how to improve a potbelly stove in the garage

The lightweight and easy-to-use metal stove “potbelly stove”, with all its advantages, has one significant drawback: low efficiency.
To heat a room, an ordinary metal potbelly stove usually spends 50-70% of its efficiency, the rest of the heat simply flies out into the chimney.
It is clear that it is very difficult to reconcile with such a situation, but unfortunately, few stove owners take radical measures to increase the efficiency of the furnace. Although, as experience shows, with a little skill and spending a little time you can get a fairly effective stove from this gluttonous design.

Why increase efficiency?

The compact dimensions of the stove mean that the surface that heats up during operation is small. Not much heat flows outside and the room quickly cools down. Sometimes it seems that the return from the potbelly stove is weak.

To help it increase efficiency, several tasks are solved:

the duration of combustion and smoldering increases;
a sufficiently high combustion temperature is ensured;
a high level of traction is achieved.

Standard potbelly stove efficiency

Design

In some cases, traction force can be directly related to operating conditions, for example:

The potbelly stove needs to be inspected from time to time for cracks, especially pay attention to the slabs and the perimeter of the firebox door. If cracks have formed in these places, then these places need to be covered up or completely replaced. The decrease in draft may also be due to the fact that during use, soot has accumulated inside the pipe on the walls and the clearance has become smaller.. You can even determine how well the stove is working by the color of the flame

For example, if the flame is red with dark stripes, then there is not enough air. If you often hear a hum from the chimney and the flame is bright white, then there is too much air. And if the flame has a golden-orange color, then the draft in the stove is normal

You can even tell how well a stove works by the color of the flame. For example, if the flame is red with dark stripes, then there is not enough air. If you often hear a hum from the chimney and the flame is bright white, then there is too much air. And if the flame has a golden-orange color, then the draft in the stove is normal.

Methods to increase efficiency

There are several ways to increase the efficiency of a potbelly stove in the garage and stop freezing. They are complex in varying degrees: from a sandbox to an updated design. All of them are produced without serious financial costs, and improvised means are used for their implementation. Let's consider each method for increasing the efficiency of a potbelly stove separately.

Changing the chimney

The efficiency of a potbelly stove is directly affected by the shape of the chimney. To ensure that heat transfer does not suffer, the pipe design must meet certain parameters.

The pipe must be vertical. Angles with an inclination of no more than 45 degrees are allowed. If conditions force you to insert 90-degree angles, then you should try to use them as little as possible.

Angle 90, replace with 45

Make the chimney higher

Brick screen around the stove

The brickwork around the device allows you to retain heat and protect yourself and others from contact with hot metal. Properly placed masonry increases heat transfer by about a quarter. When the potbelly stove is heated, the brickwork heats up. After the fuel burns, it will continue to share the collected heat. Experts advise laying bricks not close to each other, but 30 centimeters from the walls of the firebox.

To lay out the screen, you will need a couple of dozen heat-resistant bricks:

the screen is laid out on clay mortar;
the first row is laid out according to the intended markings;
in the second row, ventilation gaps are made the size of half a brick;
the brick is laid out in accordance with a pre-designed shape and size for the opening;
A steel strip is attached to the last row for additional fixation.

Improving heat transfer using fuel

A metal stove is heated in different ways: from wood to sawdust with small debris. To improve heat transfer in a potbelly stove, compressed sawdust, briquetted industrial waste and coal are used.

Compressed sawdust burns out much more slowly - one load is enough for many hours of smoldering.
Briquettes are made from wood shavings and waste. The pressed composition allows them to smolder for a long time, because they cannot flare up. Briquettes smolder evenly and for a long time, increasing the heat transfer of the potbelly stove.

Sawdust briquettes

It is also worth assessing the traction force. This can be done by looking at the color of the flame. If there is not enough air, the flame turns red and dark stripes appear; if there is too much oxygen, the flames become bright white. The draft, and with it the efficiency of the stove, is normal when the flame is golden-orange. For better traction, you can blow the potbelly stove using a conventional fan.

