Heating with wood and electricity. Combined heating boilers. What are the advantages of wood-fired boilers

When choosing a method of autonomous heating, owners of a private house often face a difficult choice. On the one hand, you should choose a model for the cheapest fuel so that heating costs are minimal. On the other hand, it is difficult to get full confidence in the possibility of a continuous supply of energy, which is especially true for centralized pipelines (gas, electricity).

Therefore, combined options are becoming increasingly popular, for example, a wood and gas boiler. This is the only way to guarantee that the heating season will run with a stable heat supply. Moreover, the choice is not limited to such modifications. Pellets are combined with electricity, coal with wood models, for example, as in combined boilers. Universal heaters easily allow you to bypass seasonal tariff increases, as well as, for example, use nightly price reductions, etc.

Combined modifications, for example, a wood-gas-electricity heater, are often installed to replace old wood-burning stoves or their coal-fired counterparts. firewood and coal are the most affordable in all regions of our country, while they have a relatively low price. The heating system itself is often not redone, limited to replacing a wood-burning boiler with a combined model.

Varieties of combined boilers

Separate universal heating equipment depending on the type of fuel used.

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combined boilers

So, the following combined options are distinguished:

Gas + Solid fuel. Allows you to quickly replace the main gas when it was turned off as a result, for example, of an accident on the line. A wood and gas boiler is one of the most popular solutions due to the good availability of wood.
Gas + Liquid fuel. Such options are convenient in case of periodic failures in gas supply, but require the organization of storage of diesel fuel stocks.
Gas + Electricity + Liquid fuel. A combined option for savings in the absence of a guarantee of timely supplies of gas and diesel fuel.
Gas + Solid and liquid fuel. One of the most versatile models for heating cottages. Great replacement for wood burning stoves.
Gas + Solid and liquid fuel + Electricity. This model makes the owner of a private house completely independent of tariffs and other factors that affect the change of energy carrier. For example, a wood-gas-electricity appliance.

There are universal boilers without connection to a gas main, for example, for coal and firewood with the ability to connect heating elements to be powered by electricity. Heating boilers combined gas firewood are often installed in conditions of interruptions in gas supply. Firewood for heating, including special granules (pellets), causes less inconvenience during storage than other types of fuel. Yes, and there is no smell, as, for example, from diesel fuel (and a gas boiler, sometimes, gives a slight smell).

Another option - a combined gas-firewood-electricity boiler - allows you to become completely autonomous with any changes in tariffs and in other situations. For a wood-gas-electricity device, you don’t have to worry about the same firewood stocks, power outages, etc.

Features of gas-fired boilers for the home

First of all, it is worth noting that in most cases, the gas main is taken as the main fuel, and they switch to wood heating in the event of a shutdown for periods of maintenance or accidents. Of course, for a completely universal approach, it is worth installing a combined wood-gas-electricity appliance, but not everyone can be satisfied with the cost of electricity.

In general, combined boilers can be fired with different solid fuels, almost without changes in its design. So, firewood, coal, briquettes, pellets - everything is on the same level in terms of prevalence, the choice depends on the price of various types in a particular region. That is why gas-fired boilers are popular, solid fuel is easy to replace with an analogue.

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Secondly, it is important to consider that solid fuel boilers are made of steel and cast iron, which makes them resistant to constant high temperatures during the heating season. This is especially important if coal is used as fuel, which gives a noticeably higher temperature in the furnace.

But that also adds to the hassle. The heavy weight of the equipment in some cases requires the strengthening of the flooring in the room in the house allocated for its installation. Cast iron boilers for heating gas-firewood require this without fail. Gas-fired modifications made of light grades of metal can be mounted on a regular floor, in place of a previously occupied wood or coal stove. Wood-gas-electricity appliances are usually light in weight.

There are two more types of combined models: single-circuit (they work only for heating the heating system) and double-circuit (the second circuit heats water for the water supply system in the house). So, the gas-firewood device can be used as a boiler even in the warm season. The same applies to the device firewood-gas-electricity.

It is also worth noting this feature. In addition to the removal of smoke through the pipe when burning with solid fuels, there are solid combustion products that settle in the pan and require periodic disposal.

The most interesting for heating boilers are universal gas-firewood-pellets, which have the ability to work autonomously without human intervention for a long time. Such a heater, instead of wood or gas, is able to work with special granules. Such a combined option eliminates the need to stock up on firewood, because. pellets are usually always on sale. Alternatively, a combined boiler is still convenient.

The most advantageous sides of boilers heating gas firewood

If we put aside the requirements for arranging a separate room in the house, combined wood-fired gas heating boilers will have a whole set of excellent qualities.

The operation of such a universal heating device does not require special skills. Even options such as combi boilers.
The cost of combined models is slightly higher than analogues that can only work, for example, with coal, pellets and a gas version. You can mount it instead of a wood-burning stove, they take up even less space than usual.
The dimensions of a gas-fired heating model, of course, are larger than gas models, but do not exceed analogues with a wood-burning firebox. The wood-gas-electricity device has the same dimensions.
High efficiency - up to 90%. The wood-burning method of heating a room is one of the most effective, the main thing is to use dry, no more than 20% humidity, firewood.
Small emission of harmful substances into the atmosphere.

