Heating with wood or coal is not very pleasant. You have to heat it often, especially in cold weather; it takes a lot of time and effort. In addition, the fluctuating temperature - sometimes cold, sometimes hot - does not bring joy either. These problems can be solved by installing a heat accumulator (heat accumulator) for heating.
What is a heat accumulator for heating?
In the simplest case, a heat accumulator for a heating system is a container filled with coolant (water). This container is connected to the heating water boiler and to the heating system (through pipes of a suitable diameter). In more complex devices, a heat exchanger is located inside the container, connected to the heating boiler. The hot water supply comb can also be powered from this container through another heat exchanger.
Heat accumulators for heating are usually made of steel - regular, structural or stainless steel. They can be cylindrical or parallelepiped-shaped (square). Since they are designed to retain heat, much attention is paid to insulation.
What is it needed for
Installing a heat accumulator (TA) for individual heating can solve several problems at once. Most often, TAs are placed where they are heated with wood or coal. In this case, the following tasks are solved:
- A water tank is a guarantee that the water in the system will not overheat (if the length of the heat exchanger and the tank capacity are correctly calculated).
- Using the heat accumulated in the coolant, it is maintained normal temperature after the fuel supply has burned out.
- Due to the fact that there is a reserve of heat in the system, you need to heat it less often.
All these considerations force you to buy a very expensive heat accumulator for heating.
Some craftsmen make. This is an economical option, but it also costs at least 20-50 thousand rubles. With a purchased TA you will have to spend many times more than with a homemade one.
Heat accumulators are not cheap, but the result of their use is worth it. Firstly, it increases safety (the heating system will not boil, pipes will not burst, etc.). Secondly, you won’t have to heat it so often. Thirdly, a more stable temperature, since the container with water is a buffer that smoothes out temperature fluctuations that characterize heating with wood and coal (it’s hot, then it’s cool). Therefore, these devices are also called “heating buffer tanks”.
Connecting two boilers via a buffer tank is easy and simple
Separately, it is worth mentioning the saving of firewood and coal. In a heating system without TA, on relatively warm days it is necessary to limit the access of air, reducing the combustion intensity. Otherwise the house is too hot. Since conventional solid fuel (SF) boilers are not particularly designed for such modes, the efficiency of the boiler in this case is very low. Most of the heat simply flies into the chimney. In the case of an installed water heat accumulator, everything is exactly the opposite: you do not need to limit combustion. The faster the water heats up, the better. It is only important to correctly calculate the system parameters.
Another option is a heat accumulator for heating with a built-in tubular electric heater (TEH). This makes it possible to further increase the time between starts of the solid fuel boiler. Moreover, if there is a night tariff in your region, you can turn on the electric heating at night. Then it won’t hurt your wallet so much. You can also solve the problem of insufficient power of the selected and installed heating boiler.
There are other areas of application. For example, some owners install two boilers. To reserve just in case, since one type of fuel is not always available. This practice is quite common. Connecting them via a heat accumulator greatly simplifies the wiring. There is no need to install a lot of shut-off and control valves. Put the boilers into a heat accumulator - and that’s all there is to it. By the way, you can connect to the same container. They also easily fit into such a scheme. By the way, the heat stored on a sunny day with the help of solar collectors can be heated for up to two days.
Owners of electric boilers install a buffer tank to save money. Yes, this increases the volume of coolant that has to be heated, but the boiler is started during the reduced tariff - at night. During the day, the temperature is simply maintained by the heat that is “stored” in the heat accumulator. How profitable this method is depends on the region. In some regions, night rates are significantly lower than day rates, i.e. It is quite possible to make heating cheaper.
How to calculate the volume of TA
In order for a heat accumulator for heating to perform its functions, its volume must be selected correctly. There are several methods:
- by heated area;
- by boiler power;
- according to the time available.
Most of the methods are based on experience. For this reason, there is a “fork” in the recommendations. For example, from 35 to 50 liters per square meter of heated area. How exactly to determine the number? It is worth taking into account the region of residence and the degree of insulation of the house. If you live in a region with not the most severe winters or the house is well insulated, it is better to take it at the lower limit or so. Otherwise - on the top.
When choosing the volume of a heat accumulator for heating, two points must also be taken into account. The first is that a large amount of water will allow you to heat it much less often. Due to the stored heat, the temperature can be maintained for a long time. But, on the other hand, the time to “accelerate” this volume to desired temperature(heating to 85-88°C is considered normal). In this case, the system becomes very inertial. You can, of course, take a more powerful boiler, but paired with a buffer tank, this will cost a considerable amount. Therefore, you have to maneuver, finding the optimal solution.
By heated area
You can select the volume of the heat accumulator for the heating system according to the area of the room. It is believed that 35 to 50 liters are needed per ten square meters. The selected value is multiplied by the quadrature divided by ten to obtain the desired volume.
For example, in the heating system of a house with an area of 120 m² with average insulation, it is better to install a heat accumulator for heating 120 m² / 10 * 45 l = 12 * 45 = 540 liters. This will not be enough for the Middle Zone, so you should look at containers with a volume of approximately 800 liters.
In general, to make it easier to navigate, for a house with an area of 160-200 square meters, located in the middle zone, with average insulation, the optimal tank volume is 1000-1200 liters. Yes, with such a volume, you will have to heat it more often in cold weather. But this will not undermine your budget too much, and will allow you to live quite comfortably almost all winter.
By boiler power
Since the boiler will have to work on heating the water in the tank, it makes sense to calculate the volume based on its capabilities. In this case, 50 liters of capacity are taken per 1 kW of power.
You can make it even simpler - use the table (the values that are optimal in terms of cost and performance are shaded in yellow)
The calculation is simple. For a 20 kW boiler, a TA of 1000 liters is suitable. With such a volume of heat storage for heating, you will have to heat it twice a day.
According to the desired duration of downtime and heat loss
This method is more accurate, as it allows you to select dimensions specifically for the parameters of your home (heat loss) and your wishes (duration of downtime).
