Heating devices for heating systems. Modern water heating devices
One after another, economic crises are hitting the planet, which, coupled with a rapidly decreasing amount of resources, creates a need for the development and use of energy-saving technologies. This trend has not bypassed heating systems, which strive to maintain or even increase their efficiency while consuming significantly less resources. Let's figure out what new technologies for heating a private house, apartment and industrial premises, decomposing the heating system into four main components: heat generator, heating device, heating system and control system.
The boiler heating system is the most productive, although also the most expensive (after electric heaters) of all modern autonomous heating technologies. Although the boiler itself is an invention with ancient history, modern manufacturers have managed to modernize it, increasing efficiency and adapting it to different types of fuel. Thus, there are three main (fuel-burning) types of boilers - solid fuel, gas, liquid fuel. Electric boilers that are somewhat out of this classification, as well as combined or multi-fuel boilers, combine the qualities of two or three types at once.
Solid fuel boilers
An interesting trend is a return to the traditions of the past and the active use of solid fuels: from ordinary firewood and coal to special pellets (pellets pressed from wood processing by-products) and peat briquettes.
Solid fuel boilers are divided according to the type of fuel into:
The classic ones “accept” any type of solid fuel without any problems, are extremely reliable and simple (in fact, this is the oldest heat generator in the history of mankind), and are cheap. Among the disadvantages: “capriciousness” in relation to wet fuel, low efficiency, inability to adjust the temperature of the coolant.
A pellet boiler is a heating device that runs on wood waste compressed into small pellets. They are distinguished by high efficiency, long-term operation on one load, an extremely convenient pellet loading system (filled from a bag or bag), and the ability to customize the boiler. The only significant drawback is the rather expensive pellets for heating, the price of which ranges from 6900 to 7700 rubles per ton, depending on the ash content and calorific value.
The next type is pyrolysis heating boilers, operating on pyrolysis gas extracted from wood. The fuel in such a boiler slowly smolders rather than burns, due to which it gives off noticeably more heat. Advantages: high efficiency and reliability, adjustable heat transfer, up to half a day of operation without reloading. The only drawback is the need to connect to the electrical network, which can cause the house to be left without heat during power outages.
Standard boilers long burning loaded with any types of solid fuel, with the exception of wood: coke, brown and coal, peat briquettes, pellets. There is another variety, designed specifically for working with wood and slightly different in design. Advantages: work up to five days on oil products and up to two days when loaded with wood. Disadvantages: relatively low efficiency, need for constant cleaning.
Gas boilers
Mains gas is the most economical of all types of fuel, and boilers running on it are considered the most convenient to use and maintain. This is explained by their fully automated operation and absolute safety, for which many sensors and controllers are responsible. They do not have any disadvantages as such, although they do require a gas line or constant delivery of new cylinders.
Liquid fuel boilers
It cannot be said that such heating systems are innovative, but they have been consistently in demand for decades and are therefore worthy of mention. The main types of liquid fuel: diesel fuel and liquefied propane-butane mixture. Advantages over solid fuels: almost complete automation of operation. Disadvantages: extremely high cost of heating, second only to electricity.
Electric heating
It is distinguished by a wide variety of heating systems and individual devices. These are electric convectors (which in turn are in-floor, floor-mounted and wall-mounted), and electric boilers, and fan heaters, and infrared heaters, and oil radiators, and heat guns, and the well-known warm floor. Their common and so far insurmountable drawback is the extremely high cost of heating. The most economical of them are infrared radiators and heated floors.
Heat pumps
These heating systems are modern in the full sense of the word, despite the fact that they appeared back in the 80s. Then they were available only to wealthy people, but now many have gotten used to collecting them by hand, thanks to which they are slowly but surely gaining popularity. A very simplified principle of their operation is to extract heat from the air, water or ground outside the house and transfer it into the house, where the heat is transferred either directly into the air, or first into the coolant - water.
Solar systems
Another developing one at a fast pace technology - solar heating systems, better known as solar panels.
Advantages:
Flaws:
Thermal panels
They are thin rectangular (usually) plates fixed to the wall. The back side of such a plate is covered with a heat-accumulating substance that can heat up to 90 degrees and receives heat from the heating element. Energy consumption is only 50 watts per 1 square meter, unlike older electric fireplaces that require at least 100 watts for the same area. Heating occurs due to the convection effect.
In addition to being economical, thermal panels differ in:
There is only one drawback - thermal panels become unprofitable in the spring and early autumn, when the home only needs a little heating from evening to morning.
Monolithic quartz modules
A unique development by S. Sargsyan - Candidate of Technical Sciences. Externally, the plates are very similar to thermal panels, but the principle of their operation is based on the high heat capacity of quartz sand. The heating element transfers thermal energy to the sand, after which it continues to heat the home, even when the device is unplugged. The savings, as in the case of thermal panels, are 50% of the costs of standard electric heaters.
PLEN - film radiant electric heaters
This innovative heating system is as simple as it is ingenious: power cable, heating elements, dielectric film and reflective screen. The heater is fixed to the ceiling, and the infrared radiation it produces heats objects located below. These, in turn, transfer heat to the air.
The main advantages of PLEN:
Thermal hydrodynamic pumps
These devices, also known as cavitation heat generators for heating systems, generate heat by heating the coolant using the principle of cavitation.
The coolant in such a pump rotates in a special activator.
At the sites of rupture of an integral mass of liquid, as a result of an instantaneous decrease in pressure, bubbles-cavities appear, bursting almost instantly. This causes a change in the physicochemical parameters of the coolant and the release of thermal energy.
