A heat exchanger is one of the elements of devices where thermal processes take place to transfer energy from a heated body to a cold one. All modern heat engines, from a home heating system to a nuclear reactor, which, in fact, is the same boiler, are equipped with such heat transfer parts. They are only performed from different materials and have sophisticated control, security systems.
Purpose, types of metal heat exchangers
The design and performance of heating devices depend on the purpose, principle of operation, and the material of the heat exchanger. For example, it is impossible to create a compact cast iron product for a parapet or wall heater. Since carbon steel or cast iron have a significant density, and hence the mass. The old cast iron boilers are a thing of the past. Today, small-sized heating structures with light parts and a higher level of energy transfer are popular. These include gas wall boilers with copper heat exchanger.
In the production of a thermodynamic structure, materials such as:
copper;
steel of different grades;
cast iron;
aluminum;
silumin.
In modern household heating boilers most of its surface is occupied by a heat exchange unit. The economic and environmental parameters of the boiler depend on the design and type of material.
Depending on the purpose, by such types as heating, cooling, condensing, evaporating. According to the principle of operation, the blocks are regenerative, recuperative and mixing. The first two types have the common name "thermal surface apparatus". One example of such units is radiators in cars. Their purpose is to participate in the operation of the engine cooling system. Heated water is in contact with air through the walls of copper-aluminum heat exchangers.
In mixing (contact) machines, two working streams (hot and cold) are mixed with each other. A similar process is observed in jet condensers, where the atomized liquid uses the energy of condensation. They are easier to manufacture and are characterized by increased heat capacity. But the scope is limited.
Which heat exchangers are better - copper or aluminum?
In heating equipment, the material of the future is increasingly being used - an alloy of aluminum and silicon. A similar eutectic structure made it possible to combine two dissimilar substances - a metal and a mineral. The result is a material with excellent casting properties. Heat exchangers without welds and complex shape increase the energy exchange surface. The task of creating such structures is to optimize heat transfer with the minimum dimensions of the heat transfer unit.
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Aluminum-silicon alloy heat exchanger has good anti-corrosion resistance. The absence of welds, folds gives the product high strength. Another advantage is the optimal mechanical resistance to the low-temperature reverse flow of the coolant. Now the large temperature gradient of the supply and return circuits is not dangerous for the metal.
Thermal devices made of steel and copper alloys
Since mass production household appliances focused on the manufacture of ferrous metal heat exchangers, then gas boilers with a copper heat exchanger are considered a prestigious product. Copper has high heat transfer characteristics. Therefore, small boilers with a small amount of coolant can be used to heat a large house. As a result, the devices are very compact.
Important! Often, buyers are interested in which heat exchanger to choose - steel or copper. It is necessary to proceed from the physico-chemical properties of ferrous and non-ferrous metals. The specific heat capacity of copper is lower than that of steel.
That is, to heat an equal amount of a substance, copper needs to transfer less heat than steel. Accordingly, the inertia of the heating system, where the steel heat transfer unit is located, is greater. The automation of the boiler, working with a copper heat transfer unit, reacts faster to an increase in the temperature of the coolant. As a result, this leads to fuel savings. An even greater reaction of the heating system to heating occurs when the pump is running. In addition, it provides improved circulation even with broken pipe slopes and prevents water from boiling.
Comparing copper heat exchangers for boilers with steel ones, we can say that the latter are more plastic. This factor is important because there is a constant process of interaction with open fire. As a result, thermal stresses of the metal develop and cracks appear. Steel is more durable in this regard and can withstand a large number of cycles: heating - cooling.
The note! The disadvantages of steel, in addition to inertia, increased specific heat, include:
susceptibility to corrosion;
increased surface area of the heater;
a large amount of coolant;
a significant amount of heating devices.
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Steel gas boilers by weight range from 70 kg and above. The more power, the larger the dimensions. A very important parameter of the boiler is the thickness of the metal wall.
The manufacture of copper heat exchangers compared to steel heat exchangers is advantageous even from the point of view of their maintenance. The roughness coefficient of copper is 130 times less than that of steel. Due to this, the hydrodynamic resistance of copper products during the movement of liquid through them reduces the degree of pollution and scale formation.
