Liquid fuel heating boilers

The basic element of any heating system is one or more devices that use fuel or energy to heat rooms and make hot water. There are many options, and the choice depends on your needs. After all, a usual wood-burning stove with a pot on it and a source of water in the form of the nearest well can cope with this task, if you expect to live in one, maximum two rooms in winter. This option is completely self-contained, requires virtually no cost you can get water in a bucket, the wood is also not a problem , but the modern concepts of comfort is poorly consistent. By the way, this article was written in about that environment, but as they say, “don’t confuse tourism with emigration”.

Heating Technology

In winter it is simply impossible to live in such conditions all the time – it takes too much time to maintain a minimum level of comfort, which in the city is taken for granted. It is possible to exclude manual labor during permanent residence in the countryside, but of course you will have to pay for the pleasure: first, by buying the appropriate equipment, and then – by paying energy bills. However, one way or another, the arrangement of heating in a country house in the absence of district heating will involve costs, and the main task is to find a reasonable compromise between price and comfort.

What do we heat?

Review of all possible options for home heating would take too much space. However there is a sense to mention the basic technical decisions, having set for the beginning some boundary conditions. So, we have a detached house with electricity and a water source. e. Well or well. Actually the only thing that is missing is heat. This problem is solved most easily if the house is also connected to the gas, but if it is absent or will be “in the future”, you will have to look for other sources of thermal energy. There are several variants.

Electricity. The easiest and cheapest option in terms of initial costs. However, it requires powerful, possibly three-phase wiring, and heating with it costs the most.

Heat pumps. The principle of operation is based on “taking away” heat from the environment: air, water or most often the earth. Requires many times less energy compared to electric heating, but is quite expensive. On the other hand, there is no need to worry about refill of “fuel.

Solar collectors. They cost less than heat pumps, but they are not suitable for year-round heating. However, it is advantageous as one of the elements of the heating system: the main in warm weather and auxiliary in winter. Solar energy is free, the cost of electricity is minimal or non-existent.

In all other cases, the heat must be obtained by burning various “organics”. To begin with, it should be noted that, in general, the heating of the room can be air or liquid, and for this you will need a furnace or boiler. Let’s stop on the second variant: the furnace heating from the point of view of heating of several premises is not too convenient, and the problem of hot water supply organization it does not solve.

The main element of any boiler is a heat exchanger, in which the energy of the fuel heats the coolant. And the first thing you need when choosing a boiler, – to decide on the fuel used. All substances can be in one of three aggregate states: solid, liquid and gaseous, so there are three different types of boilers.

Solid fuel boilers. They are inexpensive to operate and convenient from the point of view of fuel storage: it is enough to make a lean-to for coal and allocate a separate dry room for firewood or, for example, peat, so as not to expose them to moisture. Disadvantages of such boilers are several: to support the constant burning need to be manually, loading a new portion of fuel into the furnace several times a day and removing the ash.

Interest may be represented by the varieties of pyrolysis boilers, which burn gas emitted during the thermal decomposition of wood, while visiting the boiler room will have to be once every day or two. However, pyrolytic boilers are also more expensive. There are also boilers that run on pressed wood pellets – pellets. They can work for days without “refilling” the bunker, and they need to be cleaned even less often.

In any case, it is unreal to fully automate the process of loading solid fuel in the home – not the right scale. Therefore, if you do not want to learn the profession heater, we have to think about other options: the wood itself is only in fairy tales, but to bring the boiler liquid or gaseous fuel is not difficult.

Gas boilers. If there is a gas line to the house, the problem of heating is solved quite simply. Such boilers are on the market in great numbers – you just have to choose. And here the choice is usually associated with a wall or floor version of the boiler, mostly depending on the required capacity. There is also no problem of fuel storage, and the ratio “cost of heating/level of automation” is one of the highest.

The quality of gas is almost stable, the only “minus” is associated with its quantity, or rather, variability of pressure “in the pipe” at different times of the year. Not all varieties of gas boilers, especially floor boilers, are equipped with burners that can operate at low pressure, and if the flame “sits” on the burner, it quickly deteriorates. At high pressure, the flame can quickly burn the heat exchanger.

Manual pressure adjustment requires a certain skill or calling a specialist, and modulated boilers i.e. modulating boilers require a higher degree of automation control. e. With a system of automatic maintenance parameters burners for floor boilers are much more expensive.