Compared to heating with electricity or gas boilers, combined gas-fired heating boilers can provide complete independence from utilities. Wood stoves have always been used as the basis of warm home comfort, because. this type of fuel is the easiest to get anywhere.

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What to pay attention to?

When selecting a model, it is necessary to take into account several rules, non-observance of which will lead to an error. As a result, the boiler may not be suitable for a particular house, for example, it may not be powerful enough and the room will be cold. For example, a wood and gas appliance is dependent on the pressure in the line, and when it is lowered, it can give off noticeably less heat.

In technical specifications, in addition to power, the area of \u200b\u200bthe house for which it is designed is usually indicated. The calculations are made by professionals and it is quite accurate. You can use various tables found on the Internet. Particular attention should be paid to power when choosing the most versatile options, such as a wood-gas-electricity appliance.

It is worth considering the possible decrease in gas pressure in the line. This can significantly reduce the heating power. In the absence of a “reserve”, you will also have to use additional heaters powered by electricity. There is no point in heating with such characteristics, it will have to be modernized and incur additional costs.

The next step is to determine the purpose of the combined boiler for heating. It can be purchased both as the main source of heat and for additional heating of running water, i.e. immediately choose the combined option.

Such a boiler is more profitable than a separate boiler, because wood or gas is already consumed for heating, and a separate water heater is usually powered by electricity. Wood heating often allows you to win also in the speed of reaching the desired temperature.

Are there any features in operation?

When buying a combined boiler with wood and gas heating, several operational points must be taken into account, without which the use of firewood as the main source of heat can lead to the fact that the universal method will cause considerable problems.

So, a wood-burning boiler during its operation gradually clogs the chimney with soot, which must be periodically cleaned. Without this, the efficiency of smoke removal will gradually decrease, up to the appearance of problems with ignition, smoke in the room, etc.

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If heating on gas or electricity can operate continuously, then the wood-burning boiler burns out completely after a maximum of 3-4 hours, after which the heating system inevitably begins to cool down. Loading a new portion is done manually, which requires the presence of the owner's home. Therefore, often combined modifications with wood or pellet fuels are used, if possible, in gas heating mode.

Pellets partly allow you to automate the procedure for heating with wood fuel, but you still have to follow the process. Yes, and the stock must be created in advance, otherwise you can be left without heating in the coldest period of the year.

Every year, modern autonomous heating systems are becoming more and more popular among owners of suburban real estate. For one reason or another, traditional gas heating units are rejected by the owners of private houses (mainly due to the high cost and inaccessibility of gas) and they are being replaced by universal combined boilers.

These are surprisingly reliable, functional and productive devices, thanks to which you can provide heating for a house or any other property.

Combined heating boilers: electricity and wood as the main fuel

At present, wood-fired and electric heating boilers are in the greatest demand among combined equipment. A feature of this technique, as you can already see from the name, is the simultaneous operation of both solid fuel (wood, woodworking waste) and electricity. Such versatility is provided due to the unique thoughtful and rather practical design of the equipment.

By and large, heating boilers for wood and electricity differ from traditional solid fuel boilers only in an additionally built-in heating element (installed in the heat exchanger tank). It should be noted that such heating equipment also uses an automation system that allows you to change the boiler power, operating modes, and also provide switching between fuel types.

Heating technology: accessories and functionality extensions

A variety of combined heating boilers, gas, firewood and electricity are often equipped with special sensors and other systems, due to which the performance of the equipment is significantly increased. Such sensors allow equipment to automatically turn on electric heating elements, thereby ensuring the continuity of heating.

Such versatility is especially effective in cases where the power of the equipment in the combustion mode of firewood or other solid fuels is not enough.

Any heating boiler on electricity and wood is also good because it copes well with low-power operating modes. The instruction for such a technique assumes that even with irregular operation of the boiler, it will be able to effectively maintain a constant minimum temperature in the room, eliminating the possibility of freezing of the liquid in the heating system.

Design features of boilers

Any heating boiler for wood and electricity, as a rule, has a rather simple, but at the same time well-thought-out design. Often, a firebox is installed at the bottom of the unit, where any solid fuel is loaded, whether it be firewood, coal or peat.

The heat released during the combustion of the fuel heats the heat exchanger with the liquid, which subsequently enters the heating system.

Heat source: firewood - electricity in the house

If you switch the heat source to the mode of operation on electricity, then the coolant in the system will be heated by heating elements. Yes, and with low-power operation, it is electricity that allows you to automatically maintain a constant minimum temperature of the coolant.

Installation and operating conditions of combined boilers

Unlike traditional heating units, boilers using a combination of several types of energy require special installation and maintenance conditions. It is especially important to consider these requirements for the installation process if the work is done by hand.

To begin with, it is necessary to indicate the fact that a special separate room must be allocated for such heating units in a private house. Also, it is necessary to provide a concrete cushion for the unit, equip the chimney and ventilation system. On our website you can see photos and videos of installed boilers in various houses.