Let's calculate the volume of a heat accumulator for a house with a heat loss of 10 kW/hour and an idle time of 8 hours. We will heat the water to 88 °C, and it will cool down to 40 °C. The calculation is as follows:
For these conditions, the required capacity of the heat accumulator for heating is 1500 liters. This is because heat loss of 10 kW/hour is too much. This is a house with virtually no heating.
Types of buffer tanks, features of their use
We will talk about the “filling” of heat accumulators for heating. Outwardly, they all look the same, but the inside may be completely empty, or there may be heat exchangers. Usually this is a pipe - smooth or corrugated - twisted into a spiral. It is by the presence, quantity and location of these spirals that a heat accumulator for heating is distinguished.
Buffer tanks for heating systems come with different “fillings”
Without heat exchanger
Essentially, it is just a thermally insulated tank with direct connection to the boiler and consumers. Such a heat accumulator can be used in systems where the same coolant is acceptable. For example, you can’t connect the hot water supply like that. Even if water is used as a coolant, its composition is far from drinking water or even that which can be used for domestic needs. As a technical one, it’s possible, but not in all cases.
The second limitation is the pressure on consumers. In any operating mode operating pressure consumers should not be lower than the pressure in the boiler and the tank itself. Since the system is single, the pressure will be common. Everything is clear here and no explanation is required.
The third limitation is temperature. The maximum temperature at the boiler outlet should not exceed the level permissible temperatures all other system components. This also requires no explanation.
A heat accumulator without a heat exchanger is simply a sealed insulated container with pipes for connecting the boiler and consumers
Basically, this is the most cheap option heat accumulator for heating, but the choice is not the best. The fact is that the boiler heat exchanger will not last long. The entire considerable volume of water will be pumped through it and a considerable amount of salts will be deposited. And if there is also a water consumption - as a hot water supply - then the source of salts will become inexhaustible, as it will be replenished with fresh water from the tap. So we install a heat accumulator without a heat exchanger as a last resort - if we really don’t have the funds for more expensive devices.
With a heat exchanger in the lower or upper part of the tank, with two (bivalent)
Installing a heat exchanger connected to the boiler solves many problems. A small volume of coolant circulates through this circle and does not mix with the rest. So a lot of salts will not be deposited on the boiler heat exchanger. In addition, problems with pressure and temperature are eliminated. Since the circuit is closed, the pressure in it does not affect the rest of the system and can be any within a reasonable range.
Temperature restrictions remain: it is important that the coolant does not boil. But this can be solved - there are special ways to solve it.
But where is it better to install the heat exchanger from the boiler in the heat accumulator - at the top or at the bottom? If you place it at the bottom, there will be constant movement in the container. The heated coolant will rise up, the colder one will fall down. This way all the water in the container will be more or less the same temperature. This is good if you need the same temperature for all consumers. In such cases, heat accumulators with a lower heat exchanger are chosen.
If the boiler spiral is located in the upper part, the coolant is heated layer by layer. The most heat It turns out in the upper part, gradually decreasing downwards. This temperature stratification can be useful if you supply water at different temperatures. For example, you can feed it hotter into radiators. The pipes going to them must be connected to the topmost terminals. The heated floor needs a warm coolant - we take it from the middle. So this is a good option too.
There are also heat accumulators with two heat exchangers. Outputs from different heat sources are connected to them. This could be two boilers, a boiler + solar collectors, or other options. Here you just have to decide which source to connect up and which down. In some TA models, spiral heat exchangers are nested one inside the other. Then everything is simpler - you figure out which source can heat the larger volume, and connect it to an external heat exchanger. The second is to the internal.
Options for DHW
Installing a heat accumulator solves the problem of hot water supply. There are several ways to provide water heating for technical needs.
As already mentioned, heated water can be taken directly from the tank. But its quality will be technical. Do you want to use this for showering, bathing, washing dishes - no questions asked. No - you will have to install a heat accumulator with a special heat exchanger and connect it to the comb cold water, tie. But the water will be of proper quality.
Another option is a heat accumulator with a built-in hot water tank. Applicable for cases when warm water It is not needed at a time when the coolant is actively heating. The tank located in the upper part retains heat, so that even when the rest of the volume cools down, the water remains warm. Tanks can be additionally equipped with heating elements. This will make it possible to have water at the desired temperature in any case.
What are the benefits of a heat accumulator for heating with a built-in hot water tank? Space is saved. To place a heat exchanger and an indirect heating boiler next to each other, it will take a lot more space. The second advantage is that there are small cost savings. Minus - if the buffer tank fails, you lose both hot water and heating.
Using gas boiler We do not need to independently maintain a certain temperature in the heating circuit - this is done automatically. But everything changes when a solid fuel boiler is installed in the house. The fuel in it burns unevenly, which leads to cooling or overheating of the heating system. A heat accumulator for heating will help compensate for these fluctuations and stabilize the temperature in the circuit. A capacious storage tank will be able to retain excess thermal energy, gradually releasing it into the heating system.
In this review we will look at:
- How heat accumulators for heating systems work;
- How to calculate the required volume of a battery tank;
- How storage tanks are connected;
- The most popular models of thermal storage devices.
Let's go through these points in more detail.
Operating principle of heat accumulators
If you install a solid fuel boiler in your house, there will be a severe need to regularly add new portions of firewood. It's all about the limited volume of the combustion chamber - it cannot accommodate an unlimited number of logs. And their automatic feeding systems have not yet been invented, if you don’t take into account pellet boilers with automation. In other words, you will have to monitor the operation of the heating system yourself.
These boilers develop maximum power at the moment when firewood is happily blazing in them. At this moment, they provide a lot of excess energy, so users dose the firewood carefully, placing it one log at a time. Otherwise the house will be too hot. There is nothing good about this, since this increases the number of approaches, which is already high. The problem is solved using a heat accumulator.