Sandbox

If you have no desire at all to re-equip your stove, add anything to it, or experiment with different types of fuel, there is the simplest and most economical method. A box is placed on the potbelly stove, in which two buckets of sand are placed.

Place 2 of these buckets in a box on top of the stove.

Redesign of the structure

Steel corners welded on the sides strengthen the device itself and increase the temperature of the furnace. Metal side screens are also screwed on for these purposes.

Craftsmen attach sheets of iron 6 centimeters from the walls of the firebox. This is done so that the heat energy is transferred using convection, due to which air moves between the installed plates and the body of the potbelly stove.

Install protective metal screens

To prevent the heat energy from disappearing so quickly, you can use a metal cassette. It is a cylindrical object welded from a sheet of steel. It is called a cassette because it is inserted into the combustion chamber. A little firewood is loaded into the cassette, turned over and placed in the potbelly stove so that the firewood itself gradually falls onto the heated coals and ignites. While the wood already in the firebox is burning, the remaining wood in the cassette is dried and lights up after the first layers.

Using additional coolant

The stoves are complemented with water tanks and so-called water jackets in order to use them as an additional coolant and save energy.

The water jacket is designed as follows. A U-shaped tank in which water is heated is mounted in the housing. Two pipes branch off from the tank: for supply and processing. The tank itself is fed by tapping into the pipeline.

The efficiency of a potbelly stove increases without the help of specialists and serious financial investments. To make the stove heat up better, we can resort to changing the design, additionally covering it with masonry, or simply change the type of fuel. All these methods differ in complexity, but have one thing in common - they work.

How to increase the heat output of a furnace

So, how to increase the efficiency of such a stove? There are several simple ways. The most basic one is to put a brick screen around the stove. The bricks don’t even need to be held together with clay; just lay them on top of each other. You can fold such a screen near the side walls, or you can fold it at both side and rear walls. The brick will heat up while the fire is burning, and when it becomes small or goes out, it will give off heat. You won't have to add fuel often. One of the features of a potbelly stove is that the stove is light and mobile. With such a screen, it will not lose its mobility, because the bricks can be disassembled at any time, the stove can be rearranged and the screen can be folded in a new place.

https://youtube.com/watch?v=SNKEQmQMxl4

There is another method with a screen, which also increases heat transfer. In this case, a sheet metal screen is mounted at some distance from the side and/or rear wall of the stove. The sheets can be secured using long bolts. In this case, the effect of convection is added.

There is another simple way to increase heat transfer. This time the stove's chimney is being modernized. Typically, such stoves have a straight chimney. It is removed through the roof of the room in which the stove is installed. If you add several bends to the pipe, then the heat transfer will increase, although not by much. In this case, the pipe will resemble the letter S.

If you want it to be much warmer, then you need to take 2 tanks from old-style washing machines. The tanks are welded together, and a chimney is passed through them. Thus, above the potbelly stove, which is heated with wood, there is also a stove of the same size, heated by hot smoke. Heat transfer almost doubles.

Another method is to weld additional ribs onto the stove and chimney, for example, from metal angles. In this case, the chimney must be made of thick metal. Such fins significantly increase the heated surface area. An increase in area leads to faster heating of the surrounding air. The room becomes warmer. In addition, thick metal retains heat even when the fire in the firebox is no longer burning.

But still, it will not be possible to endlessly increase the efficiency of this heating device. And if you want to have a full-fledged stove in the room, you will have to build it out of brick according to all the rules, so that the stove retains heat for a long time, for example, all night. For example, there is no need to increase the efficiency of a Russian stove; it already retains heat for a very long time. True, in order to fold it correctly, you will have to call a stove specialist.

https://youtube.com/watch?v=GeMINGFp_lo

Ways to increase efficiency

Potbelly stoves are made in various shapes and sizes. But they have one drawback in common - low efficiency. More than half of the thermal energy, in the literal sense of the word, flies out into the chimney. The irrational use of heat has led to the fact that the owners of these heating devices began to think about possible changes in the design of the furnace to increase its efficiency. The solution to this problem could be a partial modernization of the potbelly stove. There was no single concept for solving this issue, and each stove owner began to solve the problem independently, by trial and error.

