Furnace with a water circuit for heating the house

A person sitting in front of a fireplace or stove is unlikely to have the idea that these heaters have a low efficiency .Contemplation of fire and sensation from the living heat will not be replaced by any up-to-date boiler , whose burner flame is hidden in its bowels and can not be seen by the eye, and each kilowat tt of heat energy is carefully selected and the is transferred to the heat carrier. But, it turns out, there is a beautiful, even elegant compromise solution - it's a stove with a water circuit for heating the house.

Furnace heating

furnace has always been a kind of "heart" of the house. It has always traditionally stood in the center, and all life was boiling near its .In the oven, food was prepared, near , was heated in winter. A well-heated furnace accumulated so much energy that even after the fire was quenched, the still gave the heat to all households for a long time, spreading it like a sun in all directions from its massive walls. And fuel for the furnace - conventional firewood in Russia has always been a lot, most importantly, do not be lazy and stock up them in the summer.

Furnace heating has a number of indisputable advantages:

• Firstly, the stoves do not need to be connected to gas and electric networks, they use mainly firewood as fuel, which is a renewable fuel, they will always be abundant at reasonable prices in most of Russia,and sometimes completely free.

• . Secondly, the most comfortable radiant heating is realized in furnaces, when massive walls of the furnace radiate heat, transferring it to surrounding objects and air.
• Third, the oven can combine several functions at once: heating itself, cooking, heating water.

• Fourthly, , the contemplation of open fire in the fireplaces( and they are, in fact, furnaces) creates the a comfortable atmosphere.
• Fifthly, the massive structure of the furnace in the cold season can accumulate a huge amount of thermal energy, which it will gradually give away. In the summer, everything happens on the contrary : the oven, which is always built on a separate foundation, "dumps" excess heat energy into the ground from hot air, that is, it is a kind of air conditioner.
• And, finally, furnace heating does not harm the environment if uses natural fuel in , because combustion processes in nature occur constantly.

Add a little tar in the barrel of honey and list the shortcomings of stove heating:

• Stove heating requires constant human participation: the setting up of firewood, cleaning the ash and chimney, adjusting the traction and other operations, although for a holiday home it is more than a minus.

• The more power a furnace has, the more its geometric dimensions, and this "eats" the useful area of ​​the house.
• The can only heat the rooms that are in direct contact with it. In remote premises it is necessary to construct or install still one oven, as it was done in old houses.
• Traditional brick Russian stove because of its inertia for a very long time goes to the operating mode. Part of this defect is deprived of modern fireplaces, stoves of burzhuyki and Booleryany .
• Furnace heating has a low efficiency - no more than 40% and usually have excess capacity. When furnace enters the operating mode and warms up, it is almost impossible to stand next to it, but then, cooling down, it gradually gives heat. At the same time a lot of energy just flies into the atmosphere through the chimney.
• The process of burning fuel in the furnace is more difficult to control than in boilers. Extinguish the furnace instantly is almost impossible, which increases the level of fire danger.
• Furnaces require chimneys with good draft so that combustion takes place intensively, and flue gases escape into the atmosphere and do not penetrate into the rooms. Chimneys must be isolated from combustible building structures.
• It is required for the furnace to store a solid fuel stock constantly, which must be replenished periodically, and slag and ash need to be recycled.

If we sum up all of the above, then we can say that the furnaces have a right to exist, but in many respects they all equally lose to other types of heating. In general, troublesome business is the furnace. If in the conditions of a summer cottage where a person appears periodically - this is a pleasant trouble, then in the houses of permanent residence the operation of the furnace becomes a routine and is most often a forced measure when, for example, there is no possibility to organize another heating system due to the absence of main gas.

Why does heating with a coolant win at the oven?

As mentioned earlier, one of the main problems of the furnaces is the inability to heat remote from their premises. In modern models of furnaces and fireplaces, manufacturers tried to solve this problem by supplying their heating devices with convection air ducts, to which the can connect air ducts. Warm air from the furnace is carried through the rooms, heating them. Very good solution, which, by the way, works fine in some houses.

The air in such furnaces functions as a coolant, that is, a substance that is capable of receiving heat from the furnace and then transported to its destination and give its to the remote location. To do this, we only need to build a duct system, which is not without its drawbacks and is connected with by certain difficulties:

• First, air ducts have large dimensions, they can often be hidden behind building structures.
• Secondly, air ducts have a strong resistance to the movement of heated air, especially if they have many turns. Therefore, there are restrictions on their length.
• Thirdly, air has a low specific heat capacity , therefore, to transmit defined amount of thermal energy for remote from the room oven requires a large amount of heated air. To do this, either construct air ducts of a larger size, or force the heated air with a fan.
• And, finally, transmits a large amount of dust, soot and other contaminants that are always present near the furnace.

best and most common coolant used in home heating systems, is water because of its advantages:

• Water has a very high specific heat capacity ( C = 4,187 kJ / ( kg * ° to ) ) compared to dry air( With = 1,005 kJ / ( kg * To ) ), so it can receive and transmit a large amount of heat energy to a significantdistance.
• The heated water can easily be transported to the desired location by pipelines, which have small dimensions.