It is interesting that even with the current level of scientific and technological development, the process of cavitation energy generation is poorly understood. A clear explanation for why the energy gain is greater than its costs has not yet been found.
Air conditioner as a heater
Almost everything modern models air conditioners are equipped with a heating function. Oddly enough, the air conditioner has three times the efficiency of standard electric heaters: 3 kW of heat from 1 kW of electricity versus 0.98 kW of heat from 1 kW of electricity.
Thus, an air conditioner for heating in winter can temporarily replace a switched-off heating system or a broken electric fireplace. However, due to the fact that air conditioners do not use heating elements to heat the air, their efficiency drops with every degree of temperature outside the window. Besides, severe frost overloads the device, and operation in this mode can lead to breakdown. The best option There will be use of air conditioning in the off-season.
Convectors
Since a convector heating system is an extremely broad concept, and almost every modern heating device uses the convection effect, we will make a reservation in advance that we are talking here only about individual water and electric convectors. They represent placed in metal case fin heater.
The air circulating between the ribs of the device heats up and rises, and in its place air masses that have already cooled during this time are drawn in.
This endless circulation is called convection. Based on the heat source, convector heaters are divided into water and electric, and based on location - into in-floor, floor-mounted and wall-mounted. Also, any of them can work on the principle of either natural convection or forced (with a fan).
Although the types of convectors and the features of each of them are a topic for a separate article, we can highlight the general advantages of using these heaters:
So which is more profitable financially?
As a summary of this section, let’s compare the cost of heating using different types of fuel: wood, pellets, coal, diesel fuel, propane-butane mixture, regular main gas and electricity. At average prices for each type of fuel and with the average duration of the heating season being 7 months, during this time you will have to spend:
The leader is obvious.
Heating devices
First of all, modern heating radiators are bimetallic and aluminum models. However, there is a stable demand for both steel and cast iron products, which is due to the new approach of manufacturers to the manufacture of seemingly outdated heating devices. Let us briefly describe the advantages and disadvantages of each type.
Aluminum
They are most popular in the post-Soviet space for their price/quality ratio (cheaper than bimetallic, in many ways more reliable than steel and cast iron).
Advantages:
- the best heat transfer among all analogues;
- expensive models can withstand pressure up to 20 bar;
- light weight;
- simplest installation.
Disadvantages: poor corrosion resistance, especially noticeable at the junction of aluminum with other metals;
Bimetallic
Generally recognized best type radiators. They got their name due to the combination of steel (inner layer) and aluminum (casing) in their design.
Advantages:
Disadvantages: high price.
Steel
They are poorly suited for multi-storey buildings and centralized heating systems in general, but show all their best properties in private houses and fit perfectly into heating systems production premises in factories and factories. You can read more about steel heating radiators.
Advantages:
- heat transfer is above average;
- rapid onset of heat transfer;
- low cost;
- aesthetic appearance.
Flaws:
Cast iron
It should be understood that modern cast iron heating radiators are no longer lumpy and heavy relics of the past that “decorated” almost every house during the Soviet era. Modern manufacturers significantly improved their appearance, making them almost indistinguishable from bimetallic or aluminum models. Moreover, there is a growing fashion for the so-called, the shapes and patterns of which bring the atmosphere of the early 20th century into the house.
Advantages:
Disadvantages: huge weight and the ensuing difficulties with installation (special supports-legs are often required).
Heating system
Most modern country houses use a horizontal heating system, the main difference of which from vertical distributions is the partial (less often - complete) absence of vertical risers.
In Russia, such a type of horizontal system as a single-wire heating system (or single-pipe) is especially popular.
They involve natural movement of water, without a circulation pump. From the heating device, the coolant flows through a riser to the second floor of the building, where it is distributed over radiators and transmission risers.
Water circulation without a pump is made possible by changing the density of hot and cold water.
A single-pipe system has a number of advantages over a two-pipe system:
Control system
Additional benefits can be provided by a heating system controller - a miniature computer device capable of:
One of the main elements of water heating systems - a heating device - is designed to transfer heat from the coolant to the heated room.
To maintain the required room temperature, it is required that at each moment of time the heat loss of the room Qп is covered by the heat transfer of the heating device Qпp and pipes Qтp.
The heat transfer diagram of the heating device Qпp and pipes to compensate for the heat losses of the room Qп and Qadd during heat transfer Qт from the water coolant side is shown in Fig. 24.
Rice. 24. Heat transfer diagram of a heating device located near the external fence of the building
The heat Qt supplied by the coolant for heating a given room must be greater than the heat loss Qp by the amount of additional heat loss Qadd caused by increased heating building structures buildings.
Qt=Qp + Qadd
A heating device is characterized by the heating surface area Fpp, m2, calculated to ensure the required heat transfer of the device.
Heating devices, according to the predominant method of heat transfer, 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 - wave-shaped screen
Radiation from a heated panel, hitting the surface of fences and objects, is partially absorbed and partially reflected. In this case, so-called secondary radiation occurs, which is also ultimately absorbed by objects and fences in the room.
Thanks to radiant heat exchange, the temperature of the internal surface of the enclosures increases compared to the temperature during convective heating, and the surface temperature of the internal enclosures in most cases exceeds the room air temperature.
When panel- radiant heating By increasing the temperature of surfaces in the room, an environment favorable for humans is created. It is known that a person’s well-being significantly improves with an increase in the share 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 ensured with radiant heating, when heat transfer from a person by radiation decreases due to an increase in the surface temperature of the fences.
