When designing a heating system, the main goals are comfort and reliability. The house should be warm and cozy, and for this, hot coolant should always flow into the radiators without delays or temperature surges.
This is difficult to achieve with a solid fuel boiler, 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 correct the situation.
With a simple design and operating principle, it can eliminate a number of inconveniences and disadvantages classical scheme heating.
Why is it needed?
The heat accumulator is a well-insulated large-capacity tank filled with coolant and 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 coolant in the heating circuit, the heat capacity and, accordingly, the inertia of the entire system. Heating the entire volume will require more energy and time with limited heating power, but the battery will also take a very long time to cool down. If necessary, hot water from the battery can be supplied to the heating circuit and maintain comfortable temperature in the house.
To evaluate the benefits of a heat accumulator, it is easiest to consider several situations first:
- 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 drops again and so the cycle repeats. As a result, the water temperature in the circuit constantly fluctuates over a fairly wide range;
- For getting hot water installation of an additional heat exchanger or external boiler with indirect heating is required, which significantly affects the operation of the heating circuit;
- Connect to a heating system built around a solid fuel boiler additional sources heat is extremely difficult. A complex decoupling will be required, preferably with automatic control;
- A solid fuel boiler, even one that burns for a long time, constantly requires the user’s attention. As soon as you miss the time for adding a new portion of fuel, the coolant in the heating circuit is already beginning to cool down, like the whole house;
- Often the maximum boiler power 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, and an uncompromising one at that. 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 pipe register 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, 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 = m*C*(T2-T1);
- m – mass, kg;
- WITH - specific heat W/kg*K;
- (T2-T1) – temperature delta, final and initial.
If the water in the boiler and, accordingly, in the heating element is heated to 90ºС, and the lower threshold is taken equal to 50ºС, then the delta is equal to 40ºС. If we take TA water as filling, then one ton of water, when cooled to 40ºC, releases approximately 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 heat exchanger should be enough to cover the heat loss of the house;
- The time during which the coolant in the heat exchanger must heat up;
- 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 boiler’s power should be enough to heat the heating unit in a timely manner and, again, to heat the house.
Let's 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. 120 kW*hours are required per day for full heating.
The battery is used for 14 hours, which means that it needs to accumulate 5 kW * 14 hours = 70 kW * hours of heat. If you take water as a coolant, you will need 1.75 tons or a heat exchange volume of 1.75 m3. It is important that the boiler must produce all the necessary heat within just 10 hours, that is, its power must be more than 120/10 = 12 kW.
If the heat accumulator is used as a backup option in case of 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 we take the same 100 m2 house as an example, then heating it will require 240 kW*hours 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 boiler power reserve of one and a half is enough to accumulate the required amount of heat in a week or two.
The calculation is approximate, without taking into account the reduction in the thermal power of radiators depending on the temperature of the coolant and 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 heat exchanger and the boiler so that hot water enters the top of the heat exchanger, pushing cold water from the bottom into the boiler. A circulation pump is installed between the heat exchanger and the heating circuit to draw hot water from the upper part and transport it to the radiators.
However, this significantly increases the overall heat capacity of the system, and when starting the heating initially, you will have to wait until the entire volume of the heat exchanger is heated before the heat reaches the radiators.
Another option for switching on is parallel to the heating boiler. This option works well in combination with a gravity heating system. The upper outlet of the heat accumulator is connected to the highest point of the distribution box, and at the lower point - to the boiler.
The disadvantages are the same as in the first case; the entire volume of coolant in the system and in the heater is heated, which significantly increases the time to start heating.
The only advantages are ease of connection and a minimum of elements used.
Switching circuit with mixing
The best thing use a switching circuit with mixing or hydraulic isolation. 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: three-way valve, thermostats, safety group, etc. By default, the 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 heater and the target temperature in the radiators are reached, the overheating sensor installed in the boiler is triggered and it turns off. While heating is required or the heat accumulator is not warmed up, the boiler continues to operate.
If for some reason the boiler stops producing rated power or switches off completely when the temperature on the supply line 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 supply and return lines and a group of thermostats. Alternatively, they are available for sale ready-made assemblies for connecting heat accumulators - an automatic mixing unit, for example LADDOMAT.
With your own hands
If you really want, you can build a storage tank with your own hands. Ideally she should:
- withstand the nominal pressure in the system with a reserve;
- have a calculated 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 TA shape is a tall cylinder with a semicircular base and lid. The ratio of diameter to height is selected to be approximately 1 to 3-4 to promote better heat distribution inside the container.
In this case, hot water is taken from the highest point to the radiators. Just above the center, the water is diverted to the heated floor circuit, and at the lowest point of the TA the return line is connected to the heating boiler.
It is almost impossible to weld a cylindrical container yourself. 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 accumulator, you should prepare a special support platform, foundation, capable of supporting the enormous weight of 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 made
There are not many thermal accumulators on the Russian market domestic production, since only recently they began to be actively introduced into autonomous heating systems.
| Model | Additional options | volume, m3 | Operating pressure, bar | Maximum temperature, ºС | Approximate cost, rub |
| Sibenergo-therm | — | 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 |
A heat accumulator (TA, buffer tank) is a device that provides accumulation and preservation of heat for a long time for its further use. The simplest example of a heat storage device is an ordinary household thermos. As another example, we can name a conventional brick stove, which heats up when fuel is burned in it, and after the fire is finished, the stove continues to give off heat for several hours, heating the room.
