Grate bars for furnaces: purpose, types, choice, do-it-yourself installation

A little history

Previously, firewood was burned on a blind hearth - combustion air was supplied through a slightly open fire door. This method has a fire hazard - coals may fall out of the firebox. It is also difficult to accurately select the optimal combustion mode - the regulator is very rough. The ash that covered the coals over time also did not contribute to the normal combustion of fuel - it is an excellent heat insulator (in the combustion chamber of a Russian stove, this is exactly how coals were stored in the ash for the next kindling). Therefore, they began to install a grate - a grate on the hearth through which oxygen enters the combustion zone. The ash is also removed through the grate - nothing interferes with the combustion processes.

The absence of a grate or its damage is not critical - the stove operates without it. True, the efficiency is somewhat lower. And the zone of intense heating of the masonry moves below the hearth - now the base of the ash chamber is also heated. And here you need to be careful if the stove is installed on a wooden base.

Item for arranging the furnace

Choose the optimal location for the heating stove. As an example, a stove installed in the center of the room will give off heat as efficiently and evenly as possible. However, such placement of the stove is not always convenient.

Stove in the middle of the room

If the stove structure is placed against the wall (this option is the most popular and often used), cold will flow across the floor of the house.

Select in advance the location of the combustion chamber door. Design the stove so that in the future you will not have to carry fuel throughout the room, spreading dirt around the room.

The heating stove is located against the wall

The best option is to install a firebox in a room that is rarely visited.

Recommendations regarding the foundation are standard - an individual concrete foundation is installed. It cannot be connected to the main foundation.

Calculate the design of the foundation in such a way that it is able to withstand the load not only of the furnace itself, but also of the smoke exhaust structure, which is also strongly recommended to be built of brick.

Ways to solve the problem

If the grate is damaged, there are two options: fill the ash chamber with a brick or install a new grate.

The option of filling is acceptable only if the integrity is damaged or there are cracks and it is impossible to eliminate them at the base of the ash pit. At the same time, it would be good to replace the firebox door from a blank door to a door with a grille to regulate the flow of secondary air. But this option will definitely create a lot of unnecessary trouble and reduce the efficiency of the furnace. Therefore, we change the grate.

The grate is usually made of cast iron. Cast iron is very different from brick in terms of CTE - coefficient of thermal expansion. This indicator for iron is much higher than for ceramics. Therefore, the grate is always placed freely with a gap of 5-10 mm around the entire perimeter. Some manuals recommend filling the gaps between the masonry and the grate with sand. But this is very stupid advice. Unnecessary and even harmful. Firstly, the sand from the heat of the coals (and it can reach 1100 degrees Celsius) simply sinteres - vitrifies, tightly welding the grate to the masonry and depriving it of the necessary freedom. Secondly, after the first fire, this gap is filled with ash - a non-flammable and non-caking material. So why make unnecessary movements?

It is important to place the grate correctly - an inverted grate quickly becomes clogged with ash and stops working. Therefore, we remember that the grate slits expand downward, not upward. Sometimes the grate has a thickening in the middle - this is to equalize thermal stress, and not to roll the coals to the edges, as some people think.

The figure shows the correct (bottom) and incorrect (top) position of the grate

Usually the grate is placed in a brick trough or in grooves selected in the brick. If the integrity of these grooves is damaged and it is impossible to restore them, you will have to come up with some kind of supports. Sometimes they try to get out of the situation by driving nails, metal plates, etc. into the seams of the masonry. All this is in vain - the metal is quickly tempered and ceases to hold the grate, and more massive pieces of iron are unacceptable - they will tear the masonry.

Stacked and solid options

In different furnaces, the fireboxes may differ not only in size, but also in shape. In this regard, grate manufacturers produce a wide range of products, so you can choose grate bars for even non-standard shaped fireboxes.

By structure they are distinguished:

• Solid cast grate bars . In this case, a product is produced that cannot be disassembled into parts. They are produced in several standard sizes, so when selecting a product you need to rely on the total area of ​​​​the fuel chamber of the furnace.
• Prefabricated gratings are assembled from several parts. From these components you can assemble a grate for a furnace of the desired shape and size.

Buying tips

For high-quality combustion, not only the size of the grate is important, but also the weight of the fuel that it can withstand in one laying. The rods should not deform or wear out.

The grate must have a sufficient number of holes - at least 40% of the area of ​​the part itself. If this figure is lower, then there will not be enough oxygen to maintain the fire, and the ash will remain on the grate and clog the stove.

