Solid fuel boiler plants cannot operate for a long time without the intervention of a person who must periodically load firewood into the furnace. 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 completely burnt out, there is a danger of boiling up 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 the function of protecting cast iron installations from cracking at a sharp drop in the temperature of the supply water.
Connecting a solid fuel boiler with a heat accumulator
Calculation of the buffer capacity for the boiler
The role of the heat accumulator in the general heating scheme is as follows: during the operation of the boiler in normal mode, accumulate thermal energy, and after the firebox decays, give it to the radiators for a certain period of time. Structurally, the heat accumulator for a solid fuel boiler is an insulated water tank with an estimated capacity. It can be installed both in the combustion room and in a separate room of the house. It makes no sense to put such a tank on the street, since the water in it will cool down much faster than inside the building.
Given the availability of free space in the house, the calculation of the heat accumulator for a solid fuel boiler in practice is done 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... For a more accurate calculation of the buffer capacity for the boiler, it is assumed that the water in the tank heats up during the operation of the boiler plant to 90 ⁰С, and after turning off the latter, it will give off heat and cool down to 50 ⁰С. For a temperature difference of 40 ° C, the values \u200b\u200bof the heat given off for different tank volumes are presented in the table.
Table of heat dissipation values \u200b\u200bfor different tank volumes
Even if there is room for a large capacity in a building, this 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 more than is needed to heat the dwelling. A tank that is too small will not perform its function, since it will not be able to accumulate enough heat.
The selection of a heat accumulator for a solid fuel boiler is influenced by the presence of free space in the room. When buying a large storage tank, it will be necessary to provide for a foundation device, since equipment with a significant mass cannot be placed on ordinary floors. If, according to the calculation, a tank with a volume of 1 m 3 is required, and there is not enough space for its installation, then you can purchase 2 products of 0.5 m 3 each, placing them in different places.
Heat storage device for solid fuel boiler
Another point is the presence of a DHW system in the house. In the event that 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 working pressure in the heating system, which traditionally should not exceed 3 bar in residential buildings. In some cases, the pressure reaches 4 bar, if a powerful home-made unit is used as a heat source. Then the heat accumulator for the heating system will have to be chosen 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. Such a technical solution will not allow the coolant to cool down completely after stopping the boiler, the upper zone of the tank will be heated. Domestic hot water supply will operate.
Simple switching circuit with admixture
The storage device can be included in the system in different ways. The simplest piping of a solid fuel boiler with a heat accumulator is suitable for working with gravitational coolant supply systems and will operate in the event of a power outage. For this, the tank must be installed above the heating radiators. The circuit includes a circulation pump, a thermostatic three-way valve and a non-return valve. At the start of the heating cycle, water driven by the pump flows through the supply line from the heat source through the three-way valve to the heaters. This continues until the flow temperature reaches a certain value, for example 60 ° C.
At this temperature, the valve begins to mix cold water into the system from the lower branch pipe of the tank, observing the set temperature of 60 ⁰С at the outlet. Heated water will begin to flow into the tank through the upper branch pipe, directly connected to the boiler, and the battery will start charging. With complete combustion of wood in the firebox, the temperature in the supply pipe will begin to drop. When it drops below 60 ° C, the thermostat will gradually cut 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 with the three-way thermostat, is activated when the circulation pump is stopped. 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 separation scheme
Another, more complex connection scheme, implies an uninterrupted supply of electricity. If this is not possible, 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 work separately from the tank. In this scheme, the accumulator 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 fired up.
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 in one block, and the coolant goes to the tank, and not to the heating system. The principle of operation of the stirring unit remains unchanged. Such a piping of a solid fuel boiler with a heat accumulator allows you to connect as many heating branches as you like at the outlet from the tank. For example, to power radiators and floor or air heating systems. Moreover, each branch has its own circulation pump. All circuits are hydraulically separated, excess heat from the source is accumulated in the tank and used when needed.
Advantages and disadvantages
A heating system with a heat accumulator, in which a solid fuel plant serves as a heat source, has a lot of advantages:
- Improving the comfort conditions in the house, since after the fuel has burned out, the heating system continues to heat the house with hot water from the tank. There is no need to get up in the middle of the night and load a portion of firewood into the firebox.