Using a buffer tank in heating and hot water supply systems ensures uninterrupted supply of heated coolant to heating devices
regardless of whether the boiler is currently running or not.
The thermal accumulator also allows you to increase the efficiency of the entire system, increase the service life of the equipment and significantly reduce energy consumption for heating premises and hot water.
The greatest effect from the use of TA is noticeable in a system operating on the basis of a solid fuel heating boiler. This allows you to achieve significant fuel savings (up to 25-30%) and increase the boiler efficiency to 85%.
You can purchase a ready-made battery tank in a store or make it yourself. It is important to correctly calculate its capacity and other technical specifications, and also correctly connect the buffer storage tank to the heating system.
In this article:
Design features of the heat accumulator
Drawing of the storage tank
The main element of any TA is a thermal storage material with high heat capacity.
Depending on the type of material used, heat accumulators for a boiler can be:
- solid state;
- liquid;
- steam;
- thermochemical;
- with an additional heating element, etc.
For heating and hot water supply of private houses, hot water storage tanks are used, where water, which has a high specific heat capacity, acts as a thermal storage element.
Instead of water, it is sometimes used, intended for home heating systems.
An example of a water heater with an additional electric heating element for a hot water supply system is a modern storage water heater.
A conventional thermal energy accumulator is a sealed metal tank of various volumes (from 200 to 5000 liters or more), usually cylindrical in shape, enclosed in an outer shell (housing).
Between the tank and the outer shell there is an insulating layer of heat-insulating material.
In the upper and lower parts of the tank there are two pipes for connection to the heating boiler and to the heating system itself.
At the bottom there is usually a drain valve to drain the liquid, and at the top there is a safety valve to automatically bleed air when the pressure inside the buffer tank rises. There may also be flanges for connecting pressure and temperature sensors (thermometer).
Tubular electric heaters
Sometimes inside the buffer tank one or more additional heaters can be installed different types:
- electric heater (TEH);
- and/or a heat exchanger (coil) connected to additional heat sources (solar collectors, heat pumps etc.).
The main task of these heaters is to maintain the required heating temperature working fluid inside TA.
Also inside the tank there can be a DHW heat exchanger, which provides hot water by heating it with the working fluid of the heating system.
The principle of operation of the storage tank
Heating circuit with heat accumulator
The principle of operation of the TA for a solid fuel boiler is based on the high specific capacity of the working fluid (water or antifreeze). By connecting the tank, the volume of liquid increases several times, as a result of which the inertia of the system increases.
At the same time, the coolant heated to the maximum by the boiler retains its temperature in the heat exchanger for a long time, flowing to the heating devices as needed.
This ensures continuous operation of the heating system even when fuel combustion in the boiler stops.
Let's look at how the system works with a solid fuel boiler and forced supply of coolant.
To start the system, the circulation pump installed in the pipeline between the boiler and the heat accumulator is turned on.
Cold working fluid from the lower part of the heater is supplied to the boiler, heated in it and enters its upper part.
Due to specific gravity there is less hot water, it practically does not mix with cold water and remains in the upper part of the buffer tank, gradually filling its internal space due to selection by the pump cold water into the boiler.
When the circulation pump installed in the return line of the system between the heating devices and the storage tank is turned on, the cold coolant begins to flow into the lower part of the heat exchanger, displacing hot water from its upper part into the supply line.
In this case, hot working fluid is supplied to all heating devices.
The required volume of heat for heating the premises can be automatically adjusted room sensor temperature, which controls the operation of a three-way valve installed at the TA outlet in the supply line. When the room reaches the set temperature, the sensor issues a control signal to the valve, which is activated and limits the flow of hot coolant into the system, redirecting it back to the heat exchanger.
After the fuel is burned in the boiler, the hot coolant from the storage tank continues to flow into the system as needed until the cooled working fluid from the return line completely fills its internal volume.
DHW circuit with storage tank
TA operating hours when the boiler is not working, it can last for quite a long time. This depends on the outside temperature, the volume of the buffer tank and the number of heating devices in the heating system.
To retain heat inside the heat accumulator, the tank is thermally insulated.
Also for this purpose, additional heat sources can be used in the form of built-in electric heaters (heaters) and/or coolants (coils) connected to other heat sources (electric and gas boilers, solar collector etc.).
The DHW coolant built into the tank provides heating of cold water supplied through it from the water supply system. Thus he plays a role instantaneous water heater, providing the homeowners with hot water.
Connecting (piping) the heat accumulator to the heating system
As a general rule, the buffer tank is connected to the heating system in parallel with the heating boiler, therefore this circuit is also called a boiler.
Let's give the usual scheme connecting the heating system to a heating system with a solid fuel heating boiler (to simplify the diagram, shut-off valves, automation and control devices and other equipment are not indicated on it).
Simplified wiring diagram for a heat accumulator
This diagram identifies the following elements:
- Heating boiler.
- Thermal accumulator.
- Heating devices (radiators).
- Circulation pump in the return line between the boiler and the heat exchanger.
- Circulation pump in the return line of the system between heating devices and heating equipment.
- Heat exchanger (coil) for hot water supply.
- Heat exchanger connected to an additional heat source.
One of the upper pipes of the tank (item 2) is connected to the boiler outlet (item 1), and the second is connected directly to the supply line of the heating system.
