A heat accumulator, also known as a thermal accumulator, or a buffer tank, is gaining more and more popularity every year as one of the important elements of the heating system of a private house.
Moreover, in some European countries, the use of solid fuel heating boilers is generally prohibited, and the list of such countries is constantly updated. Yes, and in our country, the pace of sales of heat accumulators for heating boilers shows a steady increase from year to year.
Some domestic producers launched the production of heat accumulators designed specifically for Russian conditions and climatic features our country. Let's try to figure out what the purpose of this type of equipment is, what are its features, and most importantly, what the installation of a heat accumulator will give to a particular owner of a private house, and how to choose exactly what is needed.
Heat accumulator and its use with heat sources of various types
The principle of operation of a heat accumulator is very simple: its main task is to accumulate thermal energy when there is an excess of it in the heating system, and to give this heat during its deficit, i.e. when the heat source is not working. From this follows the main conclusion - the most efficient use of heat accumulators with heat sources, which have a pronounced periodic nature of work.
These include the majority, very common both in Russia and abroad. And also rapidly gaining popularity, especially in the south,. It is clear that solid fuel boilers heat water only during combustion, and solar collectors are useless at night.
But that's not all, even electric heating boilers in combination with heat storage can be more efficient. If the difference between daytime and nighttime electricity tariffs is significant, for example, the nighttime tariff is more than 2 times less than the daytime one, you can make the heating system in the house so that it works only at night, and heat the house during the day due to the heat accumulated in the heat accumulator . By the way, taking into account the explosive growth of electricity tariffs, the economic feasibility of such a decision becomes relevant.
Another factor determining the efficiency of using heat accumulators is that a heat accumulator can become a link that combines several heat sources at once. In other words, if necessary - for example, when the cost of solar collectors will decrease even more, and the efficiency will increase - you can rebuild the heating system in your house without significant changes so that you can heat the premises to the maximum due to cheap solar energy, but at the same time, when the sun no, use a solid fuel boiler.
In this case, it becomes possible to in full accumulate all excess heat, and then, give it away as needed. In fact, the heat accumulator allows the use of various sources of thermal energy with a minimum this moment cost and at the same time ensures the stability of the system by switching between them. Of course, not everyone has this opportunity. heat accumulator- should be chosen desired model in advance.
Heat accumulator in a system with a solid fuel boiler
Currently, heat accumulators are most often used in heating systems with solid fuel boilers. Feature solid fuel boilers - the optimal mode of their operation is associated with complete combustion of fuel, i.e. achieved when operating at maximum power. Otherwise, as a result incomplete combustion fuel, toxic gases are formed, clogging of heat exchange surfaces inside the boiler occurs, soot appears in the chimney, which leads to deterioration performance characteristics and even the failure of the boiler, which is unsafe for the house and its inhabitants.
So, it is best when the boiler is working "at full". Such a regime is quite justified in the cold, but for most of the year the heating system of the house simply does not need the amount of heat received in excess - it will be too hot. If you do not have a heat accumulator, the only way out is to "heat the street", i.e. open vents. This is both expensive and inefficient.
Therefore, a buffer tank is built into the heating system - it takes away excess thermal energy, which otherwise would simply be lost aimlessly, in order to subsequently use them for their intended purpose, without spending fuel on this!
In short, a heating system with a solid fuel boiler and a heat accumulator works like this. During operation, the solid fuel boiler not only supplies the heated coolant to the heating system of the house, but also heats it up in the heat accumulator tank. After the boiler stops working, the house, accordingly, begins to cool. At this moment, the air temperature or the heat carrier temperature sensor in the heating system sends a signal to turn on the circulation pump, which ensures the supply of the heat carrier accumulated in the heat accumulator tank to the house heating system.
When the temperature of the air (heat carrier) rises to the set value, the sensor turns off the pump and the heat supply stops. At the same time, the temperature of the coolant in the tank decreases slightly, because part of the energy was transferred to the heating system. It should be noted that due to the good thermal insulation of the heat accumulator, the coolant, being inside the tank, cools down very slowly by itself. Cycles of turning on and off the pump continue until the temperature of the coolant in the heat accumulator remains higher than in the heating system. And the house will not cool down.
Experts evaluate differently. economical effect from the installation of a heat accumulator. This effect depends on many factors, some of which will be discussed below. On average, it ranges from 20%, i.e. every 5th ruble is saved. Note that the heat accumulator is especially effective in the off-season, with its frequent temperature fluctuations.
And here comes another useful property heat accumulator - in addition to improving the safety of your home and saving you money, it also gives you comfort. First, with the appearance in your house buffer tank, you will have to load fuel into the boiler much less often. If you have calculated and installed everything correctly, if in your house good thermal insulation, using a heat accumulator, you can heat your solid fuel boiler not several times a day, but up to 1 time in 2 days.
Secondly, the heat accumulator is able to smooth out the "temperature jumps" associated with the cooling of the coolant in the heating system, because. this system becomes more stable and inertial. Thirdly, it helps to simplify the maintenance of a solid fuel boiler and even increase its service life. Fourthly, with the help of a heat accumulator, you can additionally provide your home hot water, but this feature is not available on all models.
How to choose the right heat accumulator
First you have to calculate the volume of the heat accumulator. This is important because depend on volume dimensions buffer capacity. It should be remembered that you still need to find the “right” place in the house in order to first bring in a heat accumulator of considerable width and height through the doorways, and then install it next to the solid fuel boiler, as is most often the case in practice. Of course, only a specialist can make accurate calculations, because. this requires taking into account many specific factors, but in any case, you need to understand what kind of buffer capacity you are buying.