- The presence of a container protects the boiler water jacket from boiling and destruction. If the electricity is suddenly cut off or the thermostatic heads installed on the radiators cut off the coolant due to reaching the desired temperature, then the heat source will heat the water in the tank. During this time, the electricity supply may resume or the diesel generator will be started.
- The supply of cold water from the return pipeline to the red-hot cast-iron heat exchanger after a sudden start of the circulation pump is excluded.
- Heat accumulators can be used as hydraulic dividers in the heating system (hydraulic arrows). This makes the operation of all branches of the circuit independent, which gives additional savings in thermal energy.
The higher cost of installing the entire system and the requirements for the placement of equipment are the only disadvantages of using storage tanks. However, these investments and inconveniences will be followed by minimal operating costs in the long term.
Heat accumulator is a unit for collecting and increasing heat for the purpose of its further use. The device is used in private houses, apartments, at enterprises, as well as for pre-heating engines. The heat accumulator for the heating system allows to reduce energy costs for space heating and hot water supply. The units are installed in the piping of a solid fuel boiler or connected to the solar system.
Purpose of the unit
The work of a solid fuel boiler in the heating system is a certain cyclicality. First, fuel is put into it, ignited, and then the boiler gradually reaches its maximum power and transfers thermal energy through the coolant to the heating system.
The firewood bookmark gradually burns out, the heat transfer decreases, and the coolant cools down. During the period of peak power, part of the heat energy remains unclaimed, and during the afterburning of the fuel, on the contrary, it will not be enough. To repeat the cycle, the solid fuel should be loaded again.
Partially this problem can be solved by a pyrolysis boiler of long burning, but during its operation, the peaks of production and consumption of thermal energy often do not coincide. To resolve this situation, an energy storage device for the heating system is installed, which is known as a buffer tank or heat storage.
Connecting a solid fuel boiler with a heat accumulator
The operation of this unit is based on the high heat capacity of water. If, during the period of maximum boiler power, a certain amount of water is heated, then subsequently its energy potential can be used for heating needs.
For example, water, when cooled by 1 ° C, can heat 1 m³ of air by 4 ° C. The simplest heat accumulator for heating boilers is a vertical tank with four nozzles cut in different directions. There are heat accumulators with a variety of storage materials:
On one side of the body, two branch pipes are connected to the boiler piping, and on the other, to the heating system. After starting the heater, the circulation pump starts pumping the coolant through the buffer tank.
Cold coolant enters the lower part of the accumulator, and hot coolant enters the upper part. Due to the significant difference in density, the water will not mix, and the hot coolant will gradually fill the entire container.
Usually the volume of a thermal accumulator for heating is calculated in such a way that one fuel load is enough to fill the tank with hot water completely. That is, all the energy of the boiler, excluding losses, is converted into heat, which will be accumulated in the storage tank.
Thermal insulation allows you to maintain a high water temperature for a long time. When the boiler stops working, the heating system continues to function. Thanks to the pump, hot water from the accumulator enters the pipelines and heating devices of the house.
In place of the hot coolant, cooled water again enters the buffer tank through the lower branch pipe from the return line of the pipeline. When using an electric boiler, the heating circuit with a heat accumulator can be used at night when the reduced tariff is in effect.
Boiler room schemes with a heat accumulator
All accumulators are vertical cylindrical tanks. They differ from each other only by the elements located inside the structure. There are several types of thermal accumulators:
All such designs can be produced in various variations depending on the complexity of the heating circuit, the number and types of heaters and water circuits used. Complex devices can be easily identified by the numerous nozzles coming out of the container.
Heat accumulator or Buffer tank. And why is it needed. Storage tank or buffer capacity principle
In our houses this is exactly the kind of heating - we would not put a bad one on ourselves.
My team and I installed the same heating system in more than 60 houses.
Send a request
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Teploakkumulator and night tariff of electricity is the most profitable and cheapest system after the main gas.
All other heating options - wood pallets, wood boilers, diesel fuel - are more expensive in any case. And you need to bother with them, constantly monitor that there is firewood or gas.
Here is a diagram of my heating system.
fig. storage tank in the heating system
What we have?
From the heat accumulator through the heat head (the temperature can be adjusted), the heat carrier is supplied to the floors. Here I still have a coil wound, which removes heat from the heat accumulator, and already from it, from the coil, the coolant goes to the floors.