Understandably, the main limitation of gas-fired boilers is the presence of a gas line. However, there is also an option that uses liquefied natural gas propane-butane . Tank for its storage gas holder is installed on the site. The LNG pressure is much more stable than in the gas pipeline, while the main disadvantages are the high cost of LNG, the cost of the gas storage tank, the need to coordinate the project with regulatory agencies and periodic checks of the gas storage tank and the system as a whole.

In addition, not everyone will dare to install on the site a tank of a few cubic meters filled with liquefied gas. However, this is more of a psychological nature: a properly operated gas holder is safe.

Wall hung gas boilers

The cast iron boiler for heating and hot water with the built-in liquid fuel burner De Dietrich GTU 1200 V

Liquid fuel boilers. Can work on various types of liquid fuel. In the vast majority of cases in our country “diesel” models are used. Almost all of them are manufactured in the floor version, easy to automate, in addition, they are structurally fully similar to the gas floor standing boilers.

Sizes of burners are standardized, the burner itself is just a heat source, the fuel supplied by pipeline. For the work of the boiler it does not matter what burner burns, as long as the fuel supply parameters are set correctly: the flare does not touch either the burner or the boiler walls.

Boilers of average capacity as applied to heating of one “average” house – the most universal type of heat generators. To transfer a liquid fuel boiler to gas, it is usually enough just to replace the burner, without making changes to the rest of the system. In general, it is enough to have only two burners: diesel and gas, and reconfiguring them for a particular fuel or gas is not a complicated matter, although it does require a specialist call.

Such modification may be required if the site had a gas main, and the need to purchase liquid fuel is no longer necessary. In fact to change the type of fuel you need only to unscrew a few screws, remove one burner, install another, connect it to the automation system, the fuel source and adjust. However, small boilers with built-in diesel burner are produced, their “gasification” can be somewhat complicated: you may also need to replace or install other decorative panels or the front wall of the case.

“Salt, sir

After this “brief” review can go to the main topic of the article – domestic floor standing boilers for liquid fuels. By default, we will assume that its role is played by “diesel” as the most affordable source of energy. The difference between the types of liquid fuels is not principal, and the boiler conversion to heating oil or diesel fuel is usually associated only with the appropriate readjustment of the liquid fuel burner. By the way, and the gas burner for the main and liquid gas is set differently.

In our case, the term “household” does not mean the level of performance, but the purpose – individual heating of a single house. Universal combination boilers that can operate on several types of fuel, are unreasonably expensive for private users, and most centralized heating systems in apartment buildings or settlements in general differ only in capacity and some details of the performance of boilers and burners.

Basic elements of heating system

These include primarily the boiler with a burner, but it is only part of the system. To work the boiler needs fuel, you need a reservoir for its storage, for the combustion of fuel needs the air supply – you need to ensure its flow. Gases formed during combustion must be led outside – you also need a chimney. The boiler must be connected to the heating system of the building – and this is a completely separate topic.

It would be nice to heat water sanitary by the boiler, so you need a boiler, by the way, this water should be supplied from a separate source by a separate pump. To create an autonomous heating system will also require devices to regulate the operation of all components, and therefore the connection to the power grid to supply automatic systems.

Of course, you need all kinds of connecting fittings, safety devices, sensors and more. In general, the total cost of the system can exceed the cost of the boiler by two, three or more times, and to select all the components you can not do without a specialist. But first things first.

Diesel boilers

Liquid fuel boiler with a boiler Viessmann Vitola 200 in the cut

The three sources and the three main parts of the boiler

The main element of any boiler is a heat exchanger. It can be of steel or cast iron. Steel is lighter, little sensitive to shocks, better tolerate temperature fluctuations during operation, but their life is somewhat lower: steel is subject to corrosion, especially in the presence of chemically active combustion products of fuel, and burns a thin steel sheet relatively quickly.

However, in modern boilers the heat exchangers are made of special alloy stainless steel, and their estimated service life is 10-20 years. Cast-iron heat exchangers can serve for half a century, but they are much heavier, requiring accuracy in installation and operation. They will burn for a long time, but can crack on impact or a large temperature difference between the coolant “output” and “input.

Some companies for the manufacture of such heat exchangers use special plastic cast iron, designed specifically to operate in such systems. In other cases, involve devices that do not allow significant temperature differences between the fluid “input” and “output. Most often it is a bypass system, if necessary, return to the boiler part of the hot water if the temperature drop becomes larger than allowed.

In addition, the cast iron boiler has a great inertia: quickly change the temperature it is not able to, when you turn on first warms up a hundred or more kilograms of heat exchanger, and only then can you count on the heating of the coolant. The same happens when you change the operating mode and turn the boiler off. But the inertia is also a “plus” for liquid fuel boilers.