One of the lower pipes of the heat pump is connected to the boiler inlet, and a pump (item 4) is installed in the pipeline between them, ensuring the circulation of the working fluid in a circle from the boiler to the heat pump and vice versa.
The second lower pipe of the TA is connected to the return line of the heating system, in which a pump is also installed (item 5), which ensures the supply of heated coolant to the heating devices.
To ensure the functioning of the heating system in the event of a sudden power outage or circulation pumps failure, they are usually connected in parallel to the main line.
In systems with natural circulation of coolant, there are no circulation pumps (items 4 and 5). This significantly increases the inertia of the system, and at the same time makes it completely energy independent.
Heat exchanger for hot water supply(pos. 6) is located in the upper part of the TA.
The location of the additional heating heat exchanger (item 7) depends on the type of incoming heat source:
- for high-temperature sources (heating elements, gas or electric boiler) it is placed in the upper part of the buffer tank;
- for low-temperature ones (solar collector, heat pump) - in the lower part.
The heat exchangers indicated in the diagram are optional (items 6 and 7).
What to consider when purchasing
Selecting a heat storage device for heating
When choosing thermal battery for individual heating of a house, it is necessary to take into account the volume of the tank and its technical parameters, which must correspond to the parameters of the boiler and the entire heating system.
These include, in particular:
1. Dimensions dimensions and weight devices that should enable its installation. In case it is impossible to find appropriate place in a house for a tank with the required capacity, it is possible to replace one tank with several smaller buffer tanks.
2. Maximum pressure working fluid in the heating system. The shape of the buffer container and the thickness of its walls depend on this value. At a system pressure of up to 3 bar, the shape of the tank is not particularly important, but if this value possibly increases to 4-6 bar, it is necessary to use toroidal-shaped containers (with spherical lids).
3. Maximum permissible temperature working fluid for which the unit is designed.
4. Material storage tank for the heating system. They are usually made from mild carbon steel with a moisture resistant coating or of stainless steel. Stainless steel containers have the highest anti-corrosion properties and durability in operation, although they are more expensive.
5. Availability or possibility of installation:
- electric heaters (heaters);
- built-in heat exchanger for connection to the hot water supply, which ensures the supply of hot water to the house without additional water heaters;
- additional built-in heat exchangers for connection to other heat sources.
Comparison of popular models
Many domestic and foreign manufacturers produce heat storage tanks. Let's give comparison table some models of Russian and foreign models with a capacity of 500 liters.
| Model | NIBE BU-500.8 | Reflex PFH-500 | ACV AK 500 | Meibes PSX-500 | Sibenergo-therm | PROFBAK TA-VV-500 |
|---|---|---|---|---|---|---|
| Manufacturer country | Sweden | Germany | Belgium | Germany | Russia | Russia |
| Tank volume, l. | 500 | 500 | 500 | 500 | 500 | 500 |
| Height, mm | 1757 | 1946 | 1790 | 1590 | 2000 | 1500 |
| Diameter, mm | 750 | 597 | 650 | 760 | 700 | 650 |
| Weight, kg | 145 | 115 | 150 | 120 | 165 | 70 |
| Max operating pressure, bar | 6 | 3 | 5 | 3 | 6 | 3 |
| Max operating temperature, °C | 95 | 95 | 90 | 95 | 90 | 90 |
| Connection to DHW | option | No | No | No | No | option |
| Additional heating | option | No | option | No | No | Heating element 1.5 kW |
| Approximate cost, rub. | 43 200 | 35 100 | 53 200 | 62 700 | 28 500 | 55 800 |
This table clearly shows that the price storage tank for heating with approximately the same parameters can be within fairly wide limits.
The cost mainly depends on the material (carbon steel or stainless steel), its shape (regular or toroidal), as well as the availability of additional options or the ability to install them.
Calculation of container volume
The main parameter when purchasing a buffer tank for a solid fuel boiler, as well as for it, is the capacity of the heat accumulator, which directly depends on the power of the heating boiler.
There are various calculation methods 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 (approximately 2-3.5 hours).
Compliance with this condition allows you to get maximum efficiency boiler with maximum fuel economy.
The easiest way to calculate stipulates that one kilowatt of boiler power must correspond to at least 25 liters of the volume of the buffer tank connected to it.
Thus, with a boiler power of 15 kW, the capacity of the storage tank should be at least: 15 * 25 = 375 liters. In this case, it is better to choose a capacity with a reserve, in in this case– 400-500l.
There is also this version: the larger the tank capacity, the more efficiently the heating system will work and the more fuel you will save. However, this version imposes limitations: search free space in the house for installation of a heat accumulator large sizes, as well as the technical capabilities of the heating boiler itself.
Coolant capacity volumes have an upper limit: no more than 50 liters per 1 kW. Thus, the maximum volume of the storage tank with a boiler power of 15 kW should not exceed: 15 * 50 = 750 liters.
Obviously, using a heat exchanger with a volume of 1000 liters or more for a 10 kW boiler will cause additional fuel consumption to heat such a volume of working fluid to the required temperature.
This will lead to a significant increase in the inertia of the entire heating system.
To provide your home boiler room with environmentally friendly fuel, we recommend learning how to make.
Solid fuel boilers are more difficult to switch to automatic operation. So "smart" electrical devices, How GSM module, help make the heating system more or less self-regulating. Go to.