Accordingly, the heating of the heat accumulator for me occurs due to the heating elements, i.e. electricity. And plus, if there is not enough heat, I still connect the wood-burning boiler (but for 4 winters I heated it a maximum of 10 times and then purely for the sake of maintaining its functionality, I drove the pumps, cleaned the chimney with fire, etc.)
As for main gas, why don't I use it?
I have two pipes running along the site. But the owners set very high prices for connections. One asks for 800 thousand rubles, the other 1.1 million rubles. This is not serious at all.
I calculated and it turned out that such a connection will pay off in 66 years. That is, the pipes are not state-owned, but private.
That is, if the connection to the gas costs 300,000 rubles (I also include the gas project, bringing gas into the house, connecting it to your heating system), then there is probably some logic. So that it will pay off with you (and then it will pay off for 20 years).
Now let's return to the heating system of the frame house with the help of a heat accumulator and a night electricity tariff.
When is it relevant?
➤ First - and most importantly - good insulation of your home. Correctly made project and insulation in the walls 150-200 mm, and in the ceiling 200-250 mm of basalt wool.
➤ Second, the availability of dedicated electricity capacity. You should have a minimum of 15 kW. That is, if you have a category of land for permanent residence, then power engineers provide you with 15 kW power in three phases by default. It's enough.
➤ The third parameter is the presence of a night tariff. If you, for example, connect to the Moesk system, they will offer you a night tariff (from 11 pm to 7 am) by default.
We will use this tariff to the maximum, when electricity is three times cheaper than during the day.
When is the best time to lay and build a home heating system?
This is best thought out during the design phase of your home. Because the most efficient heating system with a heat accumulator works in conjunction with warm floors.
I have seen when a heat accumulator is used in conjunction with radiators. But the disadvantage is that the heat accumulator is a large capacity. It is quite difficult to heat it up, you need a lot of power. And in principle it can be heated up to 80-85 ºС, and the radiator will remove all this from you in 3-4 hours. And by evening the house will be cold.
When designing a heating system, the main goals are comfort and reliability. The house should be warm and comfortable, and for this, a hot coolant should always enter the radiators without delays and temperature jumps.
With a solid fuel boiler, this is difficult to implement, because it is not always possible to fill a new portion of firewood or coal on time, and the combustion process itself is uneven. A heat accumulator for heating boilers will help to correct the situation.
With a simple design and principle of operation, it is able to eliminate a number of inconveniences and disadvantages of the classic heating scheme.
Why do you need
The heat accumulator is a well-insulated large-capacity tank filled with a coolant, water. Due to the high heat capacity of water, when the entire volume is heated, a significant reserve of thermal power is accumulated in the tank, which can be used for its intended purpose at a time when the boiler cannot cope or is completely inactive.
The heat accumulator actually increases the volume of the coolant in the heating circuit, the heat capacity and, accordingly, the inertness of the entire system. It will take more energy and time to heat the entire volume with limited heating power, but it will take a very long time for the battery to cool down. If necessary, hot water from the accumulator can be supplied to the heating circuit and maintain a comfortable temperature in the house.
To appreciate the benefits of a heat storage device, it is easiest to consider a few situations to begin with:
- A solid fuel boiler only periodically heats up the water. At the moment of ignition, the power is minimal, during active combustion, the power increases to a maximum, after the bookmark burns out, it decreases again and so the cycle repeats. As a result, the water temperature in the circuit constantly fluctuates in a fairly large range;
- To obtain hot water, it is required to install an additional heat exchanger or an external boiler with indirect heating, which significantly affects the operation of the heating circuit;
- It is extremely difficult to connect additional heat sources to a heating system built around a solid fuel boiler. A complex decoupling is required, preferably with automatic control;
- A solid fuel boiler, even if it burns for a long time, constantly requires the user's attention. It is worth skipping the time of laying a new portion of fuel, as the coolant in the heating circuit already begins to cool down, like the whole house;
- Often the maximum boiler output is excessive, especially in spring and summer when maximum output is not required.
The solution for all of the above situations is a heat accumulator, moreover, an uncompromising one. and the most affordable in terms of implementation and cost. It acts as a junction point between the solid fuel boiler and the heating circuit (s) and is an excellent base platform for enabling additional functions.