With panel radiant heating, it is possible to lower the air temperature in the room compared to the usual (normative for convective heating) (on average by 1-3° C), and therefore the convective heat transfer of a person increases even more. It also helps improve 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. This makes it possible to reduce the consumption of thermal energy for space heating.
Among the disadvantages of the panel radiant heating system, the following should be noted:
Some additional increases in heat loss through external fences in those places where heating elements are embedded in them;-
The need for special fittings for individual regulation of heat transfer of concrete panels;
Significant thermal inertia of these panels.
Devices with a smooth outer surface are sectional radiators, panel radiators, and smooth-tube devices.
Devices with a ribbed heating surface - convectors, finned pipes (Fig. 26).
Rice. 26. Diagrams of heating devices various types(cross section): a - sectional radiator; b - steel panel radiator; c - smooth-tube device of three pipes; g - convector with casing; D - device made of two finned tubes: 1 - channel for coolant; 2 - plate; 3 - edge
Based on the material from which heating appliances are made, a distinction is made between metal, combined and non-metallic appliances. Metal appliances are made mainly 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, into which steel or cast iron heating elements (panel radiators) or finned metal pipes are placed and a non-metallic (for example, asbestos) casing (convectors).
TO non-metallic devices These include concrete panel radiators with embedded plastic or glass pipes, or with voids, as well as ceramic, plastic and other radiators.
By height, all heating devices are divided into high (over 650 mm in height), medium (over 400 to 650 mm), low (over 200 to 400 mm) and baseboard (up to 200 mm).
Based on the magnitude of thermal inertia, devices of low and high inertia can be distinguished. Low-inertia devices have a small mass and hold a small amount of water. Such devices, made on the basis metal pipes small cross-sections (for example, convectors) quickly change the heat transfer to the room when regulating the amount of coolant admitted into the device. Devices with high thermal inertia - massive, containing a significant amount of water (for example, concrete or sectional radiators), heat transfer changes slowly.
For heating devices, in addition to economic, architectural, construction, sanitary, hygienic and production and installation requirements, thermal technical requirements are also added. The device is required to transfer the greatest heat flow from the coolant through a unit area to the room. To fulfill this requirement, the device must have an increased value of the heat transfer coefficient Kpr, compared with the value of one of the types of sectional radiators, which is taken as the standard (cast iron radiator type N-136).
In table 20 shows thermal performance indicators and symbols indicate other indicators of devices. The “plus” sign indicates positive indicators of the devices, and the “minus” sign indicates negative indicators. Two pluses indicate indicators that determine the main advantage of any type of device.
Table 20
Design of heating devices
A sectional radiator is a device of convective-radiation type, consisting of individual columnar elements - sections with round or ellipse-shaped channels. Such a radiator releases about 25% of the total heat flux transferred from the coolant into the room by radiation (the remaining 75% by convection) and is called a “radiator” only by tradition.Radiator sections are cast from gray cast iron and can be assembled into devices of various sizes. The sections are connected on nipples with gaskets made of cardboard, rubber or paronite.
Various designs of single-, double-, and multi-column sections of various heights are known, but the most common are double-column sections (Fig. 27) of medium-sized (installation height hm = 500 mm) radiators.
Rice. 27. Double-column radiator section: hp - full height; hm - installation height (construction); b - construction depth
The production of cast iron radiators is labor-intensive; 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 intersectional 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 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- This is the most common heating device today.
Currently, the industry produces cast-iron sectional radiators with a construction depth of 90 mm and 140 mm (type “Moscow” - abbreviated as M, type IStandardI - MS and others). In 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. The heating surface of heating devices is measured by a physical indicator - a square meter of heating surface and a thermal indicator - an equivalent square meter (ecm2). An equivalent square meter is the area of a heating device that emits 435 kcal of heat in 1 hour with a difference average temperature coolant and air 64.5 ° C and water consumption in this device is 17.4 kg/hour according to the flow pattern 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 collectors connected by vertical columns (columnar form), or horizontal channels connected in parallel and in series (serpentine form). The coil can be made of a steel pipe and welded to one profiled steel sheet; such a device is called a sheet-tube device.
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. Diagrams of channels for coolant in panel radiators: a - columnar; b - two-way coil, c - four-way coil
Steel panel radiators differ from cast iron in their lower mass and thermal inertia. With a weight reduction of approximately 2.5 times, the heat transfer rate is no worse than that of cast iron radiators. Their appearance meets architectural and construction requirements; steel panels are easy to clean from dust.
Steel panel radiators have a relatively small heating surface area, which is why it is sometimes necessary to install panel radiators in pairs (in two rows at a distance of 40 mm).
In table 22 shows the characteristics of manufactured stamped steel radiator panels.
Table 22
Continuation of the table. 22
Continuation of the table. 22
Concrete panel radiators (heating panels) (Fig. 35) can have concrete heating elements of a coil or register shape 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 that of other devices with a smooth surface, as well as high thermal stress of the metal. Devices, especially combined types, meet strict sanitary, hygienic, architectural, construction and other requirements. The disadvantages of combined concrete panels include difficulties in repair, high thermal inertia, which complicates the regulation of heat supply to the premises. The disadvantages of attachment-type devices are the increased cost of manual labor during their manufacture and installation, reduction usable area floor of the room. Heat loss through additionally heated external fences of buildings also increases.
A smooth-tube device is called a device made of several steel pipes connected together, forming channels for the coolant of a coil or register shape (Fig. 36).
Rice. 36. Forms of connecting steel pipes into smooth-tube heating devices: a - coil 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 the hydraulic resistance of the device. When the pipes in the register are connected in parallel, the coolant flow is divided, its speed and the hydraulic resistance of the device are reduced.