A heat accumulator for heating is a storage tank in which hot coolant accumulates. Moreover, energy is supplied to the heating circuit in a strictly dosed manner, which ensures temperature stability. Due to this, household members get rid of temperature fluctuations and frequent trips to lay firewood. Storage tanks are capable of accumulating excess thermal energy and smoothly releasing it into heating circuits.
Let's try to explain the principle of operation on the fingers:
The simplicity of the thermal accumulator design not only increases the reliability of the unit, but also simplifies repairs and scheduled maintenance.
- Installed in a heating system with a heat accumulator, the heating boiler is loaded with firewood and produces a large amount of thermal energy;
- The resulting energy is sent to thermal battery and accumulates there;
- At the same time, with the help of a heat exchanger, heat is collected for the heating system.
The buffer tank for heating (also known as a heat accumulator) operates in two modes - accumulation and release. In this case, the boiler power may exceed the required thermal power for heating the home. While the wood is burning in the firebox, heat will accumulate in the thermal accumulator. After the logs go out, energy will continue to be drawn from the battery for a long time.
Lazhebok’s heat accumulators for greenhouses and greenhouses are designed in approximately the same way - during the day they accumulate heat from the sun, and at night they release it, warming the plants and preventing them from freezing. They just look a little different.
Heat accumulators for heating systems are also necessary if they are used as a heat source. solar panels or heat pumps. The same batteries cannot provide heat around the clock, since at night their efficiency drops to zero. During daylight hours, they will not only heat the house, but also accumulate thermal energy in the storage tank.
Heat accumulators can be useful when using electric boilers . This scheme justifies itself on a two-tariff payment system. In this case, the system is configured so that heat accumulation occurs at night, and its release begins during the day. Thanks to this, consumers have the opportunity to save money on energy consumption.
Types of heat accumulators
The heat accumulator for the heating system is a capacious tank equipped with solid thermal insulation - it is responsible for minimizing heat loss. Using one pair of pipes, the battery is connected to the boiler, and using the other pair, to the heating system. Additional pipes may also be provided here for connecting the DHW circuit or additional sources thermal energy. Let's look at the main types of heat accumulators for heating systems:
Subject to availability circulation pump It becomes possible to use several buffer tanks at once, which allows you to evenly heat several rooms at once.
- Buffer tank is a simple tank without internal heat exchangers. The design provides for the use of the same coolant in the boiler and batteries, at the same permissible pressure. If you plan to pass one coolant through the boiler and another through the batteries, you should connect an external heat exchanger to the heat accumulator;
- Heat accumulators for individual heating with lower, upper or several heat exchangers at once - such heat accumulators allow you to organize two independent circuits. The first circuit is a tank connected to the boiler, and the second is a heating circuit with radiators or convectors. The coolants do not mix here; there may be different pressures in both circuits. Heating is carried out using a heat exchanger;
- With a flow-through heat exchanger of the DHW circuit or with a tank - for organizing hot water supply. In the first case, water can be consumed throughout the day and evenly. The second scheme involves the accumulation of water for the purpose of quickly releasing it at a certain time (for example, in the evening, when everyone takes a shower before going to bed) - indirect boilers that accumulate water are designed in a similar way.
The design of heat accumulators for heating can be very different, the choice suitable option depends on the complexity of the heating system, its characteristics and the number of sources of hot coolant.
Some heat accumulators are equipped with heating elements with thermostats, which makes it possible to provide consumers with heat at night, when the coolant has already cooled down and there is no one to throw firewood into the firebox. They are also useful when using heat pumps and solar panels.
Calculation of heat accumulator volume
We have come very close to complex issue– to calculate the required volume of the heat accumulator. To do this, we will use the following formula – m=W/(K*C*Δt). The letter W denotes the amount of excess heat, K is the efficiency of the boiler (we indicate decimal), C is the heat capacity of water (coolant), and Δt is the temperature difference, determined by subtracting the temperature of the coolant on the return pipe from the temperature on the supply pipe. For example, it can be 80 degrees at the outlet and 45 at the return - in total we get Δt=35.
First, let's calculate the amount of excess heat. Let's assume that for a house with an area of 100 sq. m. we need 10 kW of heat per hour. The burning time on one stack of firewood is 3 hours, and the boiler power is 25 kW. Consequently, in 3 hours the boiler will generate 75 kW of heat, of which only 30 kW needs to be sent for heating. In total, we are left with 45 kW of excess heat - this is enough for another 4.5 hours of heating. In order not to lose this heat and not reduce the amount of loaded firewood (otherwise we will simply overheat the system), you should use a heat accumulator.
As for the heat capacity of water, it is 1.164 W*hour/kg*°C - if you don’t understand physics, just don’t go into details. And remember that if you use a different coolant, its heat capacity will be different.
Having carried out the necessary calculations using our advice, you can easily select the model that most accurately satisfies all your needs.
In total, we have all four values - this is 45,000 W of heat, the efficiency of the boiler (let's assume 85%, which in fractional calculations will be 0.85), the heat capacity of water is 1.164 and the temperature difference is 35 degrees. We carry out calculations - m=45000/(0.85*1.164*35). With these figures, the volume is equal to 1299.4 liters. We round up and get the capacity of the heat accumulator for our heating system equal to 1300 liters.
If you cannot carry out the calculations yourself, use special calculators, auxiliary tables or the help of specialists.
Connection diagrams
The simplest scheme for connecting a heat accumulator to a solid fuel boiler involves using the same coolant at equal pressure in the boiler and the heating system. For these purposes, the simplest storage tank without heat exchangers is suitable. Two pumps are installed on the return pipes - by adjusting their performance, we will ensure temperature control in the heating system. There is a similar scheme using a three-way valve - it allows you to regulate the temperature by mixing the hot coolant and the cooled coolant from the return pipe.
Heat accumulators with a built-in heat exchanger are designed to work in heating systems with high pressure coolant. To do this, heat exchangers are located inside them, connected through a circulation pump to the boilers - this is how a supply circuit is formed. The internal storage tank with a second circulation pump and batteries forms a heating circuit. Different coolants can circulate in both circuits, for example, water and glycol.
