Making a jet furnace do it yourself

A jet furnace or rocket furnace was the result of a deviation from the tradition of manufacturing equipment for space heating. It is considered an economical heat generator, whose design is elementary. Therefore, many people think about building a jet furnace with their own hands.

Description, advantages and disadvantages of the furnace-rocket

The heat generator for heating the air in the room is called a stove-rocket or a jet furnace, as when working in case of excessive air intake it produces special sounds. This noise can be mistaken for the roar of a jet engine. In normal mode, the equipment operates with a barely audible rustling sound.

The rocket oven serves as a device for heating the house and cooking.It takes about 6 hours to burn one batch of wood in such equipment, more than in a standard metal furnace.The reason for this is the creation of a heat generator on the basis of an upper-burning furnace.

Fireplace of the jet furnace

The flame from the jet furnace can escape

The advantages of the furnace-rocket include:

  • energy independence;
  • The simplicity of the design, consisting of available parts, connected in minutes;
  • The ability to give a lot of heat, despite the quality of the fuel being loaded.

There are some drawbacks to the jet furnace:

  • manual control, which means continuous monitoring of equipment operation;
  • the danger of getting burned, because the walls of the equipment become extremely hot;
  • inappropriate use in the bath, because it does not get to warm up.

The unit, which during the work produces a rocket rumble, it happens:

  • portable (a unit of metal pipes, buckets or gas cylinder);
    Portable version of a reactive furnace

    Portable rocket furnaces are commercially manufactured by the industry.

  • stationary (created from chamotte bricks and metal containers);
    Brick brick oven

    Such a unit is more difficult to build than a metal furnace.

  • equipment for heating air with a stove bench.
    Reactive oven with a place for rest

    The bed is equipped behind the rear wall of the furnace.

Portable structures are manufactured in large batches, because they are used for hikes.The basis of these heat generators is a pipe composed of several segments.However, such structures, unlike aggregates based on fireclay bricks, are not reliable. The walls of the refractory blocks increase the heat transfer of the jet furnace. If desired, you can add to it a bed in the form of a sofa or bed, decorated with clay or sawdust.

Details and operation of a jet heat generator

An elementary rocket furnace is a device of two pipe fragments connected by a tap at an angle of 90 degrees. The combustion chamber in this heat generator is usually the area in the horizontal part of the structure. But sometimes the fuel is laid in the vertical section of the apparatus, for which the rocket furnace is constructed of two pipes of different length, mounted vertically and connected by a common horizontal channel.

Reactive furnace design elements

Through the furnace passes the primary and secondary air

The operation of a jet furnace is based on two actions: the unimpeded passage of wood gases through a pipe and the afterburning of gases produced by the combustion of fuel.Slivers and firewood in the furnace of this heat generator are put in place after a readily inflammable material like paper burns there.On the open section of the pipe put the container with water or other contents. At the same time, between the structure and the installed capacity, a small amount of space is required to create thrust.

The operation of the furnace-rocket

The processes occurring inside a stationary jet furnace resemble the work of pyrolysis heating units

Calculation of parameters (table)

The volume of the furnace should be determined with knowledge, because it affects the power and amount of heat generated by the heating equipment.Calculating the dimensions of the reactive heating equipment, use the index of the inner diameter of the drum D, the value of which can fluctuate within 300-600 mm.You also need to know the cross-sectional area of ​​the drum. To determine this indicator, the rocket furnace should use the formula: S = 3.14 * D ^ 2/4.

The main dimensions of the jet furnace are presented in the table:

Parameter Value
Drum height H From 1.5D to 2D
The height of the insulating coating drum 2 / 3H
The thickness of the insulating coating of the drum 1 / 3D
The cross-sectional area of ​​the primary chimney From 0.045S to 0.065S (optimally from 0.05 S to 0.06 S). The higher the primary chimney, the better.
Minimum clearance between the top edge of the primary chimney and the drum cover 70 mm.At a lower value, the aerodynamic resistance of the gap for gases passing through it will be excessively large.
Length and area of ​​the flame tube The length and area of ​​the primary chimney
Cross-sectional area of ​​the blower Half the cross-sectional area of ​​the primary chimney
Cross-sectional area of ​​the external chimney From 1,5S to 2S
The thickness of the cushion from adobe under the flue with a stove bench 50–70 mm (in the presence of wooden beds under the bench - from 25 to 35 mm)
The height of the coating over the flue duct 150 mm. Reducing is not recommended, otherwise the furnace will accumulate less heat.
External chimney height not less than 4 m

Particular importance is attached to the length of the flue with a stove bench. The maximum permissible values ​​are shown in the table:

D (diameter) Length
300 mm 4 m
600 mm 6 m

The volume of the secondary ash chamber is also an important indicator, depending on the volume of the drum and the primary chimney.