• The water is absolutely harmless, non-toxic and does not burn.
• Water is always available, you can say that it is almost free.

The main lack of water is its the high freezing point is 0 ° C, while it expands in volume and damages the heating system devices. In addition, high corrosive activity to black metals in water combined with atmospheric oxygen. Rigid water - with a high content of calcium and magnesium salts leads to the formation of scale on the internal surface of pipes, heat exchangers and radiators, which sharply reduces their characteristics. All this requires special measures:

• In houses of year-round living, in a wintertime dangerous for water, the heating system does not threaten anything, since it is constantly at work. Modern gas and electric boilers have the function of protection, which will not allow the temperature of the coolant to fall below + 5 ° C .
• In houses where a person does not appear in the winter, the water from the system can simply be drained, but in this case there will be accelerated corrosion of the steel parts of the heating system. Another one output is the use of special antifreezes, which reduce the freezing point, but they are not compatible with all boilers and radiators, costly cost and eventually age.
• Very often in heating systems where the coolant is water, the reserve electric boiler is put on guard, the task of which is to maintain the temperature in the house, and hence the coolant, at defined minimum level. When hosts appear, boiler is started, the stoves or fireplaces are melted and the temperature is raised to the desired value. After the county "on the post" the "guard" again comes in.

• To reduce the corrosive activity of water in it add special additives or make the system closed. Then atmospheric oxygen does not penetrate into the heating system and corrosion stops or goes very slowly and does not affect the overall service life of the heating system.

Of course, the question arises - is it possible to combine the charms of stove heating with the merits of systems where the coolant is water. And at the same time try to get away from the shortcomings of one and the other. Completely to solve this problem was not possible, but there are quite good technical solutions both industrially produced, and realized by domestic Kulibin .Consider them, and after that it will be possible to do certain conclusions.

Overview of commercially available ovens with a water circuit for heating

Among all the options for implementing a furnace with a water circuit, one must choose those that are already in use and are successfully used. And first of all you need to pay attention to the already finished products, which the industry produces. And that's why:

• In the vast majority of cases the ready-made will cost cheaper than self-made or built.
• The creation of ready-made furnaces is performed by whole teams of highly qualified specialists who have rich experience, who count on the design, develop the production technology and operating rules.
• Special heat-resistant grades of steel and cast iron are used in the production, which are not available to the common man on metal warehouses .
• The quality of industrially manufactured furnaces is higher than those made by handicrafts, as high-technology equipment is used.

• All ovens coming on the market from manufacturers go through a long and painful process of testing and processing a package of documents from licensing and controlling bodies.
• Industrially manufactured furnaces are guaranteed by the manufacturer, they can be provided with spare parts, they are easier to install, they are easy to choose a chimney, they are supplied with a set of ready-made standard projects for creating a heating system or integrating into an existing one.

Currently there are many well-known and not very well-known manufacturers in the furnace equipment market: ABX ( Czech Republic), NordFlam( Poland), EdilKamin( Italy), MBS( Serbia), Thermophore ( Russia), Romotop( Czech Republic),Chazelles( France), Invicta( France), Vira( Russia), Panadero ( Spain), Storh( Germany) and many other . As an example, we decided to show two models of furnaces with a water circuit: the fireplace furnace " Aquarius " from from Thermophore and oven "Armada 20" manufactured under the trademark Vira. Both of these models we intends to introduce from quality manufacturers, as with equal technical characteristics some Western "colleagues" are either indecent or simply shamelessly expensive.

Fireplace fireplace with water circuit "Aquarius"

A well-known company on the market "Thermofor" produces a fireplace firebox "Aquarius", which can be equipped with a water heat exchanger for heating purposes. For the furnace can be built any favorite portal, so that it has become a harmonious part of the interior of the house. This product is available in two versions, both with a water heat exchanger and without it. We specifically indicated in the table the technical characteristics of both models for comparison.

Models	Aquarius	Aquarius TO
Power of fireplace fireplace, kW	12	12
Volume of heated room( maximum), cu.m	200	200
Dimensions, W * D * H, mm	690 * 515 * 930	690 * 515 * 930
Dimensions of the door opening of the furnace, mm	315 * 535	315 * 535
Weight, kg	68	77
Volume of the combustion chamber, l	70.7	62.5
Maximum loading volume, l	56	52
Maximum log size, mm	545	545
Diameter of chimney, mm	200	200
Minimum height of chimney, m	5	5
Volume of heat exchanger, l	-	11.6
Maximum heat output, kW	-	6
Maximum working pressure,kgf / sq.cm	-	0.5

The design features of this fireplace fireplace model are:

• The large heat-resistant glass of the furnace door is protected from soot settling and allows to observe with fire.
• The solid volume of the firebox provides a long burning.
• The firebox is additionally protected with chamotte stone, which extends the term of its service.
• The overall dimensions allow you to choose a standard facing for fireplaces or make your own.
• Fireplace hearth with heat exchanger " Aquarius TO" can only be connected to open heating systems.