The devices are welded from pipes DN = 32-100 mm, located from each other at a distance of 50 mm greater than their diameter, which reduces mutual radiation and accordingly increases heat transfer to the room. Smooth-tube devices 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).
The characteristics of smooth-tube registers are given in Table. 23.
Table 23
A 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 helps increase heat transfer by increasing air mobility near the surface of the heater. A convector with a casing transfers up to 90-95% of the total heat flow into the room by convection (Table 24).
Table 24
A device in which the heater fins perform the functions of the casing 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. Still they find wide application. This is due to the ease of manufacture, installation and operation, as well as low metal consumption.
The main technical characteristics of convectors are given in table. 25.
Table 25
Continuation of the table. 25
Continuation of the table. 25
Note: 1. When installing multi-row KP baseboard convectors, a correction is introduced for the heating surface depending on the number of rows vertically and horizontally: for a two-row installation vertically 0.97, three-row - 0.94, four-row - 0.91; for two horizontal rows the correction is 0.97. 2. The performance of end and pass-through models of convectors are the same. Pass-through convectors have index A (for example Nn-5A, N-7A).
A finned pipe is a convective-type device, which is a flanged cast-iron pipe, the outer surface of which is covered with jointly cast thin ribs (Figure 33).
The outer surface area of a finned pipe is many times greater than the surface area of a smooth pipe of the same diameter and length. This makes the heating device particularly compact. In addition, the lower surface temperature of the fins when using a high-temperature coolant, the comparative ease of manufacture and low cost determine the use of this heavy device, which is ineffective in terms of heat engineering. The disadvantages of finned tubes also include their unmodern appearance, small mechanical strength ribs and the difficulty of cleaning from dust. Finned tubes are usually used in auxiliary premises(boiler houses, warehouses, garages, etc.). The industry produces round ribbed cast iron pipes 1-2m long. They are installed horizontally in several tiers and connected in a coil pattern with bolts using “rolls” - flanged cast iron double bends and counter flanges.
For comparative thermal characteristics of the main heating devices in table. Figure 25 shows the relative heat transfer of devices 1.0 m long under equal thermal-hydraulic conditions when using water as a coolant (the heat transfer of a cast-iron sectional radiator with a depth of 140 mm 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 length; Convectors without a casing and especially single smooth pipes have the lowest heat transfer.
Relative heat transfer of heating devices 1.0 m long Table 26
Selection and placement of heating devices
When choosing the type and type of heating device, the purpose, architectural layout and features of the thermal conditions of the room, the place and duration of stay of people, the type of heating system, the technical, economic and sanitary-hygienic indicators of the device are taken into account.
Rice. 38. Cast iron finned pipe with round fins: 1 - channel for coolant; 2 - ribs; 3 - flange
To create a favorable thermal regime, choose devices that provide uniform heating of the premises.
Metal heating devices are installed mainly under light openings, and under windows the length of the device is desirable to be at least 50-75% of the length of the opening; under shop windows 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 coincide (deviation of no more than 50 mm is allowed).
Devices located near external fences help to increase the temperature of the internal surface at the bottom of the outer wall and window, which reduces the radiation cooling of people. Rising currents of warm air created by appliances prevent (if there are no window sills blocking the appliances) the entry of cooled air into work area(Fig. 40a). In the southern regions with short warm winter, as well as during short-term stays of people, it is permissible to install heating devices near the internal walls of the premises (Fig. 39b). At the same time, the number of risers and the length of heat pipes are reduced and the heat transfer of devices increases (by about 7-9%), but air movement with a low temperature near the floor of the room, which is unfavorable for human health, occurs (Fig. 40c).
Rice. 39. Placement of heating appliances in rooms (plans): a - under the windows; b - near the internal walls; n - heating device
Rice. 40. Air circulation patterns in rooms (sections) with different locations of heating devices: a-under windows without a window sill; b - under windows with a window sill c - y interior wall; n - heating device
Rice. 41. Location of the heating device under the window of the room: a - long and low (preferably); b - tall and short (undesirable)
Vertical heating devices are installed as close as possible to the floor of the premises. When the device is raised significantly above the floor level, the air near the floor surface may become supercooled, since the circulating flows of heated air, closing at the level of the device, do not capture and warm up the lower part of the room in this case.
The lower and longer the heating device (Fig. 41a), the more even the room temperature and the better the entire volume of air is heated. A tall and short device (Fig. 41b) causes an active rise of a stream 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 heating device to cause an active upward flow of warm air can be used to heat rooms of increased height.
Vertical metal appliances are usually placed openly against the wall. However, it is possible to install them under window sills, in wall niches, with special fencing and decoration. In Fig. 42 shows several techniques for installing heating devices in rooms.
Rice. 42. Placement of heating devices - a - in a decorative cabinet; b - in a deep niche; c - in a special shelter; g - behind the shield; d - two tiers
Covering the device with a decorative cabinet that has two slits up to 100 mm high (Fig. 42a) reduces the heat transfer of the device by 12% compared to installing it openly against a blank wall. To transfer a given heat flow into a room, the heating surface area 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, it is possible to install devices hidden, in which the heat transfer does not change (Fig. 42c) or even increases by 10% (Fig. 42d). In these cases, there is no need to increase the heating surface area of the device or it can even be reduced.