Advice. If you are not confident in your own abilities, entrust all installation work to qualified specialists. Real masters will perform the entire range of work in the shortest possible time, ensuring their high quality and compliance with requirements and standards. In addition, you will have a guarantee for the work performed.

Advantages of solid fuel and electricity boilers

If we compare the combined equipment for heating country houses with traditional gas or simple solid fuel boilers, then their advantages become simply obvious:

Availability and low price of fuel. Due to the possibility of working on solid fuel, it is possible to ensure the combustion of almost any waste from the woodworking industry, the cost of which is simply a penny;
Versatility. Due to the presence of TEN heaters in the design, it is possible to receive heat from the boiler even when there is no possibility of using firewood;
Profitability. Wood and electricity are the most affordable types of fuel in our time, and therefore you can save a lot on installing a combined boiler and heating your home. Savings are especially relevant in the light of the regular rise in gas prices;
Ecological cleanliness and absence of harmful emissions from the heating system;
Availability of automation systems and special programmers. Such equipment makes it possible for the heating equipment to work in automatic mode in the absence of owners in the house;

High quality heating. Woodworking industry products, like electricity, emit a lot of heat, and therefore the heat carrier will be heated as quickly and efficiently as possible. In addition, there are no significant energy losses, as the combined equipment has a well-thought-out design;
Duration of trouble-free operation.

Conclusion

Combined heating systems are a great choice for any private home. The availability of fuel, reliability, versatility and high performance favorably distinguish the units from the total number of heating boilers on the domestic market.

Some half a century ago, the concept of "autonomous heating" meant only one type of heater - a wood-burning stove with a rough heat exchanger.

Today, there are many modern units, compact and safe, capable of extracting heat from other energy sources - gas, diesel fuel, electricity.

They have found wide application in the private sector and are used to heat houses, cottages and even individual apartments in high-rise buildings.

Installation of a double-circuit gas boiler modern modification in a three-room apartment and connecting it to an autonomous heating system will entail a significant reduction in utility bills.

In country houses automated heating equipment can simplify the process of heating a building, eliminating the need to control the degree of combustion of wood / coal and maintain a flame in the furnace furnace.

Natural gas is considered the cheapest energy source., but not all areas, especially summer cottages, are gasified. And the only alternative to solid fuel in such settlements is electricity, so electric heating boilers are widely used there.

But unfortunately, in our conditions, the power supply of objects of the third category, which include summer cottages and residential villages, cannot be called stable. According to the current legislation, the power supply organization has the right to turn off the supply of electricity to these facilities for three days without warning.

And if there was any large-scale accident that requires more time to restore the network, then the organization responsible for the power supply is obliged to notify the residents about the planned dates.

In any case, in winter, even a three-day shutdown can be fraught with a country or residential building - freezing and destruction of water-bearing communications, moisture condensation on internal surfaces, building structures, which leads to the rapid growth of mold fungi and violation of decorative finishes.

How to be in this situation? The best solution would be to install a combined boiler in the heating system that operates on both solid fuel and electricity.

Scheme and principle of operation of the combined boiler "electricity - firewood"

Design

Structurally, boilers "electricity - firewood" resemble conventional solid fuel units, equipped with a heat exchange tank.

The main difference from the latter is the presence of one or more tubular electric heaters built into the tank and a more complex automatic control system.

The combined boiler can be operated both in separate modes (only solid fuel or only electricity), and in a joint one.

For example, you heat a country house with firewood during the day. At night, the temperature drops and the electric heater turns on automatically, maintaining the set parameters.

Combination boiler structure

The design of heating equipment of the "electricity - firewood" class assumes the presence of the following mandatory elements:

Frame. Manufactured from sheet steel coated on the outside with heat-resistant paint.
Firebox for solid fuel. It is located at the bottom of the unit, under the tank.
Smoke pipe. It is usually located at the top of the back of the device.
Ash blower. It is separated from the furnace by means of a grate.
There are four doors on the front surface of the boiler: furnace, blower, air and shurovochnaya.
Also mandatory elements of combined boilers are protective, adjusting and instrumentation: pressure gauge, gate lock, regulator, ground bolt, heat limiter, temperature sensor, drain pipe, pressure relief valve and others.

Specifications

The main technical characteristics of combined boilers "electricity - firewood" include:

thermal power of the unit when operating on solid fuel and from the mains;
consumed electric power;
weight and dimensions of the device.

Choice of combined heating boiler

The choice of a hybrid boiler is primarily affected by performance. The higher it is, the larger the area the heating system can heat. Today, there are two main approaches to calculating the required performance of heating equipment:

Average. According to this calculation, it is assumed that with a room height not exceeding 2500 centimeters, to create a normal temperature, about one kilowatt of productivity is required for every ten square meters of heated area. So, for a small country house with an area of 80 square meters. you will need an 8 kW apparatus, and for a larger country cottage with an area of 250 sq. m. it will be necessary to install equipment with a capacity of 25 kW.
Based on heat loss. It is generally accepted that the level of heat loss in houses without additional thermal insulation (for example, monolithic concrete) is 120-200 watts per square meter, in old houses with thermal insulation - about 90-120, and in modern thermal houses with three-layer vacuum double-glazed windows, the loss value is 60-90 watts per square meter.