The volume of the heat accumulator directly depends on the power of the solid fuel heating boiler. There are several methods preliminary calculation based on determining the ability of a solid fuel boiler to heat the required volume of working fluid to a temperature of at least 40 ° C during the combustion of one full load of fuel, i.e. in about 2-3 hours. It is believed that in this way the maximum efficiency of the boiler is achieved with maximum fuel economy.
But, as a rule, for starters, you can use the following calculation method: 1 kW of power of a solid fuel boiler must correspond to at least 25 liters, but not more than 50 liters of the volume of the heat accumulator connected to it.
Thus, with a heating boiler power of 15 kW, the capacity of the heat accumulator must be at least: 15 * 25 \u003d 375 liters. And no more than 15 * 50 = 750 liters. It is better to choose with a margin, i.e. about 400-500 liters.
In general, manufacturers of heat accumulators offer products of various volumes - from 40 to 10,000 liters. Attention! Heat accumulators with a capacity of more than 500 liters may not fit through the doorway of your house.
What type of heat storage is right for you
The type depends on your needs, ie. how exactly you want to use it. There are 4 conditional type thermal accumulators:
- A simple body accumulator, for connection to a single heat source;
- Buffer tank for the simultaneous connection of several heat sources, such as a solid fuel heating boiler and a solar collector. It differs from the previous type by the presence of a lower coil;
- A heat accumulator with a DHW coil is designed for both heating and production hot water in flow mode;
- A heat accumulator with an internal tank for hot water supply (tank-in-tank design) is used both for heat storage in the heating system and for the preparation and accumulation of hot water that is used in everyday life.
Alexander Fedotov, Head of Sales Department
“The choice of a heat accumulator depends on the goals that the heating system is designed to solve. This could be heating the building or providing heating and hot water. In the first case, a conventional insulated tank can be used, in the second it is already underway about the appliance with various built-in heat exchangers.
When choosing a heat accumulator, it is necessary to take into account the type of the main heat source and their quantity in the heat supply system. Power is also an important factor. thermal device and hourly heat consumption».
In addition, the heat accumulator can be additionally equipped with one or more heaters for autonomous water heating, when necessary.
The price of a heat accumulator depends on its volume, type, as well as on additional options and, of course, on the manufacturer's brand.
Making a heat accumulator with your own hands
The Internet is replete with various kinds of recommendations for craftsmen on how to make a heat accumulator on your own, assuring that there is nothing difficult in this. On the one hand, the abundance of these recommendations once again emphasizes the importance of heat accumulators in the heating system - useless things are not discussed. On the other hand, it makes a sane person think: when you have to make a choice between buying a heat accumulator from a certified manufacturer and paying a little more, or making it “in the garage” but saving your money, you need to first think about the consequences.
What is a heat accumulator ✮Big choice heat accumulators on the portal site
Because even the greatest folk craftsman, when constructing a heat accumulator from an iron barrel, as is often recommended on various sites, must understand what such imaginary savings will lead to. Firstly, the temperature of the coolant inside the heat accumulator can be close to 100°C, and secondly, there is an increased pressure inside the system. No one can predict how the handicraft buffer tank will behave during operation. Whether it is worth putting your home at risk is an open question. Everyone makes a choice.
When designing a heating system, the main goals are comfort and reliability. The house should be warm and comfortable, and for this, hot coolant must always flow into the radiators without delays and temperature fluctuations.
With a solid fuel boiler, this is difficult to implement, because it is not always possible to fill up on time new portion firewood or coal, and the combustion process itself is uneven. A heat accumulator for heating boilers will help to correct the situation.
With a simple design and operation principle, it is able to get rid of a number of inconveniences and shortcomings. classical scheme heating.
Why do you need
The heat accumulator is a well-insulated reservoir large capacity filled with coolant, water. Due to the high heat capacity of water, when the entire volume is heated, a significant supply 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 inertia of the entire system. It will take more energy and time to heat the entire volume with a limited heating power, but it will also take a very long time to cool the battery. If necessary, hot water from the accumulator can be supplied to the heating circuit and maintain comfortable temperature in the house.
To appreciate the benefits of a heat storage, it is easiest to consider a few situations to begin with:
- A solid fuel boiler only periodically heats 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, 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 interchange will be required, preferably with automatic control;
- Solid fuel boiler, even long burning constantly requires user attention. It is worth skipping the time for laying a new portion of fuel, as the coolant in the heating circuit is already starting to cool down, like the whole house;
- Often the maximum power of the boiler 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, uncompromising and the most affordable in terms of implementation and cost. It acts as a decoupling point between the solid fuel boiler and the heating circuit(s) and an excellent base platform for enabling additional functions.
By design, the heat accumulator can be:
- "empty" - a simple insulated container 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:
Calculation
The power accumulated by a heat accumulator (TA) is calculated based on the volume of the container, or rather the mass of the liquid in it, the specific heat 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 is the mass, kg;
- FROM - specific heat W/kg*K;
- (T2-T1) - temperature delta, final and initial.
If the water in the boiler and, accordingly, in the TA is heated to 90ºС, and the lower threshold is taken equal to 50ºС, then the delta is equal to 40ºС. If we take water as filling TA, then one ton of water, when cooled by 40ºС, releases approximately 46 kWh of heat.
The stored energy should be enough 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 in the heat exchanger should be heated;
- The power of the main heat source.
