Economical heating system of a country house based on a solid fuel boiler, from "A" to "Z"
In the presented material, in order, all stages of creating an effective heating system for a country house with a solid fuel boiler are considered. Starting with the choice of equipment and power calculation, ending with the installation diagrams and operating rules.
Content:
Choosing the optimal type of solid fuel boiler and equipment
At the moment, there are 4 main types of solid fuel boilers.
Traditional, it's classic
Morally obsolete design, with extremely low efficiency - less than 60%. It requires frequent maintenance, manual loading of fuel from 4 to 8 times a day. The main advantages are low cost, high reliability and extreme unpretentiousness.
Long burning boilers
Their technology was developed back in the 70s of the last century and brought to its logical conclusion using modern means of temperature control. The presence of forced-circulation circulation pumps makes this system a little more efficient than the classic, but volatile. Without going into particularities of the combustion process, we note that the loading of fuel into a long-burning boiler can occur exclusively cyclically - this is uneconomical with frequent changes in temperature and very inconvenient to maintain. In combination with a complex strapping scheme and a whole list of restrictions during kindling, this machine is very difficult to operate.
Pyrolysis Boilers
A relatively new type. The principle of heat supply is based on the combustion of pyrolysis gas, which is released after heat treatment of the fuel. Manufacturers regulate the efficiency of such boilers more than 90%, which is just an advertising gimmick. With this calculation of efficiency, the energy spent on the pyrolysis process is taken into account.
Pyrolysis is the process of decomposition of wood when heated without access of air, which is accompanied by the release of combustible gas.
The 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 fuel moisture is not more than 10%. With increasing humidity, the efficiency of beneficial heat dissipates rapidly. There are additional risks that arise during operation. The largest is the potential flow of pyrolysis gas. With the systematic loading of the apparatus with high humidity fuel, the gas generator chamber burns out quickly. To prevent this, it is recommended that the boiler furnace be lined before each heating season.
Pellet type
The most technologically advanced solid fuel boiler that you can choose. It includes a set of control systems, process automation and security. At the moment, such equipment is the most expensive, but the most technically advanced:
- high efficiency - 85-90%;
- full automation of the process of loading fuel pellets;
- flexible control system of temperature conditions in rooms;
- high degree of safety during operation.
The device and technical characteristics of the pellet boiler:
1. Hopper for pellets;
2. Pellet auger;
3. Auger motor;
4. A pipe for supplying fuel to the burner;
5. Fuel dispenser to the burner;
6. Electric ash cleaner;
7. Heat exchanger - triple passage of high-temperature gases gives high efficiency;
8. Control Panel;
9. Control windows for the presence of fuel pellets in the hopper.
Schematic principle of the operation of a pellet heating boiler.
Fuel pellets that are used as fuel in these boilers.
In turn, pellet boilers can be divided into three types, according to the type of structure of the main element of the combustion chamber.
Torch burner
This is the least economical technology used in this type of equipment. Fuel combustion occurs in the air stream created by the fan, at temperatures up to 12000C. A distinctive feature of this technology is the versatility and simplicity of fuel quality.
When choosing this type of burner, you must make sure that there is an additional metering chamber (highlighted in the figure) with a flap shut-off valve that prevents reverse combustion. This will make the pellet feeding process more economical and safe.
Grate
With this method, fuel granules are fed into the storage hopper, and from there they are poured under their own weight onto the grate. Below, air is pumped that supports combustion. Grid-irons can be fixed and mobile. The latter are used to burn fuel of large fractions with high ash content.
Combustion chamber, a pellet feed valve is highlighted.
Grate, it is also mounted in a conical tray.
Retort burners
Steel or cast-iron bowl on which combustion occurs. Granules are fed through the chute from below with a special loading auger. Primary combustion air is supplied in the same way. Secondary air to control and intensify the process is supplied through the holes in the retort.
Video: Pellet feed in a retort burner
Additional equipment for the boiler
Almost all modern models have the following functionality as standard:
1. Automatic ignition - the use of a high-temperature hairdryer in a thermally protected fail-safe housing is optimal. Metal or ceramic heating elements are also used, but they are less durable. The electrode method is very sensitive to the moisture content of the granules.
2. System control. Basically, various types of thermostats are used to control the temperature of the coolant and lambda probes, which determine the amount of residual oxygen in the flue gases. Both detectors control the power of the fan forcing air into the furnace.
