One of the main elements of water heating systems - a heater - is designed to transfer heat from heat carriers to a heated room.
To maintain the required room temperature, it is required that at each moment of time the heat loss of the room Qp be covered by the heat transfer of the heater Qpp and pipes Qtp.
The scheme of heat transfer of the heater Qpr and pipes to compensate for the heat loss of the room Qp and Qdop during heat transfer Qt from the side of the water coolant is shown in fig. 24.
Rice. 24. Scheme of heat transfer of a heater located at the outer fence of the building
The heat Qt supplied by the coolant for heating this room should be greater than the heat loss Qp by the amount of additional heat loss Qadd caused by increased heating building structures building.
Qt \u003d Qp + Qadd
The heating device is characterized by the area of the heating surface Fpr, m2, calculated to ensure the required heat transfer of the device.
Heating appliances according to the predominant method of heat transfer, they are divided into radiation (ceiling radiators), convective-radiation (devices with a smooth outer surface) and convective (convectors with a ribbed surface).
When heating rooms with ceiling radiators (Fig. 25), heating is carried out mainly due to radiant heat exchange between heating radiators(heating panels) and the surface of the building structures of the room.
Rice. 25. Suspended metal heating panel: a - with a flat screen; b - with a wave-shaped screen; 1 - heating pipes; 2 - visor; 3 - flat screen; 4 - thermal insulation; 5 - wavy screen
The radiation from the heated panel, falling on the surface of fences and objects, is partially absorbed, partially reflected. In this case, the so-called secondary radiation arises, which is also eventually absorbed by the objects and enclosures of the room.
Radiant heat transfer raises the temperature inner surface fences compared to the temperature during convective heating, and the surface temperature of the internal fences in most cases exceeds the temperature of the air in the room.
With panel radiant heating, due to the increase in the temperature of the surfaces in the room, an environment favorable for humans is created. It is known that a person's well-being improves significantly with an increase in the proportion of convective heat transfer in the total heat transfer of his body and a decrease in radiation to cold surfaces (radiative cooling). This is exactly what is provided with radiant heating, when the heat transfer of a person by radiation decreases due to an increase in the temperature of the surface of the fences.
With panel radiant heating, it is possible to lower the normal (normative for convective heating) air temperature in the room (on average by 1-3 ° C), and therefore the convective heat transfer of a person increases even more. It also improves a person's well-being. It has been established that under normal conditions, people's well-being is ensured at an indoor air temperature of 17.4 ° C with wall heating panels and at 19.3 ° C with convective heating. Hence, it is possible to reduce the consumption of thermal energy for space heating.
Among the disadvantages of the panel-radiant heating system, it should be noted:
Some additional increase in heat loss through external fences in those places where heating elements are embedded in them; -
The need for special fittings for individual control of heat transfer of concrete panels;
Significant thermal inertia of these panels.
Devices with a smooth outer surface are sectional radiators, panel radiators, smooth-tube devices.
Devices with a ribbed heating surface - convectors, ribbed tubes (Fig. 26).
Rice. 26. Schemes of heating devices various kinds(cross section): a - sectional radiator; b - steel panel radiator; c - smooth-tube device of three pipes; g - convector with a casing; D - a device of two finned tubes: 1 - channel for the coolant; 2 - plate; 3 - rib
According to the material from which heating devices are made, metal, combined and non-metallic devices are distinguished. Metal appliances are mainly made of gray cast iron and steel (sheet steel and steel pipes). Copper pipes, sheet and cast aluminum and other metals are also used.
In combined appliances, a heat-conducting material (concrete, ceramics, etc.) is used, in which steel or cast-iron heating elements (panel radiators) or finned metal pipes are embedded, and a non-metallic (for example, asbestos-comeptpy) casing (convectors).
Non-metallic appliances include concrete panel radiators with embedded plastic or glass pipes or with voids, as well as ceramic, plastic and other radiators.
By height, all heaters are divided into high (more than 650 mm high), medium (more than 400 to 650 mm), low (more than 200 to 400 mm) and plinth (up to 200 mm).