By design, the heat accumulator can be:
- "Empty" - a simple insulated tank with a direct connection;
- with a coil or register of pipes as a heat exchanger;
- with built-in boiler tank.
With a full body kit, the heat accumulator is capable of:
Payment
The power accumulated by the heat accumulator (TA) is calculated based on the volume of the container, more precisely the mass of the liquid in it, the specific heat capacity of the liquid used to fill it, and the temperature difference, the maximum to which the liquid can be heated, and the minimum target, at which it can still be carried out. heat intake from the heat accumulator to the heating circuit.
- Q \u003d m * C * (T2-T1);
- m - weight, kg;
- С - specific heat capacity W / kg * K;
- (T2-T1) - temperature delta, final and initial.
If the water in the boiler and, accordingly, in the TA heats up to 90 ° C, and the lower threshold is taken equal to 50 ° C, then the delta is 40 ° C. If we take water as the filling of the TA, then one ton of water, when cooled to 40 ° C, releases about 46 kW * hours of heat.
The stored energy must be sufficient for the intended use of the heat accumulator.
To select the required volume of the heat accumulator, it is necessary to determine:
- The time during which the accumulated energy in the TA should be enough to cover the heat loss of the house;
- The time during which the coolant must be heated in the TA;
- The power of the main heat source.
For periodic operation of the boiler during the day
If it is needed to switch the boiler operation only to night or day mode, when heat is supplied for a limited time, then the TA power should be enough to cover the heat loss of the house for the remaining time. At the same time, the power of the boiler must be sufficient to heat the heating unit at the specified time and, again, to heat the house.
Suppose that a solid fuel boiler is used with firewood laying only during the day for 10 hours, the estimated heat loss of the house for the coldest period of the year is 5 kW. 120 kW * hours are required per day for full heating.
In this case, the battery is used for 14 hours, which means that it is necessary to accumulate 5 kW * 14 hours \u003d 70 kW * hours of heat. If we take water as a coolant, then 1.75 tons or a TA volume of 1.75 m3 will be required. It is important that the boiler should also give out all the necessary heat within only 10 hours, that is, its power should be more than 120/10 \u003d 12 kW.
If the heat accumulator is used as a backup in case of a boiler failure, then the stored energy should be enough for at least a day or two to cover all heat losses in the house. If, as an example, we take the same house of 100 m2, then it will take 240 kW * hours to heat it in two days, and a heat accumulator filled with water must have a volume of at least 5.3 m3.
But in this case, the TA does not necessarily have to heat up in a short period of time. A one and a half boiler capacity reserve is enough to accumulate the required amount of heat in a week or two.
The calculation is approximate, without taking into account the decrease in the thermal power of the radiators, depending on the temperature of the coolant and the air in the room.
In the simplest case, the heat accumulator is connected in series between the boiler and the heating circuit. A circulation pump is installed between the TA and the boiler so that hot water enters the upper part of the TA, pushing cold water from the lower part into the boiler. Between the TA and the heating circuit, a circulation pump is installed to draw hot water from the upper part and transport it to the radiators.
However, at the same time, the total heat capacity of the system rises significantly, and at the initial start of heating, it will be necessary to wait until the entire volume of the TA heats up before the heat reaches the radiators.
Another connection option is parallel to the heating boiler. This option works well in combination with a gravitational heating system. The upper outlet of the heat accumulator is connected to the uppermost point of the dispenser, and at the lower point - to the boiler.
The disadvantages are the same as in the first case, the entire volume of the coolant in the system and in the TA is heated, which significantly increases the time to start heating.
The only advantages are ease of connection and a minimum of used elements.
Connection diagram with admixture
The best thing use a connection scheme with admixture or hydrofluidic isolation... Three-way valves with thermostat are used. In this case, the heat accumulator is installed as a separate element of the system, parallel to the heating circuit.
The main part of the automation is installed on the supply pipeline: a three-way valve, thermostats, a safety group, etc. By default, the three-way valve directs the heating medium from the boiler to the radiators until the room temperature reaches the required level.
As soon as there is no need for active heating, the valve transfers part of the coolant from the boiler to the heat accumulator, dumping excess heat.
When the maximum water temperature in the TA and the target temperature in the radiators are reached, the overheating sensor installed in the boiler is triggered and it turns off. In the meantime, heating is required or the heat accumulator is not warmed up, the boiler continues to operate.
