The question of how to heat a boiler with firewood, at first glance, looks simple and a little ridiculous: what’s complicated here — put firewood on yourself, that’s the whole science. But this is only at first glance. Solid fuel boilers designed for firewood are one of the most difficult heating devices to operate.
The efficiency of a wood-burning boiler depends not only on its device. The amount of heat generated by the boiler and fuel consumption savings are affected by the quality of the wood (they are dry or wet), the type of wood from which the wood is made, the ability of the owner to effectively use the boiler control system (valves, dampers, valves).
And only last of all, the efficiency of the heating device is influenced by the technological features that the designers laid down in their brainchild.
But writing instructions on the topic “how to heat a boiler with firewood” is an empty exercise. How to read it afterwards. Why? Yes, because today there are many models and varieties of solid fuel boilers on the market: they differ not only in the device, but also in the principle of operation. The operation of a boiler with traditional combustion is different from a pyrolysis boiler or a long-burning boiler.
The manufacturer of the boiler
Therefore, carefully read the manufacturer’s instructions for the equipment you have chosen: it describes in detail how to heat your boiler, how to regulate the intensity of gorenje and other important points. I want to touch upon the general essential issues related to the furnace of a traditional solid fuel wood-burning boiler.
About wood
As mentioned above, fuel quality is of great importance. And to increase the efficiency of heating equipment, and to increase its service life. This is especially true of wood, which is a very unstable fuel. The efficiency of the boiler depends on the uniform fuel consumption and equalization of their calorific value. This is the most important thing for modern technological heating devices burdened with automation.
Wood also differs in its technical qualities — moisture content, specific energy, heat of combustion. That is why manufacturers of boiler equipment insist on choosing high-quality fuel.
Pellets and fuel briquettes are more efficient fuel for a wood-burning boiler
The easiest way to achieve this requirement will be the choice of artificial “logs— – pellets, fuel briquettes.
In the manufacturer’s recommendations, as a rule, there is an indication of how long the logs are suitable for a particular model oven. There are varieties of boilers that contain a combustion chamber, logs one meter long.
Log to log discord
Wood of different tree species has different densities and, therefore, has the ability to emit heat. But, in addition, there are other important characteristics of wood that affect the operation of the boiler: the amount of non-combustible (ballast) substances and the presence of resin contamination in the chimney and internal structure.
- birch firewood;
Birch has dense wood, so it burns hot and emits a lot of heat – 3750 kcal, even if the wood is raw. It is highly flammable. But when burning such wood, especially raw, resin is released – a substance useful in medicine, cosmetology or to protect surfaces from rotting, but extremely harmful to the inside of the boiler.
Soot on the boiler heat exchanger
- alder wood;
Burning alder wood practically does not emit soot. In addition, burning alder wood helps to clean the chimney. Alder is easily ignited, burns well and emits a sufficient amount of heat – 2100 kcal.
- aspen wood;
Burning aspen, as well as alder, cleans the chimney. But by themselves, such firewood emits little heat – up to 1650 kcal.
- pine wood;
Pine burns well and quite hot (3800 kcal), but pine wood is resinous, a lot of soot is formed during combustion.
“Bundles” of chopped firewood
- fir wood;
Spruce firewood is comparable in quality to pine, but has a slightly higher specific heat of combustion – 3900 kcal, besides they are less resinous.
- wood from Apple and pear;
Firewood from fruit trees – apple or pear trees – have dense wood, which means that they emit a lot of heat, burn and smolder for a long time. But these breeds are usually grown for the sake of fruit, so such firewood is rare. Another feature: the trunks of pears and apple trees are gnarled, the chocks are prickly, and the logs are knotty, it is difficult to put them tightly in the oven.
- oak, beech, ash wood;
Oak, beech, ash have dense wood, when these rocks gorenje a lot of heat is released – up to 3600 kcal. Of the disadvantages of oak or beech wood, their rarity in sale and the difficulty in splitting and burning them in the boiler can be called.
Given the described qualities of wood as fuel, a good owner stores different types of firewood: some – to ignite easily, the second – to burn long and hot, the third – to periodically clean the chimney from soot.
How to melt the cauldron
In cycling, the most difficult thing is not to go, but to start the movement and finish it. And in the boiler – the most difficult thing is to gain heat. Do not expect that heating the boiler will take you little time: you will have to allocate about an hour for this procedure.
