The simplest solutions for organizing heating a private house will always be popular, especially among home craftsmen. This also includes a wood-fired rocket stove, which can be done with one's own hands without significant financial costs. The heater is quite interesting and deserves special attention. Consider the principle of operation of the rocket furnace, advantages with disadvantages and methods of manufacturing at home.
How a rocket stove works
It is noteworthy, but the so-called rocket or jet furnace actually has nothing to do with jet thrust, and even more so with space flights. This popular name arose for 2 reasons: due to some similarity of the working unit to an inverted rocket and due to the buzzing sound. True, it appears in a certain mode of burning wood and indicates too much air supplied to the firebox.
Important. The mode in which the rocket stove buzzes violently or even roars is inefficient and uneconomical. During normal operation of the stove, only a quiet rustling sound is heard.
At the moment, there are 2 types of reactive wood stoves:
- portable;
- stationary (heating).
The simplest portable modification of the rocket-type stove is made in series under the name "Robinson" and is intended for heating water and cooking in camp conditions. For her example, the easiest way to understand the principle of operation of the unit. In fact, it is a pipe in the form of an inverted letter "G", as shown in the diagram:
How the rocket furnace works:
- Firewood is inserted into the horizontal part of the pipe, which serves as a receiving hopper for fuel, and is set on fire from the side of the vertical section.
- Inside the L-shaped channel, natural draft occurs due to the temperature difference between the incoming air stream and the exhaust flue gases.
- The burning rate of a rocket furnace increases as the housing warms up, so it is necessary to limit the air supply. Otherwise, the wood will very quickly burn out in vain - all the heat will fly out into the pipe.
The principle of operation of the so-called jet furnace is to use the energy of the upward flow of combustion products. The higher the temperature of the walls of the firebox, the more wood burns, and the flame becomes more powerful.
Due to the resulting natural traction, a simple Robinson steel stove heats a large water tank in a dozen minutes. And if you make the vertical section insulated, as shown in the diagram, then after heating it will be possible to burn quite thick logs.
Stationary version of the furnace
Stationary do-it-yourself rocket furnaces for heating a house are equipped with a special hood to preserve the heat of flue gases, followed by transferring it to the room. In this case, the overall picture of burning wood is somewhat different. With a limited supply of primary air and fuel combustion, pyrolysis gases begin to be released. They are burned in the lower part of the vertical pipe, where secondary air is supplied through a separate channel.
Note. In this regard, a wood-burning stove - a rocket is similar to a pyrolysis heater of long burning, only it does not use a fan to force air.
The incandescent products of combustion, rising under the hood, begin to cool, after which they descend in the space between the walls and fall into the chimney channel. At the same time, 3 forces act on gases:
- Gravity It forces the colder and heavier gases to sink and head toward the exit to the chimney duct.
- Pressure of new combustion products coming in at higher temperatures from the firebox.
- Natural chimney draft force.
The sum of these three forces makes it possible to attach smoke channels of arbitrary shape to the rocket-type stove, if only to take away more heat. In practice, this is used to make a heated stove bench from a rocket furnace, as shown in the diagram:
Note. There is another way to prevent the release of heat along with flue gases to the outside. To do this, a chimney is made from a rocket furnace with a water jacket and two pipes that are connected to heating devices.
About the advantages and disadvantages
The so-called reactive stove is the cheapest option for a heating device in a private house. In this regard, it has no equal. Moreover, a good master is able to make a brick stove in such a way that it will look pretty decent in the interior of the room. In fact, it is necessary to refine only the protruding metal cap and the lid of the fuel chamber. The rest of the unit along with the flues will be hidden from view.
Homemade rocket stoves can not be called ultra-efficient, but in general, this figure largely depends on the homeowner. If you constantly burn raw wood, then there will be little sense from this. As it makes no sense to get a “roaring” regime from the heat generator, mistakenly believing that it is the best. Here it is necessary to limit the air supply manually, as is done in long-burning heaters.
Loss of useful heat through the chimney affects many furnaces, including missile ones, so in this case it will not hurt to fit a water circuit to the flue pipe, as mentioned above. Well, a large amount of heat will allow you to select a stove bench, although you will have to work hard for its construction. The remaining negative sides of the rocket look like this:
- The unit requires constant supervision and manual control, since any automation is absent in it.