Important! Today, manufacturers save on metal and reduce the thickness to the limit. This increases the likelihood of rapid burnout. Therefore, when buying, it is necessary to focus on the wall thickness of the heater at least 3 mm.
Geyser with a copper heat exchanger
The geyser incorporates a heat exchanger, the water in which is heated by a burner. Copper with a high heat transfer coefficient quickly transfers heat to the bath water. Copper products work the better, the less different impurities in the alloy. In their presence, the walls of the container heat up unevenly, which causes them to quickly burn out. Sometimes, in order to lower the price of a copper heat exchanger, they reduce the wall thickness and the diameter of the tubes. The mass of the empty apparatus is up to 3.5 kg.
The heat exchange block is made in the form of a tube. In the lower part, it has the shape of a snake with ribs. A metal sheet is installed around it, and a spiral pipe is installed on top of it. In addition to copper, galvanized and stainless steel are used. Which heat exchanger is better, copper or stainless steel, says the very fact of the cost of the device. Copper is 20 times more expensive than steel alloy. But it transfers heat better and is more economical in operation. Stainless steel is more durable.
Important! Before you buy geyser with a copper body exchanger, you should study its technical parameters. A good thing won't be cheap. Copper oxidizes when in contact with water. This process is especially observed at the place of supply cold water. There is condensation. high humidity corrodes the wall of the tube, and fistulas appear. On thin walls, they form quickly. Good quality products will last a lifetime.
Cleaning the Copper Heat Exchanger
As a result of many years of work on heating the coolant, layers are formed on the surface. They degrade the performance of the boiler. If they are ignored for a long time, the unit may fail. To eliminate calcium and other inorganic substances, copper heat exchangers are washed with special chemicals or air is supplied to the cavity under high pressure.
Floor gas boilers for home heating have been used for a long time and have proven themselves well. Huge selection single-circuit and double-circuit models, presented on the market of heating appliances, will allow even the most capricious buyer to choose a unit with the necessary technical parameters and characteristics.
Like any technique, gas boilers have their pros and cons.
Floor standing gas boiler requires sufficient space for installation TO benefits floor gas boilers include:
- Ease of operation. Gas boilers do not need continuous monitoring and are easy to maintain.
- Sufficiently high efficiency with inexpensive fuel.
- Large coverage area. The boiler is able to heat large houses.
Flaws:
- A fair amount of documents and permits, without which the installation of the boiler is impossible.
- The need to build a chimney before installation.
- Installation must only be carried out in adequately ventilated rooms.
- It cannot be installed tightly against a wall or located between two walls so as not to disturb the flow of oxygen to the burner.
Principle of operation
The principle of operation of a floor gas boiler is quite simple: natural gas during combustion, it releases heat and transfers it to a heat exchanger located inside the structure. Then water passes through the heat exchanger and, heating up during the operation of the boiler, is transferred to the room heating system.
Outdoor gas boiler device For right choice you should pay attention to the heat exchanger. The efficiency of your boiler will directly depend on its quality.
Type of heat exchangers
Heat exchangers are made of three types:
Advice. Read consumer reviews and consult with the installers. As practice shows, time-tested modifications can last a very long time.
What types of burners are
By burner type floor standing boilers are divided into two types: boilers with pressurized burner and atmospheric boilers.
The atmospheric boiler has a simpler design, a little cheaper and there is practically no noise from it.
The type of boiler burner will affect its final cost A boiler with a pressurized burner (it can also be called a replaceable, fan, hinged) has a higher price due to the burner, but also a higher efficiency.
Attention! Such a boiler can use not only gas, but also liquid fuel.
The basic package often includes only atmospheric type burners, but if you decide to install a pressurized burner, you will have to purchase it separately.
Single-circuit floor standing gas boilers
Such boilers are designed only to create a heating system. Provide space and hot water such a system cannot. This requires separate heating elements. Single-circuit boilers in our time can be arranged economically or optimally.