Calculation of area, size and number of heating devices
The area of the heat-transferring surface of the heating device is determined depending on the type of device adopted, its location in the room and the connection diagram to the pipes. In residential premises, the number of devices, and therefore the required heat transfer of each device, is usually determined by the number window openings. In corner rooms, another device is added, placed in a blank end wall.The task of the calculation is, first of all, to determine the area of the external heating surface of the device, which, under the design conditions, provides the necessary heat flow from the coolant into the room. Then, from the catalog of devices, based on the estimated area, the nearest commercial size of the device is selected (number of sections or brand of radiator (length of the convector or finned pipe). 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; the type of radiator accepted for installation indoors; b4 - correction factor taking into account the method of installing the radiator in the room; L3 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 estimated area of the heating device, m2.
Depending on various design features, heating devices on the market have different characteristics. The main thing when installing them is correct selection the desired model, optimally suited for a particular case.
Varieties
Most often, the classification of heating devices is carried out according to the following criteria:
- the coolant used, which can be heated water, gas or even air;
- material of manufacture;
- operational characteristics: size, power, installation method and the ability to regulate the heating rate.
It is better to select the optimal option, taking into account the characteristics of the building’s heating system, operating conditions, observing all the requirements for heating devices.
In addition to the performance of devices, it is worth considering the possibility of their installation. For example, in the absence of gas supply and the impossibility of organizing water heating, the only option would be electrical appliances.
Water system
The most commonly used and therefore have the widest range of heating devices are water heating systems. This is explained by their good efficiency and optimal level of costs for acquisition, installation and maintenance.
Structurally, the devices are not too different from each other. Inside each there are channels for flow hot water, the heat from which is transferred to the surface of the device, and then, using convection, to the air of the room. For this reason they are called convection.
In water heating systems can be used the following types radiators:
- cast iron;
- steel;
- aluminum;
- bimetallic.
All of these heating devices have their own characteristics, thanks to which they are selected for each specific case depending on the area of the room, the nuances of installation, the quality and type of coolant (which is sometimes antifreeze).
The power of each device is regulated by the number of sections, which can be selected by almost anyone. Although, if the estimated length of one battery is more than 1.5–2 m, it is recommended to install two smaller devices next to each other.
Cast iron was one of the most popular materials in domestic heating systems. His choice, as a rule, was due to the relatively low cost. Later, such devices began to be used less frequently, since they have a small heat transfer coefficient (only 40%), due to which the power of one section is approximately 130 W. Although they can still be found in old-style systems. In modern interiors, designer models of cast iron radiators are sometimes used.
The advantages of such devices are a large surface area that transfers heat to the room and a long operating period (up to 50 years). Although there are still more disadvantages - these include the relatively large volume of coolant used (up to 1.4 liters), the difficulty of repairs, the inertia of heating, due to which the temperature of the device increases relatively slowly, and even the need for periodic (at least once every 3 year) cleaning. In addition, heavy sections are very difficult to install.
The use of aluminum radiators allows us to ensure the maximum level of heat transfer - the power of the section can reach 200 W (which is enough to heat 1.5–2 sq. m).
Their cost is quite affordable, and their low weight allows you to install them yourself. True, the operation of the device is possible for only 20–25 years.
Their advantages include the presence of convection panels in the design, which improve air circulation over the surface, ease of installation of devices for regulating the intensity of coolant flow, as well as ease of installation. The radiator section, with a power of up to 180 W, is capable of heating about 1.5 square meters. m area.
Despite the advantages that such heating devices have, there are also problems with their use. So, for example, for bimetallic radiators It is not recommended to dilute water with antifreeze, which, although they do not allow the system to freeze, have a negative effect on internal surfaces heating devices.
In addition, these options are the most expensive of all that are used in a water heating system.
Electric heating devices
All electrical appliances used if it is impossible to install a water heating system have different features and characteristics - from power to the principles of heat generation. At the same time, the main disadvantages of any such equipment are the high cost of operation and the need to install an electrical network capable of withstanding heavy loads (with a total power of electric heaters of more than 9–12 kW, a network with a voltage of 380 V is required). Each variety has its own advantages.
The design that electric heating devices of this type, allows you to quickly heat the room with the help of air flows moving through them.
Air enters the devices through holes in the lower part, it is heated using a heating element, and the exit is ensured by the presence of upper slits. Today there are electric convectors with a power of 0.25 to 2.5 kW.
Oil devices
Electric oil heaters also use a convection heating method. Inside the case there is a special oil, which is heated by the heating element. In this case, heating can be regulated using a thermostat, which turns off the device when the air reaches the set temperature.
A special feature of the heaters is their high inertia. Due to this, heating devices heat up very slowly, however, even after turning off the power supply, their surface continues to emit heat for a long period of time.
In addition, the surface of oil equipment heats up to 110-150 degrees, which is much higher than the parameters of other devices and requires special handling - for example, installation away from objects that can ignite.
The use of such radiators makes it possible to conveniently regulate the heating intensity - almost all of them have 2-4 operating modes. In addition, taking into account the productivity of one section of 150–250 kW, selecting a device for a specific room is quite easy. And the range of most manufacturers includes models with power up to 4.5 kW.
By choosing heating devices whose operating principle is based on the radiation of heat waves in the infrared range, the owner of a private home or other premises receives the following advantages:
- noticeable reduction in energy consumption compared to traditional electrical equipment(within 30%);
- no reduction in oxygen content in the air, which relieves people in the room from headaches;
- Very high speed heating (even a cold room warms up within a few minutes).
Electric infrared heaters are usually used. Much less common gas appliances, intended mainly for heating streets, production workshops and sites or cottages.
Species
Classification of devices for infrared heating is made according to the method of emitting waves. There are film devices that transmit radiation from resistor conductors located on the surface of a special film to surrounding objects. Power – within 800 W per 1 sq. m.
