An electric boiler (EC) is a source of heating, as well as hot water supply, and has an ultra-high efficiency of up to 99%, unlike natural fuel boilers. Such heating units are indispensable in areas where there is no natural gas and coal. They do not pollute the atmosphere with emissions of harmful flue gases, operate almost silently and have a control range from 10 to 110%.
The rating of electric boilers determines the most successful modifications, which in practice provide a high level of automation and safety. Such boiler units are well integrated into the Smart Home system and do not pollute the environment.
Types of electric boilers
In the distribution network of climate technology today you can find several dozen different modifications of electric boilers, which differ from each other in the principle of operation, the flow pattern of the coolant and the operating voltage. However, all these models of boilers are united by a common approach to heat generation, which is produced by converting electricity into heat and releasing the highest efficiency, reaching 95 — 100%. Decent models are characterized by a high level of automatic protection and regulation in the range from 10 to 110%.
In order for the user to better navigate among the numerous brands of EC, they are all grouped according to several criteria:
- by type of heating elements: electrode, heating elements and induction;
- the number of heating circuits inside the boiler body: single-circuit and double-circuit;
- operating voltage: for single- and three-phase 220 V / 380 V.
The rating of electric boilers of this modification is quite high, they always occupy the first positions, despite the high cost. The principle of their operation is based on the use of heat released during the chaotic movement of ions, therefore these ECs are also called ionic and ion-exchange.
In order for the ion-exchange process to proceed inside the housing, two different-polarity electrodes are installed in the equipment, which change their electropolarity «cathode-anode» with a current frequency of 50 times / sec.
A change in polarity causes the movement of ions from one electrode to another, while the process proceeds with the release of heat, which is transferred through the walls of a closed internal heat exchanger to the heated water of the heating circuit.
At the same time, the heating coolant is in a separate “compartment”, not mixing with the heated medium. This requirement is caused by the need to create a salt balance of the heating water in order to increase the ionization process.
The special advantages of this type of boilers are high performance, ultra-low heat loss, the ability to work on low-quality electricity parameters (up to 180 V), the absence of scale on the heating heating surfaces and low dimensions. Such an electric boiler for heating a private house in the rating of climate equipment occupies a consistently high position.
The disadvantages of such modifications are attributed by experts to a relatively high cost compared to conventional heating elements, the need to change electrodes, which decrease during heating due to the transition of ions. Also, such equipment requires the installation of a serious grounding system, since current leakage through the case is possible.
Heating elements boilers
This is the most budgetary and proven version of electric boilers. Such equipment has been used for a long time at residential and industrial facilities, so its design is optimized and simplified.
The principle of operation of such devices looks something like this: EC consists of a housing in which several heating elements with high resistance are installed. When voltage is applied to the heating elements, thermal energy begins to be released, which is transferred to the circulating heated medium of the heating circuit.
A distinctive advantage of the design of such ECs is their high maintainability: in the distribution network, you can choose any necessary heating element and replace it yourself. In addition, the installation of several heating elements allows for cascade control of the heating process. Boilers of this type can work with natural and forced circulation.
The disadvantages of these ECs include, first of all, the relatively high loss of heat and energy, so their maximum efficiency does not exceed 95%. It is in connection with this that the rating of an electric boiler operating on the basis of a heating element is low.
Important! A high process of scale formation on heating elements can disable them in the first year of operation. And this is with a standard service life of 5-6 years. Therefore, for these types of boilers, internal circuit water is required, equal in composition to distilled water. Sometimes special non-freezing compounds are poured into the boiler, which help reduce the risk of breakdown.
These boilers are innovative climate technology with a perfect heat transfer process with an installation efficiency of almost 100%.
The induction boiler consists of a body and an inductor through which an electric current is passed. At the same time, heat will be released contactlessly on the conductor located in the field of the coil, which occurs due to the principle of magnetic induction. The heat, in turn, is taken away by the circulating water of the heating circuit. So, in fact, the heating process takes place.
Such designs of the boiler have their own distinctive advantages: they do not have increased requirements for the quality of the water of the internal circuit, since scale formation processes do not occur in the boiler due to non-contact heating. In addition, this is the most “quiet” type of boiler, which is also important.
