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Air heat

The water heating convectors are an extensive class of heating equipment, which has been used for many decades all over the world on a par with radiators. They are essentially different from their “radiant” counterparts – both in principle and in operation. The radiator performs two tasks during operation – it heats air and radiates heat in the form of infrared waves. The convector has a simpler job – it only heats the air.

Convectors

The convector principle is based on simple laws of physics: the cold air that passes through the heat exchanger is heated and rises upward. This creates a circulation of air in the room. Also, unlike radiator heating, convective heating involves a greater temperature difference between near the floor and under the ceiling, as the heated air rises. However, convectors cannot be used for heating without radiant heat at all. When the device is in operation the so called secondary radiant heating effect appears: the hot air, accumulated above, heats the ceiling and the surface of the ceiling starts to radiate heat and transmit it to the objects in the room.

As the convectors design does not provide for the surfaces radiating infrared waves, there is no need to leave them in view and ensure unimpeded spread of heat waves into the room. The convector can be installed behind a decorative screen, hidden behind the elements of interior – but with the obligatory condition that the surrounding items will not impede the air circulation.

Convectors are widely represented both by domestic and foreign brands Boki, Isan, Jaga, Kampmann, Kermi, Klima, Minib and many others .

WITH AND WITHOUT A FAN

Despite the general principle of the convectors operation, the models differ in the implementation of this principle. Present on the market devices are divided into two types according to the type of convection – with forced and natural convection.

Forced means the use of fans axial or tangential – they draw the air inside and increase the air exchange of the model. The tangential fan has an impeller along its entire length and runs along the heat exchanger, while the axial fan, on the contrary, is located at the end and directs the air along the heat exchanger, but can not “reach” the far end of the convector. Models with a forced convection have a lot of “pluses”, for example, the possibility of making a device with a higher power output due to more frequent arrangement of lamellas – the air under the pressure of the fan will pass through them with a high speed anyway. However, there are also disadvantages. First, fan motors need a power supply, so the convector will need to be connected to the electricity grid, which is not always possible. And sometimes it is not safe – for example, for swimming pools and other wet areas special models are designed, whose fans are powered from low voltage direct current – you can not get an electric shock from them. there are also models with remote fan, it blows air into the convector from another room through the duct. Secondly, the fan is a mechanical device and makes noise when it is running.

Convectors with natural convection, on the other hand, are silent – there are no fans in their design. In these models the air flows naturally into the unit: it goes down and inside the convector, is heated, and then comes out again into the room. They also don’t need to be connected to the electric network, which simplifies the installation. But the natural convection requires observance of some conditions. For example, restrictions on the frequency of planting blades in the heat exchanger. On the one hand, the more slats in it, the more heat it can give, but on the other hand, too often planted slats can impair the convector capacity and interfere with the free circulation of air through the device. Therefore, the distance between the lamellae is strictly read out, so they do not hinder the movement of air, and at the same time heated as effectively as possible. Some convectors with natural convection allow installation of axial fans that will, if necessary, increase the power of the devices, increasing the air flow through them. True, in this case you already need to wire them a power line, and they will not be noiseless when the fans are working.

convectors

ON THE WALL, ON THE FLOOR, INSIDE THE FLOOR

convectors are divided into floor convectors floor-mounted , floor-mounted and wall-mounted.

Floor convector – a special kind of device. Its stern is “buried” in the floor of the room, the heat exchanger is in a niche inside the cavity. On top of such a convector is usually closed by a decorative grid, which is at floor level. The grids are usually strong enough to be walked on. Floor standing models have an important advantage over other heating devices radiators, wall and floor convectors – they are barely visible and can provide very high heating power depending on the type of convection, construction of heat exchanger and other factors . That is why they are widely used in the cases when it is necessary to heat a room but unnecessary objects that draw attention are undesirable. One example of this type of application is panoramic windows. Huge panes look impressive and give a good view, but the conventional radiators or convectors can obscure the view – they have a certain height, after all. the internal floor models, because they are almost entirely below the floor level, don’t interfere with the air view. However, they are effective in heating the windows The cold air descends along the windows and enters the convector grille at the bottom, inside it passes through the heat exchanger and is blown out as warm air. This convector type is also used for heating the perimeter of the room and in some other cases.

Floor models differ in the depth of the enclosure, the number of heat exchangers and the type of convection. The depth is one of the factors that limit the installation possibilities of the floor convector as not every floor will accommodate it. Deeper radiators can reach several tens of centimeters in height, as a rule, these are samples of higher capacity. They are not intended for installation on the upper floors of buildings, they are usually installed on the first floor. Devices with small depth literally from several centimeters on the contrary allow to install them in screed of any floor, not only in the first floor. But also the power of these models will be lower than that of deep convectors.