According to the magnitude of thermal inertia, devices of small and large inertia can be distinguished. Low-inertia devices have a small mass and contain a small amount of water. Such devices based on metal pipes small sections (for example, convectors) quickly change heat transfer to the room when adjusting the amount of coolant admitted into the device. Devices with large thermal inertia - massive, containing a significant amount of water (for example, concrete or sectional radiators), heat transfer is changed slowly.
For heating appliances, in addition to economic, architectural and construction, sanitary and hygienic and production and installation requirements, thermal engineering requirements are also added. The device is required to transfer from the coolant through a unit area to the room of the largest heat flow. To fulfill this requirement, the device must have an increased value of the heat transfer coefficient Kpr, in comparison with the value of one of the types of sectional radiators, which is taken as a standard (cast iron radiator type H-136).
In table. 20 shows thermal performance and conventional signs mark other indicators of devices. The plus sign indicates positive indicators of the devices, the minus sign - negative ones. Two pluses indicate indicators that determine the main advantage of any type of device.
Table 20
Radiator sections are cast from gray cast iron, they can be combined into devices of various sizes. Sections are connected on nipples with gaskets made of cardboard, rubber or paronite.
known various designs one-, two-, and multi-column sections of various heights, but the most common are two-column sections (Fig. 27) of medium (installation height hm = 500 mm) radiators.
Rice. 27. Two-column radiator section: hp - full height; hm - mounting height (construction); b - building depth
Production cast iron radiators time-consuming, installation is difficult due to the bulkiness and significant mass of the assembled devices. Radiators cannot be considered to meet sanitary and hygienic requirements, since cleaning the intersection space from dust is difficult. These devices have significant thermal inertia. Finally, it should be noted that their appearance does not correspond to the interior of the premises in buildings of modern architecture. These disadvantages of radiators make it necessary to replace them with lighter and less metal-intensive devices. Despite this, cast-iron radiators are the most common heating device at present.
At present, the industry produces cast-iron sectional radiators with a construction depth of 90 mm and 140 mm (type "Moscow" - abbreviated as M, type I Standard - MS and others). On fig. 28 shows the designs of manufactured cast-iron radiators.
Rice. 28. Cast iron radiators: a - M-140-AO (M-140-AO-300); b - M-140; c - RD-90
All cast iron radiators are designed for operating pressure up to 6 kgf/cm2. Heating surface meters heating appliances serve as a physical indicator - a square meter of the heating surface and a thermotechnical indicator - an equivalent square meter (ekm2). An equivalent square meter is the area of a heating device that gives off 435 kcal of heat in 1 hour with a difference average temperature coolant and air 64.5 ° C and water flow in this device 17.4 kg / h according to the scheme of movement of the coolant from top to bottom.
Technical characteristics of radiators are given in table. 21.
Heating surface of cast iron radiators and finned tubes
Table 21
Continuation of the table. 21
Steel panel radiators consist of two stamped sheets forming horizontal manifolds connected by vertical columns (column form) or horizontal channels connected in parallel and in series (serpentine form). The coil can be made from a steel pipe and welded to a single profiled steel sheet; such a device is called sheet-tube.
Rice. 29. Cast iron radiators
Rice. 30. Cast iron radiators
Rice. 31. Cast iron radiators
Rice. 32. Cast iron radiators
Rice. 33. Cast iron radiators
Rice. 34. Schemes of channels for the coolant in panel radiators: a - columnar; b - two-way coil, c - four-way coil
Steel panel radiators differ from cast iron ones in their lower mass and thermal inertia. With a decrease in weight by about 2.5 times, the heat transfer rate is no worse than that of cast-iron radiators. Their appearance satisfies architectural and construction requirements, steel panels are easy to clean from dust.
Steel panel radiators have a relatively small heating surface, which sometimes requires installation panel radiators in pairs (in two rows at a distance of 40 mm).
In table. 22 shows the characteristics of manufactured steel stamped radiator panels.