Increasing the efficiency of a potbelly stove means receiving additional heat from the heating device while maintaining a constant amount of burned fuel. This can be achieved in several ways:

changing the heat transfer surface,
increase in heat removal;
using more high-calorie fuel;
increasing the heat capacity of the furnace.

The potbelly stove gives off heat to the surrounding space not only with its body, but also with its metal chimney. You can increase the heat transfer surface of the device by revising its dimensions upward. This option is possible when creating a stove with your own hands. Having already made a potbelly stove, you can do it in another way. Usually a corner is welded to a chimney made of a metal pipe. Position it with its apex facing the element along its entire length. The angle is installed around the pipe. Thus, the area of the heat transfer surface can be increased by 3-4 times, depending on the size of the corner.

Another option for increasing the heat transfer surface is to make a chimney running inside a large area. For this purpose, a chimney with turns is made. They are performed in the form of smooth transitions. It is undesirable to create turns at right angles, as the potbelly stove may start to smoke. The last section of the chimney is installed vertically. A pocket is made on it with a hatch for cleaning soot.

If it is impossible to lengthen the pipe, its design is changed. Cylinders made of pipes with a diameter of 300-400 mm are welded onto the pipe coming out of the furnace body. They are connected to each other by pipe sections with a diameter no less than that of the smoke pipe. They are welded out of alignment to increase the smoke path.

How to improve draft in a potbelly stove using fuel

Only an oven that is not filled to the brim can ensure sufficient air circulation. Determining the sufficient amount of fuel can be done as follows:

Prepare a standard size bucket and put fuel in it.
Place a small portion in the firebox and light it.
Continue adding fuel until the beginning of the hog - a horizontal chimney for removing gases - takes on a cherry tint. This volume will be minimal.
Add fuel and watch the far part of the hog - 1/5 of it should remain dark. This figure will be the maximum.

Thus, with fairly simple actions that do not require costs, you can increase the efficiency of the potbelly stove and extend the service life of its individual parts.

Ensuring heat removal

It is possible to increase heat removal by creating devices that promote natural and forced convection. To ensure natural air circulation, screens are made with a guide device that allows you to create a powerful convection flow and distribute it throughout the room. The guide apparatus is made in the form of curved strips of metal, welded to the screen and directing warm air not only upwards, but also to the sides. The prepared device is attached to the oven.

The heat removal device can also be made from scraps of water supply and profile pipes. The distance from the floor to the bottom edge of the elements must be at least 15-20 cm. The pipes are welded to the stove body and covered with a screen on the sides to protect against accidental contact. A traditional potbelly stove heats the air around it by 0.5-1.0 m, and the use of such a design allows you to increase not only the radius, but also the rate of temperature rise in the room. When the body of the heating device is heated above 60 °C, a stable convection draft appears in the device, the power of which increases as the temperature of the furnace increases.

Heat removal can be increased by using fans to blow over the heat transfer surface. Both household and old car fans are used. Devices with variable rotation speeds have proven themselves especially well. They allow you to regulate the temperature and heating time of the room in various oven operating modes.

For more efficient blowing of the furnace elements, special casings are installed that allow cold air to be directed to the hottest areas of the heating device, while it can be taken from various places in the room. A potbelly stove with pipes welded into the firebox for heating air has proven itself well. A multi-speed car fan installed on a common discharge manifold allows you to effectively heat the room.

The combined use of devices for artificial airflow and natural convection can significantly increase the efficiency of a potbelly stove, which means heating the room more efficiently.

Types of stoves for home

Classification by intended use

Heating. Such stoves are used only for heating a room as a sole or additional heater. Heating stoves circulate and heat the air.
Heating and cooking. Such stoves can be used to warm up the room and for cooking instead of a stove.

Classification depending on design

Straight-through.

The operating principle of such furnaces is as follows: air moves into the ash pan, goes up and, bypassing the grate, exits through the pipe.

Disadvantages of once-through furnaces:

Low efficiency, due to the fact that along with cold air, warm air also leaves the furnace, which could still be used to heat the room.

