The lack of a centralized gas supply complicates the life of the homeowner: in winter, you will have to warm yourself with firewood or coal, which you constantly need to enclose.
But this situation also has a positive side: the heat generator has a simple design, so you can easily make it yourself.
At the same time, the user not only saves a significant amount, but also receives a unit that best suits his needs. How to make a solid fuel boiler with your own hands, and what ideas can you borrow from factory models?
In general terms, the principle of operation of a solid fuel boiler is as follows:
- Firewood, coal and similar fuel are placed in a special chamber called a firebox.
- The loaded fuel is ignited. The process of its combustion in different boilers may have some features, but the essence always remains the same: an oxidation reaction of organic molecules occurs with the release of a large amount of heat. The burning rate, and, accordingly, the power of heat generation, will depend on the amount of air entering the furnace. It can be adjusted using a movable damper installed on the air intake (blower).
- The heat generated during the combustion of fuel, as well as the heat of flue gases, heats the contents of a special reservoir - a heat exchanger. Through the inlet and outlet pipes, the heat exchanger is connected to the heating circuit and thus becomes part of it. The medium heated in the heat exchanger, due to convection or the operation of the pump, enters the heating circuit, distributing heat energy through it.
Long burning boiler - principle of operation
The smoke formed during the combustion of fuel is removed by convection through a vertical pipe - a chimney.
Do-it-yourself solid fuel long-burning boiler - drawings, diagram, design options
There are many varieties of such heat generators. We will focus on a few main types:
Classic direct combustion boiler
The design of this boiler can be called ingenuous. It is arranged in the same way as a traditional Russian stove.The firebox is just a chamber, and the fuel is set on fire and burned in the usual way, as, for example, in a fire.
The classic boiler is easy to manufacture, but it has a significant drawback: the fuel burns out too quickly - every 4 hours you have to add a new portion. There are several ways to improve the situation:
Limit the air intake with a damper so that the fuel does not burn, but slowly smolders
This option is extremely irrational:
- Oxidation of the fuel becomes incomplete, as a result of which the smoke contains a large amount of soot, carbon monoxide (related to harmful emissions) and various toxic substances.
- Due to the low temperature of the exhaust, a large amount of condensate is formed, saturated with the aforementioned toxins.
- The efficiency of the boiler is significantly reduced.
Equip the heating system with a heat accumulator
This is a voluminous reservoir in which a supply of superheated coolant is stored. The firewood in the boiler will burn out quickly, but the heat produced in this case will not fly out into the chimney, but will remain in the heat accumulator, just as it remains in the brick walls of a Russian stove. Therefore, the boiler will need to be fired less frequently.
Equip the boiler with an automatic system with forced air supply
The idea is the following:
- after generating a sufficient amount of heat (monitored by the temperature of the coolant), the automation completely closes the damper;
- the flame goes out and the boiler, one might say, turns off;
- when the coolant cools, the automation opens the damper and starts the fan, which blows the fire in the furnace.
Pressurized boiler
The automation unit with a fan can be purchased at the store. The only drawback of this solution is the dependence on electricity supply.
Top burning boiler
In such a heater, fuel is placed in the form of a column and ignited from above. From top to bottom, the flame moves much less willingly than from bottom to top, so the bookmark burns longer. In addition, to prevent the rapid spread of fire, air is supplied precisely to the combustion zone.
A heat generator with upper combustion is quite complicated in the device, but there is a simplified version of it, available for self-production. This is the so-called Bubafonya stove, the design of which was developed by Afanasy Bubyakin.
The problem is that in the presence of a water jacket, the characteristics of this unit drop dramatically (low efficiency, the furnace smokes heavily), so it is not rational to use it as a boiler.
Gas generating (pyrolysis) boiler
Molecules of fossil fuels (biopolymers) exposed to high temperatures partially decompose into various gaseous substances (wood gas), many of which can burn. This decomposition is called pyrolysis. During normal combustion, this mixture of gases is mostly thrown into the chimney. In a gas-generating boiler, it is discharged into a separate chamber (afterburner), where it burns.
Such a boiler has a number of advantages (high efficiency, long-term operation on one tab, etc.), but it is difficult to manufacture, requires the use of special catalysts and requires forced air supply.
Diagram of a gas generating boiler
You can make a simplified version of the type of furnaces "Professor Butakov", "Breneran" and "Bullerjan", which have a semblance of an afterburner in the upper part of the furnace.
But such units, firstly, are designed for operation in the smoldering mode, the shortcomings of which we discussed above, and secondly, like Bubafonya, they lose much in their characteristics when heat is removed by water, that is, when used as a boiler.
So, the most suitable for self-production is a classic boiler, which, if there is power supply in the house, can be equipped with an automatic blower fan.
Baksi gas boilers with automatic equipment are often purchased in our country. Equipment reliability and price are the main components of success with the consumer. and unit device.
We will analyze the principle of operation of a thermostat for a heating boiler.
Do you think that wood heating has become obsolete? Long-burning boilers for a wood-burning house are an economical and efficient solution in the absence of communications. Here we consider the types of boilers and features of operation.
