An integral part of an autonomous heating system is a chimney. Proper design and proper installation of the pipe for the removal of combustion products will prevent the appearance of an unpleasant odor of carbon monoxide during the burning of firewood.
What should be the chimney for a solid fuel boiler
The main purpose of the chimney is to remove exhaust gases after burning wood in the furnace. The ability to remove combustion products is characterized by natural draft, which creates a chimney due to rarefaction of air when the height changes from the place of intake of combustible gases to the level of emission into the atmosphere. The change in atmospheric pressure between the lower and upper points of the pipe is measured in Pascals. This characteristic depends on the value of the height and diameter of the gas outlet channel.
For the smooth operation of solid fuel equipment, boiler manufacturers indicate the vacuum value for the models being sold. Depending on the capacity of the heating unit, the requirements for the chimney change: the higher the productivity, the higher the vacuum. In order to save the consumer from complicated calculations of the length and diameter of the chimney, the manufacturers of boilers indicate the recommended diameter and height of the channel for the removal of combustion products.
ATTENTION! With the independent manufacture of a heating boiler, the size of the chimney is similar to that of industrial analogues in terms of power.
The main requirements for the chimney are matching the length and cross section of the channel to create the required draft. The shape of the cross section also affects the quality of traction, but to a lesser extent. The channel material must withstand high temperatures and not corrode. Condensate formed inside the pipe has destructive properties.
Is it possible to make a chimney for a solid fuel boiler with your own hands
Installation of a simple channel does not require high qualifications. It is important to observe the correct assembly and monitor the tightness of the joints of the mounting elements of the structure.
A complex chimney consisting of horizontal channels lined with bricks, designed to use the heat of combustion products for heating purposes, will require the involvement of an experienced stove-maker. An independent study of the features of masonry brick chimneys will allow you to complete the work, but will take a lot of time.
Installation of a chimney flue from metal pipes will not take much time and will allow you to completely remove combustion products with the correct selection of diameter and height. Manufacturers of heating equipment offer a wide selection of metal products for the removal of combustion products. They have various sizes and convenient fasteners.
IMPORTANT! When assembling the connections, the upper element of the chimney is inserted into the bottom so that condensate flows down the inner surface of the channel!
What material do you need to make a chimney from
Modern chimneys are made of:
Asbestine chimneys have long been used for the removal of combustion products. At the beginning of the XXI century, researchers revealed the harmful effects of this material on human health when heated. Given the low cost, asbestos pipes are in demand until today. They are connected to the boilers through metal adapters.
Glass chimneys have a very high cost. Ceramic pipes are difficult to install. Both of these materials are rarely used to remove exhaust gases, but due to the fact that the inner surface is very smooth, there are people who want to build such a chimney.
Brick chimneys traditionally used in the construction of furnaces. To connect the brick structure to the boiler, metal transitions and connecting elements are used.
The presence of condensate inside the chimney makes the use of steel pipes inefficient. They wear out quickly. A common material for flue ducts is heat resistant stainless steel. Systems of this material are equipped with all kinds of adapters, turns and fasteners, which allow you to quickly and efficiently install pipes for the removal of combustion products. A smooth inner surface contributes to good traction and makes system maintenance convenient. The heat-resistant properties of the material can withstand high temperatures when using coal.
What knowledge about the chimney is needed for making it yourself
For independent execution of works on the assembly of the smoke exhaust channel, it is necessary to understand that an air stream must pass through the working hole, ensuring the required combustion mode of solid fuel equipment. This flow is measured in cubic meters. m / hour. The need to change the magnitude of the movement of hot air is due to the thermal characteristics of the boiler.
The greater the boiler output, the greater the amount of air flow must pass through the chimney. In other words, the draft is directly proportional to the power of the heating equipment. Usually, special tables are used to determine the diameter and height of the smoke exhaust duct or similar parameters are recommended by boiler manufacturers.
REFERENCE! SNiPami provides for the calculation of draft heating equipment for exhaust gas. The calculation is due to the large amount of initial data of the boiler, chimney materials and comes down to determining the vacuum expressed in Pascals. Such a calculation does not give a clear definition of the size of the pipe.
What tools will be needed
To perform installation work on the installation of the chimney channel you will need:
- measuring devices;
- locksmith tool;
- drill, hammer drill;
- wooden blocks.
IMPORTANT! When installing the flue channel, the connection of metal elements is performed using wooden spacers. Hammering is prohibited on the end of the pipe.