The required power of heating equipment is calculated based on their formula:

Boiler power = heat loss x area / 1000.

It turns out that for the same country house, made according to modern technologies, it is necessary to install a heating unit with a capacity of 4.8-7.2 kW, and erected without thermal insulation - 9.6-16 kW.

Advantages of combi boilers "electricity - firewood"

Consider the advantages of such boilers on the example of products from the Teplodar company. You can get acquainted with the assortment and detailed characteristics on the official website.

The main advantage of such heating equipment is the ability to produce heat from various energy sources - electrical energy and solid fuel.

Moreover, most modern modifications of these units are able to function equally effectively on various types of solid fuels - granular pellets, coal, peat, briquettes, firewood and others.

This is what causes the rapidly growing popularity of such heating equipment.

Hybrid units are especially convenient in country houses, in which people do not live permanently, but, say, visit every weekend.

For these purposes, during the absence of residents on a boiler powered by electricity, the minimum mode is set to maintain the temperature in the rooms of the order of + 5 ... + 10 degrees, and upon arrival, the owners turn on the heating at full power, throw firewood into the furnace and the country house warms up quickly.

After reaching a comfortable temperature, you can turn off the heating element, using only firewood for heating, or set it to the “support” mode, in which the firebox takes on the main load of heat generation, while the electric heater is connected only if you suddenly forgot to add fuel.

This function is carried out automatically, there is no need to constantly be on duty near the combi boiler.

What to pay attention to?

When buying a combi boiler "electricity - firewood", you should pay attention to the following factors:

the possibility of connecting a water heating circuit and its type;
heat exchanger material. Cast iron is the most corrosion-resistant, but in the case of frequent temperature changes, it may crack. Steel, on the other hand, has greater ductility, but is subject to corrosion processes. Therefore, in the case of constant operation of the unit in winter, the first modification should be preferred. The second is more suitable for giving with a periodic visit. When using a steel heat exchanger, it is desirable to use liquids as a coolant that have anti-corrosion properties and are unable to freeze at low temperatures;
safety valve. This element today is an indispensable element that ensures the safety of the operation of the heating system. If the safe pressure threshold is exceeded, this valve automatically releases part of the superheated coolant into the prepared container;
ceteris paribus, preference should be given to designs with a larger solid fuel chamber. Its size directly affects the required frequency of laying firewood;
grate material. Cast iron is considered the best, since it is able to “work” normally with all types of solid fuels: firewood, coal, peat, pellets and others;
also need to take into account overall dimensions of the boiler, its weight to predict in advance the possibility of installation in the selected location.

Which combi boiler to choose?

Today in Russia, due to the ever-growing demand for hybrid boiler equipment, a lot of new foreign-made products appear, and the production of its own thermal products is being established.

I would like to pay special attention to the Russian manufacturer. Our domestic hybrid units are mainly produced on imported equipment and the quality of the final product is no worse than that of imported analogues with the same technical characteristics.

For example, the Russian combined unit manufactured by Evans is adapted for burning any type of solid fuel, it works equally well on coal, pellets, and wet wood. The efficiency of the boiler is average - up to 75 percent.

Of the main advantages - small size and weight. But the price for it is three times less than that of the Finnish analogue produced by the Jäspi Group. These are one of the few hybrid devices that have found a mass consumer in Russia.

This is explained, first of all, by the similarity of climatic conditions, that is, Finnish thermal equipment works well in the harsh Russian winter.

In addition, the manufacturer of boiler equipment has been on the heat engineering market for more than a dozen years, therefore it uses verified manufacturing technologies.

Video. To combined boiler TEHNI-X KOT-15-U-P-premium:

Combined heating: installation and installation requirements

Combined type boilers, due to the use of different types of fuel, require greater installation parameters than products operating on a single energy carrier. So, for the safe operation of units of the "electricity - firewood" type, the following conditions must be observed.

Requirements for the premises

First, the room must be finished with non-combustible materials that are unable to spread fire.
Secondly, it is forbidden to install any non-hermetic electrical equipment (IP below 44) in wet rooms - showers, bathrooms.
Thirdly, the room must be equipped with high-quality supply and exhaust ventilation, preferably forced. This will ensure the flow of outdoor air saturated with oxygen, which, in turn, will contribute to the complete combustion of the fuel.
And fourthly, before installing heavy heating equipment, the mass of which is several centners, it is necessary to consider strengthening the floor surface.

Chimney Requirements

Since from time to time the heater has to be operated on solid fuel, a chimney must be installed.

The main condition for a high-quality chimney pipe is the absence of holes, slots, holes in it, hermetic connection of all joints and the presence of good draft, which is ensured by installing the chimney in such a way that its upper part protrudes above the roof level at least half a meter.