From the technical specifications for this device is seen that through the water heat exchanger the furnace can transfer water up to 6 kV tt of thermal energy, which means that the area of ​​heated premises can be of the order of 50-60 m2 with a ceiling height of 2.5 meters. The remaining 6 kW of power can be directed to the heating of the room where the fireplace is installed, so when constructing the portal, convection flows near the furnace should be arranged with the output of the warm of the air above the fireplace.

This fireplace, as, in principle, and any oven with a water circuit is strictly forbidden to ignite without water in the heat exchanger, this will lead the to a quick failure of it. The connection option " Aquarius TO" to an open heating system with natural circulation is shown in the following diagram:

Thus, in addition to its decorative function, the fireplace can heat a small house. In order for heat transfer to be more intensive, it is possible to put a circulating pump with bypass on the return line. In the absence of electricity, natural water circulation will occur, and the will turn on the pump with the .There are models of fireplaces that can be included in a closed type heating system, but we will not consider them in this article.

Solid fuel heating boiler « Armada 20 »

This boiler is produced in Russia at the plant " Bermash " in the city of Berezovsky. The reader may think that the authors left the topic of the article, because it is about furnaces with a circuit for heating, but it suddenly went about boilers. So boiler "Armada" is none other than oven of the same manufacturer called "Legion" in which instead of convection heating pipes of air have placed water circuit from the pipes. Has this unit ceased to be an oven? Of course not! The coolant simply changed.

Furnaces have traditionally been called such heat generators, which heat directly in the with their presence of radiant heat( IR radiation), as well as heating air. The boilers are designed to heat the water, which will then be sent to various heating devices: radiators, convectors, warm floors and others. The main task of the boiler is to heat the coolant, and the ovens to heat everything around them. But we will not deviate from the name declared by the manufacturer and tell about the boiler "Armada 20".Its technical characteristics are presented in tabular form:

Technical characteristics of the boiler ARMADA 20
Boiler output( heating capacity), kW	20
Heated area( h = 2,5 m), sq. M.m	Up to 200
Overall dimensions( W * D * H), mm	390 * 660 * 750
Furnace depth / log size, mm	510/480
Weight( fuel and water consumption), kg	115
Combustion chamber volume, l	90
Fuel loading weight( maximum), kg	12
Recommended loading for optimum combustion, kg	4.8
Dimensions of the door opening for the furnace, mm	190 * 292
Connection thread for the heating return and return	G 1 ½ "
Water volume in the circuit,l	28
Working pressure in the system, Mpa	0.3
Power of the heater block, kW	3 * 2 = 6
Diameter of chimney, mm	120
Height of chimney( minimum), m	6
Maximum outlet temperature of coolant, ° C	95
Minimum inlet temperature of coolant, ° C	60-80

This furnace( boiler ) has some design features, which must be mentioned.

• The heat exchanger has a large number of pipes, therefore the area of ​​the heat sink in relation to the volume of the water inside the heat exchanger is maximal. This achieves a great heat output.
• The door is equipped with a transparent screen of tempered glass, which allows you to visually observe the burning of fuel.
• The top of the boiler is the hob. This allows you to reheat or cook food.
• At the top of the furnace, the partition has an detachable construction, which allows cleaning the boiler and the chimney from soot.
• The external parts of the heat exchanger are also an air convector, which is covered with panels painted with heat-resistant powder paint.
• Boiler is designed for burning firewood( preferably hardwood), fuel briquettes( eurodoors ), pellets , and also brown coal with a fraction value of at least 4 cm.
• Without water in the heat exchanger, the can not be operated - this isThe will cause the to fail quickly.
• The design of the boiler provides technological holes for the installation of the TEN , which will allow without heating in the winter to keep the temperature of the coolant in a safe range.
• The can operate both in an open and closed heating system with a working fluid pressure of 3 MPa .

Examples of the boiler piping for a closed heating system with forced circulation of coolant, as well as in open circulation with natural circulation are shown in the figures:

Thus, boiler water circuit) "Armada 20" can already heat a large enough house and while it else can be used for cooking and partially or completely heat the room where it is setthe detection. Although the basic heat sink goes in favor of water, all is equal to this boiler has not ceased to be an oven. Or, on the contrary, this furnace never became an absolutely high-grade solid fuel boiler.

