How to connect an electric boiler to a solid fuel boiler
Installation of the solid fuel boiler is the first step to an effective and economical maintenance of heat in the house. The next steps are regular tossing of firewood or other solid fuel. To keep the coolant temperature of the heating system within the operational limits is also necessary at night. And even when the house is visited only on weekends, you need to maintain a minimum temperature to avoid condensation on the internal surfaces in the room.
If the presence of condensation is not critical, when you leave after the weekend you need to wait for the boiler to stop and drain the water from the heating system to avoid freezing of the system. In the case of draining water, all metal elements are exposed to corrosion in contact with air.
There is no need to drain the coolant if antifreeze is used instead of water. However, when using antifreeze, because of the high fluidity, there are high requirements for thread seals and stop valves.
The most common solution to maintain the temperature in the heating loop, is to install an electric boiler in conjunction with a solid fuel boiler. Minimum amount of additional equipment will allow the electric boiler to take over the heating functions automatically, and the solid fuel. to shut down, without the risk of boiling. Also, the use of electric boiler eliminates the need for any manipulation with the heating system, leaving the country house until the next weekend. To monitor emergencies and remotely control the electric boiler, there is a GSM module, which monitors the mode of the heating equipment.
What pipe should be used to connect the boiler on solid fuel?
There are no strict rules, regulating what kind of pipe to use for strapping tt boiler. There is only one recommendation, related to the real experience of operation.
Section of the small circle of heating, made with metal piping (steel, copper). This is done to boil coolant and emergencies, the pipe is not spoiled and kept hermetic under the influence of high temperatures. The material of the rest of the pipeline can be chosen at will.
The most common variants of piping are:
- Metal-plastic. strapping with metal-plastic pipes, characterized by simplicity and speed of installation. If you have the necessary tools, all work can easily perform yourself. Install plastic pipes is worth only if the system provides a buffer tank, reducing the likelihood of overheating the coolant.
- Copper. strapping copper pipe, will ensure maximum heat output of the heating system. The material can withstand temperatures up to 300 ° C, does not oxidize. The disadvantages are the high temperature of the heating surface of the pipe, as well as the requirements associated with the prohibition of fittings made of aluminum.
Polypropylene. connection with polypropylene pipes is the most popular strapping option. Pipes are better than metal-plastic to withstand overheating, suitable for heating systems of any type, regardless of the selected coolant. Proper strapping a solid fuel boiler with polypropylene, requires that the supply and return sections near the boiler, made of metal. After that, using adapters, connect polypropylene. Seamless material is used, designed for heating systems (DHW pipes may not be used).
Due to the fact that heating fluid often reaches boiling point, strapping solid fuel boiler is better to use metal pipes. But, since this option is not always possible, it is allowed to use analogues. The use of polypropylene with fiberglass, in heating systems with a solid fuel boiler, has proven to be one of the most reliable and optimal ways of strapping.
How and what to insulate pipes
Warming the pipes perform with merilon or any other insulation designed for these purposes. If the pipeline is laid in the ground, as in the case of a freestanding boiler room, then, for additional protection, use PET with a large diameter.
PET pipe protects from mechanical damage. Insulation is a kind of protection against condensation, preventing burns by accidental contact with the pipes, as well as reducing heat loss. Fix the insulation with clamps or tying wire.
Basic diagrams of the strapping of the solid fuel boiler
The drawing on which the heating will be done, depends on the number of circuits of the heating element itself, the geometry and area of the room where the circuit will be located, the presence of additional and auxiliary devices.
Heating with solid fuel boiler, circuit diagram:
- Open with gravitational circulation;
- closed with natural circulation;
- Closed with forced circulation;
- manifold type.
Regardless of which connection scheme of the solid fuel heating boiler will be chosen, the circuit must be organized correctly. The temperature delta of water at the inlet and outlet of the system should not exceed 20 degrees. Otherwise side effects occur. Condensation forms on the heat exchanger, which leads to corrosion of the latter.