Advantages and disadvantages of buffer tank
Buffer tank for boiler
The main advantages of a heating system with a heat accumulator include:
- the maximum possible increase in the efficiency of the solid fuel boiler and the entire system while simultaneously saving energy resources;
- ensuring protection of the boiler and other equipment from overheating;
- ease of use of the boiler, allowing it to be loaded at any time;
- automation of boiler operation through the use of temperature sensors;
- the ability to connect several different heat sources to the heat exchanger (for example, two boilers various types), ensuring their integration into one circuit of the heating system;
- ensuring stable temperature in all rooms of the house;
- the ability to provide domestic hot water without the use of additional water heating devices.
The disadvantages of heat accumulators for heating systems include:
- increased inertia of the system (from the moment the boiler is ignited until the system reaches operating mode, much more time passes);
- the need to install TA near the heating boiler, which requires separate room required area;
- large dimensions and weight, making it difficult to transport and install;
- the fairly high cost of industrially produced heat pumps (in some cases, its price, depending on the parameters, may exceed the cost of the boiler itself).
An interesting solution: a heat accumulator in the interior of the house.
In the interior 
Installation 
1st floor 
Attic 
Basement 
Section
The use of a heat accumulator is economically beneficial not only for solid fuel boilers, but also for electric or gas systems heating
In the case of an electric boiler, The TA turns on at full power at night, when electricity tariffs are much lower. During the day, when the boiler is turned off, the premises are heated using the heat accumulated during the night.
For gas boilers savings are achieved through the alternate use of the boiler itself and the heat exchanger. Wherein gas-burner turns on much less often, which provides less.
It is undesirable to install a heat accumulator in heating systems where rapid and or short-term heating of the room is required, since this will be hampered by the increased inertia of the system.
Companies involved in the development of engineering systems have been focusing on the development of alternative technological solutions in recent years. Concepts and directions that do not involve the use of natural resources. At the very least, experts strive to minimize their consumption. A tangible benefit in this segment is demonstrated by a heat accumulator for a heating system, which is included in the existing engineering complex as an additional optimization component.
General information about heat accumulators
There are many modifications and varieties of heat accumulators, which are also called buffer heaters. The tasks that such installations perform are also different. As a rule, batteries are used to increase the efficiency of the main unit, for example a solid fuel boiler. In these cases, it is advisable to use such systems to carry out a monitoring function, which is difficult to implement in the process of servicing traditional boiler rooms in private homes. Most often, heat storage tanks with a capacity of up to 150 liters are used for this. In the industrial sector, of course, installations with a capacity of about 500 liters can also be used.
The tank itself contains elements that ensure maintenance of the required temperature of the medium. The very material from which the tank is made must be mated with layers of insulators. The active components are heating elements and copper pipes. The configuration of their placement in tanks may differ, as well as the systems for controlling the operating parameters of the battery.
Operating principle
From a storage drive's point of view, the main task is to ensure that the desired temperature regime, which is specified by the user himself. As the boiler operates, the tank receives hot water and stores it until the heating system stops functioning. Conditions for maintaining temperature balance are determined insulating materials containers and internal heating elements. A classic heat accumulator for a heating system, in essence, resembles the operation of a boiler and is also integrated into the system. That is, on the one hand, the equipment is connected to a heat source, and on the other, it ensures the operation of direct heaters, which can be radiators. In addition, the system is often used as a full-fledged source of hot water for domestic needs in constant consumption mode.
Functions of thermal accumulators
As already noted, units of this type can perform different tasks, the requirements for which determine the criteria for choosing a particular system. The basic and main functions include the accumulation of heat from the generator and its subsequent release. In other words, the same tank collects, stores and transfers energy to the direct heating element. In combination with a solid fuel boiler, the system’s functions include protection against overheating. Automated and electronic control relays are ineffective in solid fuel units. Therefore, it is practiced to optimize the operation of the boiler using a heat accumulator, which naturally collects excess energy and returns it during temperature drops. Electric, gas and liquid generators are easier to control, but with the help of a battery they can be connected into a single complex and operated with minimal heat loss.
Where can a thermal accumulator be used?
It is advisable to use a heat storage system in cases where the existing heating unit does not allow sufficient control of its operation. For example, solid fuel boilers inevitably provide for maintenance moments when their capacities are not loaded. To compensate for heat loss, it makes sense to use such a system. Also, in the operation of water and electric heating systems, this solution is economically justified. A modern heat accumulator with automatic control can be configured to operate during certain periods of time when the most economical energy consumption tariff is in effect. So, for example, at night the system will conserve a certain volume which can be used for any needs during the next day.
Where is it undesirable to use heat accumulators?
The nature of the operation of buffer batteries is designed to ensure uniform heat transfer and smooth out surges during temperature changes. But this principle of operation is not always useful. For heating systems, which, on the contrary, require an accelerated increase or decrease in temperature, such an addition will be unnecessary. In such situations, increasing the potential of the coolant due to auxiliary ones will prevent rapid cooling and heating. In addition, it is worth noting that home heat accumulators for the most part make precise temperature control impossible. It would seem that such a solution could be optimal for heating systems operating in short intervals - it is enough to heat the container in advance and then use the ready energy at the appointed time. However, maintaining the optimal state of the coolant itself requires the consumption of certain energy. Therefore, for example, a boiler room used for irregular and short-term heating of a dryer can easily do without a battery. It's another matter if we're talking about about a whole group of boilers that can be combined into one system using a buffer.