It dramatically reduces the number of on/off cycles of the burner, thus increasing its life span. In addition, do not forget that at the moment of start the burner works inefficiently, burns extra fuel and emits much more harmful substances into the atmosphere. So the inertia turns out to be to the advantage of both the consumer and the environment.

The design of most heat exchangers resembles an ordinary heating battery: several sections connected together. The door with the burner to be installed in the front section, the middle sections are identical. The capacity of the boiler mainly depends on their number. That is why the boilers of the same model range are similar in appearance and differ only in overall length depth .

Some powerful models of boilers can be purchased and in disassembled form, then the installation connection of sections is made directly in the room. Everything is simple: the more powerful the boiler, the more it weighs and it is sometimes easier to assemble it on site than try to take the assembled equipment, even a few meters, even if the width of the doorway allows it.

Heating equipment

The combustion chamber of the cast iron boiler Buderus Logano G125 has a large heat transfer area due to the many ridges

The internal space of the heat exchanger forms a furnace, where the burner is inserted, above there are several two to four horizontal rarely vertical channels, through which the burning products of combustion pass. To increase the intensity of heat exchange in the channels can be inserted turbulators, The simplest type of turbulence for a round channel – a metal bar, to which are attached in a staggered manner semicircular plates.

During maintenance the turbulators are removed and the channel becomes easily accessible for cleaning of the combustion products stuck on it. This is a very important process: the soot layer reduces the intensity of heat exchange, the thicker the layer, the more fuel will literally fly into the chimney. The door for the furnace and the horizontal channels is usually common. In more powerful boilers the channels can be located around the furnace, on its perimeter.

Since the main task of the boiler is to heat the coolant, there is no need to waste energy on heating the ambient air. To reduce heat losses and at the same time to give an attractive appearance, the heat exchanger of the boiler is removed into the body with a layer of thermal insulation.

The second most important element of the boiler – the burner itself. Most boilers are supplied without it. The exceptions are mostly the smaller models. However, many manufacturers complete their boilers with burners of their own production or offered under their own trademark . Generally speaking, you can almost always pick up a burner of another brand: all connecting dimensions are standardized.

The calculation is different here. Boiler, burner and many other elements require periodic maintenance. To call for this two experts from different firms does not resonate, so it is better not to get carried away “hodgepodge” of various elements. Even if the range of firms do not have some of their own elements of the system, you can always pick up equipment from among the recommended, in addition, pre-configure the boiler on site by a specialist.

Liquid fuel boilers are equipped with fan-type burners, forcibly conveying air into the furnace, and at the same time “pushing” the products of combustion through the smoke exhaust system. The burners themselves are technically quite complex, but their main parameter besides power, of course is the height of fuel suction by their own pump. This determines whether or not an additional pump needs to be introduced into the system.

Also the burners can be single-stage power is constant, time varies , two-stage or modulating. The more complicated is the burner, the less fuel it consumes, but its price goes up as well. In practice, for individual heating is usually enough and single-stage burner. Other elements of the burners include automatic ignition systems and safety systems that cut off the fuel supply in case of emergency situations or power outages. Regulate the output of the burner nozzle selection, as well as the parameters of the fuel pump and fan.

The main operational disadvantage of burners is the noise they create. A cardinal way to combat noise – install the boiler in a separate room, however, the equipment of small capacity and noise is small. Modern boilers can work in a living room or corridor. In some cases the burner is retracted into the boiler body and for the big capacities it is “attached” to the front wall and provided with its own noise shielding.

The third main element – the automation unit. Its main task is to maintain the set temperature of the coolant. But like any modern electronic equipment, the block can be equipped with many additional functions. And the more functions, the cheaper is the operation in the long run. In the simplest case, the boiler will maintain the set temperature in a constant mode. If a rapid warming occurs, the boiler will still continue to burn expensive fuel in the same amount. Weather-dependent control unit is equipped with remote temperature sensors in the room or outdoors and consumes fuel based on their readings without human intervention.

Among other functions are the modes of heating different rooms, summer mode operation, when only the hot water system is heated, and the heating is not involved, automatic frost protection of the house in the absence of the owners maintaining a low positive temperature , and more. The most advanced models can be controlled wirelessly by a cell phone or computer, they are able to send data on their work to the service organization, although for such “excesses” already require the connection of additional elements and controllers.

