How to make a long-burning boiler on wood and coal with your own hands

Are you sick of having to fill your boiler with fuel every time it gets chilly in the winter? We’ve got some good news for you, though! We’ll demonstrate in this article how to construct a wood- and coal-burning, long-burning boiler in your backyard. Embrace comfortable warmth that lasts for hours on end and bid adieu to the hassle of frequent refills.

Your home can be affordably heated with a highly efficient boiler that you can build with a few basic materials and basic do-it-yourself skills. When wood and coal can be used to provide warmth, there’s no need to rely only on pricey heating systems.

Building your own long-burning boiler is a terrific way to lessen your environmental impact in addition to saving money on heating expenses. Choosing to use readily available coal and wood as fuel sources instead of just fossil fuels is a more environmentally friendly way to heat your home.

This comprehensive guide will take you step-by-step through the process of building your own long-burning boiler, regardless of your level of experience with do-it-yourself projects or your desire to simply cut costs on heating bills. Prepare to relish continuous warmth and coziness throughout the winter months, thanks to your DIY heating system.

Materials Needed Step-by-Step Instructions
Steel Barrel or Drum 1. Cut a door on one side of the barrel for loading fuel.
Insulation Material (e.g., Vermiculite) 2. Line the inside of the barrel with insulation material to retain heat.
Pipe for Smoke Exhaust 3. Drill a hole at the top for the smoke exhaust pipe.
Grate or Grid 4. Install a grate or grid at the bottom for airflow.
Air Inlet Vents 5. Make air inlet vents near the bottom for proper combustion.
Firebricks or Refractory Cement 6. Use firebricks or apply refractory cement to the inside walls for durability.
Chimney 7. Connect a chimney to the smoke exhaust pipe for safe ventilation.

How to increase the duration of combustion of solid fuel

Many homeowners would love to have a solid fuel boiler that they won’t need to refill with wood every four to six hours. Taking advantage of this, producers and retailers of heating apparatus label all heat generators, including pellet generators that can operate on their own for up to seven days, with the prefix "duration of burning."

Using the smoldering mode with a restricted air supply usually justifies the length of the burning process. However, here’s why burning coal and wood in this manner is inefficient:

  1. Wood and coal boilers reach their efficiency of 70-75% during maximum combustion. During smoldering, the efficiency of the unit decreases to 40-50% (as with a conventional bubbler).
  2. Smoldering firewood emits little heat energy. Who needs a "long-burning" heat generator that does not fully heat the house??
  3. Freshly cut wood of certain species (e.g. poplar, willow) and low-calorie fuel cannot be burned normally in the smoldering mode.

When all else is equal, the only factor affecting the length of the process in solid-fuel long-burning boilers is their larger fuel chamber. The basic idea is that heat is released and the fire burns longer when there is more wood in the firebox.

These are the types of household boilers that can run for up to 24 hours on coal and 8–12 hours on wood.

  • classical, with forced air supply;
  • operating on the principle of upper combustion (like Baltic "Stropuva").

With the right equipment and welding experience, these TT-boiler designs are easily manufactured at home. Drawings of solid fuel and sawdust mine boilers can be found even on the vast expanses of the Internet; however, since these heaters are quite large and challenging to produce, they merit their own discussion.

Classic long burning boiler

This section features a homemade coal and wood heating unit that our skilled technician Vitaliy Dashko designed and built. Constantly refining the design, the master assembled to order several dozen of these heat generators in various capacities. View the following video for a quick rundown of the TT-boiler:

Boiler efficiency and dependability have already been put to the test over time on a variety of objects. The following are the technical attributes of the unit’s model that is being presented:

  • capacity – 22-24 kW;
  • duration of combustion (on average) on wood 10-12 hours, minimum – 8 hours;
  • the same, on coal – up to 1 day;
  • 75-77% EFFICIENCY;
  • maximum working pressure in the heating system – 3 bar, nominal – 1.5 Bar;
  • the amount of water in the boiler tank – 50 liters;
  • product weight – 150 kg;
  • the size of the loading opening (width x height) is 360 x 250 mm;
  • total volume of the furnace – 112 liters, useful (for fuel loading) – 83 liters;
  • firebox depth – 46 cm, optimal log length – 40 cm.

As a point of reference. Master produces long-burning boilers with a range of capacities, including 16, 24, 36, and 130 kW units. When ordering from a master, the total cost of the finished product for 24 kW is approximately 450 USD. You can speak with Vitaly directly about any queries you may have about the solid fuel boiler device and its manufacturer; his contact details are provided on the "Our experts" page.