If the gaps in the grate have a large area, then the remaining fuel will fall from the combustion chamber into the ash pan. Fuel consumption will become uneconomical.

What types of grate designs are there?

If we talk about products made of heat-resistant steel, then there are pipe and chain varieties of grates.

As for cast iron grates, there are several types:

• Tiled . Such rectangular grates are widely used in solid fuel stoves and boilers, fireplaces. We can say that these are universal products. You just need to choose the right grate size.
• Baskets . This type of grate was used in open hearths where food was prepared. Currently, they are practically never found.
• Beam . Externally, such grates resemble beams for construction. They are single or double stacked parts from which you can build a grill of any size.
• Movable gratings . The peculiarity of this design is that the grille links can be moved in a horizontal plane, changing the clearance between them. As a rule, such grates are used for long-burning furnaces.

Types of grate devices

The grates separating the combustion chamber from the ash pan are classified according to the following criteria:

• material of manufacture;
• designs.

Material of manufacture. These perforated plates are made of cast iron or steel; cast iron plates are made by industrial casting; steel plates can be made independently.

For reference. Products made of cast iron (grade SCh-15 or SCh-20) are heavier, but the cast iron grate is more heat-resistant, resistant to aggressive combustion products and is therefore preferable for the stove.

Important! The service life of steel elements is shorter, but it is also measured in years, and steel products are cheaper and can be made by hand.

* Design. Depending on the degree of staticity, grates are available in movable and fixed types.

The movable devices consist of several lattice fragments and an adjusting rod, with which you can change the angle of the lattice ribs relative to the vertical and thereby adjust the size of its gaps. Models of such units differ in the angle of rotation of the adjusting rod, but they are all used in long-burning heating units (not all modifications) and are difficult to manufacture in domestic conditions.

Fixed grate partitions are grates of various sizes and configurations, collapsible or solid, designed for a specific heater design. They are motionless after installation, and their parameters are unchanged.

According to their profile, fixed grates are also divided into groups:

• tile - a rectangular flat grate, with or without stiffening ribs at the bottom, used for any stoves, fireplaces and solid fuel boilers;
• collapsible beams - a prefabricated structure from individual longitudinal cast iron slats, which allows you to assemble a lattice device of any contour;
• basket is an outdated device used in open-type kitchen hearths.

Types of grates: from left to right - flat, beam (segmental), basket.
There is another type of movable grate - chain, but its design does not ensure complete combustion of solid fuel and is therefore used very rarely.

How to install a grate in a furnace yourself

When laying a new structure, installing a grate in a furnace does not present any great difficulties.
According to the sequential masonry scheme, the vent and the base of the firebox are laid out. A cutout is made in the foundation bricks for the grate. Then the process is simple - laying out the base, installing the grille, fixing it with cardboard. It's a different matter when repairs need to be made. Especially when the masonry itself is new and it is not possible to disassemble the entire oven, but you just need to replace the grate. In this case, first of all, you need to carefully study the structure of the furnace. It often happens that the grate bars on one side have a thermal gap, and on the other side the structure is securely fastened with a brick or even two. In this case, you will have to remove the hob and disassemble the stove masonry.

For replacement, it is recommended to select an analogue that matches all sizes of the grille to be replaced. If it is not possible to find a similar one, you can if the nature of the damage allows you to simply saw the structure with a grinder and combine the resulting parts, adding the missing elements along the edges.

Well, if you can’t find an element suitable in size, you’ll have to make a grate for the stove with your own hands.

Why is it needed?

As has already become clear, the grate is a grate that allows the air flow to penetrate directly to the combustion center below, and the ash to be removed through the holes to a specially designated place for it. So why do we need grates in a furnace? Installing a grate in a furnace allows you to solve a number of problems:

1. Divides the combustion chamber into two zones - the combustion chamber itself and a niche for ash.
2. Used for placing and drying fuel.
3. Distributes the air flow from the ash pan.
4. Promotes good traction.
5. Together with the door it makes it possible to control and regulate the flame.