Pros:

Due to the fact that such stoves are made of brick, which retains heat well, the room warms up evenly and retains heat.

Duct.

This type of furnace is an improved direct-flow furnace. That is, due to the many channels, warm air does not immediately go into the pipe, but, following them, warms the room. When installing channel furnaces, the linear dependence of the efficiency on the length and number of channels should be taken into account.

Bell bells.

Such stoves serve to retain heat in a room. Warm air, in accordance with the laws of physics, tends upward, where the cap holds it. As the air currents cool down, they become heavier and fall down. And, since the cold air is no longer needed, it comes out through the undercoat.

Advantages of bell furnaces:

They ensure uniform heating of the room due to their design.
Soot can be easily removed, as it accumulates in one place - under the hood.

Classification depending on material

Brick

Pros:

Autonomy. That is, having “refueled” the stove once, you don’t have to worry about it for a long time.
Heat retention. Brick structures conduct heat poorly, so it remains in them for a long time.

Minuses:

They take a long time to warm up.

Cast iron

Pros:

Easy to install and does not require a foundation.
Not fire hazardous.
Compact.
Heats up quickly.
Huge selection of stoves according to external data.
No additional lining required.
There are automatic cast iron stoves that independently regulate the temperature.
High efficiency.
Performance is relatively less dependent on the amount of fuel.
Low price.

Minuses:

They cool quite quickly and require additional heating.

Increasing heat capacity

The heat capacity of a potbelly stove can be increased both by increasing its weight and dimensions and by using additional heated materials. In any case, it is necessary to make design changes to the heating system. One option may be to use smoke circulation inside the oven. This can be done by installing sheets of heat-resistant metal in the firebox, thereby providing additional paths for the movement of gases. At the same time, they are burned, heating the furnace to a higher temperature. But at the same time, the temperature of the exiting smoke also increases. With a short chimney, the heat is simply released into the atmosphere.

To use this heat, a heat-storing container is installed on the exhaust pipe of the potbelly stove, which can be made either from an old gas cylinder or from a large-diameter pipe. The container is filled with large stones that retain heat well. At the same time, it is loaded to approximately 2/3 of the volume. The stones are placed on the grate. Hot gases flowing through the battery heat them up and, giving off heat, go outside.

The stones are heated to a temperature of about 400 °C. After the fuel burns out in the stove, the damper on the chimney is closed and the room is heated using the heat accumulated by the stones. In this case, the stove is in a cold state. Using such a battery allows you not only to save fuel, but also to receive heat after the stove stops working.

The battery, which increases the efficiency of the furnace, can be made of brick and installed on metal supports above its surface. But such a design cannot be used with a round stove.

The calorie content of fuel depends on its type and quality. Replacing fuel with a higher-calorie fuel is expensive and requires additional storage space. As a rule, garages are heated with waste material that is easy to find. Now, knowing how to increase the efficiency of a potbelly stove, you can begin work. It should be noted that the best results are obtained with the integrated use of methods that increase the heating efficiency of the furnace.

The third type of stove-stove

Now let’s figure out how to construct a homemade potbelly stove with a square body with thin walls and an adjustable draft. The main advantage of a square-shaped potbelly stove is its larger surface area of interaction with air, that is, greater efficiency compared to a stove based on a pipe.

The most optimal dimensions for a homemade stove will be a structure height of 800 mm and a base of 450 × 450 mm. A potbelly stove of this size will not take up much space and can easily accept almost any piece of wood.

Chimney installation diagram.

You should also determine what thickness of metal will serve as the material for the stove. Here, as in everything, a golden mean should be observed: very thick walls (about 1 cm) take too long to warm up, thin-walled metal sheets swell after heating, and the stove will become shapeless.

For these purposes, choose an average wall thickness - approximately 0.3-0.5 cm. Then the potbelly stove will retain its original appearance and will perfectly warm the room.

Eight ways to increase efficiency

The efficiency of a wood-burning stove varies between 60-80%. It all depends on its design, the length of the chimney, the materials used for its construction and the firewood used. The efficiency increases significantly when using birch and oak logs with a humidity level of 13-15%. The higher the humidity, the less heat transfer and the more resin will remain on the internal surfaces.