The drawing illustrates the components and general measurements of the DIY long-burning wood boiler:

The heat generator runs on coal as well as wood with success. Since it is not ideal to fill the chamber to the brim, the fuel compartment’s useful capacity is determined up to the lower edge of the stoking opening. The boiler operates in the following sequence:

  1. After laying and ignition of solid fuel the doors are hermetically closed.
  2. On the electronic control unit the desired temperature of the heat carrier is set, it is recommended not to be lower than 50 °С. The unit is then switched on by pressing the appropriate button and the fan is started.
  3. When heating up to the set temperature, the fan is switched off, the air access to the fuel compartment is stopped. The TT boiler is in standby mode, the wood smolders very weakly and gives practically no heat.
  4. After the temperature in the boiler tank drops, the controller gives a command to start the fan and the combustion process in the furnace resumes.

At its discretion, the controller modifies the fan’s capacity to maximize combustion efficiency. This DIY boiler burns coal and wood in an intense mode; it does not have smoldering combustion. Instead, it operates in standby mode.

The boiler drawings in section: provide an internal device representation of the unit.

The heating unit carries out the traditional method of burning solid fuels by directly transferring heat to the boiler tank’s bottom, or the vault, and the walls of the water jacket. This tank contains the heat exchanger, which removes heat from the flue gases. Through the grate, heated air from the duct is fed into the furnace from below. What guarantees the length of combustion is:

  1. The large volume of the firebox.
  2. Completely blocking the air access to the furnace in standby mode. When the fan is switched off, a gravity damper operates, closing the duct and thus preventing the chimney draught from fanning the coals.

The following drawing illustrates how the heat exchanger and rear portion are arranged:

Tools and materials for manufacturing

Low-carbon steel grades St3, 10, and 20 are typically used on the blanks for the assembly of a solid fuel boiler with a long combustion period. Heat generators made of St 20 are the best option and can last up to 15 years. Because steel with higher carbon content (St 35, 45) can roll at high temperatures, it is not a good choice for welding with heat generators.

Heat-resistant steel alloyed with molybdenum and chromium (e.g., 12XM, 12X1MF) can be used for the combustion chamber if you have the necessary welding experience and can afford to purchase more expensive metal. This article explains how to independently determine the grade of steel with a sufficient approximation.

This is a table that lists the blanks that you will need to assemble a solid fuel boiler by hand:

A helpful tip is to use guillotine shears to cut the blanks somewhere in the workshop. Thus, you will be able to cut and deburr much more quickly by hand.

You will also require the following materials:

  • angle equal-sided 50 x 4 mm for the manufacture of grates;
  • DN50 pipe – for the heat exchanger and connection pipes of the heating system;
  • DN150 pipe – to the chimney flue;
  • 60 x 40 mm profile pipe for the air channel;
  • steel strip 20 x 3 mm;
  • basalt insulation with density of 100 kg/m³ and thickness of 2 cm;
  • smooth sheet metal 0.3-0.5 mm with polymer coloring;
  • ready-made door handles;
  • cord, asbestos cardboard.

Among the equipment are a welding machine, a drill, and a Bulgarian. ANO-21 or MR-3S welding electrodes are used. The remaining items are a typical assortment of measuring tools and equipment found in every home.

Utilized in the TT-boiler automation kit, which is made in Poland and includes a temperature sensor, fan, and control unit (don’t confuse it with the Chinese version; they look the same). The control unit (KG Elektronik SP-05) and the fan (DP-02) are marked.

Assembly of the heating unit

The fuel-box body of the long-burning boiler is assembled using tack welds to join 4 mm thick metal in the first step of manufacturing. As seen in the picture, everything begins at the bottom of the unit, to which the side walls, vault cover, and door openings are tacked:

In accordance with the drawing, the bottom sheet is made for each side and doubles as the ash pan door’s bottom frame. Angle bar shelves, on which the grate will be supported, are welded inside the chamber. Every joint on the assembled fuel box is carefully welded, and its tightness is verified.

Installing the 3 mm metal water jacket is the second stage. Sections of steel strip should be welded to the fuel box’s body, allowing them to protrude by 20 mm, because the side walls are only 2 centimeters thick. They have steel cladding sheets nailed to them.

Take note! The ash chamber is not cleaned by the water jacket, which begins at the grate level.

The middle of the so-called clips is staggered. This is a steel circle that has been butt welded to the furnace after passing through the holes in the boiler tank wall. As seen in the picture, the second end of the clip is welded around the hole.

A brief explanation of how to create extra clips for the homemade solid fuel boiler’s water jacket edges. A 20 mm strip must be inserted from the end between the walls to a depth of 50 to 100 mm, and both sides must be welded.

