Practice shows that the vast majority of homeowners living in Russia, choose to heat the system with a liquid coolant. Perhaps, once this, indeed, was the most practical option.
But technology is evolving, and more and more efficient designs are emerging. Such as the various systems of air heating, allowing to heat quickly and economically any room.
The content of the article:
- The principle of operation and types of air heating
-
Operating system varieties
- Natural air circulation system
- Design with forced air movement
- Floor air heating
- Suspended air systems
- Direct-flow heating circuit
- Recirculating heating system
- Partial Recycling Scheme
- Arguments in favor of choosing the air system
-
The main elements of the heating system
- Air heating devices
- Channels for the movement of air masses
- Fans for air circulation
- Flow Distribution: Grilles and Diffusers
- Intra channel dampers and valves
- Air preparation equipment
- Automatic control systems
- Features of the competent calculation
- Conclusions and useful video on the topic
The principle of operation and types of air heating
You need to know that there are two different types air heating type, each of which can be used in practice.
The first is implemented in systems with a heater. It is essentially similar to heating with a liquid coolant with the difference that heated air is used instead of liquid. The duct heater heats the air, which moves through special pipes into heated rooms.
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Air heating is a heating system for one or a group of rooms with heated air that is preheated by steam, electricity, fire or water.
The main difference of air systems from other types of heating is that there are no heating devices in their scheme.
By analogy with water heating air circuits are gravitational and forced. In forced circuits, air movement is driven by a fan.
By the method of delivery of heated air, air systems are divided into channel and channelless.
In the channel air circuits, the gravitational principle is mainly used: the air flow prepared in the heater moves by gravity through pipes heating the surrounding space.
A rational solution to an air heating device is to combine it with ventilation, due to which sanitary and hygienic indicators of the air environment are significantly increased.
In private houses, in most cases, the air is heated by fireplaces or stoves with a heater built into the system.
When using water, gas or electric heaters, at least two are installed on the room so that if one unit fails, the second can maintain a temperature background of at least +5 degrees
Heating equipment for air heating
System without standard radiators
Forced type air system
Channelless air heating option
Duct air heating option
Combination with ventilation
Heating unit for the private sector
Heater for air heating schemes
Filled with hot air air ducts warm the room. Such systems today are little used, because in the process of operation the channels are inevitably damaged. From alternation of heating with cooling, the air ducts then expand, then narrow, which is why the joints are weakened, and cracks appear in the walls.
This leads to disruption of the air distribution process and, as a result, to uneven heating of the premises, which is undesirable. More practical is the open air heating system.
In the air heating device there is much in common with the traditional water view and less commonly used steam. The main difference is the lack of standard heating devices - radiators
The principle of its operation is as follows. The heat generator heats the air, which through the piping system is supplied to heated rooms. Here it goes outside and mixes with the air in the room, thereby raising the temperature in it.
The cooled air is directed downwards, where it enters special pipes and re-enters the heat generator for heating.
The heat carrier of air heating systems is classified as secondary, because before that, it is heated by the primary coolant - steam or water (+)
The radius of action of the heating system by heated air is divided into local and central. The first are the contours designed to serve one object (cottage, room, two or more adjacent premises), to the second apartment buildings, public and industrial facilities
All systems are divided into schemes with full recirculation of the coolant, with partial recirculation and direct flow.
Local systems with full air recirculation are channel (a) and channelless (b). These are schemes with the natural movement of heated air. If the heating is combined with ventilation, then other schemes (c, d) with partial recirculation are used. According to which part of the air is mixed with the air mass in the room without moving through the channels
All central systems are categorized as direct flow. For them, the air coolant is heated in the heating center of the building, and then delivered to the premises through air distributors. Central circuits are only channel.
Air flow systems are too expensive for the private sector. They are satisfied where ventilation is constructed, processing an air mass equal in volume to the air mass required for heating.
Central air heating is arranged in industries producing or using flammable, toxic, explosive, etc. in manufacturing. substances. In the arrangement of country houses this type is used if the transportation of heated air over a long distance is required.
The organization of the scheme for private owners is impractical because of the need to use powerful ventilation equipment.
Operating system varieties
Today, there are several varieties of air heating, each of which is necessary to meet all those who are going to install a similar structure in their home. Systems can be classified according to various criteria. Let's start with the air circulation method. Based on this, there are two main types.
Natural circulation suggests that the heated air rises up and moves independently through pipelines. Therefore, the outlets of the air ducts are located only in the upper part of the premises.
Natural air circulation system
For the operation of this design is used the property of hot air to rise up. The heated gas through the ducts laid in the walls rises into the rooms and through the holes located in the ceiling of the room comes out.
The main advantage of such systems is low cost, since there is no need to spend money on additional equipment.
However, significant shortcomings are quite a lot. First of all, the speed with which air rises through the pipes is small. Thus, the room will be heated for a long time.
In addition, when using heating with natural circulation, it is often necessary to locate the outlets of air ducts in the upper part of the room, which may not always be convenient.
The weighty minus of gravitational air heating (i.e., circuits with natural coolant movement) lies in a limited range. It varies in the range of 8 - 10 m
Design with forced air movement
Such systems are necessarily equipped with a ventilation unit, the capacity of which depends on the length and number of ducts. For large areas will require the installation of multiple devices. The main task of the equipment is to move the heated air through the ducts to heated rooms. As a result, its speed increases, and the rooms are heated in the shortest possible time.
Despite the need to install fans, such systems are ultimately more economical. Due to the increased air exchange rate, the system sucks the cooled air from the room at a sufficiently high temperature.