Table 22
Continuation of the table. 22
Continuation of the table. 22
Concrete panel radiators (heating panels) (Fig. 35) can have concrete coil or register-shaped heating elements made of steel pipes with a diameter of 15-20 mm, as well as concrete, glass or plastic channels of various configurations.
Rice. 35. Concrete heating panel
Concrete panels have a heat transfer coefficient close to those of other devices with a smooth surface, as well as a high thermal stress of the metal. Devices, especially combined type, meet strict sanitary-hygienic, architectural and construction and other requirements. The disadvantages of combined concrete panels include the difficulty of repair, large thermal inertia, which complicates the regulation of heat supply to the premises. The disadvantages of attachment-type devices are the increased costs of manual labor in their manufacture and installation, reduction usable area the floor of the room. Heat losses through additionally heated external fences of buildings also increase.
A smooth-tube device is called a device made of several steel pipes connected together, forming channels for a coil or register-shaped coolant (Fig. 36).
Rice. 36. Forms of connecting steel pipes to smooth-tube heaters: a - serpentine form; b - register form: 1 - thread; 2 - column
In the coil, the pipes are connected in series in the direction of movement of the coolant, which increases the speed of its movement and hydraulic resistance device. When the pipes are connected in parallel in the register, the coolant flow is divided, the speed of its movement and the hydraulic resistance of the device decreases.
The devices are welded from pipes DN = 32-100 mm, located at a distance of 50 mm from each other exceeding their diameter, which reduces mutual exposure and, accordingly, increases heat transfer to the room. Smooth-tube appliances have the highest heat transfer coefficient, their dust-collecting surface is small and they are easy to clean.
At the same time, smooth-tube devices are heavy and bulky, take up a lot of space, increase the consumption of steel in heating systems, and have an unattractive appearance. They are used in rare cases when other types of devices cannot be used (for example, for heating greenhouses).
Characteristics of smooth-tube registers are given in table. 23.
Table 23
The convector is a convective type device, consisting of two elements - a finned heater and a casing (Fig. 37).
Rice. 37. Schemes of convectors: a - with a casing; b - without casing: 1 - heating element; 2 - casing; 3- air valve; 4 - pipe fins
The casing decorates the heater and increases heat transfer due to the increase in air mobility at the surface of the heater. A convector with a casing transfers up to 90-95% of the total heat flux into the room by convection (Table 24).
Table 24
A device in which the functions of the casing are performed by the fins of the heater is called a convector without a casing. The heater is made of steel, cast iron, aluminum and other metals, the casing is made of sheet materials (steel, asbestos cement, etc.)
Convectors have a relatively low heat transfer coefficient. However, they find wide application. This is due to the ease of manufacture, installation and operation, as well as low metal consumption.
Main specifications convectors are given in table. 25.
Table 25
Continuation of the table. 25
Continuation of the table. 25
Note: 1. When installing KP skirting convectors in multiple rows, a correction for the heating surface is introduced depending on the number of rows vertically and horizontally: with a two-row installation vertically 0.97, three-row - 0.94, four-row - 0.91; for two rows horizontally, the correction is 0.97. 2. The indicators of the end and passage models of convectors are the same. Passage convectors have an index A (for example, Hn-5A, H-7A).
A finned tube is a convective-type device, which is a flanged cast-iron pipe, outside surface which is covered with jointly cast thin ribs (Fig. 33).
Square outer surface ribbed tube is many times larger than the surface area of a smooth tube of the same diameter and length. This gives the heater a particularly compact design. In addition, the reduced surface temperature of the fins when using a high-temperature coolant, the relative ease of manufacture and low cost determine the use of this thermally inefficient, heavy device. The disadvantages of finned tubes also include an outdated appearance, small mechanical strength fins and the difficulty of cleaning from dust. Ribbed tubes are usually used in auxiliary premises (boiler rooms, warehouses, garages, etc.). The industry produces round ribbed cast iron pipes 1-2m long. They are installed horizontally in several tiers and connected according to the serpentine scheme with bolts using "kalachi" - flanged cast-iron double taps and counterflanges.
