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Living without hot water is bad. Therefore, if the house is not provided centrally by hot water supply, it is necessary to install a water heater. If the housing is not equipped with heating from the boiler house, the CHP plant or the connection to the networks of the device for water heating is impossible for different reasons use electric boilers (although this name is not completely correct, it has already taken hold, according to the rules it's just water heaters). Let us consider in more detail the principles of the operation of boilers, and their varieties.
How does an electric water heater work?
When a current passes through a conductor having a resistance, according to the Joule-Lenz law it heats up (here is the defining formula the ratio of the parameters of the values of thermal energy and electric current according to it is Q = R * I2, here Q is the thermal energy, R is the resistance, I - current). With the conductor in the water, the heat that is released is transferred to it.
Although, it should be noted, water heaters have been announced for today, which operate on the principle of direct transferring energy (through microwave radiation) to water molecules, but time will pass when they are widely spread.
It should be noted that all electric boilers are equipped with temperature control systems, they can be assembled as by the simplest scheme with the help of bimetal switches, or be more complex up to the application microprocessors.
Also, almost all heaters, especially storage tanks, have over-pressure protection systems, most often safety valves.
There are two types of electric boilers for heating water:
- Direct-flow boiler, water is heated, passing through heat exchangers, which have a large area. Such devices are more compact and provide heat immediately after being connected to the network. However, they have a large specific electrical power and in many cases are demanding of suitable wiring and protective devices.
- Cumulative - here heaters of lower power (hence consuming less current) are used. Heating water does not occur in the flowing stream, but in the tank (which is necessarily supplied with thermal insulation). The advantage of such a device is not only in the smaller current that passes through the electric heaters, but also in that that they can easily cope with the peak (for example, in the morning when the whole family takes a shower and washed) with expenses water. Also, with widely implemented differentiated payment for electricity (at night, kilowat costs less), using them is justified for economic reasons - the water can heat up when the electricity meter counts at the minimum tariff (at night time). The disadvantages of storage electric boilers include their considerable size. If you need such a heater, be sure to understand the logic of the operation of its control systems. From this, as well as the quality of thermal insulation of its housing depends - how much the boiler consumes.
What is heating elements
In order to finally understand the principle of the electric boiler, you need to understand how the TEN is arranged (this is more correct abbreviation, although it is often used more suitable for pronunciation in Slavic languages THEN).
Decoding of the shortening of the heater is a tubular electric heater. It is a pipe (metal, porcelain, glass, etc.) in which a heating element is located surrounded by a layer of a heat-resistant dielectric.
Their geometric dimensions and shape can be the most diverse - straight, "U" - shaped, bent into a spiral. Connectors or threads for the connection of electric current can also be located in different ways, either at one end of the pipe or both. It should be noted that this device was invented and patented in the middle of the century before last.
Principle of operation
In addition, that we have considered the general principle of the operation of electric boilers, we will consider their individual varieties. And we will make a reservation, the difference is not so much with the type of electric heaters, the classification of which we have already dismantled, but more to the design features. Therefore, we will consider, some special types of electric boilers, and how they work, we will give each a small paragraph. Although these heaters differ from standard types and not much, in order to own the situation, they must be familiarized with.
Boilers electric with dry TEN
Typically, the TEN is directly in the water, and its connection to the body is separated by sealing gaskets. However, there is a variety called electric boilers with dry TEN, in them the heating elements are in cavities and are isolated from contact with water. These heaters are safer (there is a double protection against penetration of the potential hazardous for life in water, which is still a conductor) and they can use cheaper fuel elements.
Another plus of such devices is a simple replacement of the heating elements themselves, no additional gaskets are needed, you can simply remove the failed TEN and install a new one. Moreover, there is no difference what kind of this kind, such water heaters are much easier to maintain.
Double-circuit electric boiler
This unit is designed to heat water, both with the help of electric current, and with the help of heat supply systems. The main feature that has a double-circuit electric boiler is that in addition to the heaters there are also heat exchangers for hot water supply, which work from heating. This approach allows providing housing with hot water, even in the period when boiler houses or combined heat and power plants do not work.
The advantage of this system is also that the heating of water by electricity is always more expensive than the use of heat networks.
Most often these devices are equipped with an automation system that allows not only to switch heating elements, but also when necessary. And it can be both a running electric boiler, and an apparatus that operates on a cumulative basis. Even because large sizes of the device are required to accommodate two types of water heaters, two-circuit boilers are more often accumulative.
In short this is all that can be told about boilers heating water using electricity in a small article. Although in order to have exhaustive information on this topic, one must constantly monitor novelties, both in heating engineering and in the latest developments of electrical companies. But this is already a topic for the book, not an article.