Of all the heating equipment that is used today in everyday life, solid fuel boilers have been known for the longest time. Due to the simplicity of design and principle of operation, the availability of fuel, units of this type are widely used. Today, for many residents of private houses in rural areas, this technique has become a kind of «lifesaver». The ever-increasing price of household gas, the difficulties in obtaining permits for the installation of a gas autonomous heater contribute to the fact that today a solid fuel boiler, at least, has not lost its demand among the population living near forests — a source of firewood.
Today, there are two options to solve the problem of autonomous heating on solid fuel: buy a finished factory product or make a solid fuel boiler with your own hands. The cost of a modern high-tech heating unit is quite high, but the price range is wide — from 3 to several tens of thousands of rubles, which makes the device affordable to a wide range of consumers.
With a certain technical training, a solid fuel boiler can be assembled independently, using diagrams and recommendations for the manufacture of models of these devices, the most popular for do-it-yourself mounting.
Solid fuel boiler concept
A self-made autonomous solid fuel boiler is, by and large, an ordinary stove installed in a barrel of water. The main task of such a device is to heat boiler water, which will be supplied to home heating radiators, using heat from the combustion of firewood or coal.
But such a device, tempting to self-manufacture due to primitiveness, will not be effective in terms of heating and not cost-effective due to high fuel consumption — the simplest boiler designs have an efficiency of only 10-15%.
Important! The operation of a solid fuel boiler depends on the quality of the draft and, accordingly, the supply ventilation. Even a well-manufactured boiler will not be able to provide efficient space heating if the ventilation is not arranged accordingly.
Home-made boilers are assembled not only from metal, but also assembled from brick. Brick devices are usually built in country houses, where higher requirements are placed on the aesthetics of the installed equipment than in utility or technical premises.
Metal boilers are the simplest devices, the manufacture of which allows the use of improvised materials and possibly with the help of available tools. But it does not follow from this that their production and installation can be performed without, at a minimum, sketches of blanks and assemblies, as well as a well-developed technology — a sequence, methods for performing individual stages of preparatory and basic work.
Choosing the design of the heating boiler
Furnaces for heating and solid fuel boilers, with similar combustion processes, differ in functionality. A heating boiler, unlike a stove, must not only heat the room at the installation site by burning wood or coal, but also supply the heating circuit with heated coolant. But to perform the second task, it is not enough to place a heat exchanger in the furnace (section of the heating circuit) — it is also necessary to ensure the continuity of fuel combustion and uniform circulation of the coolant through this coil.
What design of the boiler to choose to make it easier to make it yourself, what difficulties will you encounter in the process of work? These questions can be answered at the design stage. Drawings of home-made solid fuel boilers give a sufficient idea of \u200b\u200bwhat this or that design looks like, and what you should pay attention to during the manufacturing process.
Each type of solid fuel boiler equipment has its own design features and manufacturing nuances. When planning an independent assembly of the heating unit, it is necessary to decide which design to give preference to — with the lower or upper (mine) method of combustion.
Units with lower combustion — this is equipment in which the door for loading firewood is located in the upper part of the combustion chamber, but the combustion of fuel occurs from below, as a result of which the upper layers of the bookmark move down under their own weight, and the afterburning of smoke occurs in the upper part. Depending on the model, the movement of air through the furnace occurs from the bottom up forcibly (fan) or naturally (draught), which causes independence from the mains, but reduced efficiency and a smaller amount of fuel loaded.
In solid fuel boilers of a mine structure, firewood is loaded through a door, which is located in the upper part of the combustion chamber. Such units are equipped with forced draft, which is directed from top to bottom — it drives smoke to the lower part of the furnace, where it burns mixed with air, and along the way it heats up and additionally dries the fuel of the lower tiers.
A unit with a lower combustion method is more suitable for self-production, so when assembling it, you can do without a fan for forced draft.
Important! The more complex the design of the equipment, the higher the technological requirements for the quality of execution of its components, which should not have deviations from the design parameters. The assembly process of such a unit is no less responsible.
According to the method of combustion, solid fuel boilers can be designed for normal operation or operate with pyrolysis — the process of decomposition of solid fuel into two components and their subsequent separate combustion. Giving preference to the second, more complex, option, you will have to take into account the need to install a second combustion chamber, which will increase the dimensions of the heater and, accordingly, require more materials.
The choice of the type of heating equipment is largely determined by the type of solid fuel that will be supplied to the heating device. If you have a large amount of firewood on hand, it would be better if the boiler you made is designed for firewood. With greater availability of hard coal, another model will do. The duration of burning bookmarks, the quality of heating are determined by the type of solid fuel boiler, its power and design efficiency.
On a note: the combustion temperature of coal is much higher than that of firewood, so the grate, heat exchanger and boiler body for coal are made of thicker steel. An alternative would be to build the body and combustion chamber of the boiler from refractory bricks.
If it is not possible to create an external body of the unit from steel of the required thickness, a brick solid fuel boiler will be a rational solution. Refractory brick lining will create a spacious, comfortable and high temperature resistant combustion chamber.
The choice of a boiler with a design of acceptable complexity must be made after analyzing the technical performance and an objective assessment of one’s competence and capabilities. If there is any doubt, in order to exclude the possibility of unjustified damage to the material, it is better to give preference to the unit of a simple design that is clear from the drawings — even such a solid fuel boiler is able to provide the house with heat in the cold season.
See also: homemade gas boiler.
Basic requirements for the design of a homemade heater
In its classic form, the heating unit, from which home heating will work, consists of the following elements:
- combustion chamber (bunker) for burning firewood, coal, fuel briquettes;
- grates through which air mass is supplied to the combustion chamber;
- tubular heat exchanger or storage tank for boiler water;
- chimney for bringing out the products of combustion of fuel;
- traction regulator.