For periodic operation of the boiler during the day
If it is needed to transfer the operation of the boiler only to night or day mode, when heat is supplied for a limited time, then the power of the TA should be enough to cover the heat loss of the house for the remaining time. At the same time, the boiler power should be sufficient to heat the TA in set time and again for heating the house.
Assume that a solid fuel boiler is used with firewood only during the day for 10 hours, the estimated heat loss of the house for the coldest period of the year is 5 kW. It takes 120 kWh 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 = 70 kW * hours of heat in it. If we take water as a heat carrier, then 1.75 tons or a TA volume of 1.75 m3 will be required. It is important that the boiler must also give out all the necessary heat within just 10 hours, that is, its power must be more than 120/10 \u003d 12 kW.
If the heat accumulator is used as a backup option in case the boiler fails, then the stored energy should be enough for at least a day or two to cover all the heat losses in the house. If we take the same house of 100 m2 as an example, then it will take 240 kWh for two days to heat it, and a heat accumulator filled with water should have a volume of at least 5.3 m3.
But in this case, it is not necessary for the TA to heat up in a short period of time. A one and a half margin of boiler power 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 heat output of 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 HT and the boiler, so that hot water enters the upper part of the HT, 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, this significantly increases the total heat capacity of the system, and at the initial start of heating, you will have to wait until the entire volume of the HA is heated before the heat reaches the radiators.
Another option for switching on is parallel to the heating boiler. This option shows itself well in combination with a gravitational heating system. The upper outlet of the heat accumulator is connected to the highest point of the dispenser, and at the lower point - to the boiler.
The disadvantages are the same as in the first case, heating occurs in the entire volume of the coolant in the system and in the TA, which significantly increases the time to start heating.
Of the advantages, only ease of connection and a minimum of elements used.
Switching circuit with mixing
The best thing use a switching circuit with mixing or hydraulic decoupling. Three-way valves with a thermostat are used. The heat accumulator is installed as separate element 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, a three-way valve directs the coolant 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, discharging 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 activated and it turns off. While heating is required or the heat accumulator is not warmed up, the operation of the boiler continues.
If, for some reason, the boiler stopped producing rated power or turned off completely when the temperature on the supply line dropped, 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. Alternatively, available for sale ready-made assemblies for connecting heat accumulators - an automatic mixing unit, for example LADDOMAT.
DIY
With a strong desire, you can build a storage tank with your own hands. Ideally, she 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, sheet steel should be taken, 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 lid. The ratio of diameter and height is selected approximately 1 to 3-4 in order to promote better heat separation inside the container.
In this case, hot water is taken from the highest point to the radiators. 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 box 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 a heat accumulator, prepare a special support platform, foundation, capable of withstanding the enormous weight of the equipment. Even the battery itself can weigh up to 400-500 kg. If its volume, for example, is 3 cubic meters, then when filled, its weight will exceed 3.5 tons.
Russian production
On the Russian market there are not so many heat accumulators domestic production, since only recently they began to be actively introduced into autonomous heating systems.
At the present time, the rise in price of all types of energy carriers, many homeowners have become seriously concerned about the issue of their economical use. One of the options is the inclusion of a large container with water in the heating circuit - a heat accumulator.
But factory-made containers are quite expensive. At the same time, some home craftsmen figured out how to make a heat accumulator with their own hands, which will come out much cheaper. This experience will be discussed in this article.
A little about the purpose and design
Before giving recommendations on the manufacture of this important unit, let's briefly define what it is for and consider its factory design. So, storage tanks with water are used in cases of periodic heating of the house, or rather:
- when operating an electric boiler with a multi-tariff meter, when the heaters can only function economically at night. The unit, working at full capacity, heats the house and accumulates thermal energy in a tank of water;
- the accumulation of heat is also necessary for solid fuel boilers, which, on the contrary, stop at night or at other times if there is no one to put a new portion of firewood or coal into the furnace;
Factory-made units are a round tank filled with water. Several coils are immersed in it, the coolant of the boiler and other heating circuits circulates in them. The design is quite complicated to manufacture and therefore not cheap, this can be seen by looking at the drawings of the heat accumulator.
If you try to take such a device as a basis in order to independently manufacture a heat accumulator, then in the end it will cost a little cheaper than the factory one. Copper or stainless steel tubes and the work of winding coils from them, sealing the bushings and insulating them will take you a lot of time and Money. For homeowners looking to assemble and install a homemade heat storage unit, there is an easier solution described below.
Calculation of the volume of the storage tank
This solution lies in the fact that a do-it-yourself heat accumulator is a conventional insulated container with two nozzles for connecting to the heating system. The bottom line is that the boiler, during operation, partially directs the coolant into the storage tank when the radiators do not need it. After turning off the heat source, reverse process: The heating system is supported by water from the accumulator. To do this, you will need to properly tie storage capacity with heat generator.
The first step is to determine the volume of the tank for the accumulation of thermal energy and assess the possibility of placing it in the boiler room. In addition, the manufacture of heat accumulators for solid fuel boilers does not have to start from scratch, there are various options selection of ready-made vessels of suitable capacity.
We propose to roughly determine the volume of the tank by the most in a simple way based on the laws of physics. To do this, you need to have the following initial data:
- thermal power required for heating the house;
- the time during which the heat source will be turned off and a storage tank for heating will take its place.