Scheme: volatile floor gas boiler - An economical option involves the addition of gas water heater flow action. Such a system will allow two water supply elements to work simultaneously with low fuel consumption.
- At the best option the heat exchanger is installed in the boiler indirect heating. This method provides for the correct matching of the powers of both devices for operation.
Double-circuit floor gas boilers
Such units are of a flow type and combined with a boiler.
Flow boilers are used quite rarely, because their ability to provide hot water is small, only up to 15 liters per minute.
Electricity-independent floor gas boiler Most often, a boiler with a boiler is used, the volume of which is selected independently and depends on the needs of the residents. The disadvantage of such a unit is that they take up a lot of space in the room. However, they will be able to fully provide hot water to those living in the house.
Boiler power selection
For the correct selection of the boiler, it is also necessary to take into account the power you need. It is calculated depending on the area to be heated and possible heat losses. Usually, the technical characteristics of the boiler contain information on what area of \u200b\u200bthe house this model is designed for. However, it is worth considering that it is better to choose a boiler with a power reserve, while the reserve should not exceed 25%, otherwise no one can guarantee you stable operation of the boiler. On average, for houses with normal heat losses, the power is calculated by simple method: 1 kW of power for every 10 sq. m. area. If the heat loss is higher than usual, then it is best to entrust the selection to specialists.
Gas boiler connected to the heating and water supply system It is also worth paying attention to the possibility of adjusting the power of the boiler. She happens:
- single-stage, when the boiler operates constantly at full capacity;
- two-stage with two boiler modes;
- with smooth adjustment, which allows you to adjust the power of work depending on your needs.
Advice. The boiler operates at full capacity only in winter period, therefore boilers with smooth adjustment, or two-stage, are considered more economical.
How to improve security
There are a number of auxiliary elements that will help secure the use of a floor-standing gas boiler, but will increase its cost.
Protect yourself by connecting protection systems to the boiler These include:
- Flame sensor. It is necessary to automatically turn off the gas if the fire goes out.
- A thermostat that turns off the boiler if the water temperature rises to an emergency level.
- Blocking the boiler in the event of a gas shutdown.
- Traction control sensor.
Dependence of boilers on automation
In modern conditions, such a factor as the dependence of a gas boiler on automation is no less important, because there are still areas where power outages are not uncommon. Most of the domestic units with atmospheric burners are able to work without electricity, while imported models most often require it.
Some models of gas boilers can only work with an uninterrupted supply of electricity. achieve energy independence boiler in two ways:
- Maximum simplification of the control system by completely eliminating automation from it. Such a design will maintain the specified coolant temperature, but will not take into account the ambient temperature.
- Use of a heat generator. This method is more advanced and consists in using a device that will allocate the electricity necessary for the operation of automation from the heat produced by the boiler itself.
The difference between boilers with forced draft and natural
Boilers with natural draft are preferable to use in small rooms. The principle of removal of combustion products in such boilers is similar to the principle of operation of a fireplace - combustion products are removed due to natural movement.
Boilers with forced draft receive air from outside through the chimney. The combustion chamber in such boilers is closed, and the chimney is a pipe in a pipe. The internal circuit is used to remove burnt gases, and the external one provides air access to the boiler.
Scheme: operation of an atmospheric gas boiler Forced draft boilers have a number of positive aspects:
- they do not burn oxygen in the room;
- do not need an auxiliary air supply;
- installation does not require the construction of a chimney.
Ignition
In addition to all the above differences, there are also two boiler ignition systems.
Piezo ignition is a practical manual ignition, it is activated by pressing the corresponding button.
Floor standing atmospheric gas boiler Electric ignition of the boiler is automated. If there is a power failure in the system, the boiler will turn on automatically after it is restored. This type of ignition is considered more economical, since it does not have a constantly burning igniter.
Condensing boilers
Conventional boilers, when burning fuel, do not use all the energy that it contains. There is also the so-called latent heat, which is lost in such boilers, leaving together with water vapor into the chimney. Condensing boilers are available to use latent heat. They cause steam to condense by cooling the exhaust gas to a low temperature. Manufacturers of such boilers indicate their increased efficiency, which according to the documentation is above 100%.