Battery characteristics
Among the main characteristics are the dimensional parameters of the unit, its capacity, maximum temperature and pressure indicator. For private homes, manufacturers offer small installations, the diameter of which can be 500-700 mm and the height - about 1500 mm. It is also important to consider weight, since in some cases specialists have to use concrete screeds to give the structure stability. The average heat accumulator weighs about 70 kg, although the exact value is directly related to the capacity and quality of the insulation of the tank. Performance characteristics come down to temperature and pressure. The first value is about 100 °C and the pressure level can reach 3 Bar.
Battery connection
A homeowner with knowledge in electrical engineering can not only independently connect a ready-made buffer to the heating system, but also completely assemble the structure. First you need to order a container in the form of a cylinder, which will become a working buffer. Next, in transit through the entire tank, it is necessary to conduct a return pipeline through the niche of the future heat accumulator. The connection should begin with the connection between the boiler return and the tank. From one component to the second, a place should be provided where the circulation pump will be installed. With its help, the hot coolant will move from the barrel to the shut-off valve and expansion tank.
You need to install the heat accumulator with your own hands in such a way that the most rational distribution of liquid throughout all rooms is assumed. To assess the quality of operation of the assembled system, you can provide it with thermometers and pressure sensors. Such equipment will allow you to evaluate how efficiently the battery will function through the connected circuits.
Water systems
A classic heat accumulator involves the use of water as an energy carrier. Another thing is that this resource can be used in different ways. For example, it is used to supply heated floors - the liquid passes through circulation pipes into a special coating. Water can also be used to ensure the operation of the shower and other needs, including technological, hygienic and sanitary purposes. It is worth noting that the interaction of boilers with water is quite common due to its low cost. Water heat accumulator is cheaper compared to electric heaters. On the other hand, they also have their drawbacks. As a rule, they come down to nuances in the organization of circulation networks. The greater the volume of resource consumed, the more expensive its organization is. Installation costs are one-time, but operation will be cheaper.
Solar systems
In water systems, the design includes a comb heat exchanger designed for a geothermal pump. But a solar collector can also be used. In essence, it turns out the center power plant, which optimizes the function of a heating station by reserving energy from different sources. Although solar thermal storage is less common, it can be used in typical heating systems. Solar collectors also retain energy potential, which is later spent on household needs. But it is important to consider that hot coolant in the form of water itself requires less energy than solar battery. The best option The use of such batteries is the direct integration of panels into places where heating should be carried out without additional transformations.
How to choose heat?
It is worth starting from several parameters. To begin with, the functionality of the system and its performance indicators are determined. The tank must completely cover the volumes that are planned to be consumed during operation of the heating system. You shouldn’t skimp on control systems either. Modern relays with automatic regulators not only make programming convenient engineering systems, but also provide protective properties. A properly equipped heat accumulator has protection against idling and provides ample opportunities for indicating temperature conditions.
Heat accumulator for heating boilers
We continue our series of articles with a topic that will be of interest to those who heat their homes solid fuel boilers. We will tell you about a heat accumulator for heating boilers (HS) using solid fuel. It's really the required device, which allows you to balance the operation of the circuit, smooth out differences in coolant temperature and also save money. Let us immediately note that a heat accumulator for electric heating boilers is used only if the house has an electric meter with separate calculation of night and day energy. Otherwise, installing a heat accumulator for gas heating boilers makes no sense.
How does a heating system with a heat accumulator work?
A heat accumulator for heating boilers is a part of the heating system designed to increase the time between loads solid fuel into the boiler. It is a reservoir into which there is no air access. It is insulated and has enough large volume. There is always water in the heat accumulator for heating, and it circulates throughout the entire circuit. Of course, non-freezing liquid can also be used as a coolant, but still, due to its high cost, it is not used in circuits with TA.
In addition, there is no point in filling a heating system with a heat accumulator with antifreeze, since such tanks are placed in residential premises. And the essence of their use is to ensure that the temperature in the circuit is always stable, and therefore the water in the system is warm. The use of a large heat accumulator for heating in temporary country houses is impractical, and a small reservoir is of little use. This is due to the operating principle of the heat accumulator for the heating system.
- TA is located between the boiler and the heating system. When the boiler heats the coolant, it enters the heat exchanger;
- then the water flows through pipes to the radiators;
- the return flow returns to the TA, and then directly to the boiler.
Although the heat accumulator for the heating system is a single vessel, due to its large size, the direction of the flows at the top and bottom are different.
In order for the TA to perform its main function of storing heat, these flows must be mixed. The difficulty is that high temperatures always rise, and cold tends to fall. It is necessary to create such conditions so that part of the heat sinks to the bottom of the heat accumulator in the heating system and heats the return coolant. If the temperature is equalized throughout the tank, then it is considered fully charged.
After the boiler has burned out everything that was loaded into it, it stops working and the TA comes into play. The circulation continues and it gradually releases its heat through the radiators into the room. All this happens until the next portion of fuel enters the boiler again.
If the heat accumulator for heating is small, then its reserve will last only for a short time, while the heating time of the batteries increases, since the volume of coolant in the circuit has become larger. Disadvantages of using for temporary residences:
- the room warm-up time increases;
- larger volume of the circuit, which makes filling it with antifreeze more expensive;
- more high costs for installation.