For a comparative thermal performance of the main heating devices in table. 25 shows the relative heat transfer of devices 1.0 m long under equal thermal and hydraulic conditions when water is used as a heat carrier (the heat transfer of a cast-iron sectional radiator 140 mm deep is taken as 100%).
As you can see, sectional radiators and convectors with a casing are distinguished by high heat transfer per 1.0 m of length; convectors without a casing and especially single smooth pipes have the lowest heat transfer.
Relative heat output of heaters with a length of 1.0 m Table 26
Rice. 38. Cast iron ribbed tube with round ribs: 1 - channel for the coolant; 2 - ribs; 3 - flange
To create a favorable thermal regime, devices are chosen that provide uniform heating of the premises.
Metal heaters are installed mainly under the light openings, and under the windows the length of the device is desirable not less than 50-75% of the length of the opening, under the showcases and stained-glass windows the devices are placed along their entire length. When placing devices under windows (Fig. 39a), the vertical axes of the device and the window opening must match (a deviation of not more than 50 mm is allowed).
Devices located at the outer fences contribute to an increase in the temperature of the inner surface in the lower part outer wall and windows, which reduces the radiation cooling of people. updrafts warm air, created by the devices, prevent (if there are no window sills blocking the devices) the ingress of cooled air into the working area (Fig. 40a). In the southern regions with a short warm winter, as well as for a short stay of people, heating devices can be installed near the internal walls of the premises (Fig. 39b). This reduces the number of risers and the length of heat pipelines and increases the heat transfer of devices (by about 7-9%), but there is an unfavorable movement of air with a low temperature near the floor of the room (Fig. 40c).
Rice. 39. Placement of heating devices in rooms (plans): a - under the windows; b - at the inner walls; p - heater
Rice. 40. Schemes of air circulation in rooms (sections) at different locations of heating devices: a - under windows without a window sill; b - under the windows with a window sill c - y inner wall; p - heater
Rice. 41. Location under the window of the heater room: a - long and low (preferably); b - high and short (undesirable)
Vertical heating devices are installed as close as possible to the floor of the premises. With a significant rise of the device above the floor level, the air near the floor surface may be supercooled, since the circulation flows of heated air, closing at the level of the device, do not capture and do not warm up the lower part of the room in this case.
The lower and longer the heater (Fig. 41a), the more even the temperature of the room and the better the entire volume of air warms up. A tall and short device (Fig. 41b) causes an active rise in a jet of warm air, which leads to overheating of the upper zone of the room and the lowering of cooled air on both sides of such a device into the working area.
The ability of a tall heater to cause an active upward flow of warm air can be used to heat rooms of increased height.
Vertical metal appliances, as a rule, are placed openly against the wall. However, it is possible to install them under window sills, in wall niches, with special fencing and decoration. On fig. 42 shows several methods for installing heaters in rooms.
Rice. 42. Accommodation heating appliances- in a decorative cabinet; b - in a deep niche; c - in a special shelter; g - behind the shield; d - in two tiers
Instrument shelter decorative wardrobe, having two slots up to 100 mm high (Fig. 42a), reduces the heat transfer of the device by 12% compared to its open installation near a blank wall. To transfer a given heat flux to the room, the area of the heating surface of such a device must be increased by 12%. Placing the device in a deep open niche (Fig. 42b) or one above the other in two tiers (Fig. 42e) reduces heat transfer by 5%. However, hidden installation of devices is possible, in which the heat transfer does not change (Fig. 42c) or even increases by 10% (Fig. 42d). In these cases, it is not required to increase the area of the heating surface of the device or even reduce it.