Choosing the most effective model
Before choosing a solid fuel boiler, it is necessary to determine its power and technical criteria that it must meet, namely:
#1. A certificate of adaptation of all boiler units for operation on the territory of the Russian Federation.
#2. The presence of several modes of work with different types of pellets.
#3. The possibility of using a different type of fuel.
#4. Level of fuel quality requirements;
#5. The presence of hot water and the ability to enable economical "summer" mode of operation;
#6. Reliability of long-term continuous work in standalone mode;
#7. The reproducible noise level in various operating modes:
- standard heating;
- enhanced heating with hot water;
- starting ignition;
- supply of fuel pellets from the inner and outer hopper;
#8. Ability to connect external additional control;
#9. Scaling control of the temperature regime of the premises;
#10. Access and ash bin size;
#11. Availability of security systems
- back draft control;
- coolant overheating control;
- automatic emergency shutdown and fire extinguishing system.
Rules for installation and arrangement of the boiler room
For convenient operation, the installation of a solid-fuel pellet boiler must be carried out in a spacious room. When placing it, it is necessary to observe the parameters of the technological indents from walls and other surfaces that are indicated in the product passport.
In practice, there have been cases when, after six months of operation, it was found that it was impossible to open the ash pan for cleaning it.
The main criterion for the suitability of the room is good natural or forced ventilation and a properly arranged chimney. The most commonly used chimney device schemes, you can see below:
Scheme A and B device of the chimney in the house. As an exhaust channel, ventilation shafts are used, arranged in a skinny wall. These channels must be isolated from the main natural ventilation system at home.
Scheme B - removal of the chimney from the boiler room located in the basement.
Schemes D and D are the device of an external chimney from a specially constructed boiler room or a house.
In all versions of the chimney device, you must install:
- spark arrester on the chimney;
- sealing the transition sleeve into the boiler room;
- drainage device.
The installation of a solid fuel boiler is recommended on a foundation pillow with a heat-insulating layer. It is necessary to install a special gas analyzer in the room, if this is not standard on the purchased model.
Pellet hopper installation rules
In addition to the built-in hopper, which has a small volume and must often be filled with fuel, many owners connect an external large-capacity hopper to the system.
Any containers are suitable for storing pellets, the main condition is the tightness of the structure, if it is located outside a heated room. When choosing the volume of the hopper, it is necessary to proceed from the standard; 1 ton of pellets takes up to 2m3. construction height is not critical.
There is an opinion that in high containers the lower layers of granules are crushed, this is not true. High-quality fuel pellets withstand quite a lot of pressure.
The container should be located no further than 12m from the boiler. Complicated design of the auger or the use of transshipment hoppers of drives is allowed, but it is necessary to use exclusively high-quality fuel. Otherwise, the dust falling into the furnace in large quantities will reduce the efficiency and may damage the feeding and dosing mechanisms of the boiler.
In the lower part of the cone of the hopper, under the exit of the fuel intake, it is necessary to provide for an audit to systematically remove the dust. If the cone has a small cross-sectional area, the mass of the granules compressed under pressure hangs. In this case, it is recommended to install a special device “screw agitator”.
Hopper connected to the boiler.
Using a heat accumulator and calculating its volume for a solid fuel boiler
When using powerful heating devices, there is a possibility of overheating of the coolant. And although modern models have perfect automation that prevents such situations, it is advisable to use special heat storage devices.
Heat accumulators perform the following functions:
- automatic regulation of the distribution of heated coolant throughout the system;
- use as an exchanger buffer when creating hybrid heating systems with several types of heating devices;
- some models can serve as a hot water boiler; increase boiler efficiency by reducing the number of draft adjustments.