Video: Overview of furnaces with a water circuit

Water circuit for heating in a brick furnace

It is very tempting to place the heat exchanger of a heating system in a brick oven, considering that simply a huge amount of energy of combustion of fuel goes to the heating of a massive structure. And in fact, ovens with a built-in boiler exist, and are successfully operated. And this design has a lot of advantages:

• Due to its large mass and its ability to store heat, brick furnaces are -specific thermal accumulator , which will take on excessive heat and, if necessary, transfer it to someone whose lacks the .
• In a large brick oven, the hob and fireplace, and the heating water circuit, , with the for all these devices, do not need to be built separately for chimneys.
• Heat transfer on the surface and in the furnace array occurs evenly, so the heat to the water circuit will be transmitted with the greatest efficiency.
• Even after the fire is completely extinguished in the furnace, the brick oven can for several hours "share" the heat with the heat exchanger of the water circuit. But here everything depends on the design and mass of the furnace.

The main disadvantage of this design is the complexity of implementation. Best of all, when using the stove as a heating boiler, the still is conceived before the begins its construction or before reconstruction. In any other case, will have plunge into the very troublesome work of disassembling the furnace and assembling its again. And the price of the error here is very high, it is very difficult to fix something.

If the owner decided on such a responsible step as the organization of the water circuit in a brick oven, then there is no way to do without specialists. Ovens should be handled by furnaces, and engineers - together with the same stove workers. No one in the head of the will come to go to treat the teeth to the car mechanic, why some homeowners hope for their own strength or rely on the "rich experience" of a neighbor, a coma, a matchmaker, a brother. That is why it is best to order a furnace design with a water circuit from specialists or use ready-made technical solutions that can be obtained for symbolic money or completely free of charge via the Internet. As they say, Google and Yandex help you.

Any incorrect intervention in the already prepared furnace violates the of its operation, contributes to the rapid of its destruction, reduces efficiency and creates an hazard to people's health and life. Let's list the typical mistakes when installing the water circuit in a brick oven:

• The heat exchanger was built into the firebox of a brick kiln, so its volume decreased sharply, which affects the power, volume bookmarks and efficiency, with for the worse. If the actively circulates the coolant by cooling the firebox, this will cause the to lower the temperature, generate a large amount of soot and a chemically aggressive condensate that will quickly "eat" the heat exchanger, if the is not made of stainless steel.

• furnace. The heat exchanger was built into the smoke channels of the furnace, which violated their throughput. As a result, some of the carbon monoxide is returned to the furnace room, and this can lead to very disastrous results.
• The heat exchanger was embedded in the masonry. When it is heated, there is a linear expansion of metals, which leads to the destruction of the furnace, the formation of cracks.
• Heat exchanger unreasonably high power built into the chimney. Circulating water reduces the temperature of the flue gases, this leads to an avalanche-like formation of condensate, which destroys both the chimney and the heat exchanger.

And similar errors with unpredictable consequences can be still very much. This still proves once again that it is better to use the ready-made technical solution and attract professionals for masonry and installation, since for the money spent on a good stainless steel heat exchanger and the baker's work, you can already buy a good solid boiler from the well-known "brand"manufacturers.

Types of heat exchangers and their location in the brick furnace

First of all, it is necessary to determine the material from which the heat exchanger will be made, which will be placed in a brick oven. There are several options, consider each of them:

• Copper heat exchangers are very effective, as the thermal conductivity of copper is one of the best, but they can not be applied inside brick furnaces. Why? The fact is, that the melting point of copper is 1083 ° C, and in the furnace it can rise to 1200 ° C.With a constantly circulating coolant, the temperature of the pipe, of course, does not rise to such values, but who can guarantee that the that the will not cause abnormal situations. In addition, copper is very afraid of aggressive chemical compounds, which abound in condensate.

• Cast-iron heat exchangers favorably differ in that they have very high corrosion resistance. Their main drawback is fragility and fear of sudden temperature changes. If a portion of cold water is run into a hot cast-iron heat exchanger, then the temperature deformation leads to the formation of cracks and the failure of it. Cast iron is difficult to handle and is produced in the form of cast parts, which are then assembled by threaded elements through the seals, which reduces their reliability .Some craftsmen use cast-iron radiators as a heat exchanger, but their efficiency is small, except for washing dishes or to take shower.

• Steel heat exchangers are the most common, as steel is an affordable and easy-to-process material. It is recommended to use heat-resistant steel with a wall thickness of at least 3 mm, and preferably 4-5 mm, for the heat exchanger of the furnace. Pipes are better to choose seamless. Unfortunately, steel is prone to corrosion, so it is necessary to heat the furnace in such regimes that are least conducive to the formation of condensate, and never drain the coolant from the water jacket.

• Stainless steel heat exchangers are the best, but also the most expensive. The is the most widely used steel grade AISI 304. It is better not to make these parts yourself, but to order them in factories where there is equipment for laser cutting of metals and welding in argon. Then the quality of the seams will be as close as possible to the material of the pipe itself.

What is the heat exchanger to be made from?

Heat exchangers can be manufactured from metal sheet, round or shaped rectangular tubes and their combinations. Let's consider their basic kinds.

