Waste Oil Furnaces

Recommendation points

How to make the stove work as efficient as possible? What does it take to create a do-it-yourself liquid fuel stove? What are the advantages and disadvantages of such furnaces and how to operate them correctly and safely? You will find answers to these questions, as well as assembly recommendations in this article..

Waste Oil Furnaces

In previous articles, I described the usual “basic” steel stoves, grateless long-burning furnaces, piston and “rocket” furnaces. The phenomenon of pyrolysis (combustion of gases), which is used in the last two types, is invariably present in the combustion of any type of fuel. The most energy-intensive fuel is rightfully considered to be synthetic and semi-synthetic oil products – gasoline, kerosene, engine oil, diesel fuel (diesel fuel) and others. It is extremely costly to use them for heating, simply by burning them in the firebox, since they are specially cleaned for operation in an internal combustion engine and therefore are expensive.

But there is one type of synthetic fluids that is not burned during use for its main purpose and remains flammable. These are technical oils. As an accompanying material for the operation of any mechanisms, used engine oil costs nothing. Moreover, it is subject to recycling, which presents a problem for owners of agricultural and urban fleets. Craftsmen, who know how to put into business everything that burns, immediately found the use of “working off” and the furnaces on waste oil were born (POM).

POM advantages

  1. Disposal of waste from the transport industry.
  2. Exceptional combustion efficiency – the content of harmful impurities in emissions is negligible.
  3. Convenient storage and transportation of fuel.
  4. High efficiency (from 90%).
  5. Compactness.
  6. Can be used as a boiler.
  7. Can be used as a stove.

Along with the advantages of POM, it has its own characteristic disadvantages that can be minimized by observing the safety rules that we will give at the end of the article..


POM in its basic form consists of four elements:

  1. Fuel tank. It is a collapsible container for storage and initial combustion of used oil (hereinafter referred to as OM or oil). It can have any shape, but it must be made of metal from 2.5 mm. In the center of the tank there is a hole with a diameter equal to the injector pipe.
  2. Injector (combustion chamber). A vertical cylindrical chamber (container) with perforated walls, in which complete combustion of fuel occurs when secondary air is supplied through the perforation holes. Attached to the tank opening.
  3. Heat exchanger. A hollow tank of arbitrary shape and size, located above the injector, into which the heated gas enters. In the basic version it has a flat shape with a platform for installing containers (kettle, frying pan). Steel bulkheads can be inside to improve heat dissipation.
  4. Chimney. To create a temperature difference and a draft effect, the height difference between the inlet and outlet of the chimney must be at least 3.5 m.The pipe also serves as a residual heat exchanger.

For the manufacture of a furnace for “working off” will need the developed skills of a welder and a locksmith. The main requirement for welds is that they must be tight. Material is also required – sheet metal and steel elements at hand.

DIY assembly recommendations

Since this product is a purely handicraft product that is not produced in factories, there are no standards or specifications for it, but there are rules that must be strictly observed, and we will pay special attention to this.

We make a fuel tank

Mandatory requirements for the tank:

  1. Collapsible or partially collapsible design. Once every one to two weeks, it will need to be cleaned of carbon deposits, coke, etc..
  2. Metal thickness from 3 mm.
  3. Center hole (injector diameter).
  4. Hole or neck (30-50 mm) on a horizontal wall with a control flap for controlling the primary air supply and fuel filling (oil filling).

In the most popular design, when the entire furnace is cooked from sheet and pipe material, the tank has the shape of a washer – so it is easier to make it from scratch from rings of two pipes of adjacent diameters. In this case, it consists of two parts: a sealed bowl with legs and a “lid” with a collar up to 1/3 of the bowl height. The optimum height from the bottom to the injector opening is from 100 to 150 mm.

Waste Oil Furnaces

Question.Is it possible to make a larger supply of fuel due to the size of the lower tank?

Answer.It is possible, but only due to its area. The flame must enter the injector – this is the condition for the operation of the entire system. When burning oil, the level of the liquid mirror in the tank gradually drops and moves away from the inlet. The moment will invariably come when the flame will cease to reach him. For constant replenishment of the fuel supply in the tank, additional feeders are arranged.

This form is not a condition – a used gas cylinder, a steel box or a thick-walled flat canister may well serve as a tank..

The flap for the control hole can be cut out of the tin with metal scissors and simply “put” on a rivet. You can make a neck from a pipe cut by welding a nut from the outside and connecting everything together with a bolt.