The task of the calculation is, first of all, to determine the area of the external heating surface of the device, which, under the calculated conditions, provides the necessary heat flow from the coolant to the room. Then, according to the catalog of devices, based on the estimated area, the nearest trade size of the device is selected (the number of sections or the brand of the radiator (the length of the convector or finned tube). The number of sections of cast-iron radiators is determined by the formula: N=Fpb4/f1b3;
where f1 is the area of one section, m2; type of radiator accepted for indoor installation; b4 - correction factor, taking into account the way the radiator is installed in the room; b3 is a correction factor that takes into account the number of sections in one radiator and is calculated by the formula: b3=0.97+0.06/Fp;
where Fp is the calculated area of the heater, m2.
Right choice, competent design and quality installation heating systems are a guarantee of warmth and comfort in the house during the entire heating season. Heating must be of high quality, reliable, safe, economical. To choose the right heating system, you need to familiarize yourself with their types, features of installation and operation of heating devices. It is also important to consider the availability and cost of fuel.
A heating system is a complex of elements used to heat a room: a heat source, pipelines, heating devices. Heat is transferred with the help of a coolant - a liquid or gaseous medium: water, air, steam, fuel combustion products, antifreeze.
Heating systems of buildings must be selected in such a way as to achieve the highest quality heating while maintaining comfortable air humidity for a person. Depending on the type of coolant, the following systems are distinguished:
Heating devices of the heating system are:
Scheme of a two-pipe heating system with forced circulation
As a heat source can be used:
The air is heated directly from the heat source without the use of an intermediate liquid or gaseous heat carrier. Systems are used for heating private houses small area(up to 100 sq.m.). Installation of heating of this type is possible both during the construction of a building and during the reconstruction of an existing one. A boiler, heating element or heating element serves as a heat source. gas-burner. The peculiarity of the system is that it is not only heating, but also ventilation, since the internal air in the room is heated and the fresh air coming from outside. Air streams enter through a special intake grille, are filtered, heated in a heat exchanger, after which they pass through the air ducts and are distributed in the room.
Adjustment of temperature and degree of ventilation is carried out by means of thermostats. Modern thermostats allow you to pre-set a program of temperature changes depending on the time of day. The systems also operate in air conditioning mode. In this case, the air flows are directed through the coolers. If there is no need for space heating or cooling, the system works as a ventilation system.
Diagram of an air heating device in a private house
Installation of air heating is relatively expensive, but its advantage is that there is no need to warm up the intermediate coolant and radiators, due to which fuel savings are at least 15%.
The system does not freeze, quickly responds to temperature changes and warms up the premises. Thanks to filters, the air enters the premises already purified, which reduces the number of pathogenic bacteria and contributes to the creation of optimal conditions to maintain the health of people living in the house.
The lack of air heating is overdrying of the air, burning out oxygen. The problem is easily solved by installing a special humidifier. The system can be upgraded to save money and create a more comfortable microclimate. So, the recuperator heats the incoming air, due to the output to the outside. This reduces the energy consumption for its heating.
Additional purification and disinfection of air is possible. To do this, in addition to the mechanical filter included in the package, electrostatic fine filters are installed and ultraviolet lamps.
air heating With additional devices
This is a closed heating system, it uses water or antifreeze as a coolant. Water is supplied through pipes from the heat source to the heating radiators. In centralized systems, the temperature is controlled by heating point, and in individual - automatically (using thermostats) or manually (cranes).
Depending on the type of connection of heating devices, the systems are divided into:
According to the method of wiring, they distinguish:
AT single pipe systems connection of heating devices in series. To compensate for the loss of heat that occurs during the successive passage of water from one radiator to another, heaters with different heat transfer surfaces are used. For example, can be used cast iron batteries With large quantity sections. In two-pipe, a parallel connection scheme is used, which allows you to install the same radiators.
The hydraulic mode can be constant and variable. In bifilar systems, heating devices are connected in series, as in single-pipe systems, but the heat transfer conditions for radiators are the same as in two-pipe systems. Convectors, steel or cast iron radiators are used as heating devices.
Scheme of two-pipe water heating country house
Water heating is widespread due to the availability of the coolant. Another advantage is the ability to equip the heating system with your own hands, which is important for our compatriots who are accustomed to relying only on their own strength. However, if the budget allows not to save, it is better to entrust the design and installation of heating to specialists.