You can increase the heat transfer of a potbelly stove and increase the efficiency indicator in the following ways - here is a list of them:

Providing pyrolysis combustion of wood - it increases efficiency by 5-10%.
Creating smoke circulation – the main task here is to maximize heat extraction from combustion products.
Creating a natural convection system will improve the airflow of the potbelly stove, increasing heat transfer and accelerating the heating of the room.
Fan blowing - as in the case of natural convection.
Lining the potbelly stove with bricks retains heat and stabilizes the temperature.
Increasing heat transfer through an air heat exchanger is a complex but very effective method.
Increasing the length of the chimney is important if there is free space in the room.

Let's look at each method in more detail. All the modifications presented in the review can be done using the example of a simple rectangular potbelly stove.

Organization of smoke circulation

It is quite easy to increase the efficiency of a potbelly stove - you just need to improve the heat extraction. In traditional stoves, it instantly evaporates into the chimney. As a result, the efficiency remains low, and the stove heats the street. In other words, you literally throw away about 30-40% of the wood, it goes to waste. The problem is solved in a simple way - you need to retain the heat inside the potbelly stove for as long as possible. For this purpose, two smoke circulations are organized in it. They allow you to increase resistance, causing heat to escape into the walls.

This problem is best solved at the initial stage of assembling the potbelly stove. Weld two pieces of sheet iron into it, as indicated in the drawing. They form two smoke circuits. Passing through them, combustion products will give off heat to the maximum. And only after that they will go up the chimney.

Scheme of a stove-stove.

Pyrolysis combustion

Combustion products are full of heat and contain flammable elements. Afterburning them with secondary air allows you to extract additional kilocalories. To achieve this, wood is burned with limited supply of primary air. The next task is to burn out what is contained in the combustion products. Pyrolysis gases burn releasing a large amount of thermal energy. It is absorbed and emitted by the metal walls of the potbelly stove. Due to this, we will be able to increase its efficiency.

To organize pyrolysis combustion, you will need smoke circulation from the previous section. At the level of the first turn, the supply tube is welded. Secondary air is supplied through it. In its presence, the pyrolysis products are burned out - the efficiency increases by 5-10% of the initial value. On a monthly basis, this will result in savings of several tens of kilograms of firewood. Be sure to provide for a secondary supply if you have already installed smoke circulation.

Creation of a convection system (+fins)

Increasing the efficiency of a potbelly stove with your own hands involves creating a convector. Natural convection improves heat removal and ensures quick heating of the room. By installing a stove with a convector in the garage, we will get an excellent heating device. Literally 15-20 minutes after ignition, a comfortable temperature will be established in the garage. Our task is the following - we need to create a convector that sucks in air from below and exhausts it from above.

The easiest way to increase efficiency is to equip your potbelly stove with a metal screen. It is a sheet of iron that wraps the stove on the sides and back like a shirt. The distance between the body and the sheet is from 3 to 5 cm. The sheet is welded onto metal spacers - make them from thin reinforcement. The result is a fairly simple convector. The only problem is that the area of thermal energy dissipation will remain the same.

Fins will help increase the efficiency of a potbelly stove. It can be done:

From a profile rectangular pipe 20x40 mm.
Made from a U-shaped metal profile.
From a traditional round inch pipe.

We scald the back and side walls with the selected material. This will help increase the dispersion area. At the same time, we will get an effective convector.

Forced airflow

Forced convection is more effective than natural convection. And it’s not so much a matter of efficiency, but rather the speed of heating the room. For these purposes, you need to use any fan – even a household one. We place it 50-60 cm from the stove, connect it to the power supply, turn it on and enjoy the result. A powerful air flow will effectively remove heat from the surface of the stove and distribute it throughout the room. The costs are minimal - you only need an old fan with a low noise level so that it does not put pressure on your ears.

