Everyone who uses it to heat their homes solid fuel boilers, they know that regardless of the model, it is impossible to organize a uniform supply and combustion of fuel in this system. When it burns out, the temperature of the coolant and air in the room drops quite quickly. The owner is forced to regularly supply fuel, and this is not always possible. Decide this problem Connecting a buffer tank to a solid fuel boiler will help. All the advantages and disadvantages of this heating system operation scheme will be discussed in this publication.

Design and principle of operation

IN simplest design buffer tank (heat accumulator, storage tank) is a thermally insulated metal tank with four pipes: two for the boiler circuit and two for the circuit heating system.

At the top of the device there is a blast valve, which, if necessary, releases excess pressure. At the bottom of this device a drain valve is installed, thanks to which the coolant can be drained. Some heat generator models provide for the presence of an electric heating element and (or) a coil for heating the coolant from other heat sources. Quite often, in the upper part of the structure there is a heat exchanger, thanks to which water is heated for the domestic hot water supply.

The operating principle of this device is as follows: the tank is filled with coolant. When starting the boiler circulation pump The boiler circuit supplies cooled coolant from the lower part of the heat accumulator, which, after heating, enters the upper part of the buffer tank. Hot coolant is lighter than cold coolant, so it is always in the upper part of the tank. While the solid fuel boiler is operating in a small circle (only through the buffer tank), the cold coolant is gradually replaced by hot one.

After all the coolant has warmed up, the circulation pump of the heating circuit is turned on, and the heated coolant from the top of the tank begins to flow into the heating system. The cooled return flows into the lower part of the storage tank, and from there into the boiler unit.

Due to the difference in density, the hot and cold coolant in the buffer tank practically does not mix.

The main advantages of this heating scheme are that when the boiler stops, this system will continue to supply the radiators with hot coolant for some time. Correct selection of buffer capacity for solid fuel boiler allows you to significantly increase the time between boiler fires, reduce fuel consumption and save money. In addition, the use of this device will smooth out temperature fluctuations in the boiler and heating circuit.

The disadvantage of heating with a heat accumulator is that a fairly long period passes between starting the boiler and warming up the radiators. Depending on the room temperature and tank capacity, this time can be 2-4 hours.

Let's digress a little, because we want to inform you that we have compiled a rating of solid fuel boilers by model. You can learn more from the following materials:

Strapping scheme

The heat generator cannot function properly without piping.

The heat generator is installed parallel to the boiler unit and the heating circuit in the gap between them. Connecting a solid fuel boiler with buffer capacity includes two circulation pumps for the boiler and heating circuit, a three-way valve (for the boiler circuit) and a balancing valve (for heating circuit), expansion tank, blast and drain valve, pressure gauge.

1. Three-way thermostatic valve on the boiler circuit it creates movement of the coolant along a small circuit until its temperature reaches the set value. After heating the coolant, the valve blocks the movement of the hot coolant and opens the way for the return flow from the heat accumulator. Installed between supply and return on the boiler circuit.
2. The balancing valve will allow you to regulate the return temperature by mixing hot coolant to it in order to prevent the formation of condensate on the boiler heat exchanger. The balancing valve on the heating circuit protects radiators from overheating by reducing the supply of coolant (bypassing the heating system) to the return.
3. The expansion tank compensates for the thermal expansion of the coolant.
4. The blast and drain valve is a safety group that operates in the event of excessive coolant pressure. A pressure gauge is an element of a safety group that shows the pressure in the system.
5. A return coarse filter is installed to protect the three-way valve

The piping scheme for a solid fuel boiler with a buffer tank, as a rule, includes circulation pumps that move the coolant along the circuits.

When it is allowed to install boilers in closed systems, this is a good option. Safety should be threefold. IN closed loop there is no open dish, but the so-called. diaphragm vessel. Also install safety valve. 1.5 bar for boilers up to 65 kW.

Installation is safe with two safety valves. We recommend setting the safety group on the power supply and going back to the safety valve itself. The installation must also have protection against boiler overheating. One of the following two solutions applies.