Condensing gas boiler Practice shows that the real efficiency of such units is higher than the efficiency of conventional boilers by about 10%, therefore, these boilers consume about the same amount of gas when heating a house.
Installation of floor boilers
Before starting installation, you must select a room, taking into account all the requirements for installation. Double-circuit floor boilers have a number of necessary parameters:
- at least 15 sq. m. should be the area of \u200b\u200bthe room in which the boiler will be installed;
- not 2.5 sq. m. should be the height of this room;
- appropriate size window
- doorway at least 80 cm;
- free access to all systems and devices.
- the presence of a chimney that meets technical requirements.
A modern floor-standing gas boiler will not spoil the interior of your bathroom or kitchen Installation steps:
- preparation of the foundation for the boiler;
- connection of the boiler to the chimney;
- connection of the boiler to the internal heating system;
- mandatory installation of a water filter;
- connection of cold water supply to the boiler;
- connection of the gas pipeline to the boiler.
The choice of a floor gas boiler is obvious if you have main gas and a desire to save on heating and hot water supply. But do not forget that in order to install the boiler, you must obtain a whole set of permits.
Before you go to the store, it is best to make a list of criteria by which the model will be selected:
Energy-saving gas boiler device - Functionality. Double-circuit work on the principle of instantaneous water heaters. If this does not suit you, choose boilers with one circuit and an additional connection of water heaters.
- Adaptation to domestic realities. The pressure in the gas pipeline and the voltage in the network do not always correspond to the standards. Therefore, it is better to choose a model that does not lose power even in extreme conditions.
- Service maintenance. First of all, pay attention to those brands whose service centers are located near your home. Thus, in case of breakdowns, repairs will be faster and cheaper.
- After choosing and purchasing a boiler, leave all the cares associated with its installation to specialists, because this is the only way to ensure a highly qualified approach to work, take all necessary safety measures and complete the installation in accordance with accepted standards.
Modern floor gas boilers are a rather conservative and traditional thing. Over the years, they have not undergone major technological changes, which once again proves their reliability.
How to choose the right gas floor boiler: video
This question necessarily arises among those who first choose a boiler for heating.
If space permits, at first glance, a cast iron heat exchanger is preferable. But this is only at first glance. Let's take a look at some of the misconceptions that lead people to opt for a bulky, expensive, and heavy floor-mounted cast-iron boiler, while ignoring light wall-mounted, which are also cheaper. At the same time, we will not focus on the psychology of such a choice.
- The main arguments of the advocates of cast iron:
- Easy to install and commission.
- The gas consumption of a cast-iron boiler is the same as that of a wall-mounted one, since the efficiency of the boilers is the same.
- Such boilers are cheaper to operate (no need to periodically flush the heat exchanger).
- The heat exchanger from cast iron is not subject to corrosion.
- The boiler will last 50 years or more.
Point one.
On the first point. Cast iron is very sensitive to temperature changes. Therefore, it is very important to correctly design the connection of such a boiler. For example, make-up of the heating system should in no case be carried out before the boiler. The difference between the supply and return should not exceed 20°C; to ensure this parameter, it is necessary to provide a system for automatic mixing of water from the supply to the return. The choice of circulation pump plays an important role. It must fully comply with the boiler, otherwise the boiler will either overheat or turn on and off frequently. Both of these are unacceptable.
The wall-mounted boiler is not afraid of temperature changes. The make-up tap for many wall models is already provided in the design of the boiler, as well as circulation pump, which is selected when designing the boiler and fully corresponds to the design parameters.
Point two.
The fact is that the passport shows the values \u200b\u200bof the efficiency of the boiler when it is operating under ideal conditions. Those. water temperature in the boiler is 60°C, there are no deposits on the heat exchanger, no soot or scale. With an increase or decrease in the temperature of the heating water, the efficiency will decrease, since in the first case, with a decrease in the temperature difference, heat transfer will decrease, in the second case, the flue gases will be colder, which will lead to a decrease in thrust and underburning of gas.