The grate, which is intended for installation in the stove, cannot be made from any metal. Since it is constantly exposed to high temperatures and oxygen, it can begin to oxidize very quickly. Only cast iron can survive in this environment for a long time

Do-it-yourself grate: materials, design, stages of work

As already mentioned, it is easier and easier to make a grate for a stove with your own hands from steel.
There are several options here. The only difference is the purpose for which the lattice needs to be made. For small stoves, which are mainly used for periodic heating of premises, for example, for a potbelly stove, you can use construction fittings with a diameter of 10-12 mm. But for capital heating or heating-cooking stoves, it is better to pay attention to two options - from structural reinforcement or from corners. The advantage of steel reinforcement lies in the availability of this material and the possibility of using previously used sections. In addition, steel reinforcement is more suitable for grates; it does not burn out so quickly, and it is not greatly deformed under the influence of temperature. On the other hand, to assemble this element it is necessary to use reinforcement with a large diameter - 16,18 or even 20 mm. This makes it possible to extend the life of the grille.

The use of steel angles makes it possible to quickly replace a worn-out element; they are not as expensive as other types of rolled products, and by their design they are able to withstand a greater number of heating and cooling cycles than a profile pipe or rod.

The manufacturing technology is quite simple. To assemble a structure from steel reinforcement, it is recommended to first make simple calculations. First you need to calculate the geometric dimensions of the lattice. Here the length, width and height of the product are taken into account. In this case, the height plays no less a role than the length and width; a discrepancy between the height and the cast iron parameter will not allow the grate to be correctly installed in place. A height that is too small will interfere with proper loading of fuel, and a height that is too high will raise the grate above the surface of the bricks, and thus create a space in which ash and unburned fuel will accumulate.

The next step is to calculate the area of ​​the grating. Next, the number of rods is calculated. First, 40% of the area is calculated, approximately how much is occupied by the spaces between the rods. And then the number of rods is calculated. When calculating, it is recommended to round the resulting values; it is not necessary to strictly adhere to the figure of 40%; nothing bad will happen if the gaps are 35 or 45% of the grating area.

The stage of practical work begins with the preparation of material for work - first, the rods are cut; accuracy and precision are required here. After this, a template for assembly is made, markings are made on a section of the board, and nails are simply hammered in to secure the sections of reinforcement. After checking the correctness of the layout, electric welding connects all the elements into one structure. First, tack is done at several points, and then all seams are finally welded around the entire circumference.

Upon completion, the resulting structure is checked in all planes; this is done on a flat surface using a bench angle - all angles must be correct, the lattice itself must be in the same plane. No bends or deformations.

What is needed for production?

It is possible to make a grate with your own hands. What to make a grate for the oven from? It is better to use heat-resistant steel as a material, because it is impossible to work with cast iron at home. To make the grille, you can use any materials that have heat-resistant characteristics. This could be fittings, corners, steel pipes or strips of metal.

To make grate bars you will need:

• the metal from which the grille will be made,
• steel rods for creating partitions;
• ruler, tool for making marks;
• grinder for cutting material;
• welding.

From reinforcement

It is not difficult to make a grate from reinforcement yourself. It is enough to select the desired length of the product and cut the reinforcement with a grinder. It is necessary to determine the number of strips and take into account clearances for ventilation.

When the required amount of material has been prepared, you can begin welding the grate using rods. Do-it-yourself grate bars for the stove made from reinforcement can be seen in the photo below:

What materials are they made from?

The most common grating models are made from two materials.

Made from heat-resistant steel

Steel grates are lightweight, but short-lived compared to cast iron, plus they burn out faster. They will be a good intermediate option for installation in a home grill, which is not used very often. Steel products are also notable for the fact that they are easier to give the required unusual shape.

Made of cast iron

Cast iron grates are stronger, heavier, more reliable and can last a long time. They are most often used to make standard tile or beam grates, which are suitable for active use. For example, in barbecues installed in kebab shops, cafes or restaurants.

Price policy

A quality product cannot have a low price. High-quality cast iron parts that will last for many years are expensive. And vice versa, light and cheap ones, made from a mixture of unknown materials, will quickly become unusable.

Approximate prices for furnace grates:

It is better to buy these products in specialized stores. They provide a wide selection of models with different materials and price categories. Consultants will help you make the right choice based on your preferences, the nature of the fuel, and the frequency of operation of the heating device.