Heat storage volume calculation table for solid fuel boiler
| Heat storage capacity (L) | Water heating time (h) at boiler power (kW) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 20 | 25 | 30 | 35 | 40 | 15 | 50 | 55 | 60 | |
| 500 | 1,2 | 0,9 | 0,8 | 0,7 | 0,6 | 0,5 | 0,5 | 0,4 | 0,4 |
| 1000 | 2,3 | 1,9 | 1,6 | 1,3 | 1,2 | 1,0 | 0,9 | 0,8 | 0,8 |
| 1200 | 2,8 | 2,2 | 1,9 | 1,6 | 1,4 | 1,2 | 1,1 | 1,1 | 0,9 |
| 1500 | 3,5 | 2,8 | 2,3 | 2,0 | 1,7 | 1,6 | 1,4 | 1,3 | 1,2 |
| 1800 | 4,2 | 3,4 | 2,8 | 2,4 | 2,1 | 1,9 | 1,7 | 1,5 | 1,4 |
| 2000 | 4,7 | 3,7 | 3,1 | 2,7 | 2,3 | 2,1 | 1,9 | 1,7 | 1,6 |
| 2400 | 5,6 | 4,5 | 3,7 | 3,2 | 2,8 | 2,5 | 2,2 | 2,0 | 1,9 |
| 3000 | 7,0 | 5,6 | 4,7 | 4,0 | 3,5 | 3,1 | 2,8 | 2,5 | 2,3 |
| 3500 | 8,1 | 6,5 | 5,4 | 4,7 | 4,1 | 3,6 | 3,3 | 3,0 | 2,7 |
| 4000 | 9,3 | 7,4 | 6,2 | 5,3 | 4,7 | 4,1 | 3,7 | 3,4 | 3,1 |
| 4500 | 10,5 | 8,4 | 7,0 | 6,0 | 5,2 | 4,7 | 4,2 | 3,8 | 3,5 |
| Green indicates the optimal volumes for the respective boiler capacities. | |||||||||
Different types and layouts of solid fuel boiler piping
There are many ways to connect the boiler and related equipment to the general heating system of the house. Consider the most common of them.
The storage tank acts as a DHW boiler
The design of the storage tank is a spiral located inside the heat accumulator.The hot heat carrier that is inside heats the running water of the hot water circuit. In case of burning and shutting down the boiler, the heat accumulator allows you to maintain an acceptable room temperature, up to 2 days. Provided that the DHW function is not used.
An automatic thermo-mixing device is used to control the intake and temperature of the coolant:
- Ball valve;
- Thermometer;
- Pump.
The device is also equipped with a non-return valve, an emergency automatic valve of natural circulation (in case of a power outage), an integrated thermal fan and fitting.
The principle of operation of the device is as follows. When the coolant reaches a certain temperature (780C), the thermal valve opens the water supply from the drive. The temperature is kept at a predetermined level by adjusting the cross section of the return passage from the central heating system to the bypass channel.
Connection diagram of a solid fuel boiler to a dual-purpose heat accumulator:
1. Security group;
2. Thermal storage tank;
3. Thermal mixer;
4. Expansion tank membrane type;
5. Valve make-up system;
6. Circulation pump of the heating system;
7. Radiators
8. Mixing three-way valve;
9. Check valve;
10. DHW circulation pump.
Connecting the heat accumulator and a separate DHW boiler
The volume of the boiler for passive heating of the DHW system depends on the number of consumers and the power of the equipment used. When tying pellet boilers, it is not recommended to use polypropylene materials and structures. The heat exchanger outlet temperature at peak loads often exceeds the performance of pipes made of polymer materials.
Harnessing a solid fuel boiler with a separate hot water boiler:
1. Boiler.
2. Security group.
3. Expansion membrane tank.
4. Circulation pump.
5. Manual three-way mixing tap.
6. Valve make-up system.
7. Radiator.
8. Domestic hot water boiler indirect heating.
9. Thermal storage tank.
Parallel connection of two heating boilers
In order to extend the service life and evenly distribute the resources used, often users combine two different types of heating sources into a single heat supply scheme. In this case, the main source of heat in the winter is a solid fuel boiler. The electric boiler is turned on in emergency mode and in the summer months when it is used to heat water.
The layout of the binding of a solid fuel heating boiler with a parallel electrical connection:
1. Pellet boiler.
2. Heating system security group.
3. Alternative boiler (electric or gas).
4. Separator for removing air from the system.
5. Circulation pump.
6. Manual three-way mixing tap.
7. Dry running protection valve.
8. Expansion tank.
9. Water make-up valve.
10. Thermal storage tank.
11. Radiator.
12. Washbasin.
13. DHW circulation pump.
The heating system based on a pellet boiler is quite complex and requires careful tuning. Before performing installation work, carefully read the instructional material provided by manufacturers.