• The sheet heat exchanger is usually located in the hottest place of the - directly in the furnace furnace, it fits the walls and ceiling and at the it has openings for loading wood and flue gas. It is made from sheet 3-4 mm thick, and from the top and from the bottom are welded pieces of pipes with a diameter of 40-50 mm for the supply and return lines. The internal clearance in the heat exchanger must not be less than 3 cm - to prevent water from boiling. At the same time, it is necessary to ensure that the upper delivery pipe is at the highest point of the heat exchanger, otherwise the can generate steam jams that, when entering the heating system, threaten with a hydraulic shock, which can damage pipes or radiators.

• Heat exchangers from pipes are also often located in the furnace. For the manufacture of such heat exchangers I take tt with a diameter of 40-50 mm or profile rectangular pipes 40 * 60 mm, 60 * 60 mm. Of these, a spatial construction is welded, which will be different in each individual furnace. The main thing is that the heat exchanger does not block the loading door, the grates and smoke channels.

• If the oven is used for cooking and has a cooking surface, heat exchangers are not made at the top of the furnace, in this case they should fit the side surfaces.

• Very often heat exchangers made of flat-plate tubes are placed in the hood of the furnace or in smoke-fired channels. They can remove less in , therefore they are usually of impressive size, but they work in softer conditions, therefore they can serve more. The main condition - they should not prevent the exit of flue gases. That is why their design is calculated in advance. To put such heat exchangers in an already prepared furnace, is strictly prohibited .

Calculation of power and dimensions of heat exchanger

Naturally, for heating purposes, the heat exchanger's power must be calculated. An improperly designed water circuit will either not provide the desired room temperature or, conversely, with excess capacity in the rooms it will be like in the Sahara desert and it will be very difficult to reduce the temperature, since it is very difficult to control the flame in a brick oven. How to do it correctly?

Heating should compensate heat loss at home, so their evaluation is the first thing to do. Such calculations of are made by heating engineers. The calculation method has a fairly complex algorithm and requires a large amount of raw data. It is rather difficult to do such on its own, but practice shows that in most cases, from 1 to 1.2 kW of heating capacity is required for every 10 m2 of the house's area. At the same height of ceilings should be from 2.5 to 2, 7 m .

After the calculation of , the heat loss can be transferred to the calculation of the power of the water circuit( heat exchanger) itself, which depends on whether the has an environment with the which temperature it is located on and its contact area with this environment. Practice shows that from each square meter of the heat exchanger it is possible to "take off" an average of 5-10 kV tt of thermal energy. But the indicative figures can not suit us, so we will count more accurately.

It is obvious that the power of the entire heat exchanger will depend on its area S and a certain indicator - the specific power of Q in , which reflects how much heat energy a heat exchanger can give in a unit area of ​​1 m2: Q = S * Q from .

The specific power as well as the value and of its can be calculated using the simple formula:

Q for = k *( Tm- tm), kcal / hour where:

• k - coefficient t Material loss in calculation of on 1 ° C with .For steel, which is used in heat exchangers k = 12 kcal / h .
• Tm is the temperature of the heating medium ( average ), which is the average arithmetic between the maximum and minimum temperatures. Tm = ( Tmax + Tmin ) / 2.
• t m is the arithmetic mean of the temperature in the water circuit of the . tm =( t for + t for ) / 2, where t for is the coolant temperature at the outlet from the heat exchanger, and t for is the inlet temperature( return) .

Assume that the furnace is operating on coal, then the average temperature in the furnace is: Tm =( 1000 ° C + 600 ° C) / 2 = 800 ° C .The temperature of the heat carrier will be: tm =( 80 ° C) / 2 = 70 ° C. Then the specific heat exchanger power will be: Q for = 12 *( 800 - 70) = 8760 kcal/hour. Let's translate calories in watts : 1 Watt = 859,85 cal , then Qu = 8760000 kcal / 859.85 = 10187.82 Watt ≈10.2 kW. It turns out, that from one square meter of the heat exchanger it is theoretically possible to remove 10 kV t t of thermal energy.

If wood is used instead of coal, then it's natural that their calorific value is lower. The maximum and minimum temperatures in the firebox will be: Tmax = 700 ° With , Tmin = 300 ° With , means Q for = 12 *( 500 - 70) = 5160 kcal / h, that in watts is 5160000 / 859,85 = 6001,05 ≈6 kW .It turns out that when the furnace is combusted with firewood it is possible to remove about 6 kV t of thermal energy from 1 m2 of heat exchanger located in the firebox.

Depending on the amount of heat required, you can calculate the required heat exchanger area: S = Q / Q for .Suppose that for heating the house requires 15 kV tt of thermal energy, then the heat exchanger area that comes into contact with the hot medium in the combustion chamber should be 15/6 = 2.5 m 2. If heat exchanger is made ofsteel sheet, the its calculated area is easy, and if of round pipes , the area of ​​each pipe calculated: Str = 2 * π * D * l, wherein D - Dia tr tr , and l - the length of the pipe .The area of ​​rectangular pipes is calculated as their perimeter, multiplied by the length. This is how you can calculate such a heat exchanger that will satisfy the need for heating the house.