Log Boiler Central Heating System. Case Study Sussex
There are many ways to hide the heating pipes so that they do not interfere and, at the same time, they are easily and quickly accessible.
What is the best insulation for heating pipes to use? Read more here.
Open circuit with gravity circulation of the coolant
This is the easiest way of strapping, which you can do yourself. In this case, the coolant movement through the system is due to the difference in density of cold and hot water. The heated coolant flows upwards, as its density is low. Cooling down, the density of the liquid increases, and therefore the coolant sinks down.
Self-flow circuit with open expansomate.
This scheme of installation of solid fuel heating boiler requires compliance with a number of rules. Thus, for good circulation of the coolant in the system the heating equipment should be installed below the radiator position by at least 0.5 m, and the expansion tank must be at the highest point of the circuit. To reduce the hydro-resistivity of the system, choose a pipe diameter of 50 mm (for the distribution pipes to the radiators pipe diameter is sufficient up to 25 mm). A large number of locking devices and fittings significantly worsen the circulation of the coolant, and therefore their number should be minimized.
Heating scheme for a private home with an open-type solid fuel boiler with natural circulation has a significant advantage in its simplicity and low cost. However, here it is impossible to control the temperature of the coolant at the outlet of the boiler, which generally reduces the efficiency of the circuit. Through Open expansion vessel Oxygen enters the coolant. It leads to corrosion of the heating circuit itself and the boiler heat exchanger. Such heating with a solid fuel boiler, the scheme in particular, can be considered as a budget option for the house, which is visited from time to time.
Closed heating system with natural circulation
If you need an inexpensive, but high quality strapping solid fuel heating boiler, the scheme above is the best option. Closed gravity system works due to the difference in density of hot and cold water. Due to its simplicity, the circuit is inexpensive to install and subsequent maintenance, it is durable. A closed safety tank prevents free oxygen from penetrating into the interior. As a result, pipes, radiators and boiler heat exchanger are less susceptible to corrosion.
Gravity circuit with a sealed expansomate.
In addition to the main heating element (boiler), the expansion vessel, the diaphragm tank, there is a “safety group“, which makes efficient and safe heating of the house with a solid fuel boiler. The scheme is supplemented by a manometer (pressure control inside the circuit) and a safety valve (through which the pressure is released).
Disadvantages: impossible to control the temperature of the coolant at the outlet, reduces the efficiency of heating in general, since the movement of the coolant occurs naturally.
Due to the fact that insulated pipes for heating dissipate less heat, the efficiency of the system increases.
You can read all about dismantling heating pipes here.
Closed loop system plus a circulating pump
Such installation of solid fuel heating boilers in a private home is considered energy efficient and cost effective. Here increases the efficiency of the circuit due to the high heat transfer fluid. The volume of water in the system is reduced, which reduces energy consumption for heating. In a closed system with forced circulation there is no need to install pipes of large diameter, as hydro-resistance to the coolant helps to overcome the circulation pump. Important choose the right electric pump. The thermal fluid itself does not evaporate. After all, a sealed membrane tank is installed in the system. Closed strapping of the solid fuel heating boiler prevents the formation of corrosion within the system, which prolongs its life.
The circuit in which the coolant is not in contact with the air.
The disadvantages include energy dependence (in case of power outage the circulation pump stops its work) and expensive installation as only a specialist can connect the solid fuel boiler to the heating system of closed type correctly, and for his services must be paid.
A characteristic feature of the strapping of the closed type is a circulating pump. It forces the coolant to move through the system, due to which the heat output of heating pipes and radiators is increased. Pump operation is controlled by a temperature sensor. The pump is always installed on the pipe through which the cooled coolant returns to the boiler. In this case the service life of the equipment is significantly prolonged. Installation of solid fuel boilers and heating systems with forced circulation of the coolant in houses and apartments that are constantly used.