D (diameter) Volume
300 mm 0.1 x (Vк - Vпд) Where Vk - the volume of the drum,
Vpp - the volume of the primary chimney.
600 mm 0.05 x (Vк - Vпд)

Construction raw materials for the construction of a non-standard furnace

The production of jet heating equipment will require the availability of:

  • barrels with a volume of 200 liters and a diameter of 0.6 meters, an empty cylinder from under liquefied gas or buckets of tin to build a drum of the furnace;
  • square or round pipes of steel with a thickness of 2-3 mm, which are needed to create a blower, a combustion chamber and a primary chimney;
  • chamotte rubble and kiln clay as heat-insulating materials;
  • adobe, which serves as an outer coat layer;
  • fireclay bricks;
  • sand from the bottom of the river;
  • pieces of sheets of zinc-coated steel or aluminum for the manufacture of covers and doors;
  • asbestos or cardboard from basalt, performing the task of compactor.

Of the tools in the construction of the furnace-rocket will need a welding machine. And if you plan to make heating equipment of bricks, you have to take:

  • Master OK;
  • mortar scapula;
  • hammer pick;
  • basting;
  • sledgehammer acute angle;
  • level;
  • plumb bob;
  • roulette wheel

Preparation for the assembly of heating equipment

When choosing a place for the furnace-rocket guided by some rules:

  • reactive heating equipment is placed only in a room of not less than 16 m²;
  • without floorboards under the oven installation of equipment will be easier;
  • over the construction giving heat, it is forbidden to have beams from wood;
  • if it is implied that the chimney will go through the ceiling, then the heating equipment is placed in the middle of the house;
  • the heat generator cannot be installed near the external contour of the house, otherwise the room will lose the heated air;
  • A jet device must not be placed near the walls and partitions of their wooden materials.

To make it easier to put fuel into jet heating equipment, it is wiser to place it on the front side of the entrance. Around the furnace-rocket, it is important to leave at least a meter of unoccupied space.

In a small house, builders are advised to make room for a stove in the corner.In this case, the firebox should be directed in one direction, and the bench (if it is made) - in the other.

Place for a jet furnace in the house

The stove stands on a special platform that protects the floor from high temperatures

Having found a suitable site for the furnace-rocket, they begin to prepare it for construction work. If boards are placed on the floor in the house, they will need to be removed in the place where the equipment will be installed. Under the opened floor they dig a hole, the bottom of which is necessarily pressed.

Before construction work should be mixed with a special solution. It consists of sand and clay, connected in a 1: 1 ratio. Water will be needed so much that the building material acquires the consistency of sour cream, that is, ¼ part of the amount of dry ingredients.

Step-by-step manual for making your own hands

If you plan to make a furnace-rocket of a gas cylinder, then you can not be afraid of difficulties. The steps to create equipment from such building materials are quite simple:

  1. from the cylinder with a volume of 50 liters cut off the upper part to build a kind of cap;
    Billet parts for the furnace-rocket

    The balloon is cut from above and below.

  2. Focusing on the instructions in the drawing, with each other, weld all the parts of the product, that is, the gas cylinder, a pipe with a diameter of 10 cm (future chimney), a pipe with a diameter of 7 cm (internal channel) and another pipe with a diameter of 15 cm (the firebox);
    Drawing of the furnace-rocket from the cylinder with the supply of secondary air

    Dimensions in mm

  3. the space between the two pipes is filled with a material that retains heat, for example, with sand that has been carefully calcined, that is, purified from organic matter;
  4. To impart a stability design, the legs are welded.

To build a rocket furnace with a bench, which implies the use of bricks, you need to act differently:

  1. The area for the arrangement of the firebox is deepened, removing 10 cm of soil. The combustion chamber is formed of fireclay bricks. Formwork is created along the contour of the structure being manufactured. To make the base strong, it is recommended to lay a reinforcing mesh or metal rods in it;
    Pouring the foundation of the furnace-rocket

    The platform will harden in about two days

  2. The design is poured with liquid concrete.Then wait, when the solution hardens, and finish the work. Bricks are laid in a solid line, creating a platform for the furnace. After this, the walls of the structure are formed, exposing several rows of brick blocks;
  3. Arrange the lower channel of the structure, with one line of bricks laid across to block the combustion chamber. The blocks are arranged, leaving the vertical channel and the firebox opening open;
    Making a combustion chamber with your own hands

    Two sectors of the furnace at this stage of construction should be open.