The disadvantages include high cost and large dimensions. Such an electric boiler has an average rating due to the high price.
Single and double circuit electric boilers
Electric boilers in practice can function according to two principles. In the first case, the equipment operates according to the simplest single-circuit scheme, during which only the heat carrier circulates through the boiler, which heats the object.
In the second case, the device acts as a source of heat supply, operating on a two-circuit heating scheme. At the same time, the design of the boiler has two circuits independent of each other: in one, the water is heated for subsequent heating, and in the other, for the needs of hot water supply.
The second option is usually equipped with an external storage tank. In this case, it is possible to unload the operation of the boiler by switching to the main heating at night (with differentiated tariff metering of electricity with a minimum tariff). Storage tanks can contain a daily amount of hot water for the whole family, or they can have much more.
Important! The design of external tanks allows you to keep water hot for several days without temperature loss.
In addition, the considered connection scheme of a double-circuit electric boiler is well integrated to work with «green» energy carriers, which are: the sun, wind and heat pumps, which increases the rating of electric boilers due to the versatility of operation.
Three-phase electric boilers
All existing electric boilers operate on two types of voltage, depending on the working heating power. Boilers with a power of up to 10 kV are considered domestic and operate from a network with a voltage of 220 V. At the same time, the input power to the house must ensure the total load on both the EC and domestic consumption.
With an EC power of more than 10 kW, a three-phase power supply at the entrance to the boiler with a voltage of 380 V is required. In addition, for the operation of such equipment, a permit from the Energy Supervision Authority (for the right to install electric boilers) is required, which is quite difficult to obtain. A convincing user argument will be required explaining why he cannot use other types of heating.
Approximate calculation of the electric power of the boiler
A complete calculation of the power of an electric boiler can only be performed by specialists using a complex heat engineering software package, since it depends on the climatic characteristics, building volume of the building, type of roof and basement, glazing area and thermal resistance of the walls, as well as many other factors that, when manually almost impossible to account for.
Therefore, to designate approximate indicators, an enlarged calculation is performed, the results of which can be used when choosing boiler equipment. To determine the power of an electric boiler located in the central regions of Russia, a simple formula is used: Mek \u003d 0.1x P from,
- Mek — EC power, kW;
- P from — heating area in m2.
For example, for a two-story house with an area of 210 m2, the minimum electrical power is calculated as follows: 0.1 x 210 = 21 kW.
Additionally, a DHW system will require 25-30%, or about 6 kW.
In addition, an additional power margin of at least 15% is taken into account, so the final result will be at least 31 kW.
Important! For the northern regions of the country, this figure should be increased by 30%, and for the southern regions — reduced by 20%.
It must also be taken into account that the calculated boiler output is the maximum for the lowest outside air temperatures. There will be no more than 20-30 such days in the heating season, and the rest of the time the boiler will work with an underload in terms of power.
Therefore, when choosing a boiler, it is better to take not one, but two or three devices so that they provide the total power of the heating load. This will allow the equipment to work more stably and for a long time. In addition, the user will always have a reliable reserve for the source of heat supply in the event that, at sub-zero temperatures outside, one of the units fails in an emergency.
Which boiler is better: electric or gas
If gas is centrally connected to the house, then, of course, a gas boiler will be better than an electric one. First of all, this is explained by the price of equipment and the cost of thermal energy. Keep in mind that at the moment the prices for electric boilers and the cost of electricity are twice or more higher than gas heating.
But provided that the gas main is not connected to the site and the probability of its connection in the near future approaches zero, then the installation of an autonomous electric boiler house is a completely justified and quickly implemented project.
How to choose an electric boiler and what to look for
After the decision was made to install an electric boiler as a heat supply source, first determine the operating voltage and power, depending on the climatic characteristics of the area of \u200b\u200bresidence and the required load on heating and hot water. The first, in turn, is determined by the heating area, and the second is selected according to water use standards, depending on the number of family members and the level of hot water supply.
