The desire to reduce the cost of heating residential or utility rooms forces their owners to look for the least expensive options. At the same time, every zealous owner strives to use the most affordable and cheapest fuel, achieving maximum heat transfer when burning it. That is why the deterioration of the situation on the energy market has led to the emergence of many interesting and efficient heating devices available for repetition at home. One such installation is a liquid fuel furnace. Its main advantage is that you don't have to use expensive diesel fuel for heating - a home-made unit works great on used engine oil, which can be bought for a penny at the nearest car service. The surge of interest in homemade stove designs usually increases with the onset of cold weather. We recommend not to wait for frost and start making a furnace with your own hands, working on working off, right now.

Features of the device and use of liquid fuel stoves. Advantages and disadvantages of units

The working furnace is a compact and easy-to-manufacture heating device

Drained engine oil is a multicomponent substance contaminated with the combustion products of automobile fuel. I must say that mining burns very badly, but the volatile components that are released when it is heated, ignite easily and, during oxidation with oxygen in the air, release heat in large quantities. I must say that the features of the combustion of used engine oils in most cases determine the existing types of heating units:

• stoves with drip feed of liquid fuel;
• models using pressurization and fuel atomization;
• two-chamber units of the pyrolysis type.

In addition, a distinction is made between stoves with air and water heat exchangers, which makes it possible to install equipment of this type both in technical and in residential premises. The scope of application of stoves using waste engine oil or automobile oil as fuel is extremely wide:

• workshops and garages;
• greenhouses;
• vegetable stores;
• production facilities and warehouses;
• outbuildings;
• residential buildings (subject to the placement of heating equipment in the annex).

The availability of free fuel predetermines the popularity of used engine oil stoves among the owners of garages and service stations.

Of course, the installation of such stoves is most advisable to carry out in car services and at enterprises with their own vehicle fleet, which will allow not only to dispose of unsafe flammable liquid, but also to save on heating.

Boilers and stoves with drip feed of combustible oil

Open fired and drip fed models are the simplest and most affordable home constructions. In addition, this method of delivering liquid fuel to the working area makes it possible to transfer any solid fuel furnace or boiler for testing.

Structurally, the drip-fed unit consists of a container for oil, a hose for transporting fuel, locking and control valves, an evaporator and a nozzle. Such an oven works simply. Before ignition, the oil supply is opened, which flows by gravity from the tank and drips onto the surface of the evaporator. The fuel is ignited with a rag dipped in kerosene or solarium. Exit to the operating mode occurs only after the working bowl warms up to 350–400 ° С. In this case, the incoming liquid instantly passes into the gas phase and burns out at a high temperature. To increase the productivity of the furnaces, they are equipped with duct fans. It is possible to ensure the completeness of the combustion of the mining due to the afterburning of combustion products in the high-temperature zone with an additional air supply.

Scheme of operation of stoves with drip feed of liquid fuel

The advantages of the open combustion method include simplicity of design and the ability to adapt to the already installed heating equipment. As for the disadvantages, they are quite weighty:

• low efficiency of installations;
• difficulty with use at low temperatures due to deterioration of fuel fluidity;
• high content of harmful substances in flue gases;
• difficulty in setting up the exact fuel supply;
• rapid formation of carbon deposits on the chimney.

Despite the disadvantages, individual designs of drip-fed stoves are consistently popular with home craftsmen, especially when it comes to converting solid fuel boilers to work with liquid fuel. You can see one of these installations, which is called a flame bowl oven, in the diagram.

Heating units with burners

The use of nozzles for burning machine oil makes it possible to increase the efficiency of the units, and, accordingly, their thermal power. The principle of operation of the devices is borrowed from blowtorches and kerosene stoves, which were widely used in the 50-70s of the last century for cooking. It consists in heating the liquid fuel to the evaporation temperature and burning it in a separate chamber with forced or atmospheric air supply. In this case, part of the heat released during the combustion of oil, diesel fuel or kerosene is used to heat the next portion of fuel.

Since working off from a car service most often comes in the form of a mixture of oils with different viscosities, it should be heated and filtered before being fed to the nozzle. Schemes of factory and homemade designs using both types of air supply are presented below.

Diagram of a burner suitable for do-it-yourself manufacturing

The Babington burner has an interesting design, which does not require preliminary oil preparation. In it, mining flows down in a thin layer over a rounded bowl. A point hole is made in the center of the sphere, to which air is supplied under pressure. The principle of operation is that the air flow captures the smallest particles of oil from the surface. The dispersion that forms at the outlet is highly flammable and burns with a temperature of more than 1000 ° C.