Installing flame tubes in the boiler tank’s upper section is the third stage. Pipes are inserted into holes that are cut in the front and back walls in accordance with the drawing for this purpose. Both their ends and every joint in the water jacket are hermetically welded.

The fourth step involves the production of doors and grilles. Weld a strip in two rows to the inside of the doors, and place asbestos cord in between to act as a latch seal. Angle #5 is used to create spike grates, and the outer corner is welded downward. Thus, they act as diffusers for the air that enters the ash pan through the fan.

In the fifth phase The flue pipe and the air duct made of 60 x 40 mm pipe with the fan mounting flange are installed, and the supply and return pipe connection fittings are cut into the boiler tank walls. In the center of the back wall, directly beneath the water jacket, is where the air duct enters the ash chamber.

Step six involves welding the door hinges and inserting pieces that are 2 cm wide to secure the long-burning boiler’s decorative lining.

The final step is number seven. The boiler tank is insulated with basalt on the top and sides, which is fastened with a cord. The painted metal sheets must then be fastened to the embedded components using self-tapping screws, and the doors must be installed.

Ultimately, the control unit is mounted atop the boiler, and the fan is fastened to the air duct’s mating flange. The temperature sensor needs to be placed underneath the basalt insulation on the unit’s back wall. Furthermore, if desired, the following practical additions can be made to the design of a homemade long-burning boiler:

  • to build a water heating circuit for DHW into the boiler tank;
  • Provide a dip sleeve for the installation of a thermometer – in case of a power failure when the controller display goes out;
  • same for mounting the safety group;
  • install an electric heating element that heats up the heating medium after the wood has burned through.

A brief explanation of how to heat water for domestic use by circulating it through a solid fuel boiler. Ten meters of copper tubing with a diameter of 8 to 12 mm must be used, and the tubing must be bent into a spiral shape. The latter is led outside from the unit’s back side after being wound around the flame pipes inside the boiler tank. We receive a long-burning, two-circuit boiler.

It should be noted that the experience with using these heat generators has demonstrated that homeowners who wish to heat their homes at night must install an electric heater. In other situations, the combustion time is sufficient to avoid having to rush to the boiler room in the middle of the night to add more firewood.

Any time during the process, the legs can be fastened to the unit by choosing the right rolled metal sections. See the author’s video, "The Master: The Creator of the Heating Unit," for the specifics and mysteries surrounding the TT-boiler assembly:

We’re delving into a useful do-it-yourself project in this guide to heating and insulating your home: building a long-burning boiler that burns coal and wood. You can effectively heat your home while saving money on energy bills by using this do-it-yourself solution. We will guide you through every step of the procedure, from obtaining the supplies to putting the boiler together. By following our advice, you’ll not only keep your home warm during the cold months but, over time, lower your expenses and environmental impact. This project, which offers a sustainable heating option for your home, is both doable and rewarding, regardless of your level of experience with do-it-yourself projects.

Boiler with top burning fuel

These heat generators are known by two names in the former Soviet Union:

  1. Baltic units by Stropuva and their derivatives from other manufacturers.
  2. Bubafonya wood stoves.

The Bubafonya stove has become very popular as a heater for dachas, garages, and other buildings with low requirements to the product’s aesthetics. It is unknown which of the heaters appeared first. Not much can be said about upper combustion boilers, despite the fact that many people mistakenly believe that they are the only type of solid fuel heat generator that can operate continuously. Actually, their one and only advantage remains the same: a massive fuel box.

These boilers work on the basis of the combustion of fuel that is compressed from top to bottom by a weight. Through a telescopic pipe attached to the load, air is also supplied to the combustion zone from above. The following figure displays the unit’s working diagram:

The feedback from owners on forums indicates that Stropuva boilers had numerous operational flaws.

  1. It is not possible to add logs to the furnace until the previous one is burned out. Physically it is possible, but then the principle of top combustion will be violated, the flame will cover all fuel layers.
  2. When working on fresh sawdust and other small debris, fuel residue "hangs" on the walls.
  3. The efficiency of the TT-boiler is not very high because there is no heat exchanger in it. Because of the air heating chamber and the large fuel box, there is no space for the heat exchanger.

The heat generator no longer has any serious flaws, and you can choose to fix certain issues with the homemade version. As an illustration, arrange the ash chamber by placing the bottom and grates. The drawback associated with after-loading can also be eliminated by adding a second door between the stoking and ash doorways. Another one of our experts, Vladimir Sukhorukov, has this idea for updating the upper combustion boiler. He discusses it in his video.