Wood-burning boiler furnace is a responsible job
The beginning of the furnace is cleaning from ash and preparing the boiler for operation. After the ash pan and the combustion chamber are cleaned, you can start kindling.
Heating the boiler and chimney furnace
For your own comfort and proper start-up of the boiler, you need to warm up its furnace and chimney. If the heating device is not equipped with a forced smoke extraction system, then in order for the fuel to start burning, it is necessary to create traction. The formation of thrust is based on Archimedes’ law: heated gases become lighter and tend to “float”. To move and remove them, heating devices running on fuel combustion are equipped with a chimney.
The design of the boiler is such that the path for smoke is difficult: in its path there is a heat exchanger and a complex shape of the convective surface, which reduces the rate of combustion products. And the chimney is usually located horizontally, which also makes it difficult to move the smoke. Therefore, if the boiler does not heat up, the combustion products are looking for the easiest way. And most often the smoke begins to seep into the room.
In some cases, the vertical part of the chimney is equipped with a furnace (a small furnace that serves to heat the chimney) with a door, opening which you can burn a small amount of fuel (for example, paper) directly in the chimney.
If such a possibility is not provided, then kindling is placed in the oven – crumpled paper, birch bark – something flammable. On top of the kindling – chips, then logs of small thickness. The combustion chamber must be filled with firewood by no more than half of the calculated volume.
During kindling, it is necessary to open the chimney flap and the blower valve, providing an influx of air for gorenje. There are tips to open the boiler window before the furnace, if there is one: do not forget that oxygen is necessary for the physical and chemical combustion process.
How to heat the boiler with wood
It takes about 5 cubic meters of air to burn a kilogram of wood. If the air supply to the boiler furnace is carried out from the boiler room, it is necessary to organize supply ventilation – especially if there are no windows in the boiler room or they are sealed (with double glazing).
After laying logs, kindling begins. When steady gorenje occurs, the oven door should be closed and let the chips burn out.
Output to rated power
As soon as the combustion chamber and the chimney are sufficiently warmed up, you can proceed to the main stage of the boiler furnace. To do this, repeat the kindling process using well-burning materials. Now that the main laying of firewood has already been done, according to the instructions for the device, the main combustion chamber is filled.
After the fuel ignites, the boiler will reach its design capacity after a while. Now the gorenje process will take place for some time on its own. How long depends on the volume of the combustion chamber and the principle of operation of the boiler.
A properly working boiler is a source of warmth and comfort in a country house
Important! During heating, do not use lighter fluid or flammable gasoline, diesel fuel, and so on.
Temperature control of solid fuel boiler
The efficiency of the heating system depends on the uniform supply of temperature. And if in gas and liquid fuel boilers this issue is solved by continuous fuel supply, then in solid fuel boilers this is impossible. Yes, and the solid fuel itself gives an uneven temperature during combustion: at the beginning and end of gorenje, a portion of wood is less, in the middle of the process – more.
The system of adjusting the intensity of fuel combustion, that is, the supply of air necessary for gorenje, helps to partially solve this problem.
Thermostatic draft regulator
The boiler doors have seals, so the air under the grate enters through the lower flap. The amount of opening of the flaps of this ash pan is regulated by the thermostatic thrust regulator. It is set to the required temperature, and the controller itself is mechanically (by a chain) connected to the blower door. If the temperature is insufficient, the regulator opens the purge door, if it is large, it closes it.
Thermostatic draft regulator
It should be understood that a solid-fuel boiler is a very inert device, and the thrust regulator controls the combustion process with a large error.Gorenje Therefore, the entire heating system should be designed with this feature in mind.
Fan and controller
A smoother adjustment of the gorenje process is possible with the help of a fan that pumps a given amount of air into the furnace. The number of revolutions of the blades of the device is regulated by the controller, which takes into account the readings of the temperature sensor and the temperature value set by the user.
Gate
A shutter is a flap on the chimney, otherwise called a throttle. The damper is installed after the boiler and closes the chimney channel. Whether you need to install it or not depends on the hardware model. Some types of boilers are usually equipped with a damper, in other cases, manufacturers may recommend installing an additional damper in the chimney.
The flap allows to increase the efficiency of the heating device, partially blocking the chimney and reducing the rate of removal of heated combustion products. By what amount to open or close the flap, you can only determine by a trial method, because it depends on the temperature of the air outside, humidity, atmospheric pressure, wind direction and strength.
Properly selected heating equipment, and most importantly, its effective use will bring warmth to the house, and will add comfort to the home for the owners.
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