Since in the finished floor convector only the grille is visible, the manufacturers pay special attention to their design. They can be made of different materials – metal steel, aluminum , wood, etc. d. The metal bars are stronger, they can be made thinner and the bars that make them up can be placed both across the grating and along it. However, metal can be heated by the air and itself start to radiate heat, which will deteriorate the aerodynamics of the convector, reducing its capacity and, consequently, the power. However, it is worth noting that this phenomenon only slightly affects the final power of the device. Wooden grids are less susceptible to this phenomenon, but they also have disadvantages. Wooden bars are more fragile than metal, and therefore to increase their strength, they are made thicker, which, incidentally, reduces the capacity of the convector, and laid across. Manufacturers produce grids in different color variations, in addition to which frames of various kinds and colors are also available, so that it will not be difficult to choose a style suitable to any interior.

The modern architecture of buildings is not limited to straight lines, so in addition to straight floor convectors, more complex models are possible – angular and even radius ones. Usually, such devices are made to order and with an additional charge for non-standard performances.

It is better to plan the installation of floor convectors already at the construction stage of the building in order to provide niches for them. But low models allow screed mounting if the new layer of screed is thick enough to accommodate the model enclosure . It is not desirable to install floor convectors into specially made podiums – if they are not level with the floor the devices will work worse.

Floor convectors and wall convectors differ mostly in the sizes. Wall-mounted models are usually quite high and wall-mounted. Floor convectors are low and compact they can substitute the floor convectors in some cases – for example, in heating of rooms with big windows. Thanks to the low height, floor models are hardly noticeable, it is easy to hide them even behind the furniture. There are also the so called skirting models – convectors of extremely low height up to 200 mm that are so compact that they are almost invisible and can be used for perimeter heating.

Wall and floor convectors are subdivided on models with or without a shell. Everything seems to be simple: a device with a “bare” heat exchanger is a convector without casing and inside the casing with casing. But in practice, this is not the case. The distinctive feature of the convector with a cover is that the cover in this case plays not a decorative, but a practical role, namely it creates additional draft for improved air circulation. Moreover, the vector model line can include units with the same size heat exchanger, but with housings of different height – the high ones are more effective, but they also take more space. The heat exchanger in these convectors is usually located at the bottom, closer to the floor. Convectors without a casing have either no casing at all or it only serves a decorative purpose – to disguise the heat exchanger and protect it from damage.

Convectors

By the way, both the functional and decorative casing of the convector do not heat up as much as, for example, the top of the radiator. That is why convectors are safe for people, including children – it is impossible to get burnt on the body of the device.

Convector shells are most often made of steel regardless of the type of heat exchanger – steel, combined or copper . Steel is easy to paint, so customers have the opportunity to order any color from the palette offered by the manufacturers. However, other materials are used for the construction of the casing – wood, for example, is sometimes surprising. There is nothing surprising in these experiments, since the task of the body is not radiant heating of the room, and therefore for the normal operation of the convector it is enough to make air blowing holes in the body.

The convector top is usually covered with a grid that does not interfere with air circulation, but does not allow foreign objects to enter the device, as well as distributes the flow of heated air. The grille can direct the air upwards or sideways depending on the design of the holes in it.

The wall and floor convectors can be straight or angled, depending on the manufacturing possibilities.

Wall models can be mounted with brackets, the floor models – on special legs. When installing the device, its position in space is taken into account – it is important to observe certain rules. The convector must not be too high or too low above the floor, otherwise its efficiency will be impaired. If the convector is installed in the room with rough flooring before the screed casting, take into account the planned layer of the screed so that after the end of the works the floor is not too close to the device.

Convectors

HEATING ELEMENT

The main operating element of the convector is the heat exchanger. This is where the heat transfer from the coolant to the air takes place. heat exchangers can have different constructions and be made of different materials, which determines their features and costs. For example, the heat exchangers made entirely of steel, of copper or combined – of copper and aluminum are widespread.

The most common type of heat exchanger of the convector is the lamellar one. As a rule, it is a tube with a lot of slats – blades fixed on it. The heat transfer medium is circulating within the tube, the heat from the medium is transferred to the fins. The air in its turn passes between the rows of lamellas and is heated. The way the lamellas and tubes are connected plays an important role, because the gaps between them reduce the efficiency. In the case of steel heat exchangers, the tubes and fins can be welded together to ensure good heat transfer. The copper elements of the heat exchangers are connected by soldering. Combined heat exchangers with copper pipes and aluminum lamellas require a different approach, because these materials can not be connected by welding or soldering. Often those heat exchangers are formed by mandrelling method: first the lamellas are put on the pipe, and then a mandrel with a meter above its original diameter is passed through the pipe. As a result the tube is widened and the lamellas are cut into it. Also widespread method of connection without using mandrels when the design of lamellae implies the presence of collars which, when pulling the pipe through the lamellae tightly grasp it.