Criteria for selecting grates for a furnace

The choice of grate is determined by several factors, which include the following:

• Type of heating device (structure).
• The type of fuel used - the grate model will depend on this point. If you plan to heat the stove with coal, then you should purchase more massive grates that can withstand considerable mechanical load and extremely high temperatures. Lighter weight products are suitable for wood fireplaces and stoves.
• The grate must correspond in size to the seat in the combustion chamber. More precisely, the dimensions of the grate are usually immediately included in the design of the furnace, based on the sizes of these products offered for sale.
• The distances between parallel grate bars for wood-burning stoves must total at least 40% of the grate area. This factor will help to avoid difficulties when cleaning the product from ash. In addition, gaps less than recommended will create obstacles to the free circulation of air flow. And this, in turn, will lead to a decrease in the productivity of the heating device, as well as to a decrease in the level of safety of its operation. Insufficient air exchange creates difficulties both for complete combustion of fuel and for normal traction. And the delay of combustion products is unacceptable, as this is fraught with very serious consequences.

If the gaps of the grate are larger than necessary, then not only ash, but also unburned fuel particles will fall into the ash pan. The consequence is a completely unnecessary waste of fuel, since unburned particles of firewood or coal that have fallen into the ash pan will no longer produce the expected heat transfer. And in this case, everything is not very good with security.

Practical advice for choosing

When choosing a grate of a certain model, it is necessary to take into account not only the type of material and size of the fireplace, but also the type of fuel used. Thus, coal-fired heating devices require the installation of a grate of 300-350x205 millimeters. Fireplaces using wood or briquetted fuel require the use of a grate from 140x120 mm to 330x252 mm. The grate bars must be able to withstand the weight of one load of fuel. All these nuances can be clarified with the seller of the store where you are planning to purchase stove fittings. Solid combustion products will freely fall through the grill bars if the gaps occupy slightly less than forty percent of the area of ​​the entire device. If the gaps take up less space, then air will not be fully supplied to the fuel, and the fireplace will begin to operate at a slower rate. And if the area of ​​the gaps is larger, the fuel will begin to burn instantly, without having time to release heat into the room.

Dimensions of grate for the furnace

The dimensions of cast iron grates for a furnace depend on the type of fuel. Their possible sizes are presented in the table.

If it is necessary to install beam gratings, you need to remember that the length is 250, 330 and 470 mm.

Tile grate

One of the most common types of grate is the tiled grate. The main feature of this design is the observance of strictly fixed dimensions. This grille is designed for an installation site of a certain size.

A mandatory condition must be met - the presence of a gap between the outer perimeter of the grate and the walls of the firebox of at least 5 mm. If this size is not maintained, the cast iron grate may expand greatly when heated and damage the firebox.

Specifications

A structure of any size can be assembled from beam grates.
Depending on the type of fuel used and the design of the boiler, the grate bars are made of monolithic parts or hollow pipes. The latest models are air-cooled, which reduces the likelihood of metal melting. The shape and size correspond to the firebox of the appliance and the door configuration through which they must pass during installation.

The following types of grates can be installed in ovens:

• Tiled. They are a rectangular product with parallel crossbars. They are universal, as they have different intervals for all types of fuel.
• Baskets. Products with a volumetric configuration that is effective but difficult to maintain.
• Beam. They are set parts from which grates of any size and configuration can be assembled. They are used in self-manufacturing of boilers for assembling non-standard grates.

The correct choice of grate is as important as the chimney, damper and vent. Every detail is important in making a boiler.

Main functions of grate bars

The grate bars are installed in the firebox; as combustion proceeds, the waste is poured into the ash pan.
Any boiler is a structure where each part performs a specific task, ensuring the uninterrupted operation of the entire device.

The grate bars in the furnace perform the following functions:

1. Placement of fuel - coal, firewood, briquettes, and other flammable items. Air enters through the blower, ensuring the presence of oxygen necessary for the thermal reaction.
2. Removing ash and ash. As the loaded material burns out, it turns into a powder and spills down through the grates. The fuel settles on the surface of the metal, and the flow of oxygen to it improves. This frees up space for loading the next portion of fuel.

The efficiency of the boiler depends on the design of the grates; the correct choice of metal for its manufacture ensures the longevity of the device.

Recommendations for choosing cast iron grates for the stove

A correctly selected grate increases the efficiency of the furnace and reduces fuel consumption. Which option is best depends on:

• type of oven;
• firebox dimensions;
• fuel used.

Type of oven

Each type of grate is better suited to a certain type of heating device. for conventional stoves and fireplaces. in solid fuel boilers. Although flat ones are also used, especially in small models.

For long-burning devices, choose a movable option for better regulation of air flow. And when using open stoves, it makes sense to choose a basket model.