Tip: For proper operation system, it is necessary that the performance of the heating circuit pump is slightly higher than that of the boiler pump. For a house with an area of ​​up to 300 m 2, the required boiler pump parameters are 25/40; (25 mm connection diameter, 40 – head 4 m); pump parameters for the heating circuit 25/60 (25 mm connection diameter, 40 - pressure 6 m). Fine adjustment is made after the initial start-up of the system.

Some boilers have a cooling coil already built into the boiler. For example, in other steel boilers and in all cast iron boilers the coil must be connected to the system as separate element. This solution is usually used for large boilers, for example with an output power of more than 50 kW, for which an external cooling coil is not sufficient.

Each installation must be secured with 1.5 bar and 2 bar safety valves. It's time to connect the boiler to the chimney, which is usually used in the form of a straight pipe about 35 cm long or in the form of an elbow. For example, a direct connection connection is shown in the following figure.

6. Don’t forget about installing a cooling valve on the supply pipe, which, when the coolant temperature exceeds 90°C, mixes tap water into it.

A rough calculation of the buffer capacity of a solid fuel boiler is made according to the algorithm: for 1 kW of boiler installation power, a tank with a volume of 20 to 40 liters is required. It is these indicators that allow the system to work most efficiently. You can calculate the volume of the tank more accurately (up to a liter), but then you will have to take into account: the heated area, calculate the heat loss of the home under various weather conditions, find out the amount of coolant that the system needs per hour of operation at the lowest temperature in your region. The time between fires of the boiler installation must be multiplied by the calculated value. The result obtained will be the volume of the heat accumulator required for your system.

How to make your own battery tank

Due to the fact that these installations are quite expensive, many of our compatriots ask: “How to make a buffer tank for a solid fuel boiler with your own hands?” In principle, nothing is impossible for a person with “straight hands”, knowledge of the basics of heating engineering, and possessing necessary material, a tool, the skills to use it and an indecent amount of free time.

If you have all of the above, then you need to:

• weld a sealed container of the required volume; Must be used stainless steel, thickness of at least 1.5 mm.
• make an insertion of fittings with a diameter of 1 inch and with the necessary threads for connection with boiler equipment and the heating system;
• embed a blast valve into the upper part of the device, and a drain valve into the bottom;
• insulate the tank basalt fiber, 100 mm thick.
• weld a casing made of thin galvanized steel, based on the external dimensions of the insulated tank.
• Place the device on the legs.
• Paint the device.

Based on experience, you won’t be able to save money by making your own heat accumulator for a solid fuel boiler. For almost the same money, a new battery tank will be safer, more durable and functional.

The piping of a solid fuel heating boiler must take into account all the features of this type of thermal energy generators, as well as the complexity and composition of the heating system itself: the number of circuits, the circulation pattern, the method of wiring and regulating the supply of coolant. In addition, the piping scheme for a solid fuel heating boiler must be chosen in such a way as to ensure not only the greatest efficiency, but also maximum safety of its operation. In this article we will look at several schemes of varying complexity that can be used, depending on the type and complexity of the heating system.

Fig. 1 Boiler piping diagram in an open system with natural circulation

The simplest is the wiring diagram for a solid fuel boiler for a single-circuit heating system with natural (gravitational) coolant circulation. As a rule, such systems use metal (most often steel) pipes with relatively large diameter, corresponding to the diameter of the boiler outlet and inlet pipes. It is best if their diameter is the same. This will allow, along with other factors, to reduce hydraulic resistance and create Better conditions for natural circulation. Such schemes are characterized by maximum simplicity and in the boiler piping it is necessary to try to avoid unnecessary elements that, to one degree or another, impede the natural movement of the coolant. Therefore, it is necessary to use shut-off or control valves to a minimum and only in places where it is impossible to do without them. Also, the presence of various filters in the circuit of such a system is undesirable. Most often, such systems are open. The expansion tank in them performs the function of creating excess pressure and removing air, therefore it is installed at the highest point, at the maximum possible height (under the ceiling or in the attic).

In Fig. 1: 1 - boiler; 2 — chimney; 3 - supply pipe (diameter 40-50 mm); 4 — “return” (diameter 40-50 mm); 5 - pipe (1/2); 6 - open type expansion tank.