If for some reason the boiler stops delivering the rated power or turns off completely when the supply temperature drops, water from the heat accumulator is mixed into the heating circuit, replenishing the heat loss of the system.
You can use several three-way valves on the distribution and on the return and a group of thermostats. As an option, ready-made assemblies for connecting heat accumulators are on sale - an automatic mixing unit, for example LADDOMAT.
With your own hands
If you wish, you can build a storage tank with your own hands. Ideally, it should:
- with a margin to withstand the nominal pressure in the system;
- have an estimated volume;
- be protected from corrosion and high temperatures;
- be completely sealed.
For manufacturing, you should take sheet steel, preferably stainless steel with a thickness of at least 3 mm, taking into account the total load and pressure.
The standard form of TA is a tall cylinder with a semicircular base and a lid. The ratio of diameter to height is selected approximately 1 to 3-4 to promote better heat separation inside the container.
In this case, hot water is drawn to the radiators from the highest point. Slightly above the center, the water is diverted to the underfloor heating circuit, and at the lowest point of the TA, a return line is connected to the heating boiler.
It is almost impossible to weld a cylindrical container on your own. It is easier to build a parallelepiped with a similar configuration and aspect ratio. All corners should be further strengthened.
The container must be insulated. For this, it is better to use basalt or mineral wool with a thickness of at least 150 mm to reduce heat loss through the walls.
To install the heat storage device, prepare a special support platform, foundation, capable of supporting the enormous weight of the equipment. Even the battery itself can weigh up to 400-500 kg. If its volume is, for example, 3 cubic meters, then when filled, its weight will exceed 3.5 tons.
Russian production
There are not so many domestically produced heat accumulators on the Russian market, since only recently they began to be actively introduced into autonomous heating systems.
| Model | Additional options | volume, m3 | Working pressure, bar | Maximum temperature, ºС | Approximate cost, rub |
| Sibenergo-term | — | 0.5 | 6 | 90 | 28500 |
| PROFBAK | DHW circuit | 0.5 | 3 | 90 | 56000 |
| GidroNova-HA750 | Electric heating element | 0.75 | 3 | 95 | 58000 |
| ELECTROTHERM ET 1000 A | DHW circuit, additional heat exchanger | 1.0 | 6 | 95 | 225000 |
Homeowners are often unable to buy modern heating equipment and are looking for alternative solutions. Take at least a buffer tank (otherwise, a heat accumulator), an indispensable thing for heating systems with a solid fuel boiler. A storage tank with a volume of 500 liters costs about $ 600-700. That is, the price of a thousand-liter barrel reaches 1000 cu. 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 indicated amount. Our task is to tell you about the manufacturing methods.
Where is the heat accumulator used and how it works
The thermal energy storage device is nothing more than an insulated iron tank with nozzles for connecting water heating mains. 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 solid fuel boiler. The storage tank works for heating at night, after burning wood or coal. Thanks to this, the homeowner rests calmly, and does not run into the boiler room. It is comfortable.
- When an electric boiler serves as a heat source, and electricity consumption is recorded by a multi-tariff meter. Energy at the night rate costs half the price, so during the day the heating system is fully provided by the heat accumulator. It is economical.
An important point. The hot water storage tank increases the efficiency of the solid fuel boiler. After all, the maximum efficiency of the heat generator is achieved with intensive combustion, which cannot be constantly maintained without a buffer tank that absorbs excess heat. The more efficiently firewood is burned, the less its consumption. This also applies to a gas boiler, whose efficiency decreases in low combustion modes.
An accumulator tank filled with heating medium operates according to a simple principle. While the heat generator is engaged in heating the premises, the water in the tank is heated to a maximum temperature of 80-90 ° C (the heat accumulator is being charged). After the boiler is turned off, hot coolant is supplied to the radiators from the storage tank, which provides heating of the house for a certain time (the heat battery is discharged). The duration of work depends on the volume of the tank and the air temperature outside.
How a factory-made heat accumulator works 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;
- heat-insulating layer 50-100 mm thick, depending on the insulation used;
- outer sheathing - thin painted metal or polymer cover;
- connecting nipples embedded in the main container;
- immersion sleeves for thermometer and manometer installation.