Collector connection heating boiler with solid fuel unprepared person to perform independently is difficult, and therefore the services of a specialist is needed. However, this method of heating your home is considered energy efficient. The explanation is simple: each radiator or any other device of heat transfer from the coolant to the air in the room is connected to the circuit individually through the manifold. The last device plays the role of a kind of distributor of the coolant and has the form of a pipe with a large diameter, from which there are outputs to each radiator in the house.
Manifold wiring is very convenient and practical.
You don’t know how to perform manifold heating system on the solid fuel boiler? The scheme is complicated enough for a person without proper education and experience. That’s why the services of a specialist is needed here.
The advantage of the manifold distribution is that it allows you to control the temperature of each radiator in the house. Because the batteries are connected individually. It is convenient in case of breakage of one of the heating devices. To replace it, you do not need to completely turn off the heating in the house. On the other hand if one of the rooms in the house is not used it can be not heated at all by cutting off the heating medium flow. Installation of supply and return pipes to each battery is made under the floor screed, which improves the aesthetic characteristics of the interior and additionally heats the floor. Collector system allows you to create several loops in the house with different temperature regimes, because you can connect a solid fuel heating boiler with a hydrostring.
The type of device is taken into account when designing the connection scheme.
For boilers with manual control
Only shutoff valves are used in this circuit. To disconnect one boiler from the system and connect the other, you need to open or close 2 taps. If it is necessary to cut off the unit completely, for example, for repair work, screw 4.
It is recommended to choose models with built-in expansion tanks, t. к. 1 standard capacity of the system may not be enough. To use the tank of an idle heater, the heater is not completely cut off, only 2 taps along the course of the coolant are shut off.
For automatic boilers
This option is not similar to the previous one by the presence of additional elements:
In the system with automatically controlled heaters, the valves are constantly left open. Under such conditions, most of the fluid tends to move along the path of least resistance through the inoperative boiler. The heating system experiences a lack of heat.
To avoid this situation and install check valves, orienting them towards each other. They do not allow the coolant to move in the direction of the inoperative unit.
After stopping one of the boilers, operation of its circulation pump is meaningless. The pump not only wastes electricity but also interferes with the second boiler. A thermostat is installed to turn it off automatically.
Why the pyrolytic boiler has such a high efficiency
Unlike the classic solid fuel boilers there is a “reverse combustion”, i.e. heat is not produced by burning wood, but by burning the gas that is released. Now let’s understand in more detail. The same principle of operation is used in gas generator boilers, where wood is used as organic matter. The gas generated in this way burns at a temperature of up to 1200° C and generates much more thermal energy than the wood from which it is obtained. In this way you can get up to 50% more heat. The efficiency of such boilers reaches 8589%.
As a fuel can be used:
Carcinogenic substances in the exhaust gases emitted outside are minimal, which is important for environmentally conscious people
Heat generators of this type work on:
Loading and ignition of the fuel is done manually.
Features of the system
The complexity of piping is due to the specifics of the operation of the solid fuel boiler:
- Thermal inertia. Unlike gas and liquid fuel, the device cannot be quickly extinguished. Even with closed air damper the wood continues to burn for some time, releasing large amounts of heat. This increases the likelihood of overheating of the medium and, consequently, boiling and a sharp increase in pressure in the system. The piping is supplemented with a cooling coil, an emergency circuit and other elements for emergency heat removal.
- Efficiency dependence on capacity. The maximum efficiency is observed only at nominal output. If the boiler is extinguished by closing the air damper, combustion of fuel becomes incomplete. This causes a drop in efficiency and an increase in soot emission. An accumulator is integrated in the system, which stored the energy produced by the boiler and partially transfers it to the heating circuit.
- High concentration of sulfur and other elements in the flue gases due to the composition of solid fuel. When steam condenses in the exhaust, the water reacts with the impurities and turns into an aggressive acidic cocktail. For this reason, it is necessary to prevent the flow of the working environment into the heat exchanger with a temperature below 50 55 ° C, otherwise its walls will soon be destroyed. Use a mixing unit, if necessary, adding hot water from the “supply” to the “return”.
Requirements to the place of boiler installation
Solid fuel heat generator can not be located in living rooms, bathrooms or kitchens.