The form of the lamellas in the trench convectors also differs. The convectors use both plain and ribbed fins. The relief allows to increase the area of the plate and, accordingly, the heat output. The lamellas can be single, U-shaped or even meander shaped. Aluminum fins are usually thin and must be handled with care to avoid damage – bent fins interfere with the aerodynamics of the damaged coil. The steel lamellas are more solid.

The alternative to the plate structure is the wire heat exchangers Isan convectors have them . Instead of lamellas, they use a copper wire that is connected to a copper pipe and braided in a special way. Such a heat exchanger is durable and efficient, but its cost is higher than that of plate ones.

The pipes that form the basis of the heat exchanger can also be varied. Usually convectors use pipes with round cross-section because this shape gives them high strength due to the even pressure distribution in all parts of the pipe. Some models are equipped with heat exchangers with pipes of other shapes – oval, etc. d. The pipe material is important. Steel convectors use pipes that are thick enough to withstand high pressure and often can be installed in open heating systems due to the large wall thickness corrosion of such models is not as damaging as, for example, the thin-walled steel radiators that cannot be used in open systems . Copper pipes have a smoother internal surface than steel pipes, therefore they have a higher flow capacity and are also not prone to corrosion. However, heat exchangers with copper pipes must be protected against chlorinated water, which destroys them.

TEMPERATURE AT WILL

Convectors are characterized by a small capacity compared to radiators water fills only the heat exchanger tubes , and the speed of circulation of the coolant must be high to ensure efficient heat transfer and, therefore, the heat output of the device. The high flow of the coolant through the device protects the convector from freezing when the windows are open even in severe frost – the water simply does not have time to cool down to the point where it turns into ice. The large diameter of the pipe and the absence of branches, similar to columns in radiators, virtually eliminates the possibility of leaks.

The convectors are easy to regulate. If the water flow to the unit is cut off, the unit will cool down very quickly and stop heating. Therefore, convectors work well with thermostatic valves that allow you to set the desired room temperature and keep it at the desired level without human control. Thermostatic valves with high flow capacity are used for the assembly of the convectors, so the fittings do not create significant hydraulic resistance at the entrance to the unit and do not reduce the efficiency of heating. Thermostatic valves with different types of thermostatic valves standard, remote, with electronic control, etc can work with convectors, as well as with radiators. d. . The convector manufacturers can equip them at the factory with thermostatic valves or leave this issue to the customer, equipping the models with connectors without valves.

Some convectors have the possibility to regulate the power through design – inside the body of such a model there is a flap that can be returned and used to block the way of heated air. But, unlike the thermostatic valves, the damper requires manual operation.

BOTH WINTER AND SUMMER…

Convectors can be used not only for space heating but also for cooling. For this purpose they are filled with coolant water or a special liquid from a chiller instead of heat carrier. The same convector can perform different tasks in different seasons: in winter – work for heating, in summer – to cool. It is true that not every convector is adapted to this versatile work, and the manufacturers usually specify whether a particular model can be used for cooling.

To transfer the device from one mode to another, the convector is emptied and filled anew with the desired liquid. However, there are also models that are equipped with two integrated, not connected to each other circuits – for heating and for cooling. With them, when you change modes, it is enough to turn off the circulation in one circuit and turn on the other one. It must be remembered, though, that convectors have a cooling capacity much lower than heating capacity, so when designing a convective cooling project, it is important to calculate the cooling requirement, since you can easily reduce the heating capacity. In addition, in the natural mode, the convector can not work on cooling, and therefore all models with cooling support are equipped with fans.

When working in the cooling mode the condensate can form on the heat exchangers of convectors. In the floor convector models the dampness collects at the bottom of the casing and needs to be drained. Therefore in such convectors a condensate drainage system is often provided.

Convectors

TO KEEP IT CLEAN

A large volume of air passes through the convector every day, and with it, dust and other contaminants. Once inside the appliance, they deposit on the slats and other internal surfaces and over time can flow back into the air stream. In order not to turn the convector into a source of dirt it should be periodically cleaned for example with a vacuum cleaner that will draw the dust from the gaps between the slats . In some models, the body and the grid are fixed, while in others, on the contrary, removable and allowing cleaning inside the device. It is worth noting that the plate heat exchangers especially with grooved blades are more susceptible to contamination than the wire heat exchangers, whose dust is almost not retained on the wire and stays only on the bottom, where it is easy to pick up with a vacuum cleaner.

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John Techno

Greetings, everyone! I am John Techno, and my expedition in the realm of household appliances has been a thrilling adventure spanning over 30 years. What began as a curiosity about the mechanics of these everyday marvels transformed into a fulfilling career journey.

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Comments: 3
  1. Harper

    What are the different methods of air heating and how do they compare in terms of efficiency, cost, and environmental impact?

    Reply
  2. Magnolia

    What are the advantages of using air as a heat transfer medium? Are there any specific applications where air heat is preferred over other heat transfer methods?

    Reply
  3. Penelope Lawson

    What are the various methods of air heating and which one is the most efficient and cost-effective in different situations?

    Reply
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