt, or 2,500 watts, which is equivalent to the power consumption of about 10 ordinary light bulbs.
The amount of energy needed to produce 1 kg of hot water varies depending on how much heat is lost during production.
The tank requires 7800 watts per hour to be heated to the requisite 60 degrees Celsius. As a result, if you have a 120-litre tank, your hot water demand is 7.8Kws. Your requirement would be 19.5 kws if you had a 300-litre tank. The total energy required to heat the water in your house for four hours is 3840 joules.
Heating water to a temperature of 60 degrees Celsius uses about 20% of its energy content, so 7800 watts an hour is enough to heat water from 0 to 60 degrees Celsius. If the load was constant, this would require a heater that is always on. However, most households need some time between calls for hot water, so they use storage heaters, which can be turned off at night.
Heating water to just below boiling point (100 degrees Celsius) needs only a few percent of the power of heating it to 60 degrees. So 7800 watts an hour is enough to heat water from 100 to 104 degrees Celsius. Again, if the load were constant, this would require a heater that is always on.
As we have seen, it takes about 7800 watts an hour to heat a 120-litre tank of water from 0 to 60 degrees Celsius. This means that if you drew this much power from the electricity grid, you would be disconnected from it for over an hour.