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 fabrication of heat accumulators
If you are seriously concerned about installing a heat accumulator and decided to make it on your own, then first you should familiarize yourself with the factory assembly technology.
Plasma cutting of blanks for lid and bottom It is unrealistic to repeat the technological process in a home workshop, 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 plasma cutting machine, where it is used to produce blanks for end caps, housing, hatch and support.
- The lathe produces the main fittings with a diameter of 40 or 50 mm (threads 1.5 and 2 ") and immersion sleeves for control devices. A large flange for the inspection hatch with a size of about 20 cm is also machined there. A branch pipe is welded to the latter for cutting into the body.
- The blank of the body (the so-called shell) in the form of a sheet with holes for the fittings is directed to the rollers, bending it under a certain radius. To obtain a cylindrical container for water, it remains only to weld the ends of the workpiece butt-weld.
- A hydraulic press produces hemispherical caps from flat metal circles.
- The next step is welding. The procedure is as follows: first, the body is cooked on tacks, then the lids are attached to it, then there is a continuous welding of all the seams. At the end, fittings and an inspection hatch are attached.
- The finished storage tank is welded with a stand, after which it undergoes 2 permeability tests - air and hydraulic. The latter is carried out at a pressure of 8 bar, the test lasts 24 hours.
- The tested tank is painted and insulated with basalt fiber at least 50 mm thick. From above, the container is sheathed with thin sheet steel with a colored polymer coating or closed with a tight cover.
The storage body is bent from a sheet of iron on the rollers Reference. Manufacturers use different materials to insulate the tank. For example, Russian-made Prometey heat accumulators are insulated with polyurethane foam.
Instead of cladding, manufacturers often use a special cover (you can choose a color) Most factory heat accumulators are designed for a maximum pressure of 6 bar at a heating medium temperature in the heating system of 90 ° C. This value is twice the response threshold of the safety valve set for 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 do it yourself. Then get ready to go through 5 stages:
- Calculation of the volume of the heat accumulator.
- Choosing a suitable design.
- Selection and procurement of materials.
- Assembly and tightness test.
- Installation of the tank and connection to the hot 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). Determine clearly how long the water heat accumulator should replace the idle boiler, and only then proceed to the first stage.
How to calculate the volume of the tank
There are 2 ways to calculate the storage tank capacity:
- 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 power of the boiler plant, a volume equal to 25 liters of water is allocated in the tank. Example: if the capacity of the heat generator is 25 kW, then the minimum capacity of the heat accumulator will be 25 x 25 \u003d 625 l or 0.625 m³. Now remember how much space is allocated in the boiler room and adjust the resulting volume to the real dimensions of the room.
Reference. Those who want to cook a homemade heat accumulator often ask themselves how to calculate the volume of a round barrel. Here it is worth recalling the formula for calculating the area of \u200b\u200ba circle: S \u003d ¼πD². Plug in the diameter of the cylindrical tank (D) and multiply the 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 methodology just dances from the indicators that you need and is based on the formula:
m \u003d Q / 1.163 x Δt
- Q is the amount of heat that needs to be accumulated in the battery, kWh;
- m is the estimated mass of the coolant in the tank, tons;
- Δt is the difference in water temperatures at the beginning and at the end of heating;
- 1.163 Wh / kg ° C is the reference heat capacity of water.
Let us explain further with an example. Let's take a standard house of 100 m² with an average heat consumption of 10 kW, where the boiler must be idle for 10 hours a day. Then in the barrel it is necessary to accumulate 10 x 10 \u003d 100 kWh of energy. The initial temperature of the water in the heating network is 20 ° С, heating occurs up to 90 ° С. We consider the mass of the coolant:
m \u003d 100 / 1.163 x (90 - 20) \u003d 1.22 tons, which is approximately equal to 1.25m³.
Please note that the heat load of 10 kW is taken approximately, in an insulated building with an area of \u200b\u200b100 m² there will be less heat loss. The second moment: 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 will be enough with a large margin, and taking into account the seasonal temperature drop, you can easily keep within 750 liters.
Hence the conclusion: in the formula, you need to substitute the average heat consumption for the cold period, equal to half of the maximum:
m \u003d 50 / 1.163 x (90 - 20) \u003d 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 estimated period of time (in our example, 10 hours). But save money and space in the furnace room. More information on performing settlements is presented in.