In systems with combined circulation

Fig.2 Strapping diagram for open system with combined circulation

The scheme for a system with combined (combined) circulation is more complex, since it already provides for the presence in it of a special circulation pump, as well as the necessary elements of its piping (bypass, shut-off valves, filter mechanical cleaning, air valve). A bypass with a circulation pump can be installed both on the supply pipe and on the return pipe, depending on the availability of space for installation and the convenience of further maintenance.

The air valve is included in the bypass if it is installed on a horizontal section of the pipe and the design of the pump itself does not provide for the possibility of bleeding air.

In the event of a lack of electricity, the tap on the straight bypass pipe opens and the system operates with natural circulation. Instead of a tap, a valve is sometimes installed in this place, which opens automatically in the absence of electricity.

In Fig. 2: 1 - boiler; 2 - chimney; 3 - supply pipe; 4 — “return”; 5 — pipe 1/2″; 6 — expansion tank; 7 — shut-off valves; 8 - circulation pump; 9 - filter; 10, 11 - possible locations of the bypass on the “return” or supply line.

If the heating system is closed, then instead of the usual open expansion tank a sealed membrane is installed. This makes it possible to ensure the specified overpressure(usually it is about 1.5 bar (0.15 MPa). In addition, such a circuit must necessarily include a safety unit (safety valve, pressure gauge, air valve).

IN Lately, piping a solid fuel boiler with polypropylene is increasingly being used, that is, polypropylene pipes and fittings. This material has become quite popular because it is not susceptible to corrosion, is easy to install and has a relatively low cost.

In this case, it is necessary to remember such features of solid fuel heat generators as great inertia and the difficulty of quickly regulating the combustion temperature of the fuel, and therefore the coolant. Therefore, when piping such a boiler with polypropylene, it must be remembered that the supply pipe coming out of it must be metal at a distance of at least 1.5 m or until the first branch. The “return” can be completely plastic, since the liquid temperature in it rarely exceeds 70-80 ° C. But its internal diameter must correspond to the internal diameter of the metal supply pipe.

Piping diagrams in systems with hydraulic separator

In more complex systems that include several circuits (branches), piping schemes for solid fuel boilers with a hydraulic separator are often used, in the form of a cylindrical container, into the upper part of which heated coolant is supplied, and into the lower part cooled liquid from the system is supplied. From the upper part of the hydraulic separator, water is supplied to the comb (collector) and distributed between the circuits, and from the lower part to the boiler inlet pipe. Such schemes are usually used for closed systems with forced or combined circulation. Below are two possible options.

Option 1

Fig.3 Piping diagram of a boiler with a hydraulic separator (option 1)

In Fig. 3: 1 - boiler; 2 - supply pipe; 3 — safety block; 4 - tap; 5 - air valve; 6 - hydraulic separator; 7 - return pipe; 8 - circulation pump; 9 - filter; 10,11 - taps for draining and supplying water; 12 - membrane tank.

Option 2

Fig.4 Piping diagram with hydraulic separator (option 2)

In Fig. 4: 1 - boiler; 2 - chimney; 3 - heated water; 4 — safety block; 5 - tap; 6 — air valve; 7 - circulation pump; 8 - three-way thermal valve; 9 - hydraulic separator; 10 — “return”; 11 - membrane tank; 12 - feed cold water into the system; 13 - drain valve; 14 - boiler; 15 - warm floor.

Circuit with heat accumulator

Sometimes a so-called buffer tank or heat accumulator is included in a water heating system. This allows you to accumulate thermal energy during operation of a solid fuel boiler and use it to heat the room in the intervals between the firebox. The piping diagram of a solid fuel boiler with a heat accumulator usually includes shut-off and control valves, pump groups with a control unit that ensures turning on or off a particular circuit and effective work the entire system.

Fig. 5 Boiler piping diagram in a system with a heat accumulator

In Fig. 5: 1 - boiler; 2 — safety block; 3 - electrical panel; 4 — buffer tank (heat accumulator); 5 - circulation pump; 6 - three-way thermal valve; 7 — control unit; 8 - taps; 9 - membrane tank; 10,11 - pumping groups.