  4. Find the case from the old boiler and cut off the top and bottom covers on it. At the bottom of the resulting pipe install the flange, through which the horizontal heat exchanger will pass. The parts must be connected with each other by a continuous weld seam;
    Installation of the lower pipe

    Work requires accuracy

  5. An outlet branch pipe is inserted into the barrel, after which they take a brush for metal and scrub rust from the container walls. The cleaned barrel is treated with a primer composition, and a little later with a paint that is resistant to high temperatures;
  6. A horizontal chimney with welding is connected to a side outlet - the future ash pan. To facilitate its cleaning, an airtight flange is mounted;
  7. Spread the flame tube of refractory bricks. At the same time, a channel of 18 cm in height and width is formed inside the structure. Being engaged in this business, they constantly use the building level, which allows controlling the verticality of the product;
    Fire tube laying

    Pipe height is determined in advance

  8. The flame tube is covered with a protective cover, and the resulting gaps are sealed with perlite. The lower region of the vertical channel is sealed with raw clay, the function of which is to prevent the insulating material from spilling onto the floor;
  9. From the boiler, which were cut off the top and bottom, form the fuel tank. The pen must be welded to it;
  10. To improve the appearance, the structure is treated with adobe putty consisting of sawdust and raw clay. The first component of the composition serves in the same way as crushed stone in concrete, that is, prevents cracking of the furnace walls. Adobe putty is recommended to be applied over the perlite backfill;
    Furnace housing coating

    A special compound is recommended to model with gloves

  11. Create the facade of the furnace, for which from the stone, bricks, sand and sand lay out the furnace circuit. The seamy side of the structure is filled with rubble, and the front side is filled with adobe mixture, which makes the surface perfectly smooth;
  12. On the previously created base put the casing of the metal barrel.The lower nozzle of the tank is directed towards the bed. The bottom of the structure is treated with raw clay, which will ensure its tightness;
  13. To the furnace chamber down channel from the corrugated pipe. It will serve as a link between the furnace and the atmosphere from the outside;
    Making a channel through which air will flow

    At this point, the oven looks almost complete.

  14. Carry out the test kindling of the furnace, depending on how the gases are removed from the horizontal chimney. After that, the heat exchanger pipes are connected to the lower pipe installed on the red brick platform;
  15. The stove is supplemented with a smoke extraction pipe. The junction of the chimney and the heat generator is sealed with a refractory coating and asbestos cord;
  16. Using clay and saman, the bed is given the desired shape. Only the horizontal part of the structure is left unsealed, which will then be used during cooking.
    Scheme of a jet furnace with a bench

    The furnace functions as a complete system.

Design improvement

A lounger with a flue inside is not the only way to upgrade a rocket furnace.The design can be improved with a water jacket connected to the heating system, in which water circulates.This part of the design is desirable to give the appearance of the coil, created from a copper pipe, twisting on the chimney.

Scheme of a rocket furnace with a water circuit

This design gives even more heat.

Another way to improve the jet furnace is associated with the organization of the heated secondary air entering the heat pipe. This will increase the efficiency of the heat generator, but will lead to the deposition of a large amount of soot in the primary chimney. Therefore, it is better to do so that the drum cover can be removed if necessary.

The subtleties of the operation of an unconventional furnace

The rocket stove is heated by analogy with the upper-burning heat generator. It turns out that the kindling of equipment, called a rocket, should be carried out according to certain rules:

  • the main raw material for the heating of the unit must be laid only after a good heating of the structure, for which, first, sawdust or paper are placed in the blowing sector;
  • to mute the outgoing hum from the furnace, they necessarily react - they put a large batch of fuel into the combustion chamber, which will light up independently from the heated remnants of sawdust;
  • the process is closely monitoredthat is, after the wood has been laid, the flap is fully opened, and after a while, when the equipment emits a buzz, it is covered to obtain a sound similar to rustling;
  • as necessary, the flap is covered more and more, otherwise the furnace will be filled with excess air volume, which will disrupt the pyrolysis inside the flame tube and lead to a strong hum.

Since the jet furnace was originally designed for use in the field, its design is extremely simple. This allows you to cope with the manufacture of the unit ordinary home craftsman. But, despite the apparent ease, the rocket-furnace is supposed to be assembled, taking into account the correct ratio of parameters. Otherwise, the equipment will be unproductive.

  • Author:
Ksenia Zubkova
I am a philologist by education, I have been writing texts for more than 5 years.

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