About tank design
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 the factory tanks are made cylindrical, and the bottom with a lid is hemispherical? Yes, because such a container is able to withstand the pressure of hot water without additional reinforcement.
On the other hand, few people have the technical ability to mold metal on rollers, not to mention the drawing of semicircular parts. We offer the following ways to resolve the issue:
- Order a round inner tank at a metalworking enterprise, and carry out the insulation and final installation yourself. It will still be cheaper than buying a factory-assembled heat accumulator.
- Take a finished cylindrical tank and make a buffer tank on its base. Where to get such tanks, we will tell you in the next section.
- Weld a rectangular sheet metal heat accumulator and reinforce its walls.
Sectional drawing of a rectangular heat accumulator with a volume of 500 liters Advice. In a closed heating system with a solid fuel boiler, where the excess pressure can jump up to 3 bar and above, it is strongly recommended to use a cylindrical heat accumulator.
In an open heating system with zero water pressure, a rectangular tank can be used. 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 tank to the expansion tank installed at the 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 container.
A properly reinforced rectangular storage tank can also be used in a closed heating system. But in case of an emergency pressure surge from overheating of the TT-boiler, the tank will leak with a probability of 90%, although you may not notice a small crack under the insulation layer. How the unreinforced metal of the vessel protrudes when filled with water, look at the video:
Reference. It makes no sense to weld directly onto the stiffening walls from corners, channels and other rolled metal products. Practice shows that the pressure force bends the corners of a small section together with the wall, and tears off large corners at the edges.
Making a powerful frame outside is impractical, too much material consumption. A compromise option is the internal struts shown in the drawing of a homemade heat accumulator.
500L heat accumulator drawing - top view (cross section) Selection of materials for the tank
You will greatly facilitate your task if you find a ready-made cylindrical tank, originally designed for a pressure of 3-6 bar. What containers can be used:
- propane cylinders of different capacities;
- decommissioned process tanks, such as receivers from industrial compressors;
- receivers from railway cars;
- old iron boilers;
- internal stainless steel tanks for storage of liquid nitrogen.
It is much easier to make a reliable heat accumulator from ready-made steel vessels. Note. In extreme cases, a steel pipe of a suitable diameter will do. Flat covers can be welded to it, which will have to be reinforced with internal stretch marks.
To weld a square tank, take 3mm sheet metal, no more. Make stiffeners from round pipes Ø15-20 mm or profiles 20 x 20 mm. Choose the size of the fittings according to the diameter of the boiler outlet nozzles, and for the cladding buy thin steel (0.3-0.5 mm) with powder coating.
A separate question is how to insulate a self-welded heat accumulator. The best option is basalt wool in rolls with a density of up to 60 kg / m³ and a thickness of 60-80 mm. Polymers such as 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 casing of your storage tank. Unlike polymer insulation, they do not gnaw basalt fiber.
Make no mistake about extruded polystyrene foam, rodents eat it too Now we will indicate other options for ready-made vessels that are not recommended to be used for heat accumulators:
- An improvised tank from a Eurocube. Such plastic containers are designed for a maximum temperature of the contents of 70 ° C, and we need 90 ° C.
- Heat storage from an iron barrel. Contraindications - thin metal and flat tank lids. It is easier to get a good steel pipe than to strengthen such a barrel.
Assembling a rectangular heat accumulator
We want to warn you right away: if you are mediocre in welding, then it is better to order the production of a tank on the side according to your drawings. The quality and tightness of the seams is of great importance; at the slightest leak, the accumulating capacity will flow.
First, the tank is assembled on tacks, and then boiled with a continuous seam For a good welder, there will be no problems here, you just need to learn the order of performing the operations:
- Cut out blanks from metal to size and weld the body without a bottom and a lid on tacks. Use clamps and a square to fix the sheets.
- Cut holes in the side walls for stiffening. Insert the prepared pipes inside and scald their ends from the outside.
- Grab the bottom with a lid to the tank. Cut holes in them and repeat the operation with the installation of the inner braces.
- When all opposite walls of the container are securely connected to each other, begin continuous welding of all seams.
- Install the supports from the pipe sections at the bottom of the tank.
- Embed the fittings, stepping back from the bottom and lid by less than 10 cm, as shown in the photo below.
