Installing a solid fuel boiler in a residential building is both a simple and understandable task, but upon closer examination, it is associated with numerous technical and technological difficulties. Today, many citizens seek to equip their home with a solid fuel heating device. This is due to the good performance characteristics of this type of heating equipment, the absence of the need to obtain permission to install a solid fuel heater. Not the last role in terms of choosing heating equipment is played by the cost of the fuel resource and its relative availability.

However, choosing a boiler and installing it in the house is not enough. For the normal operation of the autonomous heating system, additional installation of various devices, devices and mechanisms will be required. Most of these devices ensure the normal functioning of the entire heating complex and its safety. A buffer tank or a heat accumulator for a solid fuel boiler just belongs to the category of such devices, without which not a single heating unit can fully work. What is a buffer capacity, let’s look at it in detail?

The place of the buffer tank in the autonomous heating system

Not each of us is able to comprehend and imagine how home heating should look like in the optimal version and how this or that mechanism should work. Heating devices are only a source of thermal energy, with the help of which the heat carrier is heated, which already diverges along the heating circuit. In order for the whole process to proceed as efficiently as possible and at the same time, the safety of the operation of the heating unit was ensured, a buffer tank is necessarily included in the piping.

Without this device, your solid fuel boiler (any heating device) will be a time bomb, which, at the slightest failure in the system, can cause a lot of trouble and trouble.

To answer the question why you need to install such a large unit at home, an analysis of the principle of operation of a solid fuel boiler will help.

On a note: installation of solid fuel units, operation of boilers without a buffer tank in the USA, in many European countries is prohibited.

In fact, the name of the device explains its purpose. Its main task is to play the role of a buffer between a working boiler and a heating system. The task of the buffer is to reduce or increase the heat capacity of the coolant circulating in the heating circuit. Due to its volume, the container is able to influence the temperature regime of the degree of heating of boiler water.

From the point of view of mechanics, the container is an ordinary thermos, i.e. metal integral vessel, insulated on the outside with insulating material. By location, this device is inextricably linked with the heating device. The storage tank is installed in the immediate vicinity of the boiler. What is this bulky unit in the heating system for? Everything explains the mode of operation of heating devices and the features of their design.

The principle of operation of the device


Each heater has its own, special principle of operation. Some boilers are characterized by a uniform mode of operation (gas and electric heating equipment), while others, on the contrary, are characterized by an unstable process. The intensity of heating depends on the method of fuel supply and the presence of devices that control the combustion process. With appliances running on natural gas or electricity, everything is simple and clear. To regulate the heating temperature of the coolant, it is enough to reduce or even stop the gas supply, turn off the power supply. Constant power supply ensures uninterrupted operation of boiler equipment. Both day and night, the boiler operates in automatic mode, independently adjusting the heating temperature of the coolant.

Solid fuel boilers are units with high inertia. The fuel put into the furnace burns constantly, and it is physically impossible to stop this process quickly. The thermal energy obtained in the combustion process should not be wasted. Excess heat is accumulated together with the coolant in a special container, which acts as a thermal energy accumulator.

The situation is similar with a decrease in the intensity of the boiler. When the fuel mass is burned, the boiler abruptly loses its performance, the boiler water in the heating circuit begins to cool rapidly. Without another portion of fuel, there is a threat of a decrease in temperature in heated rooms. Of course there is a way out. A new bookmark of firewood or coal will solve the problem. Another question is how often you can do this procedure, especially if the firebox turned out to be empty at night.

A solid fuel boiler connected to a buffer tank is a complex that can solve the problem of heating residential premises for you. Installing a buffer tank frees you from the frequent and hard work of loading the combustion chamber of the heater with the next amount of firewood.

On a note: It has been calculated that a correctly calculated heat accumulator (buffer tank) significantly reduces the number of furnace loads with fuel material. On average, the number of loads decreases, depending on the model and type of boiler, by 2 times. There is a real saving of your personal time and fuel resource (by 30-50%).

You can understand the principle of operation of the buffer capacity using the example of a car battery. While the engine is running in the car, the electric current generator is running in parallel. The electricity generated by the generator is stored in the battery. When the main engines stop, the battery gives back the necessary energy to the automotive systems.

The buffer tank works the same way. There is heat, the heat accumulator accumulates it, as soon as the heating installation stops producing heat, hot water from the storage tank is used to heat all heating systems.

What else is the use of buffer capacity. Main advantages


In addition to its direct purpose, the hot water storage device performs a number of other equally useful functions. Heating units operating on solid fuels, as a rule, have different stages of combustion. This is the moment of ignition, intense combustion and, accordingly, the process of attenuation. At the second stage, during intensive combustion, the boiler produces the maximum amount of thermal energy, more than is necessary for heating. In the initial and final stages, when the fuel is just starting to burn or running out, the heaters are far from their rated power.