How to make a chimney drawing
Before mounting the flue duct, it is necessary to make a sketch and make sure that the design is correctly selected. The drawing shows a side view of the house and draw a gas exhaust pipe.
When the distance from the ridge to the pipe is less than 1.5 m, the chimney is projected above the top line of the roof by 50 cm. When changing the position of the chimney to 3 m, the upper part is installed at the level of the ridge. And with a greater distance, draw a tangent line along the upper point of the pipe and roof. The slope of the drawn line should have a deviation from the horizon of no more than 10 degrees.
In addition to the sketch of the house with the display of a pipe for exhaust gas applied to it, they draw a drawing of the passage of the channel through the roof, overlapping floors and connecting to heating equipment. It can be the same, or another drawing. The connection of the boiler with the chimney is performed at a right or obtuse angle in the direction of the combustion products.
ATTENTION! Connecting pipes through an acute angle will disrupt natural draft and will not allow the smoke exhaust system to function normally. The smell of burning will be constantly present in the house, and in order to get rid of it, the connection will have to be redone.
The drawing indicates the height and diameter of the channel for exhaust gases.
How to calculate the height of the chimney for a solid fuel boiler
When calculating the value of the pipe height (Wr), a special formula is used that takes into account:
- boiler power, for example, MK = 30 kW;
- required static thrust, St = 23 Pa (for household boilers with a capacity of 25-30 kW);
- temperature of exhaust gases, Tg = 530 K (for firewood);
- ambient temperature, T0 = 290 K (for middle latitudes).
The formula uses calculated coefficients 3459 and 1.1, which are constant values.
Wr = St * Tg * To / 3459 * (Tg-1.1 * To) = 23 * 530 * 290/3459 * (530-1.1 * 290) = 3535100/3459 * 211 = 3535100/729849 = 4, 84 m
The obtained value is calculated for the accepted values of static thrust and combustion temperature. All calculations are made in Kelvin.
ATTENTION! To calculate the parameters of the coal-fired boiler pipe, the temperature of the combustion products is taken 200-400 degrees higher (depending on the type of solid fuel).
Chimney diameter for solid fuel boiler
The diameter of the channels for exhaust gas do not less than the size of the outlet pipe of the heating equipment. It is impossible to reduce or narrow the cross-section of the pipes - this impairs the draft and interferes with the combustion process. An increase in the passage size is acceptable, but with a small jump.
ATTENTION! When the boiler is manufactured on its own, the diameter of the nozzle is made the same size as that of analogues of industrial manufacturers of heating equipment. The model of mass-produced units is selected according to the power or similarity of the size of the furnace and the volume of the water jacket.
How to make a chimney for a solid fuel boiler yourself: step by step instructions
The presence of skills in working with metalwork and power tools will allow you to easily install chimney pipes with your own hands. Consider the possibility of self-assembly of a metal channel for the removal of combustion products.
- First of all, all the constituent elements are prepared: bends, transitions, extension cords and fasteners.
- Cut a hole in the roof and ceiling with a grinder and install a mounting clamp in the lower part of the roofing and under the ceiling.
- The upper chimney pipe is mounted in the designed place, having previously installed a protective umbrella and a water reflector on it.
- Collect the required number of meter (standard length for individual elements) pipes from the roof surface to the ceiling. Connect with the top element and fasten under the ceiling. When performing installation near the wall, each meter-long section of the chimney is fixed with a clamp.
- After that, pipes are assembled with a tee, which is designed to be connected to a boiler or extension cord. Then insert the upper part into the connecting bell of the chimney channel under the ceiling and join the horizontal bell of the boiler with the assembled structure. Using wooden spacers, tightly knock down the joints of the flue system. After verifying the rigidity of the fit of the individual elements, the clamps fix the assembled structure.
ATTENTION! Before drilling holes for installing clamps, it is necessary to pre-assemble the elements of the chimney for the accuracy of drilling holes.
The distance of horizontal sections should not be more than 1 meter. If the length of the connected sections of the pipe is longer, then use inclined mounting elements.
- The cavities around the pipes, at the intersection with the roof and the ceiling, for tightness, blow foam.
IMPORTANT! Use only heat-resistant mounting foam. The temperature of the gases inside the channels reaches 400 degrees.
- After completing the work, check the tightness of the ceiling, and especially the roof. Water must not leak under the water deflector and seep through the pores of the mounting hole.
The chimney is ready for operation. We can say with confidence that the use of heat-resistant stainless steel is the best solution for the construction of a chimney system. Compliance with all requirements, including fire safety, will allow the use of the assembled design over a long period of time.