Do-it-yourself heat accumulator (buffer capacity) for a solid fuel boiler: calculation and manufacturing steps

Having a heating system based on a solid fuel boiler, you must supplement it with a buffer tank. With it, you can create heat very efficiently. Solid fuel boiler equipment manifests itself as a device with complex power management. If it is capable of delivering 25 kW / h, then it is impossible to force the unit to produce 5 kW / h. Typically, power can only be reduced by 4 kW / h.

how to calculate the buffer capacity for a solid fuel boiler

Heat losses at different times of the year are different. In some months, they may be equal to the amount of heat that comes from the heating system. In this case, the most favorable temperature is formed inside the premises. If these losses are small, a lot of heat accumulates in the house, and the air temperature rises by 8 ˚ from the usual 22, it becomes too hot in the house. Excessive heat when opening the window leaves out.

buffer capacity

This situation can be prevented by making a buffer tank for a solid fuel boiler with your own hands. This node will accumulate excess heat. As soon as the wood in the boiler burns out, the accumulated heat will enter the radiators. The boiler may stand idle for a while. Downtime will depend on accumulated kilowatts and heat loss.


solid fuel boilers for a private house

The calculation will depend on the capacity of the boiler. If this indicator is 35 kW / h, the volume of the buffer tank should be 25 times the minimum of this figure. It is important to consider some nuances. For example, the power of the unit should be taken for weather, in which the building loses maximum heat. When the temperature outside the window drops to -30 ˚, and the heat loss reaches 33 kW / h, the boiler power should be the same. It is important to consider some margin in the calculations.

Features of the calculations

In order to ensure heating, the system should produce about 35 kW / h. Before making a buffer tank for a solid fuel boiler with your own hands, you need to take into account that you should not make surcharges to the power of the device, counting on the fact that the heat accumulator will absorb heat and the system will work poorly. If the temperature outside the window turns out to be –30 ˚, the boiler will work bypassing the buffer tank. But when the temperature rises, the buffer will be connected to the strapping, and excess heat will accumulate in the tank.

do-it-yourself buffer tank for solid fuel boiler

If you were wondering how to calculate the buffer capacity for a solid fuel boiler, you should know that when determining the desired value, it is important to take into account the volume of the room where the unit with the buffer and other nodes of the circuit will be located. Sometimes a situation arises when there is nowhere to put a large heat accumulator. So, for a 35 kW / h boiler, the most suitable battery has a capacity equal to 1750 liters. This value is calculated by multiplying 35 by 50, which is 1.75 m 3 . Such an aggregate cannot be placed indoors. In this case, you can calculate the minimum volume, which will be 875 liters. To do this, 35 must be multiplied by 25.

Room Parameters

After the calculations, you should consider whether there is enough room. If not, you will need to find a more suitable one. If you want to make a buffer tank for a solid fuel boiler with your own hands, and the capacity of the boiler equipment is 35 kW / h, then the calculated volume can vary from 875 to 1750 liters. In the manufacture of a cylindrical container, the dimensions may be as follows: 2 x 1 m. This option is most preferred. The first value is height, the second is diameter.

how to make a solid fuel boiler

If the volume of the heat accumulator is 1750 l, then the diameter will be 1.06 m. If it is necessary to manufacture a cylinder from a sheet of metal, its width and length should be 2 and 3.14 m, respectively. When the buffer tank is in the shape of a parallelepiped, its dimensions will be 1 x 1 x 1.75 m.

Stages of production: preparation of materials

If you decide to make a buffer tank for a solid fuel boiler with your own hands, you should take care of the following materials:

  • a metal sheet;
  • steel or copper tube;
  • threaded pipe;
  • galvanized sheet;
  • basalt or mineral wool;
  • heat resistant paint;
  • heat resistant primer;
  • profiled pipe;
  • rubber gasket;
  • corner.

The metal sheet must have a thickness greater than 2 mm. As an alternative, barrels with a diameter of 1 m are used. The wall thickness should be less than the mentioned figure. Choosing a copper tube, you get the best option for capacity, because it will have greater thermal conductivity. The diameter of the pipe should be 20 mm.

Addition to the issue of materials

As for the threaded nozzle, it should be represented by seven pieces with a diameter of 20 mm and four pieces, each of which will have a diameter of 10 mm. The profile pipe should have the following size: 5 x 5 cm or 4 x 4 cm. The corner should have a shelf of 3 cm. A rubber gasket should be selected that has a thickness ranging from 5 to 10 mm.