An important requirement that will have to be taken into account at the design stage of the boiler is the dimensions of the combustion chamber. The furnace of an autonomous solid fuel boiler should be spacious and roomy. The design of the combustion chamber is calculated in such a way that the fuel placed in it burns completely without additional mixing. Brick boilers are preferable in this regard, since brick has a lower thermal conductivity, which provides a higher combustion temperature in a ceramic furnace than in a metal unit.
The combustion chamber should be designed in such a way as to maximize the concentration of thermal energy on heating the heat exchanger.
The next, no less important aspect in the design of heating equipment is the heat exchanger of a solid fuel boiler. The efficiency of boiler equipment depends on the design of this element, the quality of the material and the performance. The name of the heat exchanger is determined by the material of its manufacture — cast iron or steel. The heat exchange coils of these units — tubular structures with a vertical or horizontal arrangement of pipes in everyday life are often called water jackets.
We will not consider cast-iron heat exchangers, since this is a cast structure, the manufacture of which is impossible at home. However, you can use ready-made cast iron assemblies, removed from old units, dismantled for some reason. Such a replacement is common when a solid fuel boiler is being upgraded or repaired.
For the manufacture of a steel heat exchanger, thick-walled pipes are used. The desired configuration of the pipe is made flexible under heating or using bends or half-bends of the appropriate diameter, connected to the fragments of the coil by electric welding.
The installation diagram for a coil for a traditional solid fuel unit will give a complete picture of how the heat exchanger should look like and in what position it is better to install it.
Step-by-step production of a solid fuel boiler. Subtleties and nuances
You will not be able to make the most economical home-made solid fuel boiler, but you can create a heating apparatus that is quite suitable for heating and hot water supply. The fact is that the assembly of industrial products is carried out on high-precision industrial equipment from specially selected materials in compliance with technological parameters. Accurate thermal calculations are the basis of each factory model of the boiler. The possibilities of working at home are incommensurably more modest than production ones, therefore, when choosing a model to be manufactured, one must proceed from existing realities, including one’s personal potential as an installer.
Tools and materials
Having a drawing and specification of the heating unit, you can decide on the list of necessary tools. Whether you want to make a large boiler or plan to assemble a small solid fuel heater with your own hands, the list of accessories will be approximately the same.
To work, you will need the following tools and fixtures:
- welding machine;
- small grinder with cutting and grinding discs (safety glasses);
- electric drill with drills for metal;
- gas keys No. 1,2;
- a hammer;
- a set of open-end or box wrenches and screwdrivers;
- 90 degree angle.
The main material in the manufacture is steel, the thickness of which for the boiler must be at least 5 mm, for the grate — from 7 mm.
In addition, you will need:
- steel corner 50×50 — for the boiler frame;
- sheet stainless steel — if there is a storage tank in the design;
- steel thick-walled pipes with a diameter of 32-50 mm — for the manufacture of a coil heat exchanger.
A complete list of materials and their consumption is compiled in advance on the basis of technical drawings.
Housing and heat exchanger manufacturing
The boiler body, which often plays the role of a combustion chamber, is the basis of the entire structure. To reduce wall deformations under the influence of high temperature, the enclosing structures of the furnace are made in two layers with backfill between the layers of dry sifted sand, which plays the role of a geometry fixer. The outer and inner shells of the furnace are made of frame, which also increases the rigidity of the structure. In addition, to increase the strength of the walls of the combustion chamber, the outside can be sheathed with a steel corner or a profile in the form of stiffeners.
According to the drawing, two openings are cut out on the front wall with a grinder or a gas cutter — for the bunker door and the ash pan.
Advice! Before cutting sheet steel, it is necessary to mark future openings with small diameter holes (3-4 mm) at the corners of the holes — this will allow cutting with greater accuracy.
After cutting blanks from sheet steel and a profile for the body, you can begin to create a heat exchanger. We use cut water pipes, which are connected by welding into a single sealed circuit. The main task is to create a hermetic flow fragment of maximum length to increase the heating area of the pipe.
How to make a heat exchanger, correctly position the pipes and perform welding, tells the video brought to your attention.
When all structural elements are ready, assembly is started, which is best done at the installation site of the unit — sometimes the dimensions and weight of the finished device do not allow it to be moved from the assembly site to the final location.
Most often, the boiler is installed on a specially constructed concrete foundation with the unit fastened by welding to embedded parts — anchors. Installation begins with the installation of the frame, after which it is equipped with components and sheathing sheets. All welded joints are made with chamfering and processing of welds — slag removal and grinding.
On a note: After assembling the body, a thorough visual check of its tightness is carried out, as a result of which additional welding of the seams is carried out.
Grates (steel grate) and a heat exchanger are installed in the finished housing, which is connected to the heating circuit by welding.
Important! It is better to entrust the manufacture of a storage tank from stainless steel with its insertion into the circuit, since working with this material requires special equipment and practical skills.
Upon completion of the assembly, for corrosion protection, the boiler is painted with two layers of heat-resistant paint with preliminary surface preparation.
A self-made heating boiler is distinguished by its durability and ease of maintenance, which consists in periodic cleaning of the furnace ash and maintenance of the chimney.
After the assembly is completed and the unit is completed with all the necessary elements, it is pressure tested with water under pressure, according to the results of which defects are eliminated, and then a set of commissioning works. Do not neglect the installation of a draft regulator, which will facilitate the operation of a solid fuel boiler in various weather conditions.