Do-it-yourself buffer tank for a solid fuel boiler: materials and tools, manufacturing process.

Solid fuel boilers are a good alternative to gas or electric. With all its advantages, they still have some disadvantages. Among them, uneven heat production and the inability to radically reduce the boiler power, which leads to inefficient use of fuel. Also, especially in the cold season, the owner has to throw firewood or coal into the furnace in the middle of the night, otherwise the heating will stop and the room temperature will noticeably decrease. To cope with all these inconveniences, the installation of a buffer tank in the system will help.

What is the buffer capacity for?

The use of a buffer tank makes the heating system more autonomous and contributes to the rational consumption of solid fuel, due to the accumulation of hot water in it. The main advantages of the installation include:

Protect the system from damage due to overheating. Excess heat will be stored and used in the future.
Economical and rational use of resources. The room will evenly warm up and will not have to open the window if the temperature in it has risen above a comfortable one.
The ability to easily connect other heat sources, for example, electric or gas boilers, into one system.
Eliminating the need to get up in the middle of the night and report fuel. The accumulated heat will heat the room for some more time.

IMPORTANT! Savings in energy consumption and overall efficiency when connected to the heating system buffer capacity is significantly increased. This happens without causing inconvenience and discomfort to the residents.

There are also drawbacks to the operation of this device. The most significant of them is a rather high cost, great weight and dimensions. This complicates the installation and requires a large space near the boiler.

Buffer capacity calculation

For maximum efficiency, it is important to choose the right amount of buffer capacity. In this case, first of all, the power of the boiler should be taken into account. Another important factor is the climate in the region. Calculating the amount of future heat of the battery should be guided by such nuances:

The temperature of the coolant in the tank with the complete burning of one bookmark should not rise above forty degrees. For this, the capacity should be approximately 20 to 55 liters per 1 kW of boiler power.
It is necessary to consider whether the tank will fit in the room next to the boiler. If not, you will have to do it less, but preferably more than 25 liters per kilowatt of power.
It is important to pay attention to the downtime of the system without a heat source. Determine the required supply of accumulated hot water in the tank so that it is enough for this time.

It is impossible to make an accurate calculation of the capacity without special programs. Ideally, it would be good to involve a specialist. But if this is not possible, then you can approximately calculate it, knowing the heat capacity of water - 4.187 kJ / kg * C, the system downtime - in most cases up to 8 hours and the boiler capacity - most often it is 25 kilowatts per hour. AT In this case, the calculation will be as follows: with a temperature difference in the tank and system of 25 degrees (25 * 3600) / (4.187 * 25) ≈ 0.86 m³ (860 liters). When cylindrical, the tank should be approximately 100 cm high and 104 cm in diameter.

Do-it-yourself buffer tank for solid fuel boiler

Due to the high cost of factory analogues, many are considering the option of creating it on their own. This task is very non-trivial and will require a good knowledge of heat and hydraulic engineering, as well as a high level of welder skills. From tools, you can not do without welding equipment, grinders, measuring instruments and drills. A large amount of materials will also be required.

Materials

Since the project is complex and the dimensions of the future battery tank are considerable, it will come out quite expensive. You can not do without the following:

If you decide to make it in the form of a cylinder, you will need metal barrels (2 pieces). For a rectangular one you will need a sheet, preferably stainless steel. It is important to draw on the thickness of this material, which should not be less than 1.5 (in the case of stainless steel) or 2 millimeters (with ordinary).
Corner, profile pipe (5 by 5 centimeters). They will be used for legs and stiffening ribs.
Copper tube or stainless steel with a diameter of 12 mm. It will take at least 10 meters.
Sleeves and fittings.
Heat-resistant insulation. The best choice would be basalt wool, as it is easy to install and does not emit toxic substances when heated.
Metal for plating, better galvanized.

High temperature resistant paint will also be required.

Production of a cylindrical tank

To create a cylinder-shaped structure, 2 gas cylinders are suitable. They are easy to get, they have a sufficient thickness and quality of the metal.

ATTENTION! Before starting work with cylinders, make sure that any gas residues are removed. Start cutting only by completely filling them with water to avoid explosion.

The main stages of manufacturing:

Cut barrels or cylinders. Cut off the covers.
Weld inside the brackets on which the tube will be attached (heat exchanger).
Set the barrels on top of each other and connect them together by welding.
Pass and install a coil made of a copper or corrugated steel tube through the holes.
Weld the bottom and cover. Into which nozzles are cut in for connection of the valve of dumping of air (top), the drain crane (bottom).
Attach fastenings for external cladding by welding. It is desirable to have different lengths (so that it turns out in the form of a rectangle - it will be more convenient and the look will be more aesthetic).

It is impossible to make a cylindrical tank from sheet steel of large thickness without special equipment.

Creating a rectangular container

It is made in such stages:

Sheets of steel are marked according to the selected volume and pre-created drawings. Welding seams also have their own thickness, which should be taken into account.
It is cut using a grinder.
Sheets are installed and tacked by welding. For the correct angle of 90 degrees, you need to use measuring instruments and fix the details.
All sheets are welded. For reliability on both (inner and outer) sides.
In the same way as with a cylindrical tank, a lid and a bottom are made.
Fastenings for sheathing, legs, additional stiffening ribs are welded.

Branch fitting

The nozzles are mounted in the holes prepared in advance for this. You need to place them as follows:

three fittings should be evenly installed over the entire height of the structure - thermometers are connected to them;
a nozzle is mounted to the top cover through the hole, to which an air vent valve will be connected;
at a distance of 30-50 cm from the bottom, 2 fittings are connected - through one of them hot water will enter the tank, and through the second climb into the heating system;
near the bottom, respectively, also 2 nozzles (one for returning the coolant to the boiler, the second from the system to the tank);
a tap is connected to the bottom to drain the water if necessary.

Final stage

The last steps before starting operation will be:

Cleaning, priming and painting the inside of the tank. Primer and paint should be several times.
After that, pre-prepared coils (heat exchangers) are connected.
The tightness and reliability of the structure are checked. This is done by supplying water under pressure.
The tank is painted from the outside.
Insulating material is installed. On pre-prepared fasteners, the outer skin of galvanized sheet steel is mounted.

If there is an opportunity to entrust this business to professionals or to buy a factory buffer capacity - it is better to do so. Since its independent production requires extensive experience with welding and skills in heat and hydraulic engineering. In addition, this will require a lot of resources, effort and time.