The principle of operation of the Babington burner

Note that the most advanced burners provide for multi-stage fuel combustion, which includes the phases of decay, combustion and afterburning of the products of chemical reactions directly in the flare.

The advantages of burner stoves include:

• Efficiency more than 90%, unattainable for other units under development;
• high-temperature flame allows to increase the power of heating installations;
• combustion of mining at 1000 ° C and more makes it possible to obtain exhaust with a minimum content of harmful impurities;
• versatility - the burner can be installed on any type of heating unit.

The cons of spraying devices can be written:

• complicated design;
• the need to use injection equipment;
• high requirements for the purity of the fuel, which force pre-filter the drained engine oil;
• the need for a liquid fuel heating device.

Note that most of the noted disadvantages relate to the most high-tech burners. Lower requirements are imposed on simple home-made devices, however, other disadvantages appear - the appearance of the smell of unburned fuel, its splashing during ignition, reduced performance, etc.

Heaters with multiple chambers

In two-volume structures, the processes of evaporation and combustion of mines take place in different chambers. Thanks to this, it is possible to achieve a high temperature and complete combustion of the fuel. In addition, a characteristic feature of this type of furnace is a very clean exhaust - there are practically no harmful chemical compounds in the flue gases.

Structurally, the unit consists of two vertically installed containers, interconnected by means of a perforated pipe of increased diameter (injector). The lower chamber is equipped with an oil filling hole. Thanks to the installed rotary-type damper, this opening also serves as a metering device for the primary air entering the combustion chamber.

The double-volume heater consists of only a few parts

Despite the simple design, the efficiency of waste oil combustion is at the level of the best examples of industrial production. Since this is laid down by the very principle of operation of the furnace, we will consider the features of its operation in more detail.

The oil poured into the lower chamber is ignited with an oiled rag. After the surface layer of the mining ignites, the air flow is reduced, obtaining a stable combustion. Volatile hydrocarbons evaporating from the surface are burned in a vertical chamber with a high temperature, which is caused by the inflow of air through the perforation of the injector. The combustion rate in the upper chamber is reduced by a forced method, which is necessary for a more complete oxidation of the reaction products with nitrogen compounds. In this zone, the so-called afterburning of the released gases occurs, due to which they decompose into safe compounds. The chimney embedded in the upper module provides the required draft and removes the residual gases outside.

Since the heat exchanger of a two-volume furnace is the upper chamber, it is often equipped with a jacket for forced convection or a jacket for supplying a heat transfer fluid.

I must say that when deciding on a design for making a stove in a garage, workshop or greenhouse, they most often stop at a two-volume unit. It has the advantages of all the furnaces described above, and is practically devoid of disadvantages, especially when it comes to using the heater in non-residential premises. As for the manufacture of a boiler to provide heat to a country house, it is better to use one of the devices built according to the scheme with a flame bowl.

Diagram of a potbelly stove with a fiery bowl

Making a two-volume potbelly stove for mining

The furnace we offer for manufacture consists of two round modules with a diameter of 350-400 mm, which are connected to each other using a piece of metal pipe with a diameter of at least 4 inches and a length of 400-450 mm. The lateral surface of the vertical chamber is covered with perforations in the form of holes 8–10 mm in diameter, made in a checkerboard pattern. The inner space of the upper module is divided by a partition, into which the burning gases strike, due to which their active mixing and a drop in the burning rate necessary for the completion of the pyrolysis processes occur. The chimney is cut into the space of the upper tank, which is located behind the partition. Its height must be at least 4 m, and a thick steel pipe must be used at the connection point, otherwise the smoke channel may burn out. At a height of 1 m from the surface of the furnace, it is allowed to build up the chimney with a galvanized, tin or ceramic pipe.

The design of the liquid fuel unit

The horizontal section of the chimney installed at the outlet of the upper module will serve as an additional heat exchanger, therefore, if possible, it is made 0.5–0.8 m in size. The exhaust gases have a sufficiently high heat capacity, which will be taken by convection, and not escaped into the atmosphere.

Photo gallery: drawings and diagrams

The presented diagrams and drawings of the described design will help you understand the manufacturing features and will allow you to determine the amount of work and the amount of material. Note that there is no need to accurately copy all dimensions - it is enough to adhere to the basic proportions and precisely observe the relative position of the parts.