The second type is carbon. In them, radiation comes from a spiral inside a sealed glass flask. Household appliances of this type have a power from 0.7 to 4.0 kW.
The advantage of the former is the ability to use them as electric heated floors. While carbon heaters are much more powerful, although they require increased fire safety measures.
Gas heating
In order to reduce heating costs, gas-fired heating appliances are often used. One of the simplest types of such equipment is a gas convector, connected either to a gas supply system or to a liquefied propane cylinder. In this case, the burner does not come into contact with the surrounding atmosphere, and oxygen enters it through a special pipe (which can be taken outside to maintain normal indoor air quality).
These types of heating devices have high power (up to 8 kW or more) and are relatively cheap to operate due to the low cost of energy.
The disadvantages include: the need to register with regulatory organizations, the provision of high-quality ventilation and the need for periodic cleaning of nozzles. In addition, if the equipment malfunctions, the amount of carbon dioxide that is hazardous to health may increase in the room. Therefore, such devices are rarely used in apartments and other premises with constant occupancy - whereas, for example, for a summer house or garage they can be simply irreplaceable.
The right choice, competent design and high-quality installation Heating systems are the key to warmth and comfort in the house throughout the heating season. Heating must be of high quality, reliable, safe, and economical. To choose the right heating system, you need to familiarize yourself with their types, installation features and operation of heating devices. It is also important to consider the availability and cost of fuel.
Types of modern heating systems
A heating system is a complex of elements used to heat a room: a heat source, pipelines, heating devices. Heat is transferred using a coolant - a liquid or gaseous medium: water, air, steam, fuel combustion products, antifreeze.
Heating systems for buildings must be selected in such a way as to achieve the highest quality heating while maintaining air humidity that is comfortable for humans. Depending on the type of coolant, the following systems are distinguished:
- air;
- water;
- steam;
- electrical;
- combined (mixed).
Heating devices for heating systems are:
- convective;
- radiant;
- combined (convective-radiant).
Diagram of a two-pipe forced circulation heating system
The following can be used as a heat source:
- coal;
- firewood;
- electricity;
- briquettes – peat or wood;
- energy from the sun or other alternative sources.
The air is heated directly from the heat source without the use of an intermediate liquid or gaseous coolant. The systems are used for heating small private houses (up to 100 sq. m.). Installation of this type of heating is possible both during the construction of a building and during the reconstruction of an existing one. The heat source is a boiler, heating element or gas burner. The peculiarity of the system is that it is not only heating, but also ventilation, since the internal air in the room and fresh air coming from outside are heated. Air flows enter through a special intake grille, are filtered, heated in a heat exchanger, after which they pass through air ducts and are distributed in the room.
Temperature and ventilation levels are controlled using 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, air flows are directed through coolers. If there is no need to heat or cool the room, the system operates as a ventilation system.
Diagram of air heating device in a private house
Installing air heating is relatively expensive, but its advantage is that there is no need to warm up the intermediate coolant and radiators, resulting in fuel savings of at least 15%.
The system does not freeze, quickly responds to changes temperature regime and warms up the rooms. Thanks to filters, the air in the room is already purified, which reduces the number of pathogenic bacteria and helps create optimal conditions for maintaining the health of people living in the house.
The disadvantage of air heating is drying out the air and burning out oxygen. The problem can be easily solved by installing a special humidifier. The system can be improved to save money and create a more comfortable microclimate. Thus, the recuperator heats the incoming air at the expense of the air exhausted outside. This allows you to reduce energy costs for heating it.
Additional air cleaning and disinfection is possible. To do this, in addition to the mechanical filter included in the package, electrostatic fine filters and ultraviolet lamps are installed.
Air heating with additional appliances
Water heating
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 ones - automatically (using thermostats) or manually (with taps).
Types of water systems
Depending on the type of connection of heating devices, systems are divided into:
- single-pipe,
- two-pipe,
- bifilar (two-furnace).
According to the wiring method, they are distinguished:
- top;
- lower;
- vertical;
- horizontal heating system.
IN single pipe systems connection of heating devices in series. To compensate for the heat loss that occurs when water sequentially passes from one radiator to another, heating devices with different heat transfer surfaces are used. For example, they can be used cast iron batteries with a large number of sections. In two-pipe systems, a parallel connection scheme is used, which allows the installation of identical radiators.
The hydraulic mode can be constant or variable. In bifilar systems, heating devices are connected in series, as in single-pipe ones, but the conditions for heat transfer of radiators are the same as in two-pipe ones. Convectors, steel or cast iron radiators are used as heating devices.
Scheme of two-pipe water heating country house
Advantages and Disadvantages
Water heating is widespread due to the availability of coolant. Another advantage is the ability to install a heating system with your own hands, which is important for our compatriots who are accustomed to relying only on own strength. However, if the budget does not allow saving, 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: the system freezes when turned off, long time warming up the premises. Special requirements are placed on the coolant. The water in the systems must be free of foreign impurities, with a minimum content of salts.
To heat the coolant, any type of boiler can be used: solid, liquid fuel, gas or electricity. Most often used gas boilers, which involves connecting to the main line. If this is not possible, then they usually install solid fuel boilers. They are more economical than designs that run on electricity or liquid fuel.
Pay attention! Experts recommend selecting a boiler based on a power of 1 kW per 10 square meters. These figures are indicative. If the ceiling height is more than 3 m, the house has large 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 unsafety of this type of space heating. Heating appliances reach temperatures of almost 100°C, which can cause burns.