Waste Oil Furnaces

We make an injector

Mandatory requirements for the injector:

  1. Height 360-380 mm. 5% less than 1/10 of the chimney height (good draft condition).
  2. Hole diameters – from 9 to 9.5 mm.
  3. The holes are arranged evenly over the surface of the injector or staggered. Distance from the bottom 20-25 mm, top 55-60 mm.
  4. Wall thickness from 8 mm (the thicker the better).
  5. Diameter 100 mm.

Waste Oil Furnaces

To make an injector out of an ordinary pipe, it is enough to perforate its walls according to the requirements above. Then it is welded strictly at right angles to the hole in the fuel tank.

We make a heat exchanger

A separate final article in the cycle about homemade stoves will be devoted to advanced heat exchangers. Here we will consider it as an element of the furnace itself, which maintains the temperature of the incandescent combustion gases and allows it to be realized for heating air or liquid.

Heat exchanger requirements (basic version):

  1. Hollow vessel with bulkhead inside.
  2. The top wall is a flat surface.
  3. Wall thickness from 3 mm.
  4. The chimney hole is off-center (for easy installation of a kettle or pot).
  5. May have an inspection hatch on the side wall for cleaning.

Waste Oil Furnaces

This element can also be in the form of a washer made similar to the fuel tank bowl. The thicker the bulkhead, the better the slab surface will warm up. The inspection hatch can be closed with a 2 mm metal sheet mounted on an exhaust sealant. An outlet with a diameter of 100 mm must have a channel – a 50-100 mm pipe section welded to the top wall.

Waste Oil Furnaces

Chimney features

The section of the chimney running in the room must be made of a steel pipe – this will make it possible to lower the exhaust temperature due to residual heat exchange. The outer section can be made from a conventional tin drainage pipe. However, with a significant temperature difference in winter, this can lead to gas coking in the knees, and the chimney will require regular (14–20 days) cleaning. The best, but also more expensive option is to insulate the pipe from the outside or install a heat-insulated one. It is allowed to arrange horizontal sections 1.5-2 m from the furnace.

Attention! Be sure to install a visor (“fungus”) at the outlet.

The joints of the chimney sections can be collapsible and do not require sealing. Gaps up to 2 mm are allowed. Larger slots will reduce pressure differences and impair natural draft. The collection of elements is carried out in such a way that the air from the furnace falls from a channel of a smaller diameter to a larger one..

It should be noted that the thrust is enhanced and maintained due to the reactive effect that occurs when the injector and heat exchanger are heated. This allows you to reduce the level of the output channel height by 10-20%.

Wood stove adapter

If you already have a steel stove, a wood-burning boiler or a stone stove in everyday life, you can adapt it to be powered by hot oil gases. The adapter is an injector with a fuel tank.

In principle, the design is completely similar to the one given above, but the firebox of the existing furnace acts as a heat exchanger. In the furnace, instead of burning fuel (wood, coal), hot gas from the burner enters and then the furnace operates in normal mode.

Recommendations for converting the furnace to an oil turbo burner:

  1. Make the adapter according to the drawings and recommendations given above. Its difference will be knee 90? without perforation on the injector.
  2. On the outlet channel of the elbow, weld a pass-through steel sheet that exactly matches the section of the loading hatch.
  3. For a secure installation to avoid accidental shifts, provide fasteners on the hatch and the passage.
  4. The adapter must be stable, and the position of the axis of the injector channel must coincide with the center of the hatch opening. This may require setting the oven to the appropriate level..
  5. The chimney pipe must be arranged in accordance with the requirements for POM.

Waste Oil Furnaces

The oil adapter will expand the capabilities of a conventional oven. This is especially true for heating garages and workshops..

Waste oil furnace without welding

With all the other advantages, the manufacture of POM without welding, at first glance, is impossible. But, as we know, the operation of the furnace and the combustion of the flame are based not on the properties of the material (steel, cast iron), but on physical and natural phenomena that constantly occur in the same way everywhere and change only under the influence of environmental conditions. We will use this inviolable law by using for the assembly of POM another non-combustible heat-absorbing material that is traditionally used for furnaces – brick.

The main advantage of the furnace design, which will allow us to implement the idea, is the constant draft. It negates the advantages of welding tightness by quickly removing carbon monoxide and combustion products through the channels of the system.

