- №1. Briefly about the principles of work
- №2. Types of solid fuel boilers according to the principle of operation
- Classic solid fuel boilers
- Pyrolysis boilers
- Boilers of long burning
- Pellet boilers
Access to electricity and gas is not everywhere, but you have to warm yourself somehow. An excellent solution is to install a solid fuel boiler. Not only does it allow you to create completelyautonomous heat supply system, so still in operation veryeconomical. Solid-fuel boilers are used as the main and reserve source of heat, and for the production of thermal energy burnfirewood, sawdust, coal or pellets. This is quite bulky aggregates, and fuel has to be thrown regularly, but low cost received energy allows solid-fuel boilers to still compete with more modern gas and electric. We'll figure out which solid fuel boiler is best for a private house, determine the power, type of heat exchanger and other nuances.
№1. Briefly about the principles of work
It would seem that the difficult in a solid-fueled boiler? He threw wood or coal in a furnace, they burnt, they heated the water, and the house was filled with warmth. In general, everything is so, but the principle of the device is somewhat more complicated.In the design of a modern solid fuel boiler, we can distinguish such basic elements:
- coolant circulation system;
- Smoke removal system;
- safety system;
- heat accumulation system.
ATfurnacefuel is supplied and burned to produce heat. This is in the classical version. There are pyrolysis boilers in which solid fuel (firewood) smolder, releasing gas, which then burns, providing heat generation. The efficiency at the same time increases somewhat, but we will deal with the peculiarities of the operation of classical and pyrolysis boilers later.
The furnace is a large container with double walls, between which there iscoolant. This is in most cases water, less often a non-freezing liquid or a mixture of water and antifreeze is used. The heat carrier receives heat from the burned fuel, circulates through pipes and radiators, heating the air in the house. Cooling down, the water returns to the boiler and everything repeats. Often, special pumps are used to improve circulation.
When burning fuel, not only heat is generated, but also gases that need to be removed. For this purpose the systemsmoke removal. The chimney removes gases from the boiler to the street, sometimes a system of forced ventilation is used to increase the efficiency of this process.
The mostgreat danger, which can happen during the operation of a solid fuel boiler, iscoolant overheating. The water can already be sufficiently heated, and the boiler will continue to produce heat. If the water boils, the heating system can not stand, especially if there are metal-plastic pipes that are sensitive to high temperatures. It is almost impossible to stop the burning of firewood or coal - it only remains to decrease the intensity, and that an overheated coolant does not enter the system,cooling heat exchanger. It receives cold water from the water pipe, but in the event of a water shut-off it is best to always have a sufficient supply of it.
The cooling heat exchanger may beis built into the boiler or located between the boiler and the rest of the heating system.It can be integrated only in the construction of a steel boiler. It works in one of two possible ways:
- first option -cooling of the heated coolant, which passes through the cooling heat exchanger. Cold water in the cooling heat exchanger is fed through a thermo-valve, which opens when the temperature of the coolant reaches + 950 ° C. The process lasts until the coolant cools down to a safe temperature;
- The second option provides forshut-off valve. If the water temperature rises to critical values, the valve does not allow it to enter the pipes. The heating system is supplied with cold water from the water main, and the superheated coolant is drained into the sewerage system. True, the water pressure should be sufficient, and in its composition there should not be an increased amount of salts that will provoke the formation of scale.
Drain heated water into the sewage system - not very smart and economical, so the design of a solid fuel boiler is better to supplementaccumulator tank. This is the buffer between the boiler and the rest of the heating system, through which thea number of important functions:
- accumulation of warm waterfor its further use, and this is fuel economy, comfort, stability in maintaining the temperature and reducing the number of trips to the firebox to fuel the fuel;
- protection from accidents. In the tank, superheated water mixes with warm water;
- possibility to use boilers of different types. The accumulator battery will be common for solid fuel and, for example, a gas or electric boiler, will allow simply organize a single heat supply system at home and insure yourself with several sources heat.
Heat accumulators are made of cast iron or steel, they receive a powerful thermal insulation.Volume of the buffer, first of all, depends on the boiler's capacity: for each 1 kW it is necessary to provide 25 liters of the tank volume. The quality of this heating system element should be the highest, so trust is better than the products of well-known manufacturers. In the online store https://www.duim24.ru/ Only heat accumulators from proven companies are represented, the range includes tanks of different volume and material of manufacture.
№2. Types of solid fuel boilers according to the principle of operation
With a similar general scheme of the device, different types of solid fuel boilers have some nuances in the design. The entire existing range can be divided into the following types:
- Classic, or traditional boilers;
- pyrolysis, or gas-generating boilers;
- boilers of long burning;
- pellet boilers.