The design of a solid fuel boiler with a heat accumulator and a hot water circuit allows for the supply of hot water without the use of dual-circuit equipment. For this purpose, internal flow-through heat exchangers or built-in tanks are used. If hot water is needed throughout the day, we recommend purchasing and installing a heat accumulator with a flow exchanger. For peak one-time consumption, batteries with hot water tanks are optimal.
Bivalent and multivalent connection schemes have also been developed - they involve the use of several heat sources at once for heating operation. For this purpose, heat accumulators with several heat exchangers can be used.
Popular models
It's time to understand the most popular models of heat accumulators for heating systems. We will consider products from domestic and foreign manufacturers.
The manufacturer of Prometheus heat accumulators is the Novosibirsk company SibEnergoTerm. It produces models with volumes of 230, 300, 500, 750 and 1000 liters. The equipment warranty is 5 years. The heat accumulators are equipped with four outlets for connection to heating and heat sources. A layer of thermal insulation made of mineral wool is responsible for preserving the accumulated energy. The working pressure is 2 atm, the maximum is 6 atm. When purchasing equipment, take into account its dimensions - for example, the diameter of a 1000-liter model is 900 mm, which is why its body may not fit into standard doorways 80 cm wide.
The price of the presented heat accumulator for heating systems varies in the range from 65 to 70 thousand rubles.
Another capacious heat accumulator for 1000 liters of water. It is equipped with one or two smooth-tube heat exchangers, but lacks thermal insulation, which must be taken into account when installing it - it will have to be purchased separately. The diameter of the case is 790 mm, but if thermal insulation is added to it, the diameter increases to 990 mm. The maximum temperature in the heating system is +110 degrees, in the DHW circuit – up to +95 degrees.
These heat accumulators are available in modifications with six or ten connections. Temperature sensor terminals are also provided on board. The tank capacity is 960 liters, operating pressure is up to 3 bar. The thickness of the thermal insulation layer is 80 mm. The use of liquids other than water as a coolant is not allowed - this applies to both circuits, and not just the heating circuit. If necessary, it is possible to connect several heat accumulators in series into a single cascade.
Homemade heat accumulators
Nothing prevents you from assembling a heat accumulator for a heating system with your own hands - for this you need to carry out calculations and draw a drawing, focusing on the required capacity. Tanks are constructed from sheet metal 1-2 mm thick, cut with a plasma cutter, cutting machine or welding machine. Heat exchangers are organized from metal straight or corrugated pipes. And in order to avoid rapid corrosion of the metal, you need to purchase a magnesium anode. Basalt wool can be used as thermal insulation.
As a bonus, we provide a detailed drawing of a heat accumulator with a capacity of 500 liters - this is enough to maintain the operation of the heating system in a small house.
Video
Solid fuel boiler systems cannot operate for a long time without human intervention, who must periodically load firewood into the firebox. If this is not done, the system will begin to cool down and the temperature in the house will drop. In the event of a power outage when the furnace is fully ignited, there is a danger of boiling of the coolant in the jacket of the unit and its subsequent destruction. All these problems can be solved by installing a heat accumulator for heating boilers. It will also be able to perform a protection function cast iron installations from cracking due to sudden temperature changes in the supply water.
Connecting a solid fuel boiler with a heat accumulator
Calculation of the buffer tank for the boiler
The role of the heat accumulator in the general heating scheme is as follows: during normal operation of the boiler, accumulate thermal energy, and after the firebox dies out, release it to the radiators for a certain period of time. Structurally, a heat accumulator for a solid fuel boiler is an insulated water container of rated capacity. It can be installed both in the furnace room and in a separate room of the house. It makes no sense to place such a tank outside, since the water in it will cool much faster than inside the building.
Taking into account the availability of free space in the house, the calculation of a heat accumulator for a solid fuel boiler in practice is carried out as follows: The capacity of the tank is taken from the ratio of 25-50 liters of water per 1 kW of power required to heat the house. To more accurately calculate the buffer capacity for the boiler, it is assumed that the water in the tank will heat up to 90 ⁰C during operation of the boiler installation, and after turning off the latter, it will release heat and cool down to 50 ⁰C. For a temperature difference of 40 ⁰C, the heat output values for different tank volumes are presented in the table.
Table of heat output values for different tank volumes
Even if there is space in a building to install a large tank, it does not always make sense. It should be remembered that a large amount of water will need to be heated, then the power of the boiler itself should initially be 2 times greater than what is needed to heat the home. A tank that is too small will not perform its functions, as it will not be able to accumulate enough heat.
The selection of a heat accumulator for a solid fuel boiler is influenced by the availability of free space in the room. When purchasing a large storage tank, you will need to provide a foundation, since equipment with a significant mass cannot be placed on ordinary floors. If, according to calculations, a tank with a volume of 1 m3 is required, and there is not enough space for its installation, then you can purchase 2 products of 0.5 m3 each, placing them in different places.
Heat accumulator for solid fuel boiler
Another point is the presence of a hot water supply system in the house. In the case where the boiler does not have its own water heating circuit, it is possible to purchase a heat accumulator with such a circuit. Of no small importance is the value of the operating pressure in the heating system, which residential buildings traditionally should not exceed 3 Bar. In some cases, the pressure reaches 4 bar if a powerful heat source is used homemade unit. Then the heat accumulator for the heating system will have to be selected in a special design - with a torispherical cover.
Some factory hot water accumulators are equipped with an electric heating element installed in the upper part of the tank. This technical solution will not allow the coolant to completely cool down after the boiler is stopped; the upper zone of the tank will be heated. There will be a supply of hot water for household needs.
Simple switching circuit with mixing
The storage device can be connected to the system according to different schemes. The simplest connection of a solid fuel boiler with a heat accumulator is suitable for working with gravity coolant supply systems and will operate in the event of a power outage. To do this, the tank must be installed above the heating radiators. The circuit includes a circulation pump, a thermostatic three-way valve and a check valve. At the beginning of the heating cycle, water, driven by the pump, flows through the supply pipe from the heat source through a three-way valve to heating devices. This continues until the supply temperature reaches a certain value, for example 60 ⁰C.