Installation is complex and requires skills and special knowledge, during operation, difficulties arise with regulating 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, and heating points. Its advantages are relative cheapness, low inertia, compactness heating elements, high heat transfer, no heat loss. All this led to the popularity of steam heating until the mid-twentieth century; later it was replaced by water heating. However, in enterprises where steam is used for production needs, it is still widely used for heating premises.
Steam heating boiler
Electric heating
This is the most reliable and easiest-to-use type of heating. If the house area is no more than 100 m2, electricity is a good option, but heating a larger area is not economically viable.
Electric heating can be used as additional heating in case of shutdown or repair of the main system. This is also a good solution for country houses in which the owners live only periodically. Electric fan heaters, infrared and oil heaters are used as additional heat sources.
Convectors, electric fireplaces, electric boilers, and heated floor power cables are used as heating devices. Each type has its own limitations. Thus, convectors heat rooms unevenly. Electric fireplaces are more suitable as a decorative element, and the operation of electric boilers requires significant energy consumption. Warm floors are installed taking into account the furniture arrangement plan in advance, because moving it may damage the power cable.
Scheme of traditional and electric heating of buildings
Innovative heating systems
Separate mention should be made of innovative heating systems, which are becoming increasingly popular. The most common:
- infrared floors;
- heat pumps;
- solar collectors.
Infrared floors
These heating systems have only recently appeared on the market, but have already become quite popular due to their efficiency and greater cost-effectiveness than conventional heating systems. electric heating. Heated floors are powered by electricity and are installed in screed or tile adhesive. Heating elements (carbon, graphite) emit infrared waves that pass through flooring, heat up people’s bodies and objects, which in turn heats up the air.
Self-regulating carbon mats and film can be installed under furniture legs without fear of damage. “Smart” floors regulate temperature thanks to a special property of the heating elements: when overheated, the distance between particles increases, resistance increases, and the temperature decreases. Energy consumption is 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 ensured by thermostats, which reduces energy costs by 15-30%.
Infrared carbon mats are convenient, reliable, economical, and easy to install
Heat pumps
These are devices for transferring thermal energy from a source to a coolant. The idea of a heat pump system itself is not new; it was proposed by Lord Kelvin back in 1852.
How it works: A geothermal heat pump takes heat from the environment and transfers it to the heating system. The systems can also work to cool buildings.
Working principle of a heat pump
There are open and closed cycle pumps. In the first case, the installations take water from an underground stream, transfer it to the heating system, remove thermal energy and return it to the point of collection. 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 not connected to gas supply. Heat pumps They are complex and expensive to install, but they allow you to save on energy costs during operation.
The heat pump is designed to use environmental heat in heating systems
Solar collectors
Solar installations are systems for collecting thermal energy from the Sun and transferring it to a coolant
Water, oil or antifreeze can be used as a coolant. The design provides additional electric heaters that turn on if the efficiency solar installation decreases. There are two main types of collectors - flat and vacuum. The flat ones have an absorber with a transparent coating and thermal insulation. In vacuum systems, this coating is multi-layered; a vacuum is created in hermetically sealed collectors. 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 hot water supply and heating system of the house 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 ready-made recipes There is no one-size-fits-all approach. It is necessary to carefully weigh the pros and cons and take into account the characteristics of the building for which the system is selected. If in doubt, you should consult a specialist.
Video: types of heating systems
The market is flooded with various heating devices for the home. Each device has its pros and cons. To help you make your choice, we have made detailed analysis each heating device, we divided them into categories and present them all to your attention.
There are four types of water radiators based on material:
- Cast iron
- Steel
- Aluminum
- Bimetallic
- Radiators with design
- Custom made radiators
- Economical (cast iron)
- Average in cost (bimetallic and aluminum)
- High cost and reliability (Tubular steel radiators, copper-aluminum)
Cast iron radiators
Cast iron are considered in an outdated way heating homes, but are still used by people. Let's figure out why. Most often, this type of heating is chosen precisely because of its price and high heat output. The main disadvantage of such a heating device is its weight and the presence of a large amount of water, which is why it is impossible to quickly change the temperature in the room. The long service life of these radiators and uniform heating of the room will make you think again about purchasing this type of heating. Bimetallic radiators
This option for heating devices is perhaps the most popular. Such radiators are made of an alloy of steel (or copper) and aluminum. We’ll talk specifically about copper-aluminum later. These radiators are considered higher in heat transfer than aluminum ones. They are also low weight and beautiful design. Steel or copper is used in parts that come into contact with liquid. These parts heat the small steel core, which in turn heats the aluminum panels. Aluminum, to the extent of its high heat transfer capacity, transfers heat well to environment. Bimetallic heating devices maintain a pressure of 20-40 atmospheres, which is three times more than cast iron ones. They can last about 20 – 30 years. The only and rather serious disadvantage is their high price. Aluminum radiators
Today it is the most popular heating device in Russia. loved by many of their technical characteristics and appearance, as well as a modest price. Such radiators can be cast or extruded. Cast radiators are more reliable and durable. The center distance for these radiators is the same as for cast iron and bimetallic ones (350-500 mm). The maximum pressure is lower than that of bimetallic ones, from 6 to 16 atmospheres. Such heating devices have high heat transfer, since aluminum quickly heats up and begins to give off heat. They have a low price, which makes them the most popular among Russian residents. The radiators are quite durable. But it is worth keeping in mind that aluminum is a very soft material and quickly becomes covered with defects. Aluminum radiators are temperature adjustable, and the temperature will change quite quickly due to the properties of aluminum. But at the same time, aluminum radiators have low resistance to corrosion and the ability to air out (air accumulates in the heating system, which needs to be vented). Their appearance makes them an excellent choice for heating your space. Water convectors