Installing the water circuit in the brick oven

Note the important features of installing the heat exchangers in a brick oven:

• The heat exchanger must only be installed in a specially designed furnace. When retrofitting old furnaces, it is necessary to contact specialists, they will make the necessary calculations and offer a design of the heat exchanger that will not disrupt the normal operation of the furnace.
• After the heat exchanger is manufactured, it is absolutely necessary to pressurize with the pressure 6 bar before and after installing it in the oven.

• Usually, heat exchangers are installed immediately after equipping the base of the furnace, and only then the masonry is produced.
• To compensate for thermal expansion, it is necessary to leave a gap between it and the furnace walls at least 10-15 mm when installing the heat exchanger. The heat exchanger is strictly forbidden to be embedded in the body of the furnace.
• The heat exchanger outlet should not be blocked with mortar. For pipes, a gap of 5 mm should be left in which a heat-resistant sealant, for example an asbestos cord, is placed. The outlet of the pipes from the furnace must be at least 10-15 cm, so that the thread can be re-threaded when the has its damaged.
• The connection of the heat exchanger with the pipes of the heating system must be done only with heat-resistant seals.

Rules for operating a furnace with water circuit

Not only is the calculation of and the installation of a heat exchanger in the furnace itself - it's quite an time-consuming and responsible operations, for the normal operation of heating is still required and a set of rules is required:

• No wayIt is impossible to operate an oven with empty heat exchangers, this will cause the to quickly burn out.
• Do not block the heat exchanger from the heating system while the oven is running. When the water is heated, it expands into the volume of the , the pressure rises, which can even lead to an explosion. It is better not to put any shut-off valves on the exits of the heat exchanger.

• Do not supply cold water to the heat exchanger when the oven is heated. Thermal deformations can disable it. The weakest point is welded seams.
• To improve the efficiency of the heating system, it is better to use a circulation pump of the appropriate capacity with bypass.

• In the heating system, it is absolutely necessary to provide a tap for draining water from the system at the lowest point.
• If necessary, special antifreeze agents can be used in the water circuit of the furnace.

Constructing a heating and cooking furnace with a water circuit by one's own hands

As it was recommended by the authors of the article, it is better to use the finished and time-tested furnace design, which is described in detail in J. Porfiriev's famous book "Furnace Works".This heating device occupies an area of ​​1020 * 1160 mm in base and has a height of 2380 mm. The heat exchanger of the water circuit measures( 750 * 500 * 350 mm) is made of sheet steel and is located in the firebox, so the cooking surface is used only for heating food. According to the author of the design, the heat transfer to the water circuit is approximately 5.5 kW at the furnace two times a day, and with the strengthened one it can reach 18 kW, which allows heating the premises with a total area of ​​180-200 m2.