The chimney must also be properly insulated., in order to exclude the occurrence of condensate, which can lead to the formation of ice plugs inside the pipe.

Electrical Requirements

The electrical network for connecting the heating elements of the combined boiler must correspond to the configuration and power of the heating equipment:

With a power consumption of up to three or four kilowatts, single-phase heaters are usually used, and if this indicator exceeds the 5-kilowatt mark, the units are equipped with three-phase heating elements.
The cross section of the electrical wiring must correspond to the maximum current consumption of the device.
Similarly, automatic protection of boiler equipment is selected: by current - in accordance with the cross section of the supply wiring. That is, the nearest higher standard value from the nomenclature of automatic protection is selected than the maximum power of the boiler, but less than the electrical wiring can withstand.
It is also recommended to connect the unit through a differential relay (residual current device) that operates at a leakage current value of 30 milliamps.
First you need to thoroughly clean the heating circuit with a special tool or install a new system.
Install ball valves on incoming and outgoing pipes.
Install the chimney in accordance with the rules for safe operation.
Connect the chimney to the boiler nozzle, carefully treat with a heat-resistant sealant.
Connect the heating system to the unit.
We check the presence of traction and the tightness of closing all the doors in the boiler.
We mount a shield with automatic protection near the unit, connect it to the mains.
With a flexible three- or five-wire cable, we connect the terminals of the boiler box to the machines. Don't forget to connect the ground wire.
In the case of a single-phase version, the device can be equipped with a Euro plug and connected to a three-pole socket.

On the video you can see how the Retra 3M solid fuel boiler is connected to electricity:

Combination boilers: installation step by step

Prices

The cost of combined heating equipment starts at $300. But these are the most low-power and unreliable boilers of Russian and Ukrainian production. Domestic units costing from $ 700 are considered optimal in terms of price / quality ratio.

For example, this is a modification of AOTVK-0-14-3, capable of effectively heating a building with an area of up to 110 square meters. The power of the boiler is 14 kW when using solid fuel and 3 kW when powered from the mains. The cost of a more powerful and larger boiler from the same manufacturer (22 and 6 kW, respectively) can reach $ 1000.

Imported units from European manufacturers are much more expensive.

Installation cost

The cost of installation and connection of combined heating boilers depends on many factors:

dimensions and weight of equipment;
the complexity of piping - shutoff valves, pump, expansion tank and other elements of the system;
the need to prepare the foundation;
the complexity of arranging the chimney.

The minimum cost of all operations for the installation and connection of hybrid heating equipment is 4,500 rubles.

Summing up this article, it is necessary to highlight the main advantages and disadvantages of combined boilers of the "electricity - firewood" type.

Advantages:

the ability to burn any type of solid fuel;
the possibility of simultaneous operation of the combustion chamber and heating elements;
independence from the availability of electricity;
the ability to maintain a minimum temperature to avoid freezing at home in the absence of the owners.

Flaws:

Of the shortcomings, only one can be distinguished - a small volume of the furnace compartment, which will require frequent laying of solid fuel in the absence of power supply. Otherwise, hybrid heating units have absorbed all the advantages of gas and solid fuel boilers.

Among multi-fuel equipment, boilers for heating a private house on wood and electricity are especially popular due to their simple and reliable design. The transition between firewood and electricity is carried out automatically.

How does a wood-fired boiler work with a heating element

Heating combined wood-electricity boilers, in their work use the possibility of using a backup heat source. It happens like this:

Almost all heating boilers for a private house on wood and electricity work in the manner described above. There are differences related to the design and the combustion principle used.

Boilers with built-in heating element

Combined heating boilers wood-electricity, with a built-in heating element, are offered in various modifications. Manufacturers offer models that differ in performance, both the units themselves and the electric heating element. The heating element is necessary to maintain the temperature of the coolant sufficient to prevent the building from cooling down.

It is impossible to use the heater as a full-fledged electric boiler, due to its insufficient power. In most boilers, a heating element is installed, with a capacity of up to 6 kW.

The consumer is offered models with a cast-iron and steel heat exchanger. Holes for the heating element are cut out by laser welding or, in the case of cast-iron analogues, are provided during the casting of the heat exchanger.

Floor combined heating boilers wood-electricity, factory assembled, have the following advantages:

Possibility to choose any type of heat exchanger.
Full automation of the combustion process, turning on / off the heating element.
Compliance with safety requirements.
Convenient adjustment of the operation of the heating element and the selection of a suitable mode.
The anti-freeze mode is provided.

Hybrid electric wood-burning boiler, factory assembled, ideal for heating a private house. The consumer is offered a wide range of products of all sizes in terms of power, allowing you to choose a heating unit, taking into account the individual characteristics of the dwelling.

Modifiable boilers

Almost any solid fuel boiler can be converted to install an electric heating element. The work is carried out as follows:

Steel boiler - heating element and thermostat, inserted directly into the heat exchanger. Installation requires welding. After installation, the holes are hermetically sealed.
Cast iron boiler - the design of the heat exchanger is somewhat different. In the body there is a water jacket surrounding the combustion chamber. Independent production of holes for the installation of a thermostat and a heating element will lead to an increase in the load on the cast-iron heat exchanger. During the work, microcracks appear, which eventually leads to the failure of the boiler. For this reason, it is not recommended to remake a cast-iron boiler for the installation of an electric heating element.