First, let's figure out what convection is. This is the transfer of thermal energy using air. Reviews say that by installing such a heating device you can save a large amount of energy. This radiator consists of copper pipe and aluminum fins. There is also a valve located on the device that regulates the temperature. air flow and a valve that removes air. Such radiators can be floor-mounted, built-in, or wall-mounted. If you have large windows in your room, then feel free to install types of water convectors built into the floor. But remember that such a convector has a rather high price. The difference between such heating devices is their versatility, due to which they can be installed in the most different places. Average price they fluctuate around 15-30 thousand rubles. Also if in your premises high humidity you can buy a special model of water convector.Steel radiators
can be panel or tubular. 60% are convectors. Panel ones differ in that in the middle of the device they have from one to three panels, each of which has two steel profiles connected along the contour. These radiators are easy to produce, as welding joins the blanks that have been stamped. The more rows a panel radiator has, the greater its heat transfer will be. Tubular heating devices consist of pipes made of steel and welded together. Such a radiator costs an order of magnitude more than a panel radiator. Even a bimetallic radiator will cost less than a tubular one. Such heating devices heat up quickly and strongly, which means they will begin to release heat into the environment faster. The pressure varies from 6 to 10 atmospheres for plastic ones, and from 8 to 15 for tubular ones. Such batteries can withstand water temperatures of about 110-120 degrees. Another important factor when purchasing such radiators will be the center distance; it starts from 120 mm and ends at 2930 mm. The main disadvantage of steel radiators is corrosion and weakness to water hammer. But if you don't have enough money to take aluminum radiator, then the steel one will cost you less, and you can buy it. Copper-aluminum radiators
are excellent for heating a private home, since the substances that make up these radiators have good inertia. This helps to quickly regulate the temperature and save money, as well as good heat dissipation. 90% work on the convection principle. Such radiators have a heat transfer rate that is 2 times higher than the bimetallic radiators described above. Such radiators are cheaper than copper ones and allow a pressure of 16 atmospheres, which is also suitable for high-rise buildings. So, you can install it even on the 9th floor. But at the same time, it is difficult to install and it is advisable to run only distilled water through it.Electric convectors
Such heating devices are much simpler and more versatile; their job is to distribute heated air throughout the room. They heat the air without drying it out. Such convectors can be floor-mounted or wall-mounted. The first ones can be placed anywhere, so they are in demand in stores. Wall-mounted ones are installed under the windows, where they immediately make the cold air from the window warm, which gives good thermal insulation of the window. This is a very cheap type of heating; they cost around 6-9 thousand rubles. At the same time, you can instantly connect them and start heating up. The only negative electrical appliances Heating costs electricity, but this depends on the power of your convector. It is important to consider that such convectors do not dry the air, but are unlikely to be your choice for installing them in your home.Oil radiators
The operation is surprisingly simple: an electric coil heats the oil, which heats the metal body. To purchase this heating device, remember a few things: 1) The more sections, the larger the heated area; 2) If you are going to leave it at the dacha for the winter, for example, then take it with frost protection. Oil radiators are safe and do not dry out the air, while being cheap and reliable.Infrared heating
This type of heating is a relatively new option for heating a home. Infrared heating can be used in ceiling, wall and floor systems. The ceiling system must be built into the ceiling so that the heat flow is directed to the floor. Consequently, the floor will be warmer than the air temperature, and this very well solves the problem of cold floors. It is based on the principle of converting electromagnetic waves into thermal energy. Such systems are quite inexpensive in terms of energy savings and are easy to install, but the devices for such systems are very expensive and infrared radiation can harm human health. But you can even do wall-mounted infrared heating with your own hands. It is enough to buy infrared film, the price of which is about 1,500 rubles per square meter. We do not immediately recommend such heating for places with harsh winters; these systems will not provide you with sufficient power. The floor system is practically no different from the wall system, only in the subtleties of installation.Gas convector
Heating in such a heating device occurs due to the combustion of gas, where combustion products are discharged through the chimney pipe. The cost of such convectors may vary depending on their specifications. With this type of heating you can set different temperatures in different rooms. The efficiency may be higher than that of boilers, but in principle the same. The disadvantages include the following: There are no different capacities, it does not heat water, you can only heat one room. Such convectors are suitable for heating cottages and garages due to the possibility of power from a gas cylinder.Heating with water heated floor
This type of heating creates high comfort by heating the floor, but not to the temperatures of conventional radiators. It should also be taken into account that the room is heated evenly. Such heating quickly heats the room, which means it has high inertia. Using this heating, you can calmly ventilate the room, and you will not feel the cold; it also increases the space in the house compared to conventional radiators. But it should be taken into account that the house must be well heated and that some difficulties may arise when installing it in an apartment. This is also a rather expensive type of heating (more expensive than radiator heating), although they say that it soon pays off in electricity savings. But also in cold winter It will be difficult for you to use this type of heating, since you cannot increase the floor temperature very high; you will still have to use additional radiator heating in the harsh winter.
Warm electric floors
This type of heating is perfect for apartment building. Here you can use a heating cable that will be stretched throughout the room and will heat it. There is also the option of heating with heating mats. This design consists of a thin cable and fiberglass; one of the advantages is that the screed is unimportant. Infrared film can also be used, but we have already talked about it above. We recommend installing such a heating system in the bathroom, kitchen and hallway. This will keep the temperature of the floor and the room as a whole warm without large expenditures of electricity.