A similar mode of operation of solid fuel apparatuses without additional equipment usually causes a number of domestic inconveniences. The fact that differences with the temperature of the coolant in the heating circuit are possible has already been said.

Important! The hot water storage tank will not allow, in the event of a long absence of fuel in the furnace, to defrost either the boiler itself or the entire heating system. Some models of buffer tanks are capable of supplying warm water to the boiler and to the heating circuit for 12-24 hours. What is important for residents of remote areas.

In the absence of a heat accumulator, when domestic hot water is intensively used in the house, problems cannot be avoided. The buffer tank is just designed to eliminate the resulting drops in the heating of residential premises and ensure the normal operation of the DHW system.

The advantages of using a storage tank are obvious, and knowing about them, you will no longer look skeptically at a bulky tank in your boiler room. Installing a buffer tank in a domestic heating system provides the following benefits:

  • operation of solid fuel heating units in economical mode;
  • increase in time intervals between loading fuel into the boiler;
  • the ability to use heaters in the summer for the operation of the hot water system;
  • technical ability to use high-power heating units in rooms with low heat loss;
  • simple and clear design of the device does not require special maintenance and has a long service life;
  • static state of the device that does not create domestic inconvenience;

Installation of a container of sufficient volume allows the installation of other heating devices in residential premises.

For example: when several heating units of different types are included in the autonomous heating system at once. Often in private households, solid fuel boilers are installed paired with electrical appliances. Both units can be freely connected to one heat storage device, and for this purpose it is not necessary to install additional parts in the system. Thanks to the buffer capacity, both units can be configured to work in terms of priority, balance their work as needed.

Assessing the benefits that the installation of a buffer tank gives to the heating system, one should not forget about safety.

For any heating devices, the main danger is overheating. A working solid fuel boiler constantly needs to be monitored. The large inertia of this type of equipment often causes overheating, as a result of which the unit can fail, and in the worst case, lead to extremely unpleasant consequences. The hot water storage tank easily eliminates this problem by removing excess load on the heater.

How to choose the right heat accumulator for your heating system

Before installing the heating system, they are determined with the type of main heat source. The volume of the heat accumulator also depends on the power of the solid fuel boiler and the volume of tasks that the device will solve during operation. The size and volume of the drive is also determined by your household needs. When choosing a buffer tank, the model of the heating unit, which has a power limit and a limited time resource, becomes a priority.

In other words:

  • when working in tandem with a solid fuel boiler, the buffer tank must ensure the accumulation of thermal energy during a one-time fuel load, which is enough to distribute the hot coolant through the system until the subsequent loading of the combustion chamber.

Here it is appropriate to say a few words about the calculated data that affect the choice of the optimal volume of buffer capacity. With the help of calculations, it is possible to determine the actual storage capacity of a particular volume of coolant, which has an impact on the heat capacity.

It is considered to be: the heat capacity of boiler water is 4.187 kJ kg/ 0C, which in turn means. For heating 1 kg. water for just 10C, an amount of thermal energy in the equivalent of 4.187 kJ will be required. For heaters, this value is 1 kcal = 1.163 W / h.


For the sake of completeness, we consider When installing a heat accumulator with a volume of 1000 liters. (1000 kg.), for heating water up to a temperature of 500C, the amount of thermal energy stored in the tank will be 1000 x 50 = 50000 kcal or 58 thousand kWh.

When hot water is consumed from the buffer tank and the water temperature drops by 50 degrees, the amount of heat will correspondingly decrease by the same value. Each connection scheme has its own method for calculating the capacity of a heat storage device, however, there are the following general requirements that must be taken into account:

  • the storage tank must be capable of accumulating the maximum amount of excess thermal energy during the combustion of fuel at a single load;
  • the higher the peak heat consumption in the heating circuit and the longer the maximum heat consumption, the more volume is required for the buffer tank;
  • in case of high combustion intensity of the boiler in short periods of time, it will be necessary to install an additional heat exchanger, either separately or integrated into the buffer tank;
  • the accumulator must have a nominal pressure inside greater than at the point of connection of the device to the system;
  • in hot water tanks with two or more built-in heat exchangers, a system with a lower working pressure is connected to the lower heat exchangers, and with a strong working pressure, on the contrary, to the heat exchangers located at the top;
  • the installation of a heat accumulator obliges the installation of an expansion tank and a safety, thermomixing valve in the system.


The correct calculation of the thermal capacity of the coolant accumulated in the accumulators will allow the solid fuel boiler to operate in normal mode. The buffer tank, complete with other safety elements, not only ensures the uninterrupted operation of the heating system, but also normal hot water supply. The buffer tank, which is also a heat accumulator, guarantees not only the safe operation of heating devices, but is also economically feasible.

The only nuance that you will have to pay attention to when equipping a home heating system is the choice of a place for a boiler room. Mounting a large volume tank will require a technological solution from you. In some cases, heat accumulators are assembled on site.


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