At this temperature, the valve begins to mix cold water into the system from the lower pipe of the tank, maintaining the set outlet temperature of 60 ⁰C. Through the upper pipe, directly connected to the boiler, heated water will begin to flow into the tank, and the battery will begin to charge. When the wood in the firebox is completely burned, the temperature in the supply pipe will begin to drop. When it drops below 60 ⁰C, the thermostat will gradually shut off the supply from the heat source and open the flow of water from the tank. That, in turn, will gradually be filled with cold water from the boiler and at the end of the cycle the three-way valve will return to its original position.
The check valve, connected in parallel to the three-way thermostat, comes into operation when the circulation pump stops. Then the boiler with the heat accumulator will work directly, the coolant will go to the heating devices directly from the tank, which will be replenished with water from the heat source. In this case, the thermostat does not take part in the operation of the circuit.
Hydraulic split circuit
Another, more complex circuit connection, implies an uninterrupted supply of electricity. If this cannot be ensured, then it is necessary to provide for connection to the network through an uninterruptible power supply. Another option is to use diesel or gasoline power plants. In the previous case, the connection of the heat accumulator to the solid fuel boiler was independent, that is, the system could operate separately from the tank. In this scheme, the battery acts as a buffer tank (hydraulic separator). A special mixing unit (LADDOMAT) is built into the primary circuit, through which water circulates when the boiler is ignited.
Connecting a heat accumulator to a solid fuel boiler
Block elements:
- circulation pump;
- three-way thermostatic valve;
- check valve;
- sump;
- Ball Valves;
- temperature control devices.
Differences from the previous scheme - all devices are assembled into one block, and the coolant goes into the tank, and not into the heating system. The operating principle of the stirring unit remains unchanged. This connection of a solid fuel boiler with a heat accumulator allows you to connect as many heating branches as you like at the outlet of the tank. For example, to power radiators and floor or air system heating. Moreover, each branch has its own circulation pump. All circuits are separated hydraulically, excess heat from the source is accumulated in the tank and used when necessary.
Advantages and disadvantages
A heating system with a heat accumulator, in which the heat source is a solid fuel unit, has a lot of advantages:
- Increased comfort in the home, since after the fuel is burned, the heating system continues to warm the house hot water from the tank. No need to get up in the middle of the night and load a portion of firewood into the firebox.
- The presence of the container protects the boiler water jacket from boiling and destruction. If the electricity is suddenly turned off or the thermostatic heads installed on the radiators turn off the coolant because the desired temperature has been reached, the heat source will heat the water in the tank. During this time, the electricity supply may be restored or the diesel generator will be started.
- The supply of cold water from the return pipeline to the hot cast iron heat exchanger is excluded after the circulation pump is suddenly turned on.
- Heat accumulators can be used as hydraulic separators in a heating system (hydraulic arrows). This makes the operation of all branches of the circuit independent, which provides additional savings in thermal energy.
Higher cost of installation of the entire system and requirements for equipment placement are the only drawbacks use of storage tanks. However, this investment and inconvenience will be followed by minimal operating costs in the long run.
Often homeowners are not able to buy modern heating equipment, so they are looking for alternative solutions. Take, for example, a buffer tank (otherwise known as a heat accumulator), an indispensable item for heating systems with a solid fuel boiler. A storage tank with a volume of 500 liters costs approximately 600-700 USD. That is, the price of a thousand-liter barrel reaches 1000 USD. e. If you make a heat accumulator with your own hands, and then install the tank in the boiler room yourself, you will be able to save half of the specified amount. Our task is to talk about manufacturing methods.
Where is a heat accumulator used and how is it designed?
A thermal energy storage device is nothing more than an insulated iron tank with pipes for connecting water heating lines. The buffer tank performs 2 functions: it accumulates excess heat and heats the house during periods when the boiler is inactive. The heat accumulator replaces the heating unit in 2 cases:
- When heating a home or with a boiler that burns solid fuel. The storage tank works for heating at night, after wood or coal burns out. Thanks to this, the homeowner can relax in peace, rather than running to the boiler room. It is comfortable.
- When the heat source is an electric boiler, and electricity consumption is recorded using a multi-tariff meter. Energy at the night rate is half the price, so during the day the heating system is completely powered by the heat accumulator. It's economical.
Important point. A hot water accumulator tank increases the efficiency of a solid fuel boiler. After all, the maximum efficiency of a heat generator is achieved with intense combustion, which cannot be constantly maintained without a buffer tank that absorbs excess heat. The more efficiently wood is burned, the less it is consumed. This also applies to a gas boiler, whose efficiency decreases in low combustion modes.
A storage tank filled with coolant operates according to simple principle. While the heat generator is heating the rooms, the water in the tank is heated to a maximum temperature of 80-90 ° C (the heat accumulator is charging). After the boiler is turned off, hot coolant begins to flow to the radiators from storage tank, providing heating of the house for a certain time (the thermal battery is discharged). The duration of operation depends on the volume of the tank and the outside air temperature.
How does a factory-made heat accumulator work? The simplest factory-made storage tank for water, shown in the diagram, consists of the following elements:
- the main tank is cylindrical in shape, made of carbon or stainless steel;
- thermal insulation layer 50-100 mm thick, depending on the insulation used;
- outer skin – thin painted metal or polymer cover;
- connecting fittings embedded into the main container;
- immersion sleeves for installing a thermometer and pressure gauge.
Note. More expensive models of heat accumulators for heating systems are additionally equipped with coils for hot water supply and heating from solar collectors. Another useful option is a block of electric heating elements built into the upper zone of the tank.
Factory production of heat storage devices
If you are seriously concerned about installing a heat accumulator and decide to make it yourself, then first you should familiarize yourself with the factory assembly technology.