After choosing the power of the heat supply source, they are determined with its scheme, which can be natural or forced. The first option can only work in houses of small area and not exceeding 2 floors. In order for the circulation in the heating circuit to have sufficient speed and cover all dead-end sections of the heating network, an expansion tank is placed in the system, selected according to the volume of the heating network.
Forced circulation of the coolant is carried out by a centrifugal pump, which can work with all types and sizes of heating objects. The main thing is to choose the right performance of the electric pump so that it matches the power of the EC.
When choosing a boiler, pay attention to the control and protection system. As a rule, EC automation is completed together with the heating unit at the factory. The user should pay attention to its configuration and control capabilities, as well as to clarify whether it has remote operation functions. The type of heat carrier temperature control system is also important. It can be weather-dependent or based on the internal air temperature in the room. Also, do not forget about obtaining information regarding the possibility of controlling a three-way valve. This is required in order to switch the coolant to different heating and hot water circuits.
This protective device must be suitable for the heat output of the unit and the amount of heating medium in the system. With a power of 30 kW, the minimum volume of coolant is selected from the ratio 1 kW \u003d 15 l: 15×30 \u003d 450 l.
The charging pressure of the expansion tank is assumed to be 1.0 bar with a maximum allowable pressure of 3.0 bar. Given that the coefficient of expansion of water at t=85 °C is 0.034, the volume of the tank should be 90 liters, with a minimum filling of 50% — 45 liters.
Expansion tanks of this size are manufactured by BAXI, Valtec, JILEX, STOUT, Wester and UNIPUMP. The price range varies from 6000 to 12000 rubles. depending on the design of the membrane and the operating pressure in the network.
A circulation pump with a “wet rotor” is mounted in the heating system for forced circulation of water from the internal circuit. The main indicators when choosing electric pumps are as follows: boiler power, temperature difference at the inlet and outlet, as well as a pressure drop that ensures the pumping of the coolant through all local resistances in the house heating network.
Gn = Qeq * 0.86 / ( t2 — t1), m3 / h, where:
- Mon — water flow through the pump, m3/h;
- Qek — thermal power, 30 kW;
- t2 – temperature in the supply pipeline, 80°С;
- t1 — temperature in the return pipeline, 40 °C.
Gn \u003d 30 * 0.86 / ( 80 — 40) \u003d 0.645 m3 / h
Pumps for a heating system in this range are produced by manufacturers: Grundfos, Leberg, OASIS, ONDO, Valtec, Vester, Wilo, ZOTA, Belamos, Whirlwind and Gileks. The cheapest kits cost from 2000 rubles.
Ability to work with a multi-tariff meter
All electric boilers can work with multi-tariff or multi-zone electric meters. Their cost of electricity is charged according to three modes:
- peak 7-10 am and 5-9 pm, 6.79 RUB/kW;
- half-peak 10 — 17, 21 — 23 hours, 5.66 rubles / kW;
- minimum from 11 pm to 7 am, 2.33 rubles/kW.
The expediency of switching to a multi-zone meter arises for consumers when electricity consumption exceeds 1000 kWh per month.
The average monthly energy consumption for an apartment of 100 m2 is over 6000 kWh. Therefore, the real savings in the use of multi-zone accounting for EC is obvious.
In order for the user to make the most of the EC during the hours of the night minimum, additional equipment power and the presence of a volumetric storage tank will be required, in which the coolant can be heated at night and circulated through the heating system in the morning.
Important! Installation of a multi-zone meter for electric boilers must be agreed with Energonadzor.
Three way valve control
Efficient heat supply systems from an electric boiler provide for the presence of a three-way valve in the circuit. It can be included in the kit, or it can be purchased separately in accordance with the characteristics of the intra-house network.
The task of this device is to perform high-quality regulation of the temperature entering the radiators. At the same time, the boiler operates with a stable load and with the same water temperature at the outlet.
Another important process is regulation by mixing cold water from the return with hot water from the boiler. It is produced by the operation of three nozzles and a mixing chamber, which the valve has. The most promising in terms of the efficiency of this process are devices with an electric drive. They can be integrated into the general automation of EC regulation.