We will show the calculation method with an example. There is a building with an area of 100 m2, where the heat generator is idle for 5 hours a day. We accept the necessary thermal power in the amount of 10 kW. This means that every hour the battery must supply 10 kW of energy to the system, and for the entire period of time it must be stored 50 kW. At the same time, the water in the tank is heated to at least 90 ºС, and the temperature at the supply in the heating systems of private houses in the standard mode is assumed to be 60 ºС. That is, the temperature difference is 30 ºС, we substitute all these data into the formula well known from the physics course:
Q = cm∆t
Since we want to know the amount of water that the heat accumulator should contain, the formula takes the following form:
m = Q / c Δt, where:
- Q is the total consumption of thermal energy, in the example it is 50 kW;
- c - specific heat capacity of water, is 4.187 kJ / kg ºС or 0.0012 kW / kg ºС;
- Δt is the temperature difference between the water in the tank and the supply pipe, for our example it is 30 ºС.
m \u003d 50 / 0.0012 x 30 \u003d 1388 kg, which occupies an approximate volume of 1.4 m3. So, thermal battery for a solid fuel boiler with a capacity of 1.4 m3, filled with water heated to 90 ºС, will provide a house with an area of 100 m2 with a heat carrier with a temperature of 60 ºС for 5 hours. Then the water temperature will drop below 60 ºС, but it will take some more time (3-5 hours) to completely “discharge” the battery and cool down the premises.
Important! In order for a self-made heat accumulator to have time to fully “charge” during the operation of the boiler, the latter must have at least one and a half power reserves. After all, the heater must simultaneously heat the house and load the storage tank with hot water.
If you want to make a storage tank from scratch, then it is best to use ordinary sheet metal 2 mm thick for this purpose. You can also cook a tank from stainless steel, but it is not at all necessary, since such material will be very expensive. For the convenience of subsequent insulation and ease of manufacture, it is better to make the container rectangular in shape. Knowing the volume of the tank, it is easy to calculate its dimensions in accordance with the conditions of its installation in the boiler room.
Advice. If you want to ensure the joint functioning of the storage vessel and the gravity heating system, then you need to make an open-type heat accumulator, that is, ensure that it communicates with the atmosphere through a tube at the top of the tank. It must be placed above the level of the radiators, for which you will have to additionally weld a stand made of steel pipes or corners.
In some cases, it makes no sense to cook a container from scratch; you can make a water heat accumulator from a barrel. A large-capacity iron barrel is well suited; two pipes will need to be cut into it to connect to the system. plastic barrels use risky due to high temperature water, except that the product label will indicate the maximum temperature of the contents up to 100 ºС.
We give the same warning to those home craftsmen who make heat accumulators from the eurocube. Of course, this is very convenient way, but this plastic container is designed for a maximum temperature of not more than 70 ºС. Therefore, the eurocube is suitable as a storage tank that works with underfloor heating, where the coolant temperature rarely exceeds 50 ºС, for radiator systems he is no good.
How to insulate a heat accumulator
Even when the tank is in a warm room, the temperature difference between air environment and coolant is too high - from 50 to 70 ºС. In order not to lose heat and not to heat the furnace with it, it is necessary to insulate the heat accumulator. The easiest way to do this is with foam plastic with a thickness of 100 mm and a density of 25 kg / m3. It is easy to glue it to metal walls and cut holes for pipes.
Good for warming and mineral wool the same thickness, although fixing it is somewhat more difficult. The density of the material is 135-145 kg/m3. For round tanks from barrels, you will have to use roll insulation type ISOVER, here you have to pretty tinker with fasteners, especially at the bottom of the tank.
The video below shows the installation and diagram of the heat accumulator with its connection to the boiler and heating system:
Conclusion
The use of a storage tank allows you to save fuel when operating wood-burning boilers and enjoy a favorable nightly rate in the case of an electric heat generator. In the manufacture of the tank is not so difficult, you just need to have some skills.
The inability to use as a source of energy for heating housing is relatively inexpensive natural gas forces the owners of houses to look for other acceptable solutions. So, in regions where there are no particular problems with the preparation or purchase of firewood, they come to the rescue solid fuel boilers. It also happens that the only alternative is Electric Energy. In addition, new technologies are increasingly being used to direct solar energy for heating needs.
All of these approaches are not without significant drawbacks. So, they include unevenness, a pronounced periodicity of the supply of thermal energy. In case of electric boiler the main negative factor will be the high cost of consumed energy. It is obvious that the inclusion of a special device in the general circuit that would accumulate currently unclaimed thermal energy and give it as needed would help to significantly increase the efficiency of the heating system, improve the efficiency, uniformity of its operation, and simplify operational operations as much as possible. It is this function that the heat accumulator performs for.
The main purpose of the heat accumulator of the heating system
- The simplest heating system with a solid fuel boiler has a pronounced cyclical operation. After loading firewood and igniting it, the boiler gradually reaches maximum power, actively transferring thermal energy to the heating circuits. But as the load burns out, the heat transfer begins to gradually decrease, and the coolant carried through the radiators cools down.
It turns out that during the period of peak heat generation, it may remain unclaimed, since a configured heating system equipped with thermostatic control will not take too much. But during the period of fuel burnout and, moreover, the downtime of the boiler, thermal energy will clearly be lacking. As a result, part of the fuel potential is simply wasted, but at the same time, the owners have to deal with loading firewood quite often.
To a certain extent, the severity of this problem can be reduced by installing a long-burning boiler, but it cannot be completely removed. The discrepancy between the peaks of heat production and its consumption can remain quite significant.
- In the case of an electric boiler, the high cost of consumed energy comes to the fore, which makes the owners think about maximizing the use of equipment during periods of preferential night tariffs and minimizing consumption during the daytime.