Diagram of a two-volume furnace with the main dimensions of parts and assemblies

What you need to make a stove that runs on liquid fuel

As always, getting started, you need to prepare the materials necessary for the construction of the furnace. Having at hand a complete set of blanks, you do not have to waste time looking for the right part. This will make it possible to build a two-volume heater in just one day. Here's what you need for this:

• sheet steel 6 mm thick;
• metal sheet 4 mm thick;
• thick steel pipe (wall thickness not less than 4mm) - 1.5 m;
• galvanized chimney pipe - 4 m;
• steel corners (shelf 40–50 mm) or profile pipe 40 × 20 mm, length 8–1 m.

You also need to prepare locksmith tools in advance. When everything you need is at hand, work goes much faster. Here is a list of the essentials:

• electric drill;
• drills for work on metal Ø6 mm and Ø9 mm;
• angle grinder (in other words "grinder");
• cutting discs for metal;
• roughing circle;
• welding machine;
• electrodes Ø3–4 mm;
• autogen.

Note that the welding seams of the unit must ensure its complete tightness - this is a necessary condition for the safety of the structure. If you are not confident in yourself as a welder, then it is better to entrust this part of the work to a professional.

What to do before starting to assemble the stove. Choosing a location

At the preparatory stage, they begin cutting the parts of the furnace according to a previously prepared drawing. This is best done with laser or plasma cutting machines found in metalworking companies. If this is not possible, then you can do with a simple gas cutter. Please note that the blanks of the cylindrical modules are cut from 4mm thick rolled metal, while the bottom and top parts must be made of thicker steel with a thickness of 6mm.

In case of emergency, you can also use an angle grinder, only in this case it will take a long time to process the edges of the parts using a grinding disc or an emery wheel.

When choosing a site for installing a stove, it is necessary to be guided not only by questions of practicality, but also by safety standards. It should not be forgotten that the walls of the convection device glow red hot during operation, so the place for its installation must meet several requirements:

• there must be at least 0.5 m of free space around the oven;
• the room must be equipped with supply and exhaust ventilation;
• the installation site of the unit must be away from areas with intense movement of air masses (wind, draft, operating fan, etc.);
• shelves and niches should not be placed above the heater;
• the presence of flammable objects and fuels and lubricants near the potbelly stove is excluded.

In addition, the working furnace is installed in such a way that the installation of the chimney is not difficult, and the chimney itself ensures the safe operation of the heating equipment.

Step-by-step instructions for assembling a stove for heating

1. Prepared metal strips with a thickness of 4 mm, of which the side walls of the modules and the spacer of the lower container will be made, are bent into rings. Of course, it is better to use a professional bending machine for this, but you can also use a suitable template. After that, the strips are welded at the junction with a continuous seam. For the manufacture of a furnace for working off with a diameter of 30 mm, it is convenient to use a household gas cylinder, cutting off two sectors with a height of 80–100 mm from it.

   

   Parts prepared for assembly

2. The bottom is welded to the lower module, which acts as a combustion chamber and oil reservoir.

   

   When installing the bottom, both the outer and inner parts of the tank pass through with a continuous seam

3. The upper container is made in a similar way, using a metal strip for the side wall with an opening for the chimney.

   

   Assembling the top module

4. In addition, a 70 mm wide metal partition is installed inside the module. Dividing the circle into three equal parts, it is mounted on the border of the third that is on the side of the chimney.

   

   Installation of a partition

5. A 130 mm long pipe, cut from a steel pipe with a diameter of 100 mm, is welded into the opening of the smoke channel. In order for the chimney to enter it, the pipe section is pre-cut across, and the cut site is expanded by 3-4 mm. A piece of steel wire is installed in the resulting gap, after which the connection is welded from the outside with a continuous seam.
   

   A chimney consisting of several parts is much easier to install. In addition, sooner or later it will have to be cleaned. This is where all the advantages of a collapsible type design come in handy.

6. Four workpieces 20–25 cm long are cut from a steel angle or shaped pipe. They are welded to the lower plane of the oil tank. They are needed as legs for the safe installation of the heater.
7. After that, a spacer is installed inside the lower module, which will hold the cover with the filling hole. The main thing is to ensure a tight fit of all parts of the fuel tank. Of course, it can be made completely welded, however, sooner or later the lower module will have to be cleaned of soot, and it will be much easier to do this by disassembling the potbelly stove into parts.
8. An injector pipe is made, for which 6 rows of holes are drilled in it using an electric drill, each of them shifting relative to the previous one to obtain a staggered perforation pattern.
9. A sliding flap is installed on the oil fill hole, which works in the same way as a door peephole with a rotating shutter.
10. The upper furnace module is welded to the oil tank lid by means of a perforated pipe installed between them. In this case, it is important to orient the parts not in a mirror image, but with a shift of the upper container by 180 °.