Chimney modification

Quite an interesting way to significantly increase the efficiency of a traditional potbelly stove. To do this, we take the following steps:

Take a small old gas cylinder or other metal container.
We weld metal tubes between the bottom and the lid.
We make cutouts in the side walls to suit the diameter of the chimney.
We cut the chimney and weld the resulting module into it.

Such a non-trivial solution will significantly increase the efficiency of your potbelly stove.

The result should be a design like the one in the picture below. Next, all that remains is to install a fan opposite the module, blowing air through the tubes. This step will help increase efficiency by removing the heat remaining in the combustion products.

In other words, our task is to cool the combustion products as much as possible, removing all remaining thermal energy from them.

Brickwork construction

It cannot be said that this method allows you to radically increase the efficiency of a metal potbelly stove. It provides:

Maintaining temperature when the flame goes out.
Safety of using the stove.
Creation of natural convection.
More uniform heat transfer.

Increased efficiency can be achieved in other ways. As for the brickwork, which follows the contours of the rear and side walls, it only complements other technical solutions.

Increasing the length of the chimney

Increased efficiency is achieved by increasing the total length of the chimney. Moreover, it is not the vertical part that increases, but the horizontal one. The bottom line is that combustion products will heat the metal of the chimney, which is why most of the heat will be retained indoors. The gases at the outlet of the chimney will become much colder.

When increasing the length of the chimney pipe, it is necessary to place the potbelly stove at one end of the room, and place the chimney itself at the other end. The horizontal section of the pipe will connect the chimney to the stove and ensure efficient heat removal.

An additional way to increase efficiency is to retrofit the chimney with convection pipes. This step will increase the heat transfer area and create additional convection.

Installation of reflective screen

This step will increase efficiency by 1-2%. We will not touch the stove itself, but will cover the corner in which the potbelly stove is installed with galvanized iron. Thus, we will prevent some of the heat from escaping into the walls, directing it into the heated room. Fireproof thermal insulation can be laid between the iron sheet and the wall.

Working with a long-burning boiler

The question of how to heat a long-burning solid fuel boiler is multivariate, since the boiler can heat both by combustion and by layer. This feature allows you to significantly increase the operating time of the unit with just one load.

Loading and lighting the device is quite simple:

Firewood is placed upward in the firebox;
chips and paper are added through the loading door;
the paper is set on fire, you must wait until the wood chips ignite;
when the door is closed, you can turn on the control unit.

If all the steps have been performed correctly, the top layer will gradually begin to flare up; while the unit is operating, the entire filling will burn through from top to bottom.

In some cases, when the entire system has not fully warmed up, a small amount of barely visible condensation may appear on the walls of the heat exchanger. Sometimes this liquid can leak out of the hatches, forming small puddles on the floor. Mostly this situation is temporary. A boiler that has proper circulation will no longer produce condensation after heating the system.

Immediately after turning on the control system, it is better to leave the solid fuel device in operating mode with a high temperature. In this case, the room and the unit itself will warm up faster, after which the temperature can be reduced.

Making an ash pit

An ash pan is a grate near a potbelly stove, on which fuel will subsequently be placed to heat the room.

A good ash pan provides the combustion chamber with a sufficient amount of air (that is, oxygen), and also provides good draft, thereby ensuring better combustion. In most cases, ash pans in potbelly stoves leave “much to be desired,” so upgrading the ash pan will help improve the performance of the potbelly stove.

An effective ash pit should be made of heat-resistant material and have a door, thanks to which you can avoid smoke in the room. Improving the ash pan will help turn an ordinary potbelly stove into something like a fireplace.

Materials and tools

a metal sheet,
fittings,
welding machine,
metal working tool,
ash door.

Instructions

Making an ash pan yourself will require certain skills from you, and the production must be in accordance with the instructions:

First you need to weld the box to the size of the potbelly stove, without the top wall and leave a rectangular cutout in the end wall. Steel is most often used in production. The dimensions must correspond to the width and length of the potbelly stove itself.
Make holes in the bottom of the stove. The diameter of the holes should be about 20 mm.

Drilling holes for the ash pan
Weld the box to the stove.
Install the door into the ash pan.

This design will give better and more uniform operation of the potbelly stove.