As you understand, filling the system and draining water every time you arrive at your dacha is troublesome, to say the least. Considering that the tank alone will be 300 liters, it makes no sense to take such measures for the sake of a few days a week.
Additional circuits are built into the tank - these are metal spiral pipes. The liquid in a spiral does not have direct contact with the coolant in the heat accumulator for heating the house. These could be contours:
- low temperature heating (warm floor).
Thus, even the most primitive single-circuit boiler or even stove can become a universal heater. He will provide for the whole house necessary warmth And hot water simultaneously. Accordingly, the heater's performance will be fully used.
In production models manufactured in production conditions, additional heating sources are built in. These are also spirals, only they are called electric heating elements. There are often several of them and they can work from different sources:
- circuit;
- solar panels.
Such heating is an additional option and is not mandatory; keep this in mind if you decide to make a heat accumulator for heating with your own hands.
Heat accumulator wiring diagrams
We dare to suggest that if you are interested in this article, then, most likely, you have decided to make a heat accumulator for heating and its wiring with your own hands. You can come up with many connection schemes, the main thing is that everything works. If you correctly understand the processes occurring in the circuit, then you can experiment. How you connect the TA to the boiler will affect the operation of the entire system. Let's first look at the most simple diagram heating with a heat accumulator.
A simple TA strapping scheme
In the figure you see the direction of movement of the coolant. Please note that upward movement is prohibited. To prevent this from happening, the pump between the heating element and the boiler must pump a larger amount of coolant than the one that stands before the tank. Only in this case will a sufficient drawing force be generated, which will remove part of the heat from the supply. The disadvantage of this connection scheme is the long heating time of the circuit. To reduce it, you need to create a boiler heating ring. You can see it in the following diagram.
Scheme of piping TA with boiler heating circuit
The essence of the heating circuit is that the thermostat does not add water from the heater until the boiler warms it up to established level. When the boiler has warmed up, part of the supply goes into the TA, and part is mixed with coolant from the reservoir and enters the boiler. Thus, the heater always works with an already heated liquid, which increases its efficiency and the heating time of the circuit. That is, the batteries will become warm faster.
This method of installing a heat accumulator in a heating system allows you to use the circuit in autonomous mode when the pump will not work. Please note that the diagram shows only the connection points of the heating unit to the boiler. The coolant circulates to the radiators in a different way, which also passes through the heat exchanger. The presence of two bypasses allows you to be on the safe side twice:
- the check valve is activated if the pump is stopped and the ball valve on the lower bypass is closed;
- If the pump stops and the check valve breaks, circulation is carried out through the lower bypass.
In principle, some simplifications can be made to this design. Given the fact that the check valve has high flow resistance, it can be excluded from the circuit.
TA piping diagram without a check valve for a gravity system
In this case, when the light goes out, you will need to manually open the ball valve. It should be said that with such a layout, the TA must be located above the level of the radiators. If you do not plan for the system to operate by gravity, then connecting the heating system to the heat accumulator can be done according to the diagram shown below.
TA piping diagram for a circuit with forced circulation
The correct movement of water is created in the TA, which allows it to be heated ball by ball, starting from the top. The question may arise, what to do if there is no light? We talked about this in an article about . It will be more economical and convenient. After all, gravity contours are made of large-section pipes, and in addition, inclines that are not always convenient must be observed. If you calculate the price of pipes and fittings, weigh all the inconveniences of installation and compare all this with the price of a UPS, then the idea of installing alternative source nutrition will become very attractive.
Calculation of heat storage volume
Heat accumulator volume for heating
As we have already mentioned, it is not advisable to use small-volume TAs, and tanks that are too large are also not always appropriate. So the question has arisen about how to calculate the required volume of TA. I really want to give a specific answer, but, unfortunately, there cannot be one. Although there is still an approximate calculation of a heat accumulator for heating. Let's say you don't know what heat loss your house has and you can't find out, for example, if it hasn't been built yet. By the way, to reduce heat loss, you need . You can select a tank based on two values:
- area of the heated room;
- boiler power.
Methods for calculating the volume of heating equipment: room area x 4 or boiler power x 25.
It is these two characteristics that are decisive. Different sources offer their own method of calculation, but in fact these two methods are closely interrelated. Suppose we decide to calculate the volume of a heat accumulator for heating, based on the area of the room. To do this, you need to multiply the square footage of the heated room by four. For example, if we have little house 100 sq. m., then you will need a tank of 400 liters. This volume will allow reducing the boiler load to twice a day.
Undoubtedly, this is the case pyrolysis boilers, in which fuel is added twice a day, only in this case the operating principle is slightly different:
- the fuel flares up;
- air supply decreases;
- the smoldering process begins.
In this case, when the fuel flares up, the temperature in the circuit begins to increase rapidly, and then smoldering keeps the water warm. During this very smoldering, a lot of energy disappears into the pipe. In addition, if a solid fuel boiler works in tandem with a leaky heating system, then at peak temperatures the expansion tank sometimes boils. Water literally begins to boil in it. If the pipes are made of polymers, then this is simply destructive for them.
In one of the articles about TA, it takes away some of the heat and the tank can boil only after the tank is fully charged. That is, the possibility of boiling, with the correct volume of TA, tends to zero.