Benefits of using differentiated electricity billing
With a competent approach to electricity consumption, feed-in tariffs can bring very tangible cost savings. This is described in detail in a special publication of the portal dedicated to.
An obvious solution suggests itself - to accumulate thermal energy at night in order to achieve its minimum consumption during the day.
- Even more pronounced is the frequency of heat generation in the case of using solar collectors. Here, the dependence is traced not only on the time of day (at night, the flow is generally zero).
Incomparable peaks of heating on a bright sunny day or in cloudy weather. It is clear that it is impossible to directly make your heating system dependent on the current “whims” of nature, but you also don’t want to neglect such a powerful additional source of energy. Obviously, some kind of buffer device is required.
These three examples, for all their diversity, are united by one common circumstance - a clear discrepancy between the peaks in the production of thermal energy and its rational and uniform use for heating needs. To eliminate this imbalance, a special device called a heat accumulator (thermal storage, buffer tank) is used.
Hajdu heat accumulator prices
heat accumulator Hajdu
The principle of its operation is based on the high heat capacity of water. If a significant amount of it is heated to the required level during the period of peak receipt of thermal energy, then during a certain period this accumulated energy potential can be used for heating needs. For example, if we compare thermophysical indicators, then only one liter of water, when cooled by 1 ° C, can heat up a cubic meter of air by as much as 4 ° C.
A heat accumulator is always a volumetric reservoir with effective external thermal insulation, connected to the heat source circuit(s) and heating circuits. The simplest scheme is best considered with an example:
The simplest heat accumulator (TA) in design is a vertically located volumetric tank, into which four branch pipes are cut into from two opposite sides. On the one hand, it is connected to the circuit (KTT), and on the other hand, to the heating circuit distributed around the house.
After loading and ignition of the boiler, the circulation pump (Nk) of this circuit begins to pump the coolant (water) through the heat exchanger. From the lower part of the TA, cooled water enters the boiler, and heated water in the boiler arrives at the top. Due to the significant difference in the density of cooled and hot water, there will be no active mixing in the tank - in the process of burning the fuel load, the HE will be gradually filled with hot coolant. As a result, with the correct calculation of the parameters, after the fuel is completely burned out, the tank will be filled with hot water heated to the calculated level. All the potential energy of the fuel (minus, of course, the inevitable losses reflected in the efficiency of the boiler) is converted into heat, which is stored in the HE. High-quality thermal insulation allows you to keep the temperature in the tank for many hours, and sometimes even days.
The second stage - the boiler is not working, but the heating system is functioning. With the help of its own circulation pump of the heating circuit, the coolant is pumped through pipes and radiators. The fence is made from above, from the "hot" zone. Intensive self-mixing is again not observed - for the already mentioned reason, hot water enters the supply pipe, cooled water returns from below, and the tank gradually gives off its heat in the direction from bottom to top.
In practice, during the combustion process of the boiler, the selection of coolant into the heating system, as a rule, does not stop, and the HE will accumulate only excess energy, which currently remains unclaimed. But with the correct calculation of the parameters of the buffer capacity, not a single kilowatt of thermal energy should be wasted, and by the end of the boiler furnace cycle, the TA should be “charged” to the maximum extent.
It is clear that the cyclical operation of such a system with an installed electric boiler will be tied to preferential nightly rates. The timer of the control unit will turn the power on and off at a set time in the evening and morning, and during the day the heating circuits will be powered only (or mainly) from the heat storage.
Design features and basic connection diagrams for various heat accumulators
So, a heat accumulator is always a volumetric tank of a vertical cylindrical design, which has highly effective thermal insulation and is equipped with nozzles for connecting the heat generation and consumption circuits. But internal construction may vary. Consider the main types of existing models.
The main types of designs of heat accumulators
1 – The simplest type of TA design. Direct connection of both heat sources and consumption circuits is implied. These buffer tanks are used in the following cases:
- If the same coolant is used in the boiler and in all heating circuits.
- If the maximum allowable coolant pressure in the heating circuits does not exceed that of the boiler and the HA itself.
In the event that the requirement cannot be met, the heating circuits can be connected via additional external heat exchangers
- If the temperature in the supply pipe at the outlet of their boiler does not exceed allowable temperature in heating circuits.
However, this requirement can also be circumvented by installing mixing units with three-way valves on circuits requiring a lower temperature difference.
2 – The heat accumulator is equipped with an internal heat exchanger located at the bottom of the tank. The heat exchanger is usually a spiral made of steel stainless pipe, regular or corrugated. There may be several such heat exchangers.
This type of TA is used in the following cases:
- If the indicators of pressure and achieved temperature of the heat carrier in the heat source circuit significantly exceed allowed values for consumption circuits and for the buffer tank itself.
- If there is a need to connect several heat sources (according to the bivalent principle). For example, a solar system (solar collector) or a geothermal heat pump come to the aid of the boiler. At the same time, the lower the temperature difference of the heat source, the lower its heat exchanger should be placed in the HE.
- If a different type of coolant is used in the heat source and consumption circuits.
Unlike the first scheme, such a TA is characterized by active mixing of the coolant in the tank - heating occurs in its lower part, and less dense hot water tends upward.
The diagram in the center of the GA shows magnesium anode. Due to the lower electrical potential, it "pulls" ions of heavy salts onto itself, preventing the internal walls of the tank from overgrowing with scale. To be replaced periodically.
3 – The heat accumulator is supplemented with a hot water flow circuit. Entrance cold water is carried out from below, supply to the point of hot water intake, respectively, from below. Most of the heat exchanger is located in the upper part of the TA.