It is allocated a separate technical room that meets these requirements:
- The presence of 1 input, width from 80 cm;
- volume. from 15 m³ 0.2 m³ for each kW capacity, but not less than 7 m³;
- ceiling height. from 2.5 m;
- The supply and exhaust ventilation must provide 3 times the air exchange and oxygen supply required for combustion of the fuel;
- Fire resistance limit of walls, partitions and ceilings. 0.75 hours.
fire extinguishing equipment is kept in the boiler room. No room or attic above it.
Advantages of the heating system
Solid fuel heating has the following advantages:
- Independence from external energy sources. Some models are 100% autonomous, t. к. They don’t need electricity either.
- Low cost of fuel: 1 kWh from wood costs 0.9, coal. 1.6, whereas from liquefied gas and diesel oil. 2.5 and 2.8 respectively. In some regions brushwood and dead wood can be found for free.
- Functionality. Many heaters are equipped with a cooking surface.
- Safety. Solid fuel does not explode like gas.
- Comfort. Unlike diesel boilers, wood and coal boilers do not produce an unpleasant smell.
In the absence of a centralized gas supply, these units are the most popular.
The negative sides of the system include:
- Low degree of automation. It is difficult to regulate the temperature of the heat carrier; every 4-5 hours it is necessary to refill the fuel.
- Dirty exhaust. It is necessary to regularly clean the chimney and heat exchanger from soot.
- Complicated piping. The presence of a heat accumulator, emergency circuit and other elements leads to an increase in the cost of the system and an increase in the amount of installation work.
- Fire hazard. Precautions are required due to the risk of soot ignition, sparks on building structures and fire escaping during reverse draught.
Some disadvantages are less apparent in the boilers of long combustion.
They are able to operate on 1 charge for 12 hours or more, pyrolysis models give a relatively clean exhaust.
Diagram of connection of heat accumulator with solid fuel boiler and electric boiler
Buffer vessel, integral part of the connection diagram of the solid fuel or electric boiler. When using two types of heat generators simultaneously installed in a single heating system, the storage tank plays the role of a hydraulic separator.
Bundling of a heat storage tank with a solid fuel boiler or an electric boiler pursues several important tasks: it accumulates and expels energy, prevents hydraulic shock and overheating of the heat carrier, provides uniform heating of the heat carrier fluid.
Requirements to homemade pyrolysis boilers
In order for the pyrolysis heating boiler, made by your own hands, to surpass the efficiency of a conventional solid fuel boiler, its design must meet strict requirements:
- the temperature in the furnace must be optimal (600-700 °С), since it is in these conditions there is the highest-quality release of pyrolysis products;
- The regulation of combustion power should not significantly reduce the efficiency;
- heating boiler must be suitable for long-term continuous combustion of fuel;
- The body of the pyrolysis gas combustion chamber must be resistant to corrosion and capable of withstanding temperatures above 1200 ° C.
It is also desirable that the design of the boiler includes a chamber for pre-drying of wood raw material.
Technical characteristics that a homemade pyrolysis boiler for heating a private house must have:
Using a homemade heating device is sometimes risky, because when the combustion process is incorrectly adjusted, the so-called “clap” can occur. an explosion of pyrolysis gas.
Selection of the optimal type of solid fuel boilers and equipment
Currently there are 4 main types of solid fuel boilers.
Traditional, also classical
Obsolete design, with an extremely low efficiency of less than 60%. Requires frequent servicing, manual loading of fuel from 4 to 8 times a day. The main advantages are cheapness, high reliability and extreme unpretentiousness.
Long burning boilers
Their technology was developed in the 70s of the last century and brought to its logical conclusion by using modern means of temperature control. The presence of positive displacement circulation pumps makes this system a bit more efficient than the classic system, but it is energy dependent.
Without going into the peculiarities of the combustion process, let us note that the loading of fuel into the combustion boiler can occur exclusively in cycles, which is not economical with frequent changes in temperature conditions and very inconvenient in service. Combined with a complex strapping scheme and a whole list of restrictions on firing, makes operation of this apparatus very difficult.