Actually, the boiler, burner and control unit are the foundation of any heating system. Most often they are purchased individually, choosing the most suitable options from several, although some firms offer and complete set, sometimes even as a monoblock, requiring only connection to a fixed heating system. Such a set may also include “bundling”: additional sensors, expansion tanks, pumps, but this is rather an exception. The rule is simple: the more power of the boiler the more possible ways of heating and the more likely that you have to select components “by site.

The fourth element…

Another important element of the system – a storage tank water heater, also known as a boiler. In contrast to the heating system, which is constantly involved quite a certain amount of coolant, hot water is used relatively rarely, but requires a large volume of in a short time. The heat exchanger of the water supply circuit in the boiler even if it is provided there can not heat much, it is much easier to prepare water in advance and consume as required.

There are varieties of boilers with built-in boilers, with separate tanks of vertical or horizontal design “column” or “stand-under-the-boiler” , with the possibility of additional heating… in general, there are a lot of variants.

Perhaps the most interesting of them – the connection to the boiler solar collector. In summer you won’t need fuel to heat water, but in winter, especially on a bright day, the manifold will “help” the boiler a little. Such options are among the typical solutions of many manufacturers of heating equipment.

…and everything else

One of the main problems you have to deal with at the arrangement of the liquid heating system is the allocation of space for fuel storage and purchase of one or more tanks. They are made of steel or plastic, several installation options are possible. The maximum volume of tank for diesel fuel installed in the boiler room next to the boiler – no more than 1 m3 50 liters for indoor installation . This is not enough for a whole season, so the tanks are installed in a separate room or buried in the ground.

The general rule is as follows: if the wall of the tank is destroyed, the fuel must not get into the soil. When outdoor installation, the tanks are placed either in a room with airtight floors and walls, or on special trays, a volume not less than the largest tank in the complex. For burial in the ground are designed double-layered tanks with a leakage sensor between the walls. In addition, the fuel system includes piping, valves, air vents and other elements.

If the tank is located far away or significantly below the burner, the capacity of its built-in pump may not be enough and you will have to add an additional circulating pump. You should also remember that as the temperature drops, diesel fuel and any other increases the viscosity and can even freeze completely, and the main places where this often happens are the filters and pipes. Also diesel fuel for the middle zone can be “summer” and “winter” in the northern regions there is also “arctic” solar fuel with a low freezing point .

Electric boilers

Liquid fuel boiler with boiler Viessmann Vitorond 100

Generally speaking, the quality of the fuel also has a direct influence on the quality of the heating, i.e. e. Frequency of maintenance, boiler efficiency, emission of harmful substances, in particular sulfur compounds, and the service life of individual elements. There is nothing to boast about: studies have shown that in terms of modern standards, the quality of domestic diesel is such that it is “not even good for heating”, and we use it to run internal combustion engines.

But, alas, this parameter does not depend on the consumer, we have to take “what they give”. All you can do is to choose a constant and reliable supplier, since other higher quality fuels for boiler e.g. biodiesel are not common in our country. In any case, at least once a year it is necessary to service both the boiler and the burner.

The liquid heating system is filled either with water or special antifreeze. Increased attention must be paid to water quality when using water. Limescale obstructing the heat exchange from the internal walls is usually almost impossible to remove and system efficiency is reduced. If you use a looped heating system, even a few changes of hard water in it is enough to seriously reduce the capacity.

In an open system DHW circuit scaling appears even faster. To reduce its formation different methods and devices are used. However, this applies mainly to boiler equipment: the sense of passing cold water through a boiler capacity up to 30-40 kW is small, it just does not have time to heat up.

To create a fully autonomous heating system must also take into account the possibility of periodic power outages. If the power supply is lost for no more than two or three hours, nothing bad happens: in the calculation of the heat balance of the building this possibility is taken into account.

It is a different matter, if the duration of an emergency shutdown is measured in days. However, the energy consumption of the system is small for burners – about a hundred watts, other equipment consumes even less . This amount can be provided by a small emergency generator or pre-charged batteries.

And last, but not least important element of heating system – arrangement of air flow, ventilation and chimney. Since the combustion of fuel produces sulfur compounds, brick pipes in operation can collapse literally during the season. Usually the chimney is made of acid-resistant stainless steel. Sometimes steel chimneys are simply inserted inside a brick chimney.

In some cases, coaxial tubes are used: the inner tube takes flue gases away, and in the intertube space is sucked in for combustion. In other cases in the boiler room is required to provide an adequate supply of air and ventilation. Specific solutions for the entire system in each case chosen individually, depending on the characteristics of the house, site and wishes of the owner.

Table: Technical parameters of oil boilers

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