This is an innovative EC automatic control system. It is installed so far only on Western modifications of electric boilers and is very expensive: sometimes its cost exceeds 50% of the price of the boiler. Nevertheless, the savings from its implementation allows the user to return the money spent in 2-3 years, which is considered a very high efficiency of investments in the heating system.
It differs from the traditional regulation of the operation of the boiler, which operates according to the temperature of the internal air. The work in the weather-dependent system is controlled by the outside air temperature, which is an order of magnitude more accurate. In addition, such a control algorithm does not have a delay effect and eliminates the inertia of the heating networks. As a result, the unit operates with minimal power consumption, and the cost of the generated unit of thermal energy is reduced by 30-40%.
Ability to connect to a load shedding relay
This is a very important boiler protection function, although the device is not supplied. The choice of a protective relay is not carried out depending on the equipment, but in accordance with the total load of electricity consumption in the house. Such a relay is able to control the power of the EC depending on the employment of the electrical network at home. In the event of an overload, for example, when the washing machine, iron and kettle are turned on at the same time, the EC power is automatically reduced.
The setting is performed according to the maximum current strength, upon reaching which the relay contact instantly opens. There are other devices that can control the load of the EC, for example, priority switches. In the event that the total power of the connected devices exceeds the maximum allowed, the relay will turn off the lower priority category and enable the highest priority category to function.
The best inexpensive electric boilers
Inexpensive electric boilers include Russian-made models, they top the rating of electric heating boilers for a private house:
- ZOTA Balance 6;
- EVAN EPO 4;
- RusNIT 208M;
- EVAN Next 7;
- EVAN Warmos-IV-5.
The best electric boilers for the home in terms of price and quality
Western-assembled models are considered more reliable boilers, but they are expensive. Based on the «price-quality» ratio, then experts advise such brands of boilers:
- Vaillant eloBLOCK VE 12;
- Protherm Skat 12 KR 13;
- Bosch Tronic Heat 3000 9;
- Protherm Skat RAY 12 KE /14;
- ZOTA 9 Lux;
- Kospel EKCO. L2 12;
- EVAN EXPERT 12.
The best electric boilers for large rooms
For large areas, several boilers can be installed for parallel operation. When using this mode, modifications of double-circuit boilers are considered the best:
- ZOTA 24 Lux;
- Protherm Skat 24 KR 13;
- ACV E-Tech S 2404;
- Savitr Premium Plus 18.
Expert Tips: The Two Best Ways to Reduce Electric Boiler Consumption
Today, the cost of electricity is quite high, which hinders the use of electric boilers for heating in the house. This can be avoided if you use effective methods to save energy, among which there are two main ones:
- Thermal protection of the external enclosing surfaces of the house;
- The use of weather-dependent control automation, a multi-zone electric meter and a storage tank for nightly water heating.
Customer reviews about electric boilers
With the use of new electric heating technologies, more and more consumers are installing electric boilers as a source of heating. After operating this equipment in conditions of maximum winter load, most users are satisfied with their purchase and are happy to exchange feedback on forums on the Internet, here are some of them:
Igor, 43 years old, Leningrad region: “I purchased an electric boiler Elvin EVP-4.5 with a power of 5 kW for additional night heating, through an indirect heating tank. Works great, though the internal circuit was filled with clean water. At night, the water in the tank heats up, during the day it is spent on heating. The scheme works almost up to — 3 C on the street, then I additionally kindle a coal boiler. At the cost of an electric boiler at night, it is cheaper than coal and clean. Worked the first year without breakdowns.
Olga, 54 years old, Kostroma: “We bought an electric boiler for the dacha Zota Balance 4.5, for 5 kW, we no longer need a total area of \u200b\u200bthe premises of 42 m2, we are very satisfied, it worked for a year without complaints.”
Electric boilers for heating systems are a profitable investment for creating modern conditions for heat supply in the house. They are silent, fully automated and can work in the «Smart Home» system.
Using the existing rating of electric boilers, you can choose a modification for any customer conditions. In order for such insulation to be effective, it will be necessary to take energy-protective measures to insulate the external structures of the house, install a multi-zone electric meter and weather-dependent automation.