This will save you from many problems in the future - leaks, breakthroughs, etc. Disadvantages - freezing of the system when turned off, a long time for warming up the premises. Special requirements apply to the coolant. Water in the systems must be free of impurities, with a minimum salt content.
To heat the coolant, a boiler of any type can be used: on solid, liquid fuel, gas or electricity. Most often used gas boilers, which involves connecting to the highway. If this is not possible, then solid fuel boilers are usually installed. They are more economical than electric or liquid fuel designs.
Note! Experts recommend choosing a boiler based on a power of 1 kW per 10 sq.m. These figures are indicative. If the ceiling height is more than 3 m, in the house big windows, there are additional consumers or the premises are not well insulated, all these nuances must be taken into account in the calculations.
Closed house heating system
In accordance with SNiP 2.04.05-91 "Heating, ventilation and air conditioning", the use of steam systems is prohibited in residential and public buildings. The reason is the insecurity of this type of space heating. Heaters heat up to almost 100°C, which can cause burns.
Installation is complex and requires skill and special knowledge, during operation there are difficulties with the regulation of heat transfer, when filling the system with steam, noise is possible. Today, steam heating is used to a limited extent: in industrial and non-residential premises, in pedestrian crossings, thermal points. Its advantages are relative cheapness, low inertia, compactness of heating elements, high heat transfer, no heat loss. All this led to the popularity of steam heating until the middle of the twentieth century, later it was replaced by water heating. However, in enterprises where steam is used for industrial needs, it is still widely used for space heating.
Boiler for steam heating
This is the most reliable and easiest type of heating in operation. If the area of the house is not more than 100 m, electricity is a good option, but heating a larger area is not economically viable.
Electric heating can be used as an additional in case of a shutdown or repair of the main system. It is also a good solution for country houses in which the owners live only periodically. As additional heat sources, electric fan heaters, infrared and oil heaters.
Convectors, electric fireplaces, electric boilers, floor heating power cables are used as heating devices. Each type has its own limitations. So, convectors heat the rooms unevenly. Electric fireplaces are more suitable as decorative element, and the operation of electric boilers requires significant energy costs. The underfloor heating is mounted with advance consideration of the furniture arrangement plan, because when it is moved, the power cable may be damaged.
Scheme of traditional and electric heating of buildings
Separately, mention should be made of innovative heating systems, which are becoming increasingly popular. The most common:
These heating systems have only recently appeared on the market, but have already become quite popular due to their efficiency and greater economy than the usual electric heating. Warm floors are powered by the mains, they are installed in a screed or tile adhesive. Heating elements (carbon, graphite) emit infrared waves that pass through flooring, heat up the bodies of people and objects, from which, in turn, the air heats up.
Self-adjusting carbon mats and foils can be mounted under furniture legs without fear of damage. Smart floors regulate temperature thanks to special property heating elements: when overheated, the distance between the particles increases, the resistance increases - and the temperature decreases. Energy costs are relatively low. When the infrared floors are turned on, the power consumption is about 116 watts per linear meter, after warming up it decreases to 87 watts. Temperature control is provided by thermostats, which reduces energy costs by 15-30%.
Infrared carbon mats are convenient, reliable, economical, easy to install
These are devices for transferring thermal energy from a source to a coolant. In itself, the idea of a heat pump system is not new; it was proposed by Lord Kelvin back in 1852.
How it works: A geothermal heat pump draws heat from environment and transfers it to the heating system. The systems can also work to cool buildings.
How a heat pump works
There are pumps with open and closed cycle. In the first case, the installations take water from the underground stream, transfer it to the heating system, take heat energy and return it to the place of intake. In the second, a coolant is pumped through special pipes in the reservoir, which transfers / takes heat from the water. The pump can use the thermal energy of water, earth, air.
The advantage of the systems is that they can be installed in houses that are not connected to the gas supply. Heat pumps are complex and expensive to install, but they save on energy costs during operation.