Cutting blanks for the lid and bottom using a plasma machine Repeat technological process in a home workshop is unrealistic, but some techniques will be useful to you. At the enterprise, the hot water storage tank is made in the form of a cylinder with a hemispherical bottom and a lid in the following order:
- Sheet metal 3 mm thick is fed to the machine plasma cutting, where blanks for end caps, housing, hatch and stand are obtained from it.
- On lathe Main fittings with a diameter of 40 or 50 mm (thread 1.5 and 2”) and immersion sleeves for control devices are manufactured. A large flange is also machined there for inspection hatch about 20 cm in size. A pipe for insertion into the body is welded to the latter.
- The body blank (the so-called shell) in the form of a sheet with holes for fittings is directed to rollers that bend it to a certain radius. To get a cylindrical container for water, all that remains is to butt weld the ends of the workpiece.
- From metal flat circles Hydraulic Press stamps hemispherical caps.
- The next operation is welding. The order is as follows: first, the body is welded using tacks, then the lids are tacked to it, then all the seams are completely welded. At the end, fittings and an inspection hatch are attached.
- The finished storage tank is welded to the stand, after which it undergoes 2 permeability tests - air and hydraulic. The latter is produced at a pressure of 8 bar, the test lasts 24 hours.
- The tested tank is painted and insulated with basalt fiber no less than 50 mm thick. The top of the container is sheathed with thin sheet steel with a colored polymer coating or covered with a thick cover.
The storage housing is bent from a sheet of iron on rollers Reference. To insulate the tank, manufacturers use different materials. For example, Prometheus heat accumulators Russian production insulated with polyurethane foam.
Instead of cladding, manufacturers often use a special cover (you can choose the color) Most factory heat accumulators are designed to maximum pressure 6 bar at a coolant temperature in the heating system of 90 °C. This value is twice the response threshold of the safety valve installed in the safety group of solid fuel and gas boilers (limit - 3 Bar). The production process is shown in detail in the video:
We make a heat battery ourselves
You have decided that you cannot do without a buffer tank and want to make it yourself. Then get ready to go through 5 stages:
- Calculation of the volume of the heat accumulator.
- Choosing a suitable design.
- Selection and preparation of materials.
- Assembly and leak testing.
- Installation of the tank and connection to the water heating system.
Advice. Before calculating the volume of the barrel, think about how much space in the boiler room you can allocate for it (in terms of area and height). Clearly decide how long the water heat accumulator should replace the inactive boiler, and only then proceed to the first stage.
How to calculate tank volume
There are 2 ways to calculate the capacity of a storage tank:
- simplified, offered by manufacturers;
- accurate, carried out according to the formula for the heat capacity of water.
The duration of heating a house with a heat accumulator depends on its size The essence of the enlarged calculation is simple: for each kW of boiler plant power, a volume equal to 25 liters of water is allocated in the tank. Example: if the productivity of the heat generator is 25 kW, then the minimum capacity of the heat accumulator will be 25 x 25 = 625 l or 0.625 m³. Now remember how much space is allocated in the boiler room and adjust the resulting volume to the actual size of the room.
Reference. Those who want to weld a homemade heat accumulator often wonder how to calculate the volume of a round barrel. Here it is worth recalling the formula for calculating the area of a circle: S = ¼πD². Substitute the diameter of the cylindrical tank (D) into it, and multiply the resulting result by the height of the tank.
You will get more accurate dimensions of the heat accumulator if you use the second method. After all, a simplified calculation will not show how long the calculated amount of coolant will last under the most unfavorable weather conditions. The proposed method is based on the indicators you need and is based on the formula:
m = Q / 1.163 x Δt
- Q is the amount of heat that needs to be accumulated in the battery, kWh;
- m – estimated mass of coolant in the tank, tons;
- Δt – difference in water temperatures at the beginning and end of heating;
- 1.163 W h/kg °C is the reference heat capacity of water.
Let's explain further with an example. Let's take standard house 100 m² with an average heat consumption of 10 kW, where the boiler must be idle for 10 hours a day. Then it is necessary to accumulate 10 x 10 = 100 kWh of energy in the barrel. The initial water temperature in the heating network is 20 °C, heating occurs up to 90 °C. We calculate the mass of the coolant:
m = 100 / 1.163 x (90 - 20) = 1.22 tons, which is approximately 1.25 m³.
Please note that a heat load of 10 kW is taken approximately; in an insulated building with an area of 100 m², heat loss will be less. Point two: so much heat is needed on the coldest days, of which there are 5 for the whole winter. That is, a heat accumulator for 1000 liters is sufficient with a large margin, and taking into account the seasonal temperature difference, you can easily keep within 750 liters.
Hence the conclusion: you need to substitute the average heat consumption for cold period equal to half the maximum:
m = 50 / 1.163 x (90 - 20) = 0.61 tons or 0.65 m³.
Note. If you calculate the volume of the barrel based on the average heat consumption, in severe frosts it will not be enough for the calculated period of time (in our example - 10 hours). But you will save money and space in the furnace room. More information on making payments is presented in.
About the design of the container
To make your own heat accumulator, you will have to defeat one insidious enemy - the pressure exerted by the liquid on the walls of the vessel. Do you think why factory tanks are made cylindrical, and the bottom and lid are hemispherical? Yes, because such a container can withstand the pressure of hot water without additional reinforcement.
On the other hand, few people have the technical ability to form metal on rollers, not to mention drawing semicircular parts. We offer the following ways to resolve the issue:
- Order a round internal tank from a metalworking enterprise, and carry out the insulation and final installation work yourself. It will still cost less than buying a factory-assembled heat accumulator.
- Take a ready-made cylindrical tank and make a buffer tank on its base. We will tell you where to get such tanks in the next section.
- Weld a rectangular heat accumulator from sheet iron and strengthen its walls.