Now let's try to calculate the volume of the heater based on the number of kilowatts in the heater. By the way, this indicator is calculated based on the square footage of the room. At 10 m 1 kW is taken. It turns out that in a house of 100 square meters there should be a boiler of at least 10 kilowatts. Since the calculation is always done with a margin, we can assume that in our case there will be a 15 kilowatt unit.
If you do not take into account the amount of coolant in the radiators and pipes, then one kilowatt of the boiler can heat approximately 25 liters of water in the heating unit. Therefore, the calculation will be appropriate: you need to multiply the boiler power by 25. As a result, we will get 375 liters. If we compare with the previous calculation, the results are very close. Only this takes into account that the boiler power will be calculated with a gap of at least 50%.
Remember, the more TA, the better. But in this matter, as in any other, one must do without fanaticism. If you install a TA for two thousand liters, then the heater simply cannot cope with such a volume. Be objective.
The main goals of the design and installation of an autonomous heating system are comfort in the home and trouble-free operation. Therefore, those people who believe that to achieve comfort it is enough to simply install a boiler and connect it to the heating system are mistaken.
And this mistake lies in the fact that sooner or later any boiler, even the best quality, can fail. And most often this happens in the midst of heating season, when the equipment operation mode is most intensive. How can you insure yourself in such a case?
There are several options:
- Have a regular stove in your home that is in working order.
- Have two boilers, one of which, with a lower power, is used only in an emergency.
- Include a device in the heating system that allows you to accumulate thermal power during operation of the boiler, capable of maintaining the temperature of the coolant at the proper level for a sufficiently long time when it stops.
The first option is good for those houses that previously had stove heating, and then were equipped with their own boiler room. It is unlikely that anyone will build a stove in a new house, for which heating from a boiler was initially provided. The second option is used infrequently, but has a right to life. Usually the main one here is a solid fuel and gas unit, and the backup is an electric boiler of not too high power, used exclusively as backup source heat.
But the third option from the point of view of reliability is the most optimal. Such a device is called a heat accumulator and is most often used in systems equipped with periodic boilers. Most often, these are solid fuel boilers (which need to be loaded with fuel several times a day) and electric units, which are profitable to turn on only at night (if electricity is cheaper at night).
What is a heat accumulator (TA)
A heat accumulator is a reservoir of a certain (rather large) capacity filled with a coolant (usually water). The tank must be well insulated from external environment. At the same time, during operation of the boiler, due to the high heat capacity of water, the coolant is heated throughout the entire volume of the tank. Due to this, a large reserve of thermal power is created, ensuring stable operation of the heating system and hot water supply (if available) during the entire period of boiler downtime. Moreover, the reason for the downtime is not important - it could just be a break between fireboxes or an accident.
With a sufficient tank volume, even a large house can last up to 2 days. At the same time, the temperature in it will drop by only 2-3 degrees. This is the most obvious and understandable advantage of having a heat accumulator in the home heating system. In fact, its capabilities are much wider. Indeed, in fact, it significantly increases the volume of coolant in the heating system circuit. At the same time, its indicators such as heat capacity and inertness also increase.
That is, the system warms up more slowly, absorbing more energy, but it also cools down for a very long time, maintaining the temperature in the house even when the boiler is not working.
There are a number of situations in which the presence of a heat accumulator in the system greatly simplifies and reduces the cost of achieving the desired results.
Fuel burns best when the boiler is operating at maximum power. But in spring and summer this power is clearly excessive. And the presence of a water tank will allow you to quickly heat the water in it to the desired temperature and stop the combustion process, saving fuel and time for servicing the boiler.
During ignition, solid fuel boilers have minimum power, as the fuel burns, it reaches a maximum and then drops again. This mode is not very useful for the operation of the heating system - the temperature of the coolant in it constantly fluctuates. The presence of a heat accumulator allows you to maintain the temperature in the system at an optimal level.
If the system has several sources of heating the coolant, and one of them is a solid fuel boiler, then connecting the others becomes very difficult. A coolant reservoir allows you to organize such connections easily and at low cost.
If it is necessary to organize hot water supply in the house, then you have to install an additional heat exchanger in the boiler or use a boiler indirect heating. All this negatively affects the operation of the heating system. And here a large tank of hot water makes it easy to get out of the situation.
Thus, the TA is a decoupling unit between the heating circuit and the boiler, allowing minimal costs implement various additional functions.
To do this, you need to build on the following data:
- heating unit power;
- the time during which the coolant in the heat exchanger must warm up;
- the time for which the thermal power accumulated in the reservoir should be enough to cover the heat loss of the house.
For correct selection it is necessary to know the thermal power of the heater.
It is calculated using the formula:
Q = m × C × (T2 – T1),
- where m is the mass of the coolant (depending on the volume of the heat exchanger), kg;
- C – specific heat capacity of the coolant;
- T2 – T1 is the difference between the final and initial water temperatures. Usually it is taken equal to 40 degrees.
One ton of water, when cooled by 40 degrees, releases 46 kWh of heat.
If you want to switch the boiler to periodic operation, for example, only to night or day mode, then the power of the boiler should be enough to heat the house for the remaining time.
Let's give an example. Suppose you use a solid fuel boiler that operates only during the daytime for 10 hours. In this case, the heat loss of the house is 5 kW, then per day 5 × 24 = 120 kW*h of thermal power will be required to maintain the heating function. The TA will be used for 14 hours. This means that it should accumulate: 5 × 14 = 70 kWh of heat. If the coolant is water, then its weight should be 70: 46 = 1.52 tons. With a margin of 15% this will be 1.75 tons, then the volume of the heat exchanger should be approximately 1.75 cubic meters. m.