The heat pump is designed to use the heat of the environment in heating systems
Solar installations are systems for collecting solar thermal energy and transferring it to a coolant
Water, oil or antifreeze can be used as a heat carrier. The design provides for additional electric heaters that turn on if the efficiency of the solar installation decreases. There are two main types of collectors - flat and vacuum. An absorber with a transparent coating and thermal insulation is installed in the flat ones. In vacuum, this coating is multilayer, in hermetically sealed collectors a vacuum is created. This allows you to heat the coolant up to 250-300 degrees, while flat installations can only heat it up to 200 degrees. The advantages of the installations include ease of installation, low weight, potentially high efficiency.
However, there is one “but”: the efficiency of the solar collector depends too much on the temperature difference.
solar collector in the domestic hot water and heating system Comparison of heating systems shows that there is no perfect way heating
Our compatriots still most often prefer water heating. Usually, doubts arise only about which specific heat source to choose, how best to connect the boiler to the heating system, etc. And yet there are no ready-made recipes suitable for absolutely everyone. It is necessary to carefully weigh the pros and cons, take into account the features of the building for which the system is selected. If in doubt, a specialist should be consulted.
heating device- this is an element of the heating system, which serves to transfer heat from the coolant to the air of the heated room.
1. Registers from smooth pipes represent a bundle of pipes located in two rows and united on both sides by two pipes - collectors, equipped with fittings for supplying and discharging the coolant.
Registers of smooth pipes are used in rooms where there are increased sanitary and hygienic requirements, as well as in industrial buildings, increased degree of fire hazard, where it is unacceptable large cluster dust. The devices are hygienic, easy to clean from dust and dirt. But not economical, metal-intensive. Estimated heating surface of 1m smooth pipe.
2. Cast iron radiators. The block of cast-iron radiators consists of cast iron sections interconnected by nipples. They are 1-2 and many channel. In Russia, mainly 2-channel radiators. According to the mounting height, radiators are divided into high 1000 mm, medium - 500 mm and low 300 mm.
M-140-AO radiators have inter-column finning, which increases their heat transfer, but reduces aesthetic and hygienic requirements.
Cast iron radiators have a number of advantages. It:
1. Corrosion resistance.
2. Fine-tuned manufacturing technology.
3. Ease of changing the power of the device by changing the number of sections.
The disadvantages of these types of heaters are:
1. High consumption of metal.
2. The complexity of manufacturing and installation.
3. Their production leads to environmental pollution.
3. Finned tubes. They are a cast iron pipe with round fins. The fins increase the surface of the instrument and reduce the surface temperature.
Ribbed tubes are mainly used in industrial plants.
Advantages:
1. Cheap heaters.
2. Large heating surface.
Flaws:
Do not meet sanitary and hygienic requirements (difficult to clean from dust).
4. Stamped steel radiators. They are two putty steel places, interconnected by contact welding.
There are: columnar radiators RSV 1 and serpentine radiators RSG 2.
Column radiators: form a series of parallel channels, interconnected at the top and bottom by horizontal collectors.
Serpentine radiators form a series of horizontal channels for the passage of the coolant.
Steel plate radiators made in single and double rows. Double-row are made of the same standard sizes as single-row, but consist of two plates.
Advantages:
1. Small weight of the device.
2. Cheaper than cast iron by 20-30%.
3. Less transportation and installation costs.
4. Easy to install and meet sanitary and hygienic requirements.
Flaws:
1. Small heat dissipation.
2. Special treatment of heating water is required, since ordinary water corrodes with metal. Found wide application in housing in public buildings. Due to the rise in the price of metal, the release is limited. High price.
5. Convectors. They are a series of steel pipes through which the coolant moves and steel finning plates mounted on them.
Convectors are available with or without casing. They are made of various types: For example: Comfort convectors. They are divided into 3 types: wall-mounted (hung on a wall h = 210 m), island (installed on the floor) and stair (built into the building structure).