Blower

The vent is the first air chamber in the furnace, which usually has a door. The blower chamber is laid out according to the dimensions of the grate. It can be wider than the grate and overlapped by overlap of rows of side walls up to the grate. Through the ash chamber, air enters the firebox through the grate; in addition, it serves to collect ash and other fuel waste.

Blower: 1 - blower chamber; 2 - blower door

The blower door can be of any size, but no larger than the blower door. Through this door it is convenient to remove ash from the wide ash chamber, and as for air, there is enough of it with a door even half as small as shown. Practice has shown that the best place for the blower door is on the second row of the stove masonry. The door is installed in the blower window, which is connected to the blower chamber. When the door is open, air rushes through the window into the ash chamber. The more the door is open, the more air will enter the ash pan and the better the fuel will burn. Air, especially coming from below, is needed to maintain fuel combustion. Hence the name - blower.

Sometimes the door is used to regulate the draft in the oven: the less the door is open, the less draft. It is not necessary to install a blower door, but it is advisable, because without it a draft can occur in devices that do not close tightly, such as valves. And then the heat will go out into the chimney, and the stove will release less heat into the room.

If there is no door, the draft is adjusted using a valve. The more the valve is open, the stronger the draft, and with it more air will enter the stove and the draft will be stronger, which means the fuel will burn better. If there is no door in the ash window, but there is a view, then the fuel will constantly burn with the same intensity, but with this intensity a lot of heat will go into the pipe, which the brick could absorb. The viewer cannot regulate either thrust or fuel combustion.

Let's say that the door is a few millimeters smaller than shown in the figure. In any case, the seams should be no more than 3-5 mm. To do this, the laying must be carried out from the door to the corner of the stove. The last seam turns out thicker than expected, and such a seam cannot be made. To maintain the thickness of the seams, you need to break off a quarter from a whole brick in the corner of the wall where the door is located. You will get a three-quarter and a quarter. Next, you need to break off a larger quarter, taking into account the thickness of the seam. It will seem to lengthen the whole brick. Instead of a whole brick, you need to put the first three-quarter and the second quarter - it will take the place of the thick seam. The masonry of the top row above this quarter will be made of a whole brick - it will block this quarter. If a thick seam is obtained near the door, then you need to do the same in this place.

If, because of the door, the firebox turns out to be several millimeters narrower and the flues are wider, then this will not affect the operation of the stove. In some areas of the country, stoves are installed without a blower at all. In these furnaces, the combustion doors have windows-openings for air intake instead of a blower. In such fireboxes, only wood and peat fuel burns, but the firewood is buried in ash and forms a lot of firebrands. When they burn out, the heat goes into the chimney, so the firebrands have to be pulled out of the firebox and placed in a bucket of water. Such ovens are made due to the lack of grates. If they exist, then they are installed above the blower chamber.

Recommendations for collecting firewood

• You can burn with different types of wood, but to prevent soot from clogging the chimneys, 1/4-1/3 of the wood should consist of aspen;
• It is more profitable to buy firewood in logs of a given length and split them yourself, then in the stored (sold) volume of firewood there will be 15% more firewood, and the price will be 20% lower;
• At the same time, you will receive logs of the largest diameters (d>40 cm) from the lower part of the tree, which gives off more heat during combustion;
• It is convenient to work with logs d>40 cm according to the scheme for chopping large-diameter logs (see figure above): 1 – we chop off the first segment with a cleaver (double chip line), 2 – then the second segment and then with a simple ax we finish the work with the deck, getting 12 -17 logs. Young people enjoy learning the basics of firewood preparation;
• We put the resulting wood chips in a separate container and carefully use them during kindling.
• The final touch of use. The flame in the stove has gone out, the red coals are giving off their last warmth, we are getting ready for bed. However, having overcome daytime fatigue, we load the firebox with washed potatoes, and in the morning there are warm baked potatoes on the table.

Of course, any stove requires care and care in operation, but how pleasant it is in the fall to feel the warmth in the house, which is created not by an electric heater, but by a live fire. If you are also a supporter of this method of heating your home and are ready to understand the diagrams presented above, your home may also have a bell-type stove that “keeps” heat for almost the whole day

You can find out additional design details, as well as details of the construction of a bell-type furnace from the author of the diagrams and its owner on his blog page

If you are also a supporter of this method of heating your home and are ready to understand the diagrams presented above, your home may also have a bell-type stove that “keeps” heat for almost the whole day. You can find out additional design details, as well as details of the construction of a bell-type furnace from the author of the diagrams and its owner on his blog page.

Photos by Vitaly Groshev.