    

    The correct operation of the furnace depends on the accuracy of the assembly.

    The installation of the burner pipe is carried out on a flat horizontal surface, using a level. Remember: even a slight deviation from the vertical position will lead to the fact that some of the gases begin to go outside, the stove will smoke and will not be able to reach the optimal operating mode.

11. A horizontal arm and a vertical elbow are welded from a steel pipe, which are attached to the outlet pipe. After installing the unit, a chimney is installed in place, with a height of at least 4 m.

    

    Finished product type. If desired, the design can be modified with an additional tank for working off as a communicating vessel

To check the furnace operability, 0.5–1 l of waste oil is poured into the lower tank, the fuel is ignited, and the unit is tested for operability and tightness.

Modernization of liquid fuel heaters

The design of a two-volume oven described above is good for use in garages, greenhouses, workshops and buildings for household purposes, but by no means in houses and dachas. In order for the unit to meet the convenience and safety requirements for residential heating equipment, it must be modified. The design change is primarily necessary for the installation of the stove in the annex. Most often, modernization concerns the transfer of a heating device from the category of convection to the class of water heating. To do this, the upper module of the furnace is equipped with an external water jacket or a built-in heat exchanger, through which the coolant is passed from the heating system of a country house or summer cottage. Of course, it is better to provide for the possibility of connecting a water circuit at the design stage, but it is also possible to modify an already existing structure. All that is needed for this is the same sheet steel and steel pipes with a diameter of 3 / 4˝-1˝. The efficiency of heating the liquid heat agent will increase if not only the upper heat exchanger of the furnace is equipped with an external casing, but also the horizontal section of the chimney. Of course, before this, you must ensure its complete tightness.

Modification of the heating unit to supply heat to several rooms requires the installation of a powerful duct fan

Furnaces modified in this way must not be operated without a switched on fan or circulation pump. Failure to comply with this requirement can lead to boiling of the coolant, depressurization or warping of the outer casing.

Features of ignition and maintenance of furnaces. Safe operation rules

Before firing up the furnace, inspect the lower container for the presence of water in it. If necessary, moisture is removed, after which 1-2 liters of used engine oil are poured into the module through the filling opening. Fuel is ignited through the same hole using a steel wire wick and oiled rags. After the oil has ignited (usually it takes from three to five minutes), the air supply hole is closed, leaving a gap of 1–2 cm wide. In this case, intensive evaporation of the combustible substance is observed, due to which the furnace operates at maximum power.

Periodically, the bottom of the oil tank, the burner pipe and the chimney are cleaned of combustion products, for which a long poker and various scrapers are used. The upper part of the structure is simply tapped to remove the soot. The unit is serviced after complete burnout of fuel from the lower tank.

It should be remembered that an oil stove, like other heating equipment with an open flame, is a fire hazardous structure. During the operation of a liquid-fuel stove, you should adhere to the rules of safe operation:

1. Preparing the oven for operation must necessarily include checking the presence of traction. For this, a lighted match is brought to one of the holes of the burner. If its flame deviates inward, then you can proceed to ignition. Otherwise, it will be necessary to clean the ducts of the unit and the chimney to ensure a normal vacuum.
2. It is forbidden to shake the working off before refueling. Water or antifreeze that gets into the oil leads to splashing of fuel through the burner injection holes.
3. The fuel level should be no more than ¾ of the height of the primary chamber. It is better to fill the oven beforehand. This will allow the oil to settle.
4. It is prohibited to use gasoline, thinners and other flammable liquids for ignition. Better to use diesel fuel or kerosene, which moisten paper or rags.
5. Any oil spilled near the heater must be immediately removed from the floor.
6. It is strictly forbidden to use water to reduce heat or stop oil burning.

Do not forget about fire extinguishing means. There must be a fire extinguisher and a container with sand near the stove.

Video: do-it-yourself stove in the garage

Thanks to my versatile hobbies, I write on various topics, but my favorites are engineering, technology and construction. Perhaps because I know a lot of nuances in these areas, not only theoretically, as a result of studying at a technical university and graduate school, but also from the practical side, since I try to do everything with my own hands.