Classic solid fuel boilers
Such boilers are much like ordinary furnaces. Heat is obtained as a result ofburning fuel burning. As the last use, as a rule, firewood or coal. Fuel is supplied through one door, and through another - the boiler is cleared of ash and other products of incomplete combustion. Traditional boilers can have both a cast iron and steel heat exchanger, they are usually used in systems with natural circulation.
Although the efficiency of this kind of devices is not the highest, they are valued forreliability, because in the design of the boiler, the minimum of electronic components that can break down. The only element of automation is a temperature regulator, but it also works by a mechanical principle. Classic boilers are durable and rarely require repairs.
Pyrolysis (gas-generator) boilers are somewhat more complicated. In their design there istwo combustion chambers. First put solid fuel (wood), at high temperature and oxygen deficiency occurspyrolysis processwith the release of pyrolysis gas. It passes into the second chamber, where it burns and gives heat to the heat carrier. From wood there is only charcoal.
The combustion temperature of pyrolysis gas is higher than that of firewood, which provides an increase in the efficiency of the boiler to 90%. If we take into account the fact that the process of smoldering wood is slower than its combustion, we can talk about another advantage - one fuel bookmark is enough for10-13 hours(for classical boilers this indicator is 5-7 hours). The fuel used is hardwood and low moisture (no more than 20%).
Boilers of long burning
This type of boiler is much like pyrolysis, but it differs in some technical features. Solid fuel smoldering in the first chamber, forms gases that burn out in the second furnace. At the same time, only the upper part of the fuel is involved in the process of decay and combustion. Due to this, it is necessary to load it less often, and the efficiency grows. One loading of firewood is enough for the boiler to worktwo days. The main disadvantage is the high cost of equipment.
They are also often called automatic boilers. According to the principle of action, they differ little from traditional ones, but apart from the firebox, they havebunkerfor storage of a stock of fuel. This means that it will be unnecessary to often approach and throw fuel into the furnace manually - everything will be done by automatics. Between loads of fuel,7 days. In addition, such a system can be very precisely adjusted for yourself. Fuel is considered one of the most environmentally friendly at the moment. Pellets are pellets that are made from wood waste (sawdust, shavings, etc.).The efficiency of such systems is 91-95%, the only negative is the high price of boilers.
No. 3. Heat exchanger material
There are not many options here. Heat exchangers can be:
- cast iron.
It is difficult to say unequivocally which solid fuel boiler is best to choose from - everything depends on the budget, operating conditions and personal requirements. Producers produce both, and those boilers.
Cast iron heat exchangers have such advantages:
- they are going tofrom individual sections, so their transportation and installation is easier. Moreover, if one of the sections is damagedcan replace, sodurabilitysuch boilers at altitudes - up to 20 years and more;
- Cast iron during use is covered with a film of iron oxide. It is dry rust, which almost does not progress, protecting the rest of the material from the negative impact. Cast ironmore resistant to corrosion, therefore, the heat exchanger will have to be cleaned less often;
- cast ironretains heat longer, this is a plus. The other side - it is warming up more slowly.
Amongminusesgreater weight, higher brittleness than steel, and poor resistance to thermal shocks. If the temperature changes sharply, the cast-iron heat exchanger can easily crack, so avoid entering the still cold heat exchanger with cold water.
The advantages of a steel heat exchanger can be attributed:
- higherstrength, and since such a heat exchanger is brewed at the factory and leaves whole, it becomes possible to manufacturecombustion chambers of complex configurations, due to which the efficiency is increased;
- highresistance to sudden temperature changes. Boilers with such heat exchangers, as a rule, receive more advanced automation, since the temperature can be controlled freely, without fear of damaging the structure;
- not such a high weight as cast iron;
- faster heating, but also rapid cooling.
On the other hand, steel is more susceptible to developmentcorrosion processes. Despite the resistance to temperature changes, with frequent similar fluctuations, cracks can occur in the welding places. In which caseit will be impossible to repair the steel boiler- will have to buy a new one, so the durability of such structures is lower.
№4. Thrust and energy consumption
Solid-fuel boilers can be divided into two types:
- nonvolatile with natural draft. They do not need special pumps, so they do not consume electricity. In such a performance, classical boilers and some long-burning boilers function. Well suited for areas where power failures often occur, can be used as a backup source of heat;
- volatile with additional thrust. The design provides for a fan, which helps the air to enter the combustion chamber. In this version, most boilers of long-term combustion, pellet and pyrolysis boilers are produced. Thanks to the control panel, you can make some adjustments.
№5. Number of loops
Single-circuit boilersOnly responsible for the heating system. There is alsodouble-circuit boilers, which allow to provide a system of hot water supply to a private house. This is very convenient, but when calculating the required power it is necessary to take this feature into account. In addition, there are boilers equippedcooking plate.
Pay attention to the fact that solid fuel boilers are installed on the floor - models with wall mount does not exist.