Boiler diagram
Homemade heater will have the following design:
- The firebox is a “box” with a depth of 460 mm, a width of 360 mm and a height of 750 mm with a total volume of 112 liters. The volume of fuel load for such a combustion chamber is 83 liters (the entire volume of the furnace cannot be filled), which will allow the boiler to develop power up to 22 - 24 kW.
- The bottom of the firebox is a grate from a corner on which firewood will be laid (air will flow into the chamber through it).
- Under the grate there should be a compartment 150 mm high for collecting ash.
- The heat exchanger with a volume of 50 l is mostly located above the furnace, but its lower part covers it from 3 sides in the form of a water jacket 20 mm thick.
- A vertical flue pipe connected to the top of the furnace and horizontal flame pipes are located inside the heat exchanger.
- The firebox and ash pan are closed with hermetic doors, and air is taken in through a pipe in which a fan and a gravity damper are installed. As soon as the fan is turned off, the damper lowers under its own weight and completely blocks the air intake. As soon as the temperature sensor detects a decrease in the temperature of the coolant to the level set by the user, the controller will turn on the fan, the air flow will open the damper and a fire will flare up in the furnace. Periodic "shutdown" of the boiler in combination with an increased volume of the furnace allows you to extend the work on one load of fuel up to 10 - 12 hours on wood and up to 24 hours on coal. The automation of the Polish company KG Elektronik has proven itself well: a controller with a temperature sensor - model SP-05, a fan - model DP-02.
Solid fuel boiler drawing
The furnace and heat exchanger are wrapped in basalt wool (thermal insulation) and placed in the body.
Manufacturing process
First of all, you need to prepare all the necessary blanks:
- Steel sheets with a thickness of 4 - 5 mm for the manufacture of fireboxes. Alloy steel of heat-resistant grades 12X1MF or 12XM (with the addition of chromium and molybdenum) is best suited, but it must be cooked in an argon environment, so you will need the services of a professional welder. If you decide to make a firebox from structural steel (without alloying additives), then you should use low-carbon grades, for example, Steel 20, since high-carbon ones can lose ductility from exposure to high temperatures (they are hardened).
- Sheet steel with a thickness of 0.3 - 0.5 mm, painted with a polymer composition (decorative sheathing).
- 4mm structural steel sheets for the hull.
- Corner 50x4 mm, from which the grate will be typed.
- Du50 pipe (flame pipes inside the heat exchanger and branch pipes for connecting the heating system).
- Pipe Du150 (pipe for connecting the chimney).
- Rectangular pipe 60x40 (air intake).
- Steel strip 20x3 mm.
- Basalt wool 20 mm thick (density - 100 kg / m3).
- Asbestos cord for sealing openings.
- Factory made door handles.
Welding of parts should be carried out with MP-3C or ANO-21 electrodes.
DIY heat exchanger for a solid fuel boiler
First, a firebox is assembled from two side, one rear and one upper walls. The seams between the walls are made with full penetration (they must be airtight). A steel strip 20x3 mm is horizontally welded from below to the firebox from 3 sides, which will serve as the bottom of the water jacket.
Next, to the side and rear walls of the furnace, it is necessary to weld short pieces of a pipe of small diameter in random order - the so-called clips, which will ensure the rigidity of the heat exchanger design.
Now, the outer walls of the heat exchanger with pre-made holes for clips can be welded to the bottom strip. The length of the clips should be such that they protrude slightly beyond the outer walls to which they are to be welded with a sealed seam.
Homemade sheet metal boiler
Coaxial holes are cut in the front and rear walls of the heat exchanger above the furnace, into which the flame tubes are welded.
It remains to weld pipes to the heat exchanger for connection to the heating system circuit.
Boiler assembly
The unit must be assembled in the following sequence:
- First, the body is made, grabbing the side walls and frames of the openings with short seams to its bottom. The lower frame of the ash pan opening is the very bottom of the case.
- From the inside, corners are welded to the body, on which the grate pan of the furnace (grate) will be laid.
- Now you need to weld the grate itself. The corners of which it consists must be welded with the outer corner down, so that the air coming from below is evenly distributed by the two inclined surfaces of each corner.
- Further, a firebox with a heat exchanger is welded to the corners on which the grate is laid.
- Firebox and ash pan doors are cut from steel sheet. From the inside, they are framed with a steel strip laid in two rows, between which an asbestos cord must be laid.
Now it is necessary to weld the mating parts of the door hinges and several brackets 20 mm wide to the boiler body, to which the casing will be attached.
The heat exchanger must be lined on three sides and on top with basalt wool, which is pulled together with a cord.
Since the insulation will be in contact with hot surfaces, it should not contain phenol-formaldehyde binder and other substances that emit toxic volatile substances when heated.
With the help of screws, the casing is screwed to the brackets.
An automation controller is installed on top of the heat generator, and a fan is screwed to the duct flange.
The temperature sensor must be placed under the stone wool so that it is in contact with the rear wall of the heat exchanger.
If desired, the boiler can be equipped with a second circuit, allowing it to be used as a water heater.
The circuit has the form of a copper tube with a diameter of about 12 mm and a length of 10 m, wound inside the heat exchanger on the flame tubes and brought out through the rear wall.