Some manufacturers, even at the stage of manufacturing the heat exchanger, provide a place for installing an electric heating element in a wood-burning boiler. In the future, you can choose a heating element of the required power. Modification is carried out quickly and does not require large material costs.

How to choose a heating boiler on electricity and wood

There are several types of boilers for wood and electricity, differing in the principle of operation and design. When choosing, pay attention to the following characteristics:

The principle of operation - the most profitable and economical, are pyrolysis boilers that operate 6-12 hours from one tab. During operation, heat is extracted in two ways: during the combustion of firewood and the afterburning of gases.
A gas-fired boiler is more expensive than a classic model, but the costs are paid off by reducing the consumption of firewood, better efficiency and heat output.
The number of circuits - single-circuit units are characterized by high performance, they are able to heat large areas. The design provides for connection only to the heating system. Water heating becomes possible only after modification (indirect heating).
Double-circuit combined boilers, simultaneously work to heat the coolant of the heating system and hot water.
Heat exchanger - There are two types of wood-fired boilers. Cast iron units are heavy, inconvenient during installation, but at the same time, they are distinguished by a long service life and high heat transfer.
Steel boilers are cheaper, sensitive to excessive overheating of the coolant, cool down quickly after the firewood has burned down. Most manufacturers focus on the manufacture of steel boilers, since production is cheaper, and they are in constant demand from consumers.

When choosing a mixed-type boiler, from electricity and firewood, it is important to calculate the required power, select equipment by manufacturer and cost.

How to calculate the power of an electric wood boiler

Domestic bi-fuel mixed wood-electricity heating boilers are offered to the consumer in different power sizes. Productivity varies from 8 to 40 kW. (in industrial analogues up to 400 kW).

Accurate calculations, taking into account the characteristics of a residential building, are carried out only after an audit of heat losses. The approximate power of a combined wood and electricity boiler is calculated using an online calculator or a special formula.

Calculations are performed as follows:

The total heated area of the building is calculated.
The amount of heat required for heating is calculated. Use the formula 1 kW = 10 m².
When calculating, for a universal double-circuit boiler, taking into account the need for heat for hot water supply, 15-20% is added to the result obtained.

Heating systems with electric wood-fired boilers are equipped with an electric heating element with a power of up to 6 kW. The performance of the heater is sufficient to prevent freezing of the coolant or full heating of 60 m² of the building.

Manufacturers of combined electric-wood boilers

In the domestic market of heating equipment, the consumer is offered boilers of European, Asian and Russian companies. The following brands are in constant demand:

- German boilers, characterized by high build quality, long service life and high cost, 3-5 times higher than what the Russian manufacturer asks for their products. In the case of Buderus, the price is fully justified. The boiler consumes fuel economically and has sensitive automation that controls the combustion process. In an additional complete set the storage boiler is offered. Productivity up to 350-400 kW.
- the consumer is offered steel boilers with a capacity of up to 18 kW and a built-in electric heater of 6 kW. Suitable for full-fledged heating of rooms with a total area of up to 200 m². In addition to the boiler Mister Hit AOTVC, a remote control unit is offered that allows you to control the combustion process using the remote control.
- one of the largest domestic manufacturers offering products that meet European standards of quality and reliability. Products are offered in the Master series. Zota boilers provide a place and a hole for installing a thermostat and an electric heater. The heating element and sensors are purchased separately and are not included in the basic package. One of the main advantages of the model is the ability to install a heating element for 9 kW, instead of the traditional 6 kW.
– the company offers heating equipment with power from 8 to 30 kW. Boilers are distinguished by low cost, minimal equipment, small dimensions and "omnivorousness". You can pick up a Karakan boiler with a hob, which is especially convenient when heating a country house.
Kupper OVK - boilers offered by Teplodar are presented in two power sizes of 10 and 18 kW. Models are equipped with a cast-iron hob, able to work on any type of solid fuel. If necessary, they are equipped with a pellet and gas burner. Kupper HVAC is the optimal solution for heating a house with a maximum area of up to 200 m².
Stoker Aqua is a brand promoted on the domestic market by Ermak. Four standard sizes are presented, in terms of performance 12, 14, 16, 18 kW. Built-in electric heater, power 1.5 - 3 kW. The automatic draft regulator is installed separately, as an option. The model has a capacious combustion chamber. The Stoker Aqua series offers boilers exclusively with a steel heat exchanger.

The main advantage of Russian heating boilers running on wood and electricity is unpretentiousness to fuel quality. In Western counterparts, heat efficiency drops sharply if the moisture content of firewood is more than 20%.

The cost of wood-electricity boilers

Prices for combined double boilers vary depending on the country of manufacture, brand awareness and technical parameters of the equipment. Moreover, even in Russian models, the difference in cost can be 10-15 thousand rubles.