List of required materials and devices

One solid row of bricks is laid out. It is very important to maintain the horizontal and rectangularity, as much of this will then depend on it. In this row, 36 red bricks are involved.
On the laying of 2 rows the formation of the bottom of the ash chamber begins. The door is sized 140 * 250 mm. There are 31 whole red bricks and one half.
It is placed according to the scheme 3 series. The number of bricks as in the previous one is 31 red whole and half.
In the 4th row, the formation of the firebox begins, therefore 11 chamotte bricks and 21 red are already used. To install the grate in the brick SHA-8 cuts are made.
At the stage of forming 4 rows, gratings are placed in the cut grooves. To compensate for thermal expansion, a gap of about 5 mm is left.
The heat exchanger( boiler)
is installed at the bottom of the firebox. When laying the 5th row, a gap of 5-6 mm is left for the thermal expansion of the heat exchanger. Behind it is a free space that connects to the horizontal channel. At the same stage 2 doors 140 * 140 mm are installed - for cleaning the channel. Used 14 red and 3 fireclay bricks.
6 row. The horizontal channel is separated from the channel behind the boiler, and the hole left in the previous row will increase the draft of the furnace. On the same row is installed the furnace door. Used 15 whole red bricks and one half, as well as 1 fireclay.
According to the scheme laid out 7 series. Used 15 and ½ red and 2 fireclay bricks.
With the laying of the 8th row, the boiler door is closed. For this purpose, a strip of 50 * 5 * 400 mm is used. In the row there are 11 and ½ red bricks and 6 chamotte.
In the 9th row the boiler feed pipe is produced. Half of fireclay bricks above the firebox door are cut obliquely. The horizontal channel is divided into two equal parts. Used 12 and ½ red brick and 7 chamotte.
On the same 9 row above the door of the furnace is installed a cut obliquely down ¾ piece of fireclay bricks.
On the 10th row, the bricks are let out inwards, so the space above the boiler narrows. Three red and 18 ½ fireclay bricks are used.
11 series. Bricks already from the ends of the furnace are also produced inward. In the bricks, cutouts are made for laying the cast-iron cooktop. It is taken into account that the thermal gap should be at least 5 mm. Number of bricks used: 10 red and 16 ½ fireclay.
The cast iron plate is mounted on the 11th row. In the place where there will be an opening in the cooking chamber, a corner of 50 * 50 * 980 mm is installed.
The cooking chamber begins to form on the 12th row. Please pay attention to the fact that the cast iron surface is removable - raised at the front and pulled out. Used 12 red and 5 fireclay bricks.
It is laid out according to scheme 13 series, which uses 16 ½ red bricks.
In the 14th row, the vertical channel is increased by the entire available width. To clean it, the door 140 * 140 mm is mounted.14 ½ red bricks are used.
15 series is laid out similarly to the previous one according to the scheme, which ensures the dressing of the seams.14 ½ red bricks are used.
In the 16th row, the facade of the cooking chamber is covered with a steel strip 50 * 5 * 980 mm and a corner 50 * 50 * 5 * 980.Used 15 red bricks.
17 series completes the overlap of the facade of the cooking chamber, for this 18 ½ red bricks are used.
18 row. For full overlapping of the cooking chamber itself, two strips of steel 50 * 5 * 980 mm are mounted, and 19 red bricks are laid out according to the drawing.
19 series completes the overlap of the entire cooking chamber. The left passage in half of the brick is needed for drawing. In the passage are cut grooves for the gate valve.32 red bricks are used.
19 series completes the installation of a small camera gate 140 * 140 mm.
20 series forms the base of the upper flues. For this, according to the drawing, halves are laid out, which will be the basis of the subsequent partitions. For cleaning and revision, 4 doors 140 * 140 mm are mounted. For laying this series requires 18 red bricks.
21 series continues the formation of partitions. It requires 17 ½ red bricks.
22 row. It requires 21 red bricks.
In the 23rd row, the upper flues are divided into 4 channels. One of them( the lower left one in the drawing) will later be the main chimney, and the others will function as a common hood separated by partitions. Used 24 red bricks.
For laying 24 rows, 24 red bricks are required.
For stacking 25 rows, 23 ½ red bricks are required.
For laying the 26th row, 23 ½ red bricks are required.
For laying the 27th row, 23 ½ red bricks are required.
For laying the 28th row, 23 ½ red bricks are required.
29 rows require 23 ½ red bricks for laying.
In the 30th row, the integration of all smoke channels starts, except for the main one. Used 20 red bricks.
31 series continues the combination of vertical channels. It requires 21 ½ red bricks.
32 series prepares the overlap of the furnace.25 ½ red bricks are used. The
33 series covers the furnace. The main channel is 130 * 260 mm in size, 35 red bricks are used.
34 series overlaps the second time the furnace. This requires 37 red bricks. To install the main smoke gate slots are cut.
A flue valve is installed and adjusted in place.
35 series completes the laying of the furnace body. A base is made for the chimney liner. To do this, you need 5 red bricks.
Drawing	Surface view	Additional view

Image	Description of materials( oven devices)	Quantity, pcs
	Brick red solid( without flue)	710
	Refractory brick refractory SHA-8	71
	Roof top door 210 * 250 mm	1
	Roof door 140 * 250 mm	1
	Ash cleaning door 140 * 140mm	7
	Grate plate 250 * 300 mm	2
	Cast iron plate 710 * 410 mm	1
	Heat exchanger made of sheet steel 750 * 500 * 350 mm	1
	Furnace damper 130 * 250 mm	1
	Latches for brewing chamber 130 * 130 mm	1
	Steel strip:
50 * 5* 400 mm	1
50 * 5 * 980 mm	2
	Steel corner 50 * 50 * 5 * 980	2
	Preheating sheet 500 * 1000 mm	1

How to proceed

Before starting work on the construction of a furnace with a water circuit, you need to carefully study the design of the furnace, see its general appearance and how it looks in the sections. This is all represented in the following three figures.

After that it is necessary to produce a heat exchanger for the water circuit of the furnace, the drawing of which is shown in the following figure.

What should I consider when making the heat exchanger?

• The walls facing the fire are made of sheet steel of 5 mm.
• External walls that carry a lower thermal load are permissible to be made of steel 3 mm.
• A gap of at least 50 mm in width must be left at the rear for the escape of gases from the firebox.
• The heat exchanger outlet( supply) is made from a seamless steel pipe with a diameter of 40 mm, and it must be welded at the highest point.
• The other output( return) is made from the same pipe and is welded at the lowest point of the heat exchanger.

Ordering masonry furnace with a water circuit

Before laying the furnace you need to build a suitable foundation for it, but in this article we will not consider this issue, and proceed to the order. Before this, we will get acquainted with the conventions that will be encountered in the future.

This construction of the furnace can be considered complete. The chimney is already realized absolutely individually, as this should take into account both the number of floors in the house, the type of overlap, the type of roofing system, roof covering, and many other factors.