Convectors are made end and through. Convectors are used for heating buildings for various purposes. Used mainly in central Russia.
Non-metallic heating devices
6. Ceramic and porcelain radiators. They are a panel cast from porcelain or ceramic with vertical or horizontal channels.
Such radiators are used in rooms with increased sanitary and hygienic requirements for heating devices. Such devices are used very rarely. They are very expensive, the manufacturing process is laborious, short-lived, subject to mechanical stress. It is very difficult to connect these radiators to metal pipelines.
7. Concrete heating panels. They are concrete slabs with pipe coils embedded in them. Thickness 40-50 mm. They are: window sill and partition.
Heating panels can be attached and built into the construction of walls and partitions. Concrete panels meet the most stringent sanitary and hygienic requirements, architectural and construction requirements.
Disadvantages: difficulty of repair, large thermal inertia, which complicates the regulation of heat transfer, increased heat loss through additionally heated external structures of buildings. They are mainly used in medical institutions in operating rooms and in maternity hospitals in children's rooms.
Plumbing heating appliances must meet the heat engineering, sanitary and hygienic and aesthetic requirements.
Thermal engineering assessment heating devices is determined by its heat transfer coefficient.
Sanitary and hygienic assessment- characterized constructive solution appliance to make it easier to keep clean.
The temperature of the outer surface of the heater must meet sanitary and hygienic requirements. In order to avoid intense burning of dust, this temperature should not exceed for residential and public buildings 95 o C, for medical and children's institutions 85 o C.
Aesthetic evaluation- the heater must not spoil internal view rooms, should not take up much space.
heating devices central heating systems are called devices for transferring heat from a coolant to a heated room. Heating devices should best transfer heat from the coolant to the room, ensure the comfort of the thermal environment in the room, without deteriorating its interior at the lowest cost of funds and materials.
Types and designs of heating devices can be very diverse. Devices are made of cast iron, steel, ceramics, glass, in the form of concrete panels with tubular heating elements embedded in them, etc.
The main types of heating devices are radiators, finned tubes, convectors and heating panels.
The simplest is heating device made of smooth steel pipes . Usually it is performed in the form of a coil or register. The device has a high heat transfer coefficient, withstands high coolant pressure. However, smooth tube appliances are expensive and take up a lot of space. They are used in rooms with significant dust emissions, for heating skylights in industrial buildings, etc.
The most widely used heating devices are radiators . Their various types differ from each other in size and shape. Radiators are assembled from sections, which allows you to assemble devices of different sizes. Usually sections are cast from cast iron, but can be steel, ceramic, porcelain, etc.
Quite widespread in heating systems are cast iron finned tubes . The ribs on the pipe surface increase the area of the heat-releasing surface, but reduce the hygienic qualities of the device (dust accumulates, which is difficult to remove) and gives it a rough appearance.
Convectors are steel pipes with sheet steel fins. The most perfect among convectors is a convector in a casing made of steel sheet. The device is equipped with a cap for regulating heat transfer. Between the finned surfaces of the device and the casing, under the influence of gravitational pressure, intensive air circulation occurs. This increases the heat removal from the finned surface by 20% or more. Convectors in a casing are compact and have a good appearance. In some designs, convectors are equipped with a special type of fan that provides intensive air movement. Artificial induction of air movement significantly increases heat removal from the device. Some disadvantage of convectors is the necessity and difficulty of cleaning from dust.
Concrete heating panels are plates with coils made of steel pipes embedded in them. Such panels are usually located in the structures of the fences of the premises. Sometimes they are freely installed near the walls.
At present, for heating large industrial workshops, hanging panels with reflective screens .
The use of panels for heating buildings satisfies the requirements of prefabricated construction and saves the metal spent on heating devices. The disadvantages of panel heating include: large thermal inertia, which complicates the regulation of heat transfer; the impossibility of changing the heating surface; the danger of pipe clogging and the difficulty of its elimination; the complexity of repairing systems; the possibility of internal corrosion and, as a result, a violation of the hydraulic tightness of the pipes.