Buderus offer luxury boilers, to purchase a universal boiler, even of low power, will cost about 150-250 thousand rubles. Domestic boilers are cheaper. Models similar in their characteristics are offered on the Russian market for 15-45 thousand rubles, depending on the manufacturer and configuration.

Where and how to install electricity-firewood boilers

Wood-fired hot water boilers with a switch to electricity are installed in accordance with the general rules of SNiP and PPB regarding the installation of solid fuel heating equipment. In particular, it states:

Models with built-in heating elements do not require an installation permit, provided that the maximum power consumption rate does not exceed 3 kW. Heating element 6-9 kW, creates an additional load on the power grid. A separate voltage line is allocated for connection.
Boilers, with a capacity of up to 40 kW, are installed anywhere in the house. A boiler over 40 kW is best placed in a separate room used exclusively for the needs of the boiler room.
The connection of the electric wood-burning boiler is carried out through separate machines located on the control room. The electric heater is not afraid of power surges in the network, but if a remote control controller is used, voltages are set.
As a boiler room, for heating a house on wood and electricity, a dry heated room is chosen, with a total area of at least 8 m². Be sure to have natural lighting and ventilation.
Universal combined boilers powered by wood and electricity are located in such a way that there is at least 50 cm to the walls lined with combustible material. Installation is carried out on a fire-resistant base. The chimney, when passing through floor slabs and roofs, is placed in a special box filled with thermal insulation material.

Dual-fuel combined solid fuel boilers for heating wood-electricity, connected to the water circuit. To replenish the coolant, it is recommended to connect a water treatment and filtration system. Additionally, a safety group is connected that automatically relieves pressure in the system.

The electricity parameters for electric heaters, with a maximum power of 9 kW, do not require the use of a three-phase power supply. The connection is made to a regular 220 V household network.

All in our time, you can increasingly see combined heating boilers that are universal for a private house, operating simultaneously on two types of fuel. Combining firewood and electricity together is a pretty smart solution, such a boiler is quite reliable, compact and practical. And if there is a power outage or a lack of fuel, you will not experience discomfort from the cold or lack of hot water during the cold period.

Modern heating boilers use solid fuel, combining it with both gas and electricity, which is more relevant for consumers. When purchasing a heating boiler that works both on wood and on electricity, several problems are solved at once:

For heating, two alternative energy carriers relative to natural gas are used at once.
The issue of cooling down the premises is being solved in the case when everything in the firebox has completely burned out, and a new portion of fuel has not yet been loaded.
Makes water heating more comfortable, since you no longer have to get up in the middle of the night and go to the boiler room to load fuel.

Combined electric wood heating boilers of the latest generation with a large firebox are made in such a way that switching to electric heating occurs automatically when the water temperature in the boiler drops below a certain mark. Naturally, the reverse transition to the combustion of solid fuel occurs with the help of external actions.

The design of the electric wood boiler

Externally, the combined TT firewood boiler is in no way different from a conventional solid fuel unit. In fact, this is the same wood-burning heating boiler, the only difference is that it has a heater installed in the heat exchanger. Another important difference from the standard configuration is the presence of a water jacket.

One of the walls of such a boiler is made by cold stamping and has a complex configuration. Heating elements are installed between the walls of the jacket and there is a special contact hole to which the electrical wiring contacts are connected.

This type of heater device is similar in design to a standard solid fuel boiler, which consists of the following main elements:

firebox (combustion chamber), a place for loading solid fuel;
outside it is washed by the coolant, which is inside the water jacket;
a water-tube or fire-tube type heat exchanger, where the combustion products transfer most of the heat to water before being released into the chimney;
at the bottom of the firebox there is a grate, and under it there is an ash chamber;
firebox and ash pan in front equipped with doors;
to adjust the intensity of combustion, there is a mechanical draft regulator or a fan-blower (if there is no manual control of the air damper).

Household combined heating boilers are distinguished by the design of a water jacket, where a place is provided for the installation of a block of tubular electric heaters - heating elements. Their contacts are brought out and connected to the control panel with the help of an electric cable, and the heating part is immersed in the coolant.

How a combi boiler works

The principle of operation of a solid fuel heater, in which electric heaters are installed, is as follows:

Kindling and heating of the boiler are carried out in the usual mode. When burning solid fuel, the temperature of the coolant is maintained using a mechanical thermostat or a fan together with a sensor, and the heating elements are turned off at this time.
After the contents of the fuel chamber burn out, the temperature of the coolant in the system gradually drops to a certain value, reaching which, at the signal of the temperature sensor, the heating element (one or more) is turned on. At this point, the boiler starts to work on electricity.
After the next portion of firewood or coal is loaded, the water in the system begins to be heated from the side of the combustion chamber, the electrical part automatically turns off until the temperature of the coolant drops to a certain value.
Electrical equipment is auxiliary.
The heater control unit is used to maintain a certain water temperature, based on the readings of the air or water sensor.

Continuous heating of water is provided by switching from one mode to another, which provides comfortable conditions in a private house.