Such a scheme is considered optimal for conditions where the consumption of hot water is sufficiently stable and uniform, without pronounced peak loads. Naturally, the heat exchanger must be made of metal that meets the standards of food water consumption.
Otherwise, the scheme is similar to the first one, with direct connection of the heat generation and consumption circuits.
4 – Inside the heat accumulator there is a tank for creating a supply of hot water for domestic consumption. In fact, such a scheme resembles a built-in indirect heating boiler.
The use of such a design is fully justified in cases where the peak of heat generation by the boiler does not coincide with the peak of hot water consumption. In other words, when the household way of life that has developed in the house involves a massive, but rather short-term consumption of hot water.
All of the above schemes may vary in various combinations- the choice of a particular model depends on the complexity created system heating, quantity and type of body sources and consumption circuits. Please note that in most heat accumulators there are many outlet pipes spaced vertically.
The fact is that with any scheme inside the buffer tank, one way or another, a temperature gradient is formed (the difference in temperature difference in height). It becomes possible to connect the circuits of the heating system that require different temperature conditions. This greatly facilitates the final thermostatic control of heat exchangers (radiators or warm floors”), with minimal unnecessary energy losses and reduced load on the control devices.
Typical schemes for connecting heat accumulators
Now you can consider the basic schemes for installing heat accumulators in the heating system.
| Illustration | Brief description of the scheme |
|---|---|
 | The temperature regime and pressure are the same in the boiler and in the heating circuits. The requirements for the coolant are the same. A constant temperature is maintained at the outlet of the boiler and in the TA. On heat exchange devices, the adjustment is limited only by a quantitative change in the coolant passing through them. |
 | The connection in the heat accumulator itself, in principle, repeats the first scheme, but the adjustment of the operating modes of heat exchangers is carried out according to a qualitative principle - with a change in the temperature of the coolant. For this, thermostatic mixing units, for example, three-way valves, are included in the circuit. Such a scheme allows the most rational use of the potential accumulated by the heat accumulator, that is, its “charge” will last for a longer time. |
 | Such a scheme, with the circulation of the coolant in the small circuit of the boiler through the built-in heat exchanger, is used when the pressure in this circuit exceeds the allowable value in the heating devices or in the buffer tank itself. The second option is that different heat carriers are used in the boiler and in the heating circuits. |
 | The initial conditions are similar to scheme No. 3, but an external heat exchanger is used. Possible reasons for this approach: - the heat exchange area of the built-in "coil" is not enough to maintain the required temperature in the body accumulator. – TA without an internal heat exchanger was already purchased earlier, and the modernization of the heating system required just such an approach. |
 | Scheme with the organization of the flow supply of hot water through the built-in spiral heat exchanger. Designed for uniform consumption of hot water, without peak loads. |
 | Such a scheme, using a heat accumulator with a built-in tank, is designed for peak hot water consumption, but not very positive. After spending the created stock and, accordingly, filling the container with cold water, heating to the required temperature can take quite a long time. |
 | A bivalent circuit that allows you to use an additional source of thermal energy in the heating system. AT this case The variant with connection of a solar collector is simply shown. This circuit is connected to a heat exchanger at the bottom of the heat storage. Typically, such a system is calculated in such a way that the main source is the solar collector, and the boiler is turned on as needed, for reheating, in case of insufficient energy from the main one. The solar collector, of course, is not a dogma - there may be a second boiler in its place. |
 | A scheme that can be called multivalent. In this case, the use of three sources of thermal energy is shown. The boiler acts as a high-temperature boiler, which, again, can only play an auxiliary role in general scheme heating. Solar collector - by analogy with the previous scheme. In addition, another low-temperature source is used, which, at the same time, is stable and independent of weather and time of day - a geothermal heat pump. The lower the temperature difference from the connected energy source, the lower the place of its connection to the heat accumulator. |
Of course, the diagrams are given in a very simplified form. But in fact, connecting a heat accumulator to complex, branched systems, with different heating circuits, and even receiving heating from sources of different power and temperature, requires highly professional design with engineering thermal calculations, using many additional adjustment devices.
One example is shown in the figure:
1 - solid fuel boiler.
2 - an electric boiler, which is switched on only as needed and only during the period of the preferential tariff.
3 - a special mixing unit in the high-temperature boiler circuit.
4 - solar station, solar collector, which on fine days can serve as the main source of thermal energy.
5 - heat accumulator, to which all circuits of heat generation and its consumption converge.
6 - high-temperature heating circuit with radiators, with regulation of modes according to the quantitative principle - only and the use of shut-off valves.
7 - low-temperature heating circuit - "warm floor", which necessarily provides for high-quality control of the heating temperature of the coolant.
8 - hot water flow circuit, equipped with its own mixing unit for high-quality regulation of the temperature of domestic hot water.
In addition to all of the above, the heat accumulator can have its own electric heaters- heating elements. Sometimes it is beneficial to maintain a given temperature with their help, without, for example, once again resorting to unscheduled kindling of a solid fuel boiler.
Special additional heaters can be purchased separately - their mounting thread is usually adapted to the connection sockets available on many models of heat accumulators. Naturally, connecting the heating electricity will require the installation of an additional thermostatic unit, which will ensure that the heating elements are turned on only when the temperature in the TA drops below set by the user level. Some heaters are already equipped with a built-in of this type.