- Firewood should be loaded quite often.
- The metal cap is heated to a temperature that causes burns in humans after touching. This is dangerous for young children.
Note. Home-made rocket-type furnaces are not suitable for heating a bath, since in normal operating conditions they are unable to generate a large amount of heat in a short period of time.
Manufacturing recommendations
The easiest way to do it yourself is a small portable stove - a Robinson rocket, whose drawing is presented below. It will require trimming of profile pipes, metal for legs and coasters, as well as welding skills. Moreover, compliance with the exact dimensions indicated on the drawing is not necessary. You can take pipes of a different section, only it is necessary to reduce or increase them proportionally, so that the parts fit together.
The most common variants of large rocket furnaces are made of a gas cylinder or a metal two-hundred-liter barrel. It must be understood that these finished elements are used as the outer hood, and the internal parts of the stove must be made of pipes of smaller diameter or laid out of fireclay bricks. Moreover, from a cylinder, you can make both a stationary heater with a small stove bench, and a unit that can be moved.
Please note that it is rather difficult to calculate the thermal power of a rocket type furnace; there is no single calculation method. It is easier to rely on ready-made drawings of already working samples and perform assembly on them. It is only necessary to compare the dimensions of the future stove with the dimensions of the heated room. For example, for heating a small room, the size of the cylinder is enough, in other cases it is better to take a large barrel. The selection of internal parts for them is shown in the diagram:
Cylinder rocket stove
In addition to the gas cylinder itself, to assemble the stove you will need:
- profile pipe 150 x 150 mm for the firebox and loading hopper;
- steel pipes with a diameter of 70 and 150 mm will go to the internal vertical channel;
- the same diameter of 100 mm in the chimney;
- insulation (basalt fiber with a density of at least 100 kg / m³);
- sheet metal 3 mm thick.
For the master who owns welding, this work will not be particularly difficult. At the cylinder, the upper part should be cut along the seam, having previously turned the valve and filling it to the top with water. Openings for installing a firebox and insert a chimney are cut out on the sides of both sides. The profile pipe is inserted connected to a vertical channel, which is discharged through the bottom of the cylinder. Further work on the manufacture of a rocket furnace is carried out in accordance with the drawing:
At the end, the upper part must be welded into place, then carefully check all the seams for permeability, so that air does not enter the furnace uncontrollably. After that, you can attach the chimney with a water jacket (if available) and proceed with the tests.
Important. To create sufficient traction, the top of the pipe should be raised above the firebox to a height of 4 m.
Brick rocket heater masonry
This version of the stove will require the cost of buying fireclay bricks, a conventional ceramic for a rocket stove will not work. Masonry is performed on a solution of chamotte clay, it is also sold in the form of a finished building mixture. How to make a stationary rocket furnace:
- First you need to dig a hole, stamp the bottom and fill the foundation with dimensions of 1200 x 400 mm and a height of 100 mm, as shown in the photo.
- After solidification, the foundation is covered with a sheet of basalt cardboard and the masonry of the combustion chamber, the hopper for loading firewood and the vertical channel are laid. A door is installed from the end of the combustion chamber to clean the ash pan.
- After the clay dries, the pit is filled up, and a pre-selected pipe or a small barrel with a diameter of 450 mm is put on the vertical channel. The gap between the brickwork and the walls of the pipe is filled with refractory insulation, for example, basalt wool, expanded clay, vermiculite.
- At the last stage, a cap of a large metal barrel with a diameter of 600 mm is put on the structure. Previously, a cutout is made in its upper part and a pipe is placed for connecting the chimney. When the barrel rolls over, it will just be down.
Conclusion
Of course, a wood-fired rocket is not the height of perfection and is attractive only because of its simplicity and cheapness. Yes, and fit it into the interior of the living room - that’s another task. This suggests the conclusion that you can build such a source of heat somewhere in the country or in a temporary hut, where people do not stay permanently. The heater is not afraid of long breaks between kindling, and it warms up quickly enough. This unit is not suitable for heating a large residential building or bath, other solutions are needed here.