Advantages of universal boilers

After installing a combined wood-electricity heating boiler, you will receive the following bonuses:

Versatility. You will have the choice of which of the two fuels to use and when.
Due to the built-in heating elements, the coolant will maintain the set temperature even after the fuel has burned out in the loading chamber. This will maintain a comfortable temperature inside the room, and in case of your long absence, it will prevent pipes and radiators from freezing.
Comfort. Maintaining the temperature with electricity will be of great service, helping to get rid of the problem of night trips to re-load fuel into the combustion chamber.
If electricity is metered according to a multi-tariff scheme, then in addition to convenience, you can also save on the night operation of heating elements.
Thoughtful device. The heat is distributed in such a way that the loss of thermal energy is close to a minimum, thanks to which the boilers are quite efficient.
Long period of operation. If properly maintained, such a boiler can serve you for at least 20 years.
Autonomy. You do not need to constantly monitor the process - for this the unit is equipped with automation. Especially in the case of operation from electricity, the operation mode using a heating element is limited to an uninterrupted supply of electricity.
You can find models with pre-built pipes in order to be able to connect the "warm floor" system.

Heating combined boilers, which work both on wood and on electricity, cope with their task even in low-power mode.

Disadvantages of combined units

Electric heaters of a universal boiler assume only maintaining the temperature of the water in the system; they cannot completely replace the combustion of solid fuel. The reason for this is the low power of the block of heating elements, which are mounted by manufacturers on solid fuel boilers. This feature, unfortunately, is one of the serious drawbacks of combined boilers for heating a private house on wood.

Heating a private house with a combined boiler that runs on both electricity and firewood has other disadvantages.

The useful volume is taken away from the loading chamber by the block of heaters, which significantly affects the burning time from one load.
The operation of the device directly depends on the stability of the power supply.
The cost of combi boilers is much higher compared to classic solid fuel boilers.
The efficiency during operation of the heating elements drops by 2-5% due to the air flow that passes through the cooled firebox. The reason for this is the constant draft in the chimney, it forces the air out of the rooms to leave through the chimney and thereby cools the water jacket of the heater.

Do not forget one more important detail. As in the case of a classic solid fuel boiler, a combined heating boiler of the wood and electricity type must be connected to the water heating through a three-way valve, as shown in the diagram below. A small circulation circuit is necessary to protect the furnace from the negative effects of condensate during kindling.

In order to prevent the walls of the combustion chamber from being covered with condensate when the temperature drops, the solid fuel boiler must be connected according to the standard scheme with a three-way valve:

In the event that the power of the heating elements is not enough to heat the coolant to a temperature of + 55 ° C or more, then condensate will never appear in the furnace of the combined boiler during ignition, and the unit with a three-way mixing valve will not be needed. But as practice shows, a small circulation circuit, nevertheless, is necessary, at least in the event of a power outage or a breakdown of one of the heating elements.

How to choose a boiler "firewood electricity"?

Manufacturers offer combined heating boilers that run on both wood and electricity, which differ in performance, power and equipment. When buying this equipment, you need to pay attention to the following points:

Power - this parameter depends on what type of fuel is used. It is necessary to determine in advance the main type of fuel for the purchased device.
The dimensions of the combustion chamber - its volume will show how often it will be necessary to load fuel.
Noiselessness - installation of a special valve will ensure quiet operation of the unit.
Number of circuits - some models heat water only with the help of heating elements.
The most economical models are those in which the coil is mounted in the combustion chamber.
Heat exchanger. It is made from both steel and cast iron. Cast iron ones are not so susceptible to corrosion, they give off heat longer, although they heat up longer, they also have a rather serious weight, and with sudden temperature changes they can crack. Steel has less resistance to corrosion and oxidation, but they are lighter and more resistant to temperature extremes.
Grids. The material of manufacture can be very different. They can be both cast iron and ceramics. Cast iron has a higher heat resistance and is suitable for the combustion of any solid fuel. Honeycomb cast iron grate with ceramic coating is suitable for bulk materials, the combustion of which consumes more oxygen.
The weight and dimensions of the unit. Due to the large dimensions, it may be necessary to reinforce the surface area where the unit will be installed with a concrete screed.

When choosing a boiler for heating a house, you need to correctly calculate the power of the device based on the parameters of the area of \u200b\u200bthe room. This will indicate how much fuel consumption will be required. If the area of the house does not exceed 80 m2, then you do not need to buy a boiler whose capacity is designed to heat a house with an area of 400 m2. This may lead to overspending of budgetary funds for the purchase of the unit, and for its subsequent operation.

A combined wood and electricity boiler is perhaps one of the most successful solutions for heating a summer house or a small private house. In a cottage that has 2-3 floors, heating elements will only save the system from freezing. Combined boilers will help out if it is not possible to use a constant and reliable source of energy. In addition, these boilers will save you quite a lot of money if you use more expensive fuel as a fallback.

For the installation of such a boiler, it is better to use the services of a specialist who works in this profile. He will advise the most suitable device model for you and install it without unnecessary problems, based on the requirements of safety rules and technology requirements.