Manufacturing process

solid fuel cast iron boiler

Before you run the heat accumulator for a solid fuel boiler, you must prepare two barrels. At one of them the bottom is cut off, at another - the top part. Together, these elements should form a capacity of 1.75 m high. The barrels are welded together. If in the end the capacity is quite high, it must be cut. A corner is welded to the outside of the top. It must be bent so that it is pressed against the barrel. A circle with a diameter of 1.07 cm is cut out of the sheet metal. The edge should coincide with the edge of the corner. Drill holes in the corner and circumference. This will fix the upper part of the buffer tank with bolts. So you can facilitate the installation of the heat exchanger and carry out its internal repair.


In order for the barrel to be sealed, use a rubber gasket. When making a buffer tank for a solid fuel boiler of 300 liters, you should take two barrels of 150 liters each, and after connecting them together, weld to the bottom and top of the stiffener. These elements may be the corners. The profile pipe is cut into 4 segments, each of which is 10 cm long. These blanks will be the legs of the container. They are welded to the heat accumulator.

And if you want to make a cylindrical container using sheet metal, the thickness of which is more than 2 mm, then it will be almost impossible to bend the material without a rolling machine. Therefore, the manufacture of a heat accumulator using this technology is best entrusted to specialists.

Work on a rectangular container

The device for the buffer tank for a solid fuel boiler is now known to you. But it can be a little different, if we take as a basis the manufacturing technology of a rectangular heat exchanger. To do this, depict the design diagram, determining the parameters of each wall. It is important to consider the thickness of the welds. This value can vary from 1 to 3 mm and depends on the welding machine and the selected electrodes.

Specialist recommendations

Next, sheet metal is cut into blanks. Two sides must be attached to each other so that they form a right angle. Elements are fixed so that they have more weight. In several places, spot welding should be done and the placement of the canvases checked. Now you can make internal and external welds. Acting on the same algorithm, it is necessary to weld the bottom and all the walls. A corner is welded on top, holes are drilled in it. It is necessary to act according to the same scheme that was used in the case of a cylindrical container. Stiffeners should be welded to each side, then you can do the legs, weld them.

Do-it-yourself solid fuel boiler manufacturing

solid-fuel boiler buffer tank

A solid fuel boiler for a private house can theoretically be made independently. To do this, you need to take a large 300 mm pipe, from which a meter piece is cut. From the steel sheet you need to cut the bottom along the diameter of the pipe and weld the elements. The legs of the boiler can be 10-centimeter channels.

When making a solid fuel boiler for a private house, you will need to make an air distributor in the form of a circle from a sheet of steel. Its diameter should be less than the pipe by 20 mm. The impeller from the corner must be welded to the bottom of the circle. The size of its shelf should be 50 mm. For this, a channel with the same dimensions is also suitable. A 60 mm pipe should be welded into the central upper part of the distributor, which should be located above the boiler. A hole is made through the pipe in the middle of the distributor disk to form a through tunnel. It is necessary for air supply.

A damper is attached to the upper part of the pipe, which will provide air flow adjustment. If you have a question about how to make a solid fuel boiler, then you should familiarize yourself with the technology. The next stage indicates the need to perform the lower part of the equipment, where the door to the ash pan will be located. Holes cut out from above. At this point, a 100 mm pipe is welded. At first, she will go at a certain angle to the side. Then up 40 cm, and then strictly vertically. Through the ceiling, the chimney passage must be protected according to fire safety rules.

The completion of the boiler is accompanied by work on the top cover. In its central part there should be a hole for the distributor pipe. The fit to the wall of the equipment should be tight. Air is not possible here.

Having made a solid fuel boiler of long burning on wood, you will have to light it for the first time. To do this, remove the lid, raise the regulator, and fill the equipment to the top. Fuel is poured with flammable liquid. Inside throw a burning torch through the regulator tube. As soon as the fuel flames up, the air flow will need to be reduced to a minimum so that the firewood begins to smolder. As soon as the gas ignites, the boiler starts up.

The cost of cast iron boilers

Solid fuel cast iron boiler, unlike steel, can only be purchased. If you do not plan to engage in independent manufacture of equipment, you can consider the prices of such equipment. For example, the KCHM-5-K model isp. 3 Kirovsky plant in Russia can be purchased for 49800 rubles. The heating area in this case varies from 210 to 800 m 2 . Power can vary from 21 to 80 kW. This single-circuit boiler is floor-standing, like KCHM-5-K isp. 71 COMBY eco i, the heating area of ​​which varies in a smaller range and starts from 210, and ends with 500 m 2 . This boiler is also single-circuit, and its power at the maximum limit is lower and is 50 kW.


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