Sectional drawing of a rectangular heat accumulator with a volume of 500 l Advice. In a closed heating system with a solid fuel boiler, where overpressure can jump to 3 Bar and higher, it is strongly recommended to use a cylindrical heat accumulator.
In an open heating system with zero water pressure, you can use a rectangular tank. But do not forget about the hydrostatic pressure of the coolant on the walls; add to it the height of the water column from the container to the expansion tank installed in highest point. That is why the flat walls of a homemade heat accumulator should be reinforced, as shown in the drawing of a 500 liter capacity tank.
A properly reinforced rectangular storage tank can also be used in a closed heating system. But in the event of an emergency pressure surge from overheating of the TT boiler, the tank will leak with a 90% probability, although you may not notice a small crack under the insulation layer. Watch the video to see how the unstrengthened metal of the vessel bulges when filled with water:
Reference. It makes no sense to weld directly onto the walls stiffeners made of corners, channels and other rolled metal. Practice shows that the pressure force bends corners of a small section along with the wall, and tears off large ones at the edges.
Making a powerful frame from the outside is impractical, the consumption of materials is too high. A compromise option is the internal spacers shown in the drawing of a homemade heat accumulator.
Drawing of a 500 l heat accumulator - top view (cross section) Selection of materials for the tank
You will make your task much easier if you find a ready-made cylindrical tank, initially designed for a pressure of 3–6 bar. What containers can be used:
- propane cylinders of different capacities;
- discarded process tanks, for example, receivers from industrial compressors;
- receivers from railway cars;
- old iron boilers;
- internal tanks of containers for storing liquid nitrogen, made of stainless steel.
It is much easier to make a reliable heat accumulator from ready-made steel vessels Note. In extreme cases, a steel pipe of suitable diameter will do. Flat covers can be welded to it, which will have to be reinforced with internal braces.
To weld a square tank, take sheet metal 3 mm thick, no more is needed. Make of rigidity round pipesØ15-20 mm or profiles 20 x 20 mm. Select the size of the fittings according to the diameter of the boiler outlet pipes, and for cladding, buy thin steel (0.3-0.5 mm) with powder painting.
A separate question is how to insulate a heat accumulator that you welded yourself. The best option – basalt wool in rolls with a density of up to 60 kg/m³ and a thickness of 60-80 mm. Polymers such as polystyrene foam or extruded polystyrene foam should not be used. The reason is mice that love warmth and in the fall can easily settle under the lining of your storage tank. Unlike polymer insulation, they do not chew basalt fiber.
Don't have any illusions about extruded polystyrene foam, rodents eat it too Now let's indicate other options finished vessels, which are not recommended for use with heat accumulators:
- An improvised tank made from a Eurocube. Similar plastic containers are designed for a maximum content temperature of 70 °C, but we need 90 °C.
- Heat accumulator made of an iron barrel. Contraindications: thin metal and flat tank lids. Instead of strengthening such a barrel, it is easier to take a good steel pipe.
Assembly of a rectangular heat accumulator
We would like to warn you right away: if you have mediocre welding skills, then it is better to order the manufacture of the tank externally according to your drawings. The quality and tightness of the seams is of great importance; at the slightest leak, the storage container will leak.
First, the tank is assembled using tacks, and then welded with a continuous seam For a good welder there will be no problems here, you just need to understand the order of operations:
- Cut metal blanks to size and weld the body without a bottom and a lid using tacks. To secure the sheets, use clamps and a square.
- Cut holes in the side walls for the stiffeners. Insert the prepared pipes inside and scald their ends from the outside.
- Grab the bottom and lid to the tank. Cut holes in them and repeat the operation with the installation of internal braces.
- When all the opposite walls of the container are securely connected to each other, begin continuous welding of all seams.
- Install supports from pipe sections at the bottom of the tank.
- Insert the fittings at a distance of less than 10 cm from the bottom and lid, as shown in the photo below.
- Weld metal brackets to the walls, which will serve as brackets for fastening thermal insulation material and sheathing.
The photo shows a stretch made from a wide strip, but it is better to use a pipe Advice on installing internal struts. To ensure that the walls of the heat accumulator effectively resist bending and do not break due to welding, extend the ends of the stretch marks outward by 50 mm. Then additionally weld stiffeners from a steel sheet or strip to them. ABOUT appearance don’t worry, the ends of the pipes will then disappear under the cladding.
Steel brackets (clips) are welded to the body to secure insulation and sheathing A few words about how to insulate a heat accumulator. First, check it for leaks by filling it with water or lubricating all the seams with kerosene. Thermal insulation is quite simple:
- clean and degrease all surfaces, apply primer and paint to protect them from corrosion;
- wrap the tank with insulation without squeezing it, and then secure it with a cord;
- cut the facing metal, make holes in it for the pipes;
- Screw the casing to the brackets with self-tapping screws.
Screw the cladding sheets so that they are connected to each other with fasteners. That's it for making a homemade heat accumulator for open system heating is finished.
Installation and connection of the tank to heating
If the volume of your heat accumulator exceeds 500 liters, then it is not advisable to place it on a concrete floor; it is better to arrange a separate foundation. To do this, dismantle the screed and dig a hole to a dense layer of soil. Then fill it with broken stone (rubble), compact it and fill it with liquid clay. Fill the top reinforced concrete slab 150 mm thick in wooden formwork.
Scheme of the foundation for the battery tank The correct operation of a heat accumulator is based on the horizontal movement of hot and cooled flow inside the tank when the battery is “charging”, and the vertical flow of water during “discharging”. To organize such battery operation, you need to perform the following steps:
- the circuit of a solid fuel or other boiler is connected to a water storage tank through a circulation pump;
- The heating system is supplied with coolant using a separate pump and mixing unit with a three-way valve allowing drainage from the accumulator required amount water;
- the pump installed in the boiler circuit should not be inferior in performance to the unit supplying coolant to the heating devices.