Do not forget that the boiler power should be sufficient to produce 120 kWh of energy in 10 hours of operation. That is, its power must be at least 120: 10 = 12 kW.
If the heater is used only for the safety of the heating system in case of an accident, then the reserve of thermal power in it should be enough for 1-2 days. That is, the power reserve must be at least 120 - 240 kWh. Then the volume of TA will be: 240: 46 = 5.25 cubic meters. m.
This approximate calculations, however, they allow you to get a rough idea of TA parameters.
There are simpler ways to calculate the volume of TA:
- The volume is equal to the area of the room in meters multiplied by 4. For example, a house has an area of 120 square meters. m. Then the volume of the tank should be: 120 × 4 = 480 l.
- The boiler power is multiplied by 25. For example, the boiler has a power of 12 kW, then the volume of the tank will be 12 × 25 = 300 liters.
You can make a reservoir for heating the coolant yourself or purchase a ready-made one. Self-production is associated with difficulties in taking into account the characteristics and features of future equipment. Not only the price of the issue will depend on this, but also the performance of the TA, as well as its durability.
The main operating parameters of heat accumulators are:
- Weight, volume and dimensions. The volume of the tank is selected according to the power of the boiler. But the larger its volume, the more economically the system as a whole will operate. A large heat exchanger will take longer to heat up, but the time between firing the boiler will also increase. If the tank is too large according to calculations and does not fit into the allocated room, then you can use several smaller containers.
- Pressure in the heating system. The thickness of the TA walls, as well as the shape of its bottom and lid, depend on this value. If the pressure in the system is no more than 3 bar, then the most common heat accumulators can be used. If the operating pressure is in the range of 4-8 bar, then you need to choose tanks with torispherical lids. Such equipment will cost more.
- The material from which the tank is made. Most often this is standard carbon steel coated with waterproof paint. But if possible, it is better to choose a stainless steel tank. It is more resistant to additives contained in the coolant and corrosion.
- Maximum fluid temperature.
- Availability of installation additional equipment: heating elements, built-in heat exchanger for connection to the hot water system, additional heat exchangers for organizing connection to other sources of heating of the coolant.
How to install a heat storage tank
The most in a simple way The installation is a vertically located TA, into the walls of which there are 4 pipes embedded, two on each side. Each pair is spaced vertically. On one side, the upper pipe is connected to the supply line of the boiler unit, and on the other, to the supply branch of the heating system. Below, on the corresponding sides of the tank, there are pipes connected to the return lines of the boiler and the heating circuit.
The return pipelines of the boiler and heating circuit are equipped with circulation pumps.
After loading fuel into the boiler and achieving stable combustion, turn on the circulation pump, supplying water from the bottom of the heat exchanger to its heating zone. At the same time, in parallel, hot coolant used for heating the premises is supplied to the heating unit through the upper pipe.
In this case, active mixing of cold and hot water in the tank does not occur - this is prevented different densities water of different temperatures.
After the fuel burns out, the tank is filled with water at the required temperature. After this, the circulation pump of the heating circuit is turned on, which pumps heated water through the system. Due to the fact that the coolant enters the system through the upper pipe, and the water used in the system and already cooled enters from below, mixing of layers of water of different temperatures does not occur, and the TA supplies water of the required temperature to the system for a long time.
Types of TA depending on design
Depending on the functional purpose, all heat accumulators are divided into the following types:
- Empty - with direct connection of circuits. In such a system, no heat exchangers are used, and the separation of cold and hot water is ensured only by the difference in their density. Homemade TAs usually have exactly this design.
- With built-in boiler. Inside the main tank there is an additional container intended for heating water in the DHW system.
- With internal heat exchanger. This model allows you to separate coolants in the circuits of the boiler and heating system. The separation of liquids is ensured by the walls of the heat exchanger.
What does the heating equipment market offer?
Our market has products from well-known foreign companies:
- Buderus (Germany) - produces universal TAs that can be used to work with solid fuel boilers of any other brands. The tanks are made of carbon steel and equipped with insulation from a layer of foam plastic 100 mm thick.
- Hajdu is a Hungarian product that is attractive due to its good price-quality ratio. The thickness of the insulation layer is also 100 mm.
- Lapesa is a Spanish company that produces heat accumulators not only for household, but also industrial purposes. For thermal insulation of tanks, polyurethane foam is used, which ensures extremely low heat loss.
- NIBE (Sweden) - produces models that allow the use of various coolant heating units (heat pump or solar collector). The thermal insulation of the tanks is a layer of polystyrene foam 80 mm thick.
- S-TANK is a Belarusian product. It is of high quality and affordable price. Can work with low quality water. Has anti-corrosion protection in the form of an enamel layer.
- GOPPO are Russian heat accumulators for heating systems, designed for pressures of 3 and 6 bar. They have 30 mm thick polyethylene foam insulation.
Choosing a heating system for the heating system of a private home is a responsible matter. If the heating installation is carried out by a specialized company, then you don’t have to worry about the correct selection of heating equipment. If you decide to do this yourself, then try to take into account all the listed parameters and choose a tank with at least a small reserve of volume.