Relatively new type. The principle of heat supply is based on the combustion of pyrolysis gas, which is released after the thermal treatment of fuel. Manufacturers regulate the efficiency of such boilers more than 90%, which is just an advertising gimmick. This calculation of efficiency takes into account the energy that is spent on the pyrolysis process.
Pyrolysis. the process of decomposition of wood when heated without access to air, which is accompanied by a release of flammable gas.
Real KDP, technically perfect, model of this type of boiler does not exceed 75-80%. And this is taking into account ideal operating conditions, which means that the humidity of the fuel is not more than 10%. With increasing humidity efficiency of useful heat output drops rapidly. There are additional risks, arising during the operation.
The biggest is the potential outflow of pyrolysis gas. If the unit is systematically filled with high-moisture fuel then the combustion chamber burns out quickly. To prevent this, before each heating season it is recommended to liner the furnace of the boiler.
The most technically perfect solid fuel boiler, which one can choose. Includes a set of control, process automation and safety systems. At the moment such a device is the most expensive, but the most technically advanced:
- high efficiency. 85-90%;
- Full automation of the process of loading fuel pellets;
- A flexible system to control the temperature modes in the rooms;
- High degree of safety in operation.
Device and technical characteristics of the pellet boiler:
Hopper for pellets; 2. Screw for fuel pellet feeding; 3. Electric screw motor;4. Pipe for fuel feeding into the burner; 5. Dispenser supplying fuel to the burner;
Electric drive of ash cleaner;7. Heat exchanger. triple passage of high-temperature gases gives a high efficiency;8. Control panel; 9. Control windows for pellets in the hopper.
Schematic operation principle of the pellet heating boiler.
Fuel pellets, which are used as fuel in these boilers.
In turn, pellet boilers can be divided into three types, by the type of structure of the main element of the combustion chamber.
This is the least economical technology used in this type of equipment. Combustion of the fuel takes place in the air flow created by a fan, at a temperature of up to 1200 0 C. A distinctive feature of this technology is versatility and unpretentiousness to the quality of fuel.
When choosing this type of a burner, make sure that there is an additional dosing chamber (see picture) with a petal shut-off valve that prevents back burning. This makes the feeding of the pellets more economical and safer.
In this method fuel pellets are fed into the storage hopper, and from there under their own weight are poured onto the grates. The air from below is blown in to keep the combustion process alive. The grates can be fixed or movable. The latter are used for burning large fractions of fuel with high ash content.
Combustion chamber, there is a valve for supplying pellets.
Grate of grates, also built into the cone tray.
Steel or cast iron bowl on which the combustion occurs. Pellets are fed along the chute from below by a special feeding screw. Primary combustion air is supplied in the same way. Secondary air for control and intensification of the process is fed through the holes in the retort.
Automatic ignition. optimally using a high-temperature hair dryer in a failsafe heat shielded housing. Metal or ceramic heating elements are also used, but they are less durable. The electrode method is very sensitive to the humidity of the pellets.
System control. Different types of thermostats to control the temperature of the heating medium and lambda probes that determine the amount of residual oxygen in the flue gases are mainly used. Both detectors control the power of the fan blowing air into the furnace.
Selection of the most efficient model
Before choosing a solid fuel boiler, it is necessary to determine its capacity and the technical criteria it must meet, namely:
#1. Availability of a certificate of adaptation of all the nodes of the boiler for work on the territory of the Russian Federation.
#2. Multiple modes of operation with different types of pellets.
#3. The possibility of using another type of fuel.
#4. The level of fuel quality requirements;
#5. Availability of DHW and the possibility of enabling the economical “summer” mode of operation;
#6. Reliability of long-term continuous operation in stand-alone mode;
#7. The level of reproducible noise in various operating modes:
#8. The possibility of connecting an external additional control;
#9. Scalable control of the temperature mode of the premises;