Prices for heat accumulators S-Tank
Heat accumulator S-Tank
Video: Specialist's recommendations for creating a heating system with a solid fuel boiler and a heat accumulator
What to consider when choosing a heat accumulator
Of course, the selection of a heat accumulator is recommended to be carried out at the stage of designing a home heating system, guided by the calculated data of specialists. Nevertheless, the circumstances are different, and it is still necessary to know the main criteria for evaluating such a device.
- The first place will always be the capacity of this buffer tank. This value is calculated in accordance with the parameters of the system being created, the power of the boiler, the required amount of energy for the needs of heating, hot water supply. In a word, the capacity should be such as to ensure the accumulation of all excess on this moment heat without losing it. Some rules for calculating capacity will be discussed below.
- Of course, the dimensions of the product and its weight directly depend on the capacity. These parameters are also decisive - far from always and not everywhere it is possible to place a heat accumulator of the required volume in a dedicated room, so the issue should be thought out in advance. It happens that the tanks large volume(over 500 liters) do not pass through standard doorways (800 mm). When estimating the mass of the TA, it must be taken into account together in the entire volume of water of a completely filled device.
- The next parameter is the maximum allowable pressure in the heating system being created or already operating. A similar indicator TA should be, in any case, not lower. This will depend on the wall thickness, the type of material used, and even the shape of the container. So, in buffer tanks designed for pressures above 4 atmospheres (bar), the upper and lower covers usually have a spherical (toroidal) configuration.
- Container material. Carbon steel tanks with anti-corrosion coating are cheaper. Stainless steel tanks are certainly more expensive, but their warranty period is also much longer.
- Availability of additional built-in heat exchangers for heating or hot water circuits. Their purpose has already been mentioned above - models are selected depending on the total complexity of the heating system.
- The presence of additional options - the possibility of embedding heating elements, installing instrumentation, safety devices - safety valves, air vents, etc.
- The thickness and quality of the external thermal insulation of the TA body must be evaluated so that you do not have to deal with this issue yourself. The better the tank is insulated, the naturally longer the “thermal charge” will be stored in it.
Features of installation of heat accumulators
Installing a heat accumulator implies compliance with certain rules:
- All connected circuits must be connected with threaded sockets or flanges. Welded joints not allowed.
- The pipes to be connected must not exert any static load on the TA sockets.
- It is recommended to install shut-off valves on all pipes connected to the TA.
- Visual temperature control devices (thermometers) are installed at all used inputs and outputs.
- A drain valve must be installed at the lowest point of the TA or on the pipe in its immediate vicinity.
- Filters are installed on all pipes entering the heat accumulator mechanical cleaning water - "mud collectors".
- In many models, a pipe is provided on top for connecting an automatic air vent. If there is none, then the air vent must be installed on the topmost outlet pipe.
- In the immediate vicinity of the heat accumulator, it is planned to install a pressure gauge and a safety valve.
- It is strictly forbidden to make any independent changes to the design of the heat accumulator that are not specified by the manufacturer.
- TA installation should be carried out only in a heated room, excluding the possibility of liquid freezing.
- A tank filled with water can have a very significant mass. The platform must be capable of withstanding such high load. Often, for these purposes, it is necessary to add a special foundation.
- No matter how the heat accumulator is installed, a free approach to the inspection hatch must be ensured.
Carrying out the simplest calculations of the parameters of the heat accumulator
As mentioned above, a comprehensive calculation of a heating system with several circuits for the production and consumption of thermal energy is a task that only specialists can do, since a lot of versatile factors have to be taken into account. But certain calculations can be done on your own.
For example, the house is installed. Its power generated at full fuel load is known. Experimentally determined the time of combustion of a full load of firewood. It is planned to purchase a heat accumulator, and it is necessary to determine how much volume will be required in order to guarantee the useful use of all the heat generated by the boiler.
We take the well-known formula as a basis:
W = m × s × Δt
W is the amount of heat required to heat up a mass of liquid m) with known heat capacity ( With) by a certain number of degrees ( Δt).
From here it is easy to calculate the mass:
m = W / (s × Δt)
It does not hurt to take into account the efficiency of the boiler ( k), since energy losses are somehow inevitable.
W=k× m × s × Δt, or
m = W / (k × c × Δt)
Now let's look at each of the values:
- m- the desired mass of water, from which, knowing the density, it will not be difficult to determine the volume. It will not be a big mistake to calculate from the calculation 1000 kg = 1 m³.
- W– excess amount of heat generated during the heating period of the boiler.
It can be defined as the difference between the energy values generated during the combustion of the fuel bookmark and spent in the same period on heating the house.
The maximum power of the boiler is usually known - this is a passport value calculated for optimal water solid fuel. It shows the amount of thermal energy generated by the boiler per unit time, for example, 20 kW.
Any owner always knows quite accurately how long the fuel bookmark burns out for him. Let's say it will be 2.5 hours.
Next, you need to know how much energy at this time can be spent on heating the house. In a word, the value of the need of a particular building for thermal energy is necessary to ensure comfortable conditions residence.
Such a calculation, if the value required power it is not known, you can produce it yourself - for this there is a convenient algorithm given in a special publication of our portal.
How to independently conduct a thermal calculation for your own home?
Information about the amount of thermal energy needed for heating a house is quite often in demand - when choosing equipment, arranging radiators, when conducting insulation works. The reader can get acquainted with the calculation algorithm, which includes a convenient calculator, by opening a publication on the link.
For example, heating a house requires 8.5 kW of energy per hour. This means that in 2.5 hours of burning the fuel bookmark, the following will be obtained:
20 × 2.5 = 50 kW
During the same period will be spent:
8.5 × 2.5 = 21.5 kW
W = 50 - 21.5 = 28.5 kW
- k– Boiler room efficiency installation. It is usually indicated in the product passport as a percentage (for example, 80%) or as a decimal fraction (0.8).
