Electric boilers, principles of operation and varieties
Living without hot water is bad. Therefore, if the house is not provided with centralized hot water supply, it is necessary to install a water heater. If the dwelling is not equipped with heating from a boiler room, CHP, or it is impossible to connect an apparatus for heating water to the networks for various reasons, electric boilers are used (although this name is not entirely correct, it has already taken root, according to the rules, these are just water heaters). Let's consider in more detail the principles of operation of boilers, and their types.
How does an electric water heater work?
When current passes through a conductor with resistance, according to the Joule-Lenz law, it heats up (here is the formula that determines the ratio of the parameters of the values of thermal energy and electric current according to it - Q = R * I2, here Q is thermal energy, R is resistance, I is current). By placing the conductor in water, the generated heat is transferred to it.
Although, it should be noted, today water heaters have been announced that work on the principle of direct energy transfer (through microwave radiation) to water molecules, but it will take time for them to spread widely.
It should be noted that all electric boilers are equipped with temperature control systems, they can be assembled according to the simplest scheme using bimetallic switches, or be more complex up to the use of microprocessors.
Also, almost all heaters, especially storage ones, have overpressure protection systems, most often these are safety valves.
Classification
There are two types of electric boilers for heating water:
- Direct-flow boiler, water is heated by passing through heat exchangers with a large area. Such devices are more compact and supply heat immediately after being connected to the network. However, they have a high specific electrical power and in many cases are demanding for suitable wiring and protective devices.
- Accumulative - heaters of lower power are used here (therefore, they consume less current). The water is heated not in a passing stream, but in a container (which is necessarily provided with thermal insulation). The advantage of such a device is not only in the lower current that passes through the electric heaters, but also in the fact that they can easily cope with peak (for example, in the morning when the whole family takes a shower and washes) water consumption. Also, with the widely implemented differentiated payment for electricity (at night, a kilowatt costs less), their use is justified for economic reasons - the water can heat up when the electricity meter counts at the minimum tariff (at night). By cons storage electric boilers can be attributed to their significant size. If you need such a heater, be sure to understand the logic of its control systems. From this, as well as from the quality of the thermal insulation of its body, it depends how much the boiler consumes.
What are heating elements
In order to finally understand the principle of operation of an electric boiler, you need to understand how the heating element works (this is a more correct abbreviation, although it is often used more suitable for pronunciation in the Slavic languages TEN).
Decoding of the abbreviation TEN - tubular electric heater.It is a pipe (metal, porcelain, glass, etc.) in which a heating element is located surrounded by a layer of heat-resistant dielectric.
Their geometrical sizes and shapes can be very diverse - straight, “U” -shaped, bent into a spiral. Connectors or threads for connecting an electric current can also be located in different ways, either at one end of the pipe or at both. It should be noted that this device was invented and patented in the middle of the nineteenth century.
Principle of operation
In addition to the fact that we have examined the general principle of operation of electric boilers, we will consider their individual types. Moreover, let's make a reservation, this difference refers not so much to the type of electric heaters, the classification of which we have already analyzed, but more to the design features. Therefore, we will consider individual special types of electric boilers, and how they work, we will devote a small paragraph to each. Although these heaters do not differ much from standard types, in order to control the situation, you definitely need to familiarize yourself with them.
Electric boilers with dry heating elements
Usually, TEN is located 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 located in cavities and are isolated from contact with water. These heaters are safer (there is a double protection against the penetration of a life-threatening potential into water, which is still a conductor) and cheaper fuel elements can be used in them.
Another plus of such devices is the simple replacement of the heating elements themselves, no additional gaskets are required, you can simply remove the failed heating element and install a new one. Moreover, there is no difference what kind it is, such water heaters are much easier to maintain.
Double-circuit electric boiler
This device is designed to heat water, both using electric current and using heat supply systems. The main feature that a double-circuit electric boiler has is that, in addition to heating elements, heat exchangers for hot water supply, operating from heating, are also located in it. This approach allows you to provide housing with hot water, even during the period when boiler houses or combined heat and power plants are not working.
The advantage of this system is that heating water with electricity is always more expensive than using heating networks.
Most often, these devices are equipped with an automation system, which allows not only switching the heating elements, but also if necessary. And it can be like a boiler flow-through electricand a device operating on the accumulative principle. Even due to the need to accommodate two types water heaters large device sizes, double-circuit boilers are more often accumulative.
In short, this is all that can be told about boilers that heat water using electricity in a short article. Although, in order to have comprehensive information on this topic, you need to constantly monitor the news, both in heating technology and in the latest developments of electrical companies. But this is already a topic for a book, not an article.