Tank-heat accumulator wiring diagram The standard connection diagram for a heat accumulator with a TT boiler is shown above in the figure. The balancing valve on the return line serves to regulate the coolant flow based on the water temperature at the inlet and outlet of the tank. Our expert Vladimir Sukhorukov will tell you how to properly strap and set up in his video:
Reference. If you live in the capital of the Russian Federation or the Moscow region, then regarding the connection of any heat accumulators, you can consult personally with Vladimir, using the contact information on his official website.
Budget storage tank made from cylinders
For those homeowners whose boiler room area is very limited, we suggest making a cylindrical heat accumulator from propane cylinders.
Homemade heat storage device paired with a TT boiler The 100 l design, developed by another of our masters, is designed to perform 3 functions:
- unload the solid fuel boiler when overheating, taking in excess heat;
- heat water for household needs;
- provide heating of the house for 1-2 hours in case of extinguishing of the TT boiler.
Note. The battery life of the heat accumulator is short due to its small volume. But it will fit in any furnace room and will be able to remove heat from the boiler after a power outage, since it is connected directly, without a pump.
This is what a tank made of cylinders looks like without lining To assemble the storage tank you will need:
- 2 standard propane cylinders;
- at least 10 m of copper tube Ø12 mm or stainless corrugations the same diameter;
- fittings and sleeves for thermometers;
- insulation – basalt wool;
- painted metal for cladding.
You need to unscrew the valves from the cylinders and cut off the caps with a grinder, filling them with water to prevent the remaining gas from exploding. Copper tube carefully bend it into a coil around another pipe of a suitable diameter. Then we proceed like this:
- Using the presented drawing, drill holes in the future heat accumulator for pipes and sleeves for thermometers.
- Secure by welding several metal brackets inside the cylinders for mounting the DHW heat exchanger.
- Place the cylinders one on top of the other and weld them together.
- Install a coil inside the resulting tank, releasing the ends of the tube through the holes. Use gland packing to seal these areas.
- Attach the bottom and lid.
- Insert an air vent into the lid and a drain valve into the bottom.
- Weld the brackets to secure the casing. Make them different lengths so that the finished product has a rectangular shape. It will be inconvenient to bend the cladding in a semicircle, and it will not be aesthetically pleasing.
- Insulate the tank and fasten the casing with self-tapping screws.
Connecting a tank to a TT boiler without a circulation pump The design feature of this heat accumulator is that it is connected to a solid fuel boiler directly, without a circulation pump. Therefore, for docking they use steel pipesØ50 mm, laid with a slope, the coolant circulates by gravity. To supply water to the heating radiators, a pump + three-way mixing valve is installed after the buffer tank.
Conclusion
On many Internet resources there is a statement that making a heat accumulator with your own hands is a piece of cake. If you study our material, you will understand that such statements are far from reality; in fact, the issue is quite complex and serious. You can’t just take a barrel and attach it to a solid fuel boiler. Hence the advice: think carefully about all the nuances before starting work. And without a welder’s qualifications, it’s not worth taking on a buffer tank; it’s better to order it from a specialized workshop.
Good day everyone! If you have come to this page of my blog, then you are interested in at least 2 questions:
- What is a heat accumulator?
- How does a heat accumulator work?
I'll start answering these questions in order.
What is a heat accumulator?
To answer this question we need to give a definition. It sounds like this: a heat accumulator is a container in which a large volume of hot coolant accumulates. The outside of the container is covered with thermal insulation made of mineral wool or polyethylene foam.
Why do you need a heat accumulator?
You ask: “Why do we need this oversized thermos?” Everything is very simple here; it allows you to optimally use the heat given off by the boiler. A powerful boiler (most often) always works in conjunction with a heat accumulator. The boiler quickly and non-stop transfers heat from the burned fuel to the heat accumulator, and it, in turn, slowly and in the required mode transfers this heat to the heating system. The system volume is much smaller than the battery capacity. This allows you to “stretch” the heat from the fuel over time. It turns out essentially. When the battery capacity is heated, the boiler constantly operates at full power, and this avoids the appearance of tarry condensate in the boiler.
How does a heat accumulator work?
As mentioned above, TA is a container in which hot water (or other) accumulates. To make everything clearer, look at the following figure: 
The container has several pipes for connecting various equipment:
- Thermal energy generator - boiler, .
- Plate heat exchanger for heating hot water.
- Various boiler equipment - safety group, expansion tank and so on.
Materials of water-containing container.
- Carbon steel various brands with (or without) protective enamel or varnish applied to inner surface- the cheapest and therefore most common material.
- Stainless steel is the most durable material, which is not subject to corrosion. Its main disadvantage is its high price.
- Fiberglass - this “exotic” material is used to make dismountable heat accumulators, which are assembled directly on site. This method allows you to carry the TA along the narrowest stairs and assemble it exactly in in the right place. If interested, watch the video of what it looks like
Heat accumulator connection diagram.
Now let's look at how the battery is included in the heating system:
From this diagram it is clear that the TA is included in the heating system as a hydraulic separator (). I recommend reading a separate article dedicated to this useful device. Let me say briefly that such a connection scheme eliminates the mutual influence of different ones and makes it possible to provide the boiler with the required volume of coolant, which has a positive effect on the life of the heat exchanger.
Thermal storage and hot water supply.
Another important issue is the installation of hot water supply in the house. This is where TA can also come to the rescue. Of course, you cannot use water directly from the heating system for sanitary needs. But there are at least two solutions:
- Connecting a plate heat exchanger to the heat exchanger, in which sanitary water will be heated - used at the most simple models TA.
- Purchasing a heat accumulator with a built-in hot water system - it can be implemented either using a separate heat exchanger (coil) or according to the “tank in tank” scheme.
You can, of course, also purchase it separately, but I believe that this can only be done if you have the necessary space in your boiler room.
Summary.
A heat accumulator is another way to increase the time between adding fuel to the boiler. In addition, TA can be used in systems with solar collectors and heat pumps. Most often, TA is used as a replacement for boilers long burning. The alternative is certainly interesting and worthy of your attention. This concludes my story. I look forward to your questions in the comments.