- With is the heat capacity of water. This is a tabular value, which is equal to 4.19 kJ/kg×°С or 1.164 W×h/kg×°С or 1.16 kW/m³×°С.
- Δt- the temperature difference by which it is necessary to heat the water. It can be determined empirically for your system by measuring the values on the supply and return pipes when the system is operating at maximum power.
Let's say this value is
Δt \u003d 85 - 60 \u003d 35 ° С
So, all the values are known, and it remains only to substitute them into the formula:
m = 28500 / (0.8 × 1.164 × 35) = 874.45 kg.
The same approach can be applied if the volume of the heat accumulator connected to is calculated. The only difference is that the calculation does not take into account the time of burning, but the time interval of the reduced tariff, for example, from 23.00 to 6.00 = 7 hours. To "unify" this value, it can be called, for example, "boiler activity period".
To simplify the task for the reader, below is a special calculator that will allow you to quickly calculate the recommended volume of a heat accumulator for an existing (planned for installation) boiler.
Buffer tank of leading manufacturers, manufactured in the factory, 500 l. will cost approximately 30,000-38,000 rubles. Making a heat accumulator for a heating boiler with your own hands will cost about half as much. The price will be even less if you install the container yourself and perform the strapping.
What volume should be the thermal storage
The principle of operation of the heat accumulator is associated with the accumulation of thermal energy during the operation of the boiler and its release after the heating equipment is turned off. In fact, the buffer tank works on the principle of an ordinary electric accumulator.The volume of the tank determines how long the heating of the building will be maintained in offline. Before proceeding with the manufacture of a heating system with a home-made heat accumulator, you will need to calculate the volume of the tank.
There are two calculation methods:
- simplified, performed using special online calculators;
- performed using mathematical calculations, according to the formula.
According to the table, the effective water heating with a self-made tank for the home, able to work offline for about 10 hours, 2.19 m³. You can reduce the volume to 1.4 m³, while the heat accumulator will be able to give off heat for 5 hours. After making the calculations, you can proceed to the manufacture of the battery tank with your own hands.
How and from what to make a buffer tank
The heat accumulator is made according to the drawing of the factory tank. Internal organization completely identical. The tank consists of the following units:- internal capacity;
- thermal insulation layer;
- outer protective shell;
- a heat exchanger for the tank, usually a copper coil;
- regulatory and shut-off valves: drain tap, safety valve, air valve, thermometer.
Heat accumulator design type
There are several types of containers, classified by shape and device. Homemade heat storage tanks are:- Cylindrical - a classic design used in the manufacture of drives in the factory. The form has many advantages: withstands heat load, water hammer. Practical for closed systems heating with high pressure in the pipeline. The main disadvantage is that the tank cylindrical shape difficult to manufacture.
- Rectangular - in the production they use metal with a thickness of 2 mm. To strengthen the design of the buffer tank, corners (stiffening ribs) are welded, pulling the opposite walls together. rectangular shape The heat accumulator copes worse with pressure. General requirement during installation: mounting the drive above the location of the radiators.
The rectangular design of the tank is widespread due to its ease of assembly. To reduce the load on the walls of the accumulator, an air vent and a relief valve are cut into the heating system. When the coolant boils (a common occurrence in solid fuel boilers), the fittings will prevent the occurrence of emergency pressure.
For gravity system heating fit open buffer tank only. The difference in design: the presence of a branch pipe in the upper part of the tank, which communicates with the atmosphere.
Battery tank material
There are many manufacturing options. The most common:- Stainless steel tank- metal and welding work are expensive. Due to the high cost, stainless steel is practically not used, except in cases where ready-made containers are used.
- plastic barrels- an important operating condition so that the material can withstand heating up to 100 ° C. To strengthen the case, you can make a border of metal strips.
- Buffer tank from "Eurocube"- not recommended. The reason is simple, the maximum heating temperature of the tank is only 70°C. When the coolant overheats, the walls are deformed and leak. But as you can see from the video, heat accumulators are also made from Eurocubes.
- aluminum container- use ready-made tanks with sufficient volume. It will be possible to make a tank from aluminum on your own only if you have the proper qualifications of the welder. Not all professional craftsmen take up the processing of this metal.
- Barrel heat accumulator(metal) - disadvantages: thin-walled steel, flat covers. Good alternative, take a blank steel pipe and make a tank by welding the bottom and top.
- Steel tank for heat accumulator(cylindrical) - best option requiring a minimum amount of material costs. It is made of sheet iron from 2 mm and thicker.
How to insulate a buffer tank
In factory drives, insulation is laid between the inner tank and the outer casing. Homemade buffer tanks for a solid fuel boiler use the same thermal insulation method.The walls of the heat accumulator are subject to insulation. It is recommended to use mineral or basalt wool not less than 6-8 cm thick. It is easy to work with cotton wool. Mineral thermal insulation the tank passes moisture and condensate (breathes), without accumulating liquid inside the fibers.
Another plus. As practice shows, buffer containers insulated with cotton do not like mice. When insulating with polystyrene foam or polystyrene foam, rodents often settle inside the heat-insulating layer. The holes that appear lead to a rapid loss of heat and a decrease in the efficiency of the drive.
Drawings for the manufacture of a heat accumulator
You can make a heat accumulator with your own hands. It is enough to calculate the volume of the tank, choose suitable material and isolation.