For laying brick POM, we need:

  1. Fireclay bricks – about 40 pieces.
  2. “Fireplace” masonry mortar or clay – 1 bag.
  3. Oil pan about 150x400x60 mm and a door (you can from the old hatch).
  4. Injector (see above).
  5. Steel sheet 6-8 mm 400×800 mm.
  6. Two steel pipes with a diameter of 120-150 mm – 1 and 1.5 m.
  7. Corrugated sleeves with clamps for pipe diameter – 3 pcs.
  8. Duct fan or “snail” – 1 piece.
  9. “Dropper” for uniform oil supply.
  10. Smooth non-combustible base.

Operating procedure

1. We lay out a flat area of ​​bricks 40×80 cm. This will be the base and the fire layer.

2. We spread the sides “on the edge” from three sides. The distance between the axes of the bricks of the walls – no more than the length of the brick.

Waste Oil Furnaces

3. Cut out the steel sheet so that it covers the entire area of ​​the box. We make holes in it for adjusting the air (side) and the injector (in the middle).

4. We install the injector on the sheet (with bolts), and the sheet on the brick box through the solution.

Waste Oil Furnaces

5. We erect 4 walls “on the edge” with a height of three bricks so that the injector has air access from all sides.

6. Lay brick on the walls, combining them. It turned out to be a flat platform with an injector channel.

Waste Oil Furnaces

7. Above the channel, place the pipe 1.5 m at the level, leveling it along one of the outer planes.

Waste Oil Furnaces

8. From above, we install a 1 m pipe strictly coaxial to the bottom on temporary fasteners (mortar, wire).

9. We cover the pipes with bricks “on the edge”. You should get a brick box – this is the heat exchanger.

Waste Oil Furnaces

10. The top wall (“cover”) can be simply laid with a brick, having previously connected the chimney channel (can be made from a corrugated hose).

11. We connect the pipes with a corrugation and install a fan on the lower pipe.

Waste Oil Furnaces

The result is an efficient stationary POM without welding..

Attention! Use this oven only with the fan on. Otherwise, overheating of the heat exchanger pipes and significant deformation is possible..

One notable drawback unites all types of oil burners – the properties of the fuel. Used oil stains surfaces and has a characteristic technical odor. When it gets on a hot surface, it burns out, leaving an unpleasant odor. The rest of the inconvenience can be reduced to naught by observing the simple rules for handling these ovens.

Twin design

For those who need to alternate the types of fuel, the option of a furnace with two reactors is suitable *.

* Reactor – the place of fuel combustion and the formation of a thermal (in this case) energy release.

A twin stove consists of two fireboxes – for solid and liquid fuels, combined into a common heat exchanger. A particular and most common case of such an arrangement is when an air heat exchanger in the form of a container is connected to an existing potbelly stove or long-burning furnace, and an oil turbo burner or adapter is subsequently mounted to it. At the same time, such a stationary structure allows you to change the type of fuel without performing additional actions.

The main advantage is the ability to carry out revision, repair work and modernization without interrupting the heating process. This is possible if there are shut-off devices on the system channels (so as not to depressurize the heat exchanger).

Waste oil furnace operating rules

In everyday life, an oil stove is no more fire hazardous than any other types of open fire-based heating devices. In most cases, they are installed in garages, workshops or utility rooms..

  1. Keep extinguishing media nearby (applies to all types of stoves) – fire extinguisher, sand.
  2. Always check the draft before firing up. To do this, bring fire to the injector hole. It should be pulled inward. If this does not happen, or the flame deviates outward, “walks”, under no circumstances light the burner! Check the elements of the stove and the chimney – possibly cleaning is required.
  3. The fuel tank must not be full. The optimum level is 3/4 from the bottom along the liquid mirror. Also, it should not be empty – leave 1/4 for the sump.
  4. Do not shake the settled oil before refueling. If there is water in it, it will sink to the bottom. Water that gets into the fuel during combustion will cause the burning oil to spray out through the nozzles (holes) of the injector.
  5. The supply valve from the feeders should be located 20-30 mm higher from the bottom.
  6. The best mode of POM operation is uniform combustion. Use drip devices for smooth fuel delivery and adjustment.
  7. Remove oil thoroughly if spilled.
  8. To ignite, moisten paper in kerosene or diesel fuel and lay on the surface of the oil.
  9. Allowed to inject air through the filling hatch when warming up.

Correctly assembled and adjusted furnace during “working off” can successfully replace the boiler. More precisely, it can become a boiler efficiently running on waste fuel. To do this, you need to equip an efficient heat exchanger. We will explain how to do this in the next article..

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