Preparation of materials

Although the round body presents certain manufacturing challenges, a square body would also not work because the fuel would "hang" in the corners. It is preferable to remove this component from the Bubafonya stove because there is an issue with the assembly of the telescopic pipe with a load. An illustration of a long-burning boiler that is about the same size as the traditional model is as follows:

Prior to building the boiler, we choose the materials based on the drawing:

  • DN 400 pipe with a 5 mm wall – for the fuel tank;
  • the same, DN 50 – for the air supply and water connections;
  • the same, DN 100 – for the chimney;
  • blank from a 10 mm thick sheet with a circular shape with a diameter of 38 cm;
  • 40 x 4 mm strip for the air distributors;
  • 16-20 mm diameter reinforcement of periodic profile – on the grates;
  • basalt wool with a thickness of 3 cm and density of 100 kg/m³;
  • thin sheet metal with polymer coating.

The water jacket’s material selection is dependent on how it is installed, as a home craftsman is unlikely to find rollers in stock that can give the metal a 3 mm cylinder shape in thickness. The following are the variations (as displayed on the scheme below):

  1. Scheme №1. Take a thin-walled pipe of a larger diameter, although it is not easy to find such a pipe, and an ordinary one will weigh the boiler down a lot.
  2. Scheme #2. Two sheets of metal to bend in 2 places at an angle of 60 °, and then weld the two halves together. You will need a press brake.
  3. Scheme No. 2 in another version. Welding jacket of 6 sheets – segments on clips.
  4. Scheme #3. Weld a rectangular box, which will increase the volume of the boiler tank.

Additionally, 3 mm sheet metal is required for the air damper, the bottom with the lid, and the framing of the doors.

Manufacturing of the heat generator

Cutting blanks and openings in the pipe wall in accordance with the dimensions shown in the drawing is the first step in the production process. Canopies and handles are affixed to parts that have been cut out to form doors. The grate in the picture is prepared using the reinforcement:

The upper combustion boiler’s assembly algorithm generally looks something like this:

  1. Cut a hole in the round billet for the load, insert the pipe into it and weld it.
  2. Weld 6 curved strips to the bottom of the weight, which will serve as air distributors.
  3. Attach the bottom to the furnace, install grates inside.
  4. By cutting a hole in the center of the cover for the air pipe, to attach it to the fuel box. Before this it is necessary to put the pipe with the load in place.
  5. Weld the chimney spigot.
  6. Assemble the water jacket according to the selected scheme, tightly weld all joints.
  7. Make tapping connections for the heat transfer medium.
  8. Perform insulation and lining of the boiler, install the doors.
  9. Place a damper on top of the air pipe.

Because a fan cannot be placed on a moving pipe, installing automation and supercharging on a durable overhead combustion boiler is challenging. A flexible hose must be made, and the temperature sensor must have a submersible sleeve. The combustion zone in these heaters is constantly displaced downward, making it impossible to place it under the insulation.

For individuals who want to improve the heating system in their home, building a long-burning boiler using coal and wood can be a satisfying project. You can design a heating solution that meets your needs and is both economical and effective by following the instructions provided in this guide. Whether you’re driven by self-sufficiency, sustainability, or financial savings, building your own boiler gives you the ability to take charge of your heating needs.

The capacity of a long-burning boiler to deliver steady heat for extended periods of time is one of its main advantages. These boilers require less frequent refueling because they can maintain warmth day and night with the right design and insulation. Long-term energy cost savings are possible by maximizing heating output and reducing fuel consumption through the optimization of combustion efficiency and heat retention.

Additionally, you can alter the boiler’s features to fit your unique needs and preferences by building your own. You can adjust the design to suit your needs, whether your top priorities are ease of maintenance, fuel versatility, or space efficiency. Furthermore, adding safety features like temperature controls and adequate ventilation guarantees safe and dependable operation of your DIY boiler.

Building a long-burning boiler is also a chance to lessen your carbon footprint and participate in sustainable practices. Utilizing wood that is locally sourced or other biomass fuels that are renewable can help reduce your dependency on fossil fuels and promote environmental conservation. Your heating system’s environmental friendliness is further enhanced by well-managed combustion processes and emissions control mechanisms, which support healthier environments and cleaner air.

In conclusion, building a long-burning boiler using coal and wood has many advantages, including financial savings and environmental protection. With a little creativity mixed with common sense, you can create a dependable and cost-effective heating system that fits your priorities and values. Warming your home with a homemade boiler will make you feel good, regardless of your level of experience with do-it-yourself projects or building.

What type of heating you would like to have in your home?
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Sergey Ivanov

I like to help people create comfort and comfort in their homes. I share my experience and knowledge in articles so that you can make the right choice of a heating and insulation system for your home.

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