- Weld metal brackets to the walls, which will serve as brackets for attaching the thermal insulation material and cladding.
The photo shows a stretch from a wide strip, but it is better to use a pipe Installation advice for internal spacers. To ensure that the walls of the heat accumulator effectively resist bending and do not break off during welding, release the ends of the guy wires outward by 50 mm. Then additionally weld steel sheet or strip stiffeners to them. Do not worry about the appearance, the ends of the pipes will then disappear under the cladding.
Steel brackets (clips) are welded to the body for attaching insulation and cladding A few words about how to insulate a heat accumulator. First, check it for leaks by filling it with water or lubricating all seams with kerosene. Thermal insulation is simple enough:
- clean and degrease all surfaces, apply a primer and paint to them to protect against 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 with fasteners. This completes the manufacture of a homemade heat accumulator for an open heating system.
Installation and connection of the tank to heating
If the volume of your heat accumulator exceeds 500 liters, then it is undesirable 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 down to a dense layer of soil. Then fill it with broken stone (quarry), compact and fill with liquid clay. Pour a 150 mm thick reinforced concrete slab into the wooden formwork from above.
Diagram of the foundation for the battery tank The correct operation of the heat accumulator is based on the horizontal movement of the hot and cooled flow inside the tank when the battery is "charged", and the vertical flow of water during the "discharge". To organize such a battery operation, you need to perform the following activities:
- the circuit of a solid fuel or other boiler is connected to a storage tank for water through a circulation pump;
- the heating system is supplied with a coolant using a separate pump and a mixing unit with a three-way valve, which allows the required amount of water to be taken from the accumulator;
- the pump installed in the boiler circuit, in terms of performance, should not be inferior to the unit supplying the coolant to the heating devices.
Tank piping diagram - heat accumulator A standard connection diagram for a heat accumulator with a TT boiler is shown in the figure above. The balancing valve on the return is used to regulate the coolant flow according to the water temperature at the inlet and outlet of the tank. Our expert Vladimir Sukhorukov will tell you how the strapping and setting is done correctly in his video material:
Reference. If you live in the capital of the Russian Federation or the Moscow region, then on the issue of connecting any heat accumulators, you can personally consult with Vladimir, using the contact information on his official website.
Budget storage tank from cylinders
For those homeowners whose boiler room area is very limited, we suggest making a cylindrical heat accumulator from propane cylinders.
Homemade heat accumulator paired with a TT-boiler The 100L design, developed by another of our craftsmen, is designed to fulfill 3 functions:
- unload a solid fuel boiler when overheating, taking in excess heat;
- heat water for household needs;
- provide heating of the house for 1-2 hours in the event of a damping of the TT-boiler.
Note. The duration of the autonomous operation of the heat accumulator is short due to its small volume. But it will fit into 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.
It looks like a tank made from cylinders 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 corrugation of the same diameter;
- fittings and sleeves for thermometers;
- insulation - basalt wool;
- painted metal for cladding.
From the cylinders, you need to unscrew the valves and cut off the caps with a grinder, filling them with water to avoid the explosion of gas residues. We carefully bend the copper tube into a coil around another pipe of a suitable diameter. Then we act like this:
- Using the presented drawing, drill holes in the future heat accumulator for pipes and sleeves for thermometers.
- Fasten with welding inside the cylinders several metal brackets for mounting the DHW heat exchanger.
- Place the cylinders one on top of the other and weld together.
- Install the coil inside the resulting tank, releasing the ends of the tube through the holes. Use stuffing box packing to seal these points.
- Attach the bottom and lid.
- Embed the air vent into the cover, and the drain cock into the bottom.
- Weld on the trim brackets. Make them in 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 work out aesthetically.
- Insulate the tank and screw the casing with self-tapping screws.
Docking the tank with a TT boiler without a circulation pump The design feature of this heat accumulator is that it is directly connected to a solid fuel boiler, without a circulation pump. Therefore, for joining, steel pipes Ø50 mm are used, 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 trifling matter. If you study our material, you will understand that such statements are far from reality, in fact, the question is quite complex and serious. You can't just take a barrel and fit it to a solid fuel boiler. Hence the advice: think carefully about all the nuances before starting work. And without the qualifications of a welder, you should not even take a buffer tank, it is better to order it in a specialized workshop.