Video: Heating and cooking oven with water circuit

Underwater stoves of water circuits for furnaces

Such a seductive occupation as the arrangement of the water circuit in the furnace is not as perfect as we would like, since in this at the first glance the right event has its pitfalls. And the topic would not be fully disclosed if the authors did not say anything about it. So, what can the owner of a stove with a water circuit for heating expect?

• First of all, such furnaces can not be operated with an empty water circuit, as mentioned earlier. Imagine a situation where a family for the weekend decides to visit the cottage in winter and melt the stove or fireplace. The prudent host, of course, has drained all the water from the heating system in the fall, so the of its needs to be refilled. Inconvenience? Of course yes! It's not a fact that the dacha has a water pipe, but a good antifreeze based on propylene glycol, filled in the system, costs a lot and can behave in furnaces unpredictably. Temperature volumetric expansion of antifreezes is much higher than that of plain water, therefore, the pressure increase is avalanche-like.
• Another underwater stone for operating furnaces with a water circuit is that that in is warm the time of year, by melting the oven for cooking or the fireplace, the owners of will be forced to put up with the fact that batteries will also be hot, The furnace can not be used, and excess heat in summer is absolutely not necessary. How to be? A possible solution to this problem is the installation of the heat accumulator , which costs much more than even a very good solid fuel boiler. Another one solution is to install radiators somewhere in the attic or basement and in summer simply switch the water circuit to them, discarding excess heat and contributing a small contribution to the global warming and melting of the Arctic ice. But again, these are extra worries and expenses.
• Almost all modern heating systems are made with forced circulation of coolant, for which special pumps are used. This allows more efficient transfer of heat and use pipelines of smaller diameters. And nothing prevents to equip the water circuit of the with and the circulation pump, safety group, expansion tank and other mandatory components of the system. But whether it is worth doing is a big question. Modern boilers are designed from the point of view of safety design, tested high pressure, have protection. The emergence of a dangerous emergency situation in cases of boilers, including solid fuel, is extremely unlikely, which can not be said about homemade designs of ovens with a water circuit. The influence of the human factor is too great in them.

So, what conclusions can be drawn. Will the boiler with a water circuit become a full-fledged boiler? Never in my life! Yes, it is more than just an oven, but still is not boiler .And vice versa - boiler is unlikely to become an oven. These devices have different functions and the intersection of can be both economically unreasonable, and also difficult to implement and in some cases simply dangerous. It is cheaper and better to have a separate oven and boiler , then each of these devices is realized in all its glory, without interfering with each other.

Ideal place for a furnace with a water circuit in terms of engineering science

Is there such an ideal place where a stove or fireplace with a water circuit is realized in all its glory? Of course, yes. Let's look at the figure, which shows the scheme of an energy-efficient house.

It is evident that one of the main components of the general system of heating and hot water supply of the house is heat accumulator , called buffer , installed in the boiler room of the basement floor. It is capacity large volume ( usually not less than 500 liters) in which are coils of heat exchangers from various heat sources. It can be a gas or solid fuel boiler , solar collector panels, and, as can be seen from the of the above figure, there was a place and a fireplace with a water circuit. Disassembling the coolant for various purposes ( radiator heating, warm floors) comes from this capacity .All "requests" are monitored by sensors with controllers and pump groups.

Hot water supply is provided from the internal tank, hermetically sealed separated from the main of .The water is heated by through metal walls. If necessary, TAN can be installed through special flanges in the inner tank with hot water, which "helps" at night, when the reduced tariffs for electricity operate. The case of buffer is enclosed by into a powerful thermal insulation made of expanded polystyrene with a thickness of at least 100 mm, which ensures minimal heat loss.

Heating systems based on the buffer of the have undoubted advantages:

• The large heat accumulator takes over the excessive heat that can be generated by solid fuel boilers, as well as furnaces with a water circuit or solar systems. This prevents overheating and extends the life of the equipment.
• The heating system with buffer capacity works more stable, since there is no dependence on only one heat source.
• Application heat accumulator allows you to save up to 30% of energy.

The main drawbacks of buffer systems are their volatility and very high on equipment. Therefore, the flawless from the engineering standpoint, the use of a furnace with a water circuit can become completely unreasonable from the point of view of the common sense. Although, of course, beyond such systems the future. In developed countries, where the state subsidizes the use of various alternative energy sources, such systems have already been used widely enough.

Conclusion

Summing up the article it can be concluded that furnaces with a water circuit can be used for heating the house, but with many reservations:

• It is best to use industrially manufactured furnaces and fireplaces that are specially adapted for water heating.
• When using a brick kiln for heating the coolant, it is best to build from scratch a specially adapted and calculated for this purpose design.
• Implementation of the furnace and boiler in one design is a difficult task, having its own reefs.
• The ideal place for ovens with a water circuit is a heating system with a buffer with .