To combat this phenomenon, modulating (with varying gas flow) burners have been designed. In boilers with a cast-iron heat exchanger, there are burners with power adjustment from 70 to 100%, and in boilers with a copper heat exchanger - from 30 to 100%. As a result, the efficiency of a wall-mounted boiler in real conditions is higher than that of a cast-iron one.
In addition, the large mass of the boiler and the large volume of water in it leads to a large thermal inertia of the system as a whole. Such a system heats up for a long time and cools down for a long time; when the heating mode is changed, the boiler either stands idle for a long time or operates with reduced efficiency. It should be noted that the downtime of the boiler, paradoxically, increases the gas consumption in general. This happens because the air in the combustion chamber is heated from the heat exchanger, draft is created through the chimney and the heated air rushes into the atmosphere, while taking heat away from the heating system.
Point three.
Here they are right. Cast iron heat exchanger with connecting dimensions 2" flush with field conditions doesn't make sense. Scale will still remain on the walls. But it should be remembered that the deposition of 1 mm of sediment on the walls of the heat exchanger reduces the performance of the boiler by 5%, while you will not notice anything, a decrease in efficiency can only be established using instruments. In a copper heat exchanger, the flow rate will decrease with the growth of such a layer of deposits, which will serve as a signal for the need for service. Having spent 1 - 2 thousand rubles, you will completely restore the operation of the boiler.
Point four.
This is also correct. Although if you do not flush the boiler, deposits inside the heat exchanger will cause uneven water cooling of the walls, leading in turn to thermal deformation of the cast iron, which can lead to the formation of cracks.
Point five.
Yes. A cast-iron boiler can work for 50 years, and a wall-mounted one only 15. Only technology and legislation do not stand still. Who knows if in 10 years all boilers except condensing ones will be outlawed?
heat exchanger- one of the most important elements of modern gas boiler equipment. And if you want the boiler you are purchasing to work with the highest possible efficiency, then first of all you need to look at what material it is made of, as well as how high quality this material is.
Actually, heat exchanger material can be anything, but in modern conditions the most widespread copper, steel and cast iron heat exchangers. Each of these materials has its own advantages and disadvantages, as well as the degree of efficiency, on which the performance of the purchased boiler equipment will depend. We suggest that you immediately begin to consider each of these types of heat exchangers.
Copper heat exchanger
Let's start with the most unpopular variety. Copper, of course, at one time was quite common. But only in view of the fact that other materials were either too expensive or simply unavailable for technical reasons. Therefore, with the advent of steel and cast iron, copper began to gradually fade into the background. And yet, if you suddenly come across a copper heat exchanger, then know that it has two critical drawbacks.
- The first is a rather high price.
- The second is a rapid burnout, leading to a quick failure of the entire heat exchanger.
Cast iron heat exchanger
Cast iron often called "eternal" material, the durability of which reaches 50 years or more. For an element such as a heat exchanger, this is very . The reason for such a high durability is the resistance of the cast iron material to burn-through, which is a real scourge of copper. In addition, cast iron, by its nature, is perfectly protected from corrosive processes (rust), without the need for any additional anti-corrosion coating.
However, the cast-iron heat exchanger cannot be called ideal. You need to know that it has two important drawbacks.
- First, cast iron is an extremely heavy material. If you have ever moved from place to place cast iron bath then you know what we're talking about.
- Secondly, the cast iron heat exchanger is very fragile. Even temperature changes can damage it, not to mention purely physical damage. One single strong blow can cause a crack to appear. And it is no longer possible to use a cracked heat exchanger. By the way, cast iron is not the most cheap material which should also be taken into account.
Steel heat exchanger
Steel heat exchangers today are the most common for the reason is simple. Steel is the cheapest of the above materials. Yes, and in their own way technical specifications it's not that far behind cast iron. Of course, the durability here will not be 50 years, but, say, 15 years, no more.
If low-quality steel is used, then you will have to change such a heat exchanger after 5 years. The reason for this is the rather rapid burning of the material under the influence of high temperatures. Well, the fact that steel is afraid of rust (corrosive processes) is known even to small children. This fact also affects the durability of the material.