№6. Calculation of solid-fuel boiler power
One of the main indicators, which should be first of all to pay attention when choosing a solid fuel boiler, is its capacity, on which it depends, what area it can provide with heat. It is necessary to proceed as one fromof the area of the heated premises.You can use the generally accepted rule: for every 10 m2 of space, 1 kW of boiler power is needed. This is subject to normal thermal insulation and ceiling height is not more than 3 m.
It turns out that a boiler of 15 kW will be sufficient for heating a house of 150 m2. He even at an outside temperature of -360C will maintain the temperature in the house + 180C. If there is insufficient thermal insulation at home, as well as in a harsh climate, it is better to take a boiler with a small margin of power.
If the boiler is to be used in a hot water supply system, this must be taken into account when calculating the heat exchanger capacity. Experts say that to provide comfort in a house, the power of a double-circuit boiler should not be lower than 24 kW in any case. More accurate calculations are best entrusted to professionals who will take into account all the features of a particular house and heating system.
№7. Type of fuel
In the furnace of a solid fuel boiler you can throwfirewood, coal, pellets and sawdust. It is a mistake to believe that the boiler's capacity will remain unchanged, no matter what fuel it is used for. Many models of boilers can work with different types of fuel, but the maximum power will be achieved only by using the fuel that the manufacturer specified as the main one. When using less caloric fuel, the power will fall by 25-30%, and if it is excessively wet, the power drop can be up to 40%.
Average parameters of heat transfer of different types of fuel:
- firewood - 2500 kcal / kg. Logs of wood usually have a length of 25-30 cm, can be sawed or chipped. It is important that the wood is dry;
- coal anthracite - 7400 kcal / kg;
- coal - 7000 kcal / kg;
- Brown coal - 3500 kcal / kg;
- pellets - 4500 kcal / kg.
№8. Volume of combustion chamber
The larger the volume of the combustion chamber, the more fuel can be loaded, and the less often run to the furnace and throw up a new portion. In the characteristics of the boiler it is customary to indicate such an indicator as the ratio of the volume of fuel loading to the boiler's power, measured in l / kW. Since the steel boiler with the same power as the cast iron will have slightly more compact parameters, for it this ratio is, l / kW. For cast iron boilers l / kW. The higher this indicator, the less often it is necessary to run to the boiler.
Boilers withtop loading of fuelthe useful volume is greater, and the fuel in this case is distributed more evenly. With front loading, especially if it is a cast-iron multi-sectional heat exchanger, it will be necessary to exert some effort to distribute the fuel evenly.
№9. What else to consider when choosing a solid fuel boiler?
Obviously, even before the purchase of the boiler it is worth determining whether the boiler will be the main source of heat or reserve. In the latter case, it is necessary to install an expansion tank or heat accumulator - it's easier to do immediately than to upgrade the existing system.
If in the future there will be an opportunityswitch to gaseous fuel, it is necessary, when selecting, to pay attention to the possibility of transforming the boiler. Many traditional boilers by installing an inflatable burner can switch to gas. Convenient, but it is worth considering that the efficiency of the converted boiler will be lower than that originally designed for gas.
№10. Producers of solid fuel boilers
We will not open America, if we say that quality largely depends on the reputation of the manufacturer. Large companies will not spoil their name with products of inadequate quality, so when choosing a solid cat it's better to pay attention to models from proven manufacturers. This is the case when it is better not to save.
To mark it is possible boilers of such marks:
- Buderus- German company, which specializes in the production of boilers of different types and purposes. Solid-fuel models operate on different types of fuel, there are classical and pyrolysis boilers, the capacity is sufficient for heating large private houses;
- Boschproduces traditional non-volatile boilers;
- Ferroli- a large Italian company, produces domestic and private boilers. Among solid fuel boilers there are coal, wood and pellet boilers. The assortment is wide, the quality is at height;
- SIME- Another Italian company that made a name in just 35 years. The products are exported to 50 countries of the world, the assortment is represented by boilers on coal and wood;
- VIADRUS- Czech boilers. Presented in a fairly wide range, reliable, safe, distinguished by a pleasant value;
- Stropuva- Lithuanian manufacturer, who often presents new solutions in the field. The latest development is a 40 kW boiler with the ability to work from one load of 30 hours;
- Protherm- quality Slovak cast iron boilers with high efficiency.
Also it is possible to note production of the domestic enterprises let out under marks"Prometheus"(for houses up to 450 m2),"Hearth"(there are two-circuit boilers),Zotaand"Smoke".
Solid fuel boilers are available, can be used in the most remote places from civilization, relatively cheap to operate and autonomous. Nevertheless, it is necessary to put up with such shortcomings as the need for constant maintenance and control, transportation and manual loading of fuel. Safety in the hands of each of us, so do not forget to check the pressure level in the expansion tank and the state of the chimney.