He simply does not have time to cool to the minimum values. Reheating is spent on much less energy, which generally results in significant cost savings.
To stimulate the movement of air to the consumer, heating systems are equipped with fans, which translates them into the category of volatile, but significantly increases the efficiency
At the location of the duct heating systems can also be divided into two groups.
Floor air heating
A distinctive feature of the system is the duct leads embedded into the floor or embedded in the plinth. The result is the most efficient distribution of heated air entering the lower part of the room.
Warm air tends upward, as a result of which rather rapid mixing of air masses occurs and the room warms up faster.
Underfloor air heating assumes that the air duct leads are located in baseboards or are embedded directly into the flooring
Suspended air systems
The scheme assumes the presence of ducts built into the ceiling or walls, whose conclusions are located strictly in the upper part of the room. Most often under the ceiling. Alternatively, suspended air ducts with the same conclusions.
Admittedly, such systems are generally less aesthetic than floor counterparts. Although there are ways of decorating and masking ducts.
In addition, the use of a floor system assumes that the temperature of the air below will be the highest. In the upper half of the room will be slightly colder.
Physicians consider this temperature distribution the best for humans. In addition, the duct pins embedded in the floor or baseboard are almost imperceptible, which greatly improves the appearance of the room.
The main drawback of suspension systems, which is especially undesirable for private houses, is considered to be lower than the top, the air temperature near the floor. The heated air heats up the upper part of the room faster and more intensively, while the floor remains cool. That is why such systems are either rarely used in residential buildings, or combined with some kind of heating.
According to the method of heat exchange, all air heating systems are divided into three types.
Suspended air ducts are best mounted during the construction phase of a building. In this case, they can be disguised during the finishing works.
Direct-flow heating circuit
The direct version has been known for several centuries. Such systems were heated by the ancient Romans and medieval Russians. The principle of direct-flow heating is very simple. In the lower part of the building, most often in the basement, a heating device is installed that heats the air entering it. Further, the heated air masses through the air ducts enter the heated premises.
The figure shows the arrangement of a direct-flow type air heating system. Such constructions were used in ancient Rome.
After that, passing through them, are displayed on the street. Thus, thermal energy is spent not only on heating the room, but also, in the direct sense, on “street heating”. That is why the direct-flow system is considered the least efficient of all and is characterized by the highest initial and operating costs.
The main advantage of this design is full ventilation of heated rooms. It is used only when the required ventilation volume equal to the volume of air masses required for heating. Such a condition may be mandatory in the operation of premises where they work with explosive, hazardous to health or unpleasant-smelling substances.
For home heating direct-flow system is used very rarely. If for some reason you need to install it, you should install the equipment for additional recovery.
This may be an air exchanger, which will allow to use part of the heat of the outgoing air to heat the incoming air masses. Thus, it will be possible to reduce operating costs.
Recirculating heating system
Heating is done using a closed loop. First, the air is heated by the heat generator and moves through the pipes inside the room.
Here it gradually cools and begins to descend to the floor, where the entrances of the exhaust ducts are located. Once in them, the cooled air moves to the heat generator, where it is again heated and the cycle repeats.
Systems with full air mass recirculation are used if there is no need to organize artificial ventilation of the room.
Such a scheme is as efficient as possible, since heat losses are practically excluded. Its main drawback is the poor quality of air that circulates inside heated premises.
Therefore, it is more often used for heating non-residential rooms or warehouses. If such a scheme is used in residential buildings, it is mandatory to install additional equipment for ionization and humidification of the air.
Partial Recycling Scheme
Such a system allows to level the main drawback of the recirculation scheme - low air quality. To do this, it includes an additional ventilation equipment, which takes the outside air and mixes it in the right proportions to the air masses circulating inside the room. Everything else is similar to the scheme with full recycling.
Systems with partial recirculation produce an intake of a part of the air outside and mix it with the part of the air mass in the room. The mixture is heated by the heater to the required temperature, then the fan is sent to the room
The system is characterized by maximum flexibility and is able to work in several modes: as ventilation, as heating or as a combined heating-ventilation.
However, it can take any desired amount of air, heat it or even cool it to the desired temperature. The scheme with partial recycling is considered optimal for arranging air heating in a private house.
Arguments in favor of choosing the air system
Compared with the usual systems operating on the liquid coolant, air schemes have significant benefits. Consider them in more detail.
- High efficiency air systems. The performance of air heating circuits reaches about 90%.
- The ability to disable / enable equipment at any time of the year. Interruption of work is possible even in the most severe winter cold. This means that a disabled heating system will not become unusable at low temperatures, which, for example, is unavoidable for water heating. It can be included in the work at any time.
- Low operational cost of air heating. No need to purchase and install sufficiently expensive equipment: valves, adapters, radiators, pipes, etc.
- The possibility of combining heating and air conditioning. The result of the combination allows you to maintain a comfortable temperature in the building in any season.
- Low inertia of the system. It provides extremely fast warming up of rooms.
- Ability to install additionalequipmentwhich is used to maintain an optimal microclimate. These can be ionizers, humidifiers, sterilizers, and the like. Thanks to this, it is possible to choose a combination of devices and filters that exactly correspond to the needs of the residents of the house.
- Maximum uniform heating of rooms without local heating zones. These problem areas are usually located near radiators and stoves. Due to this, it is possible to prevent temperature drops and their consequence - undesirable condensation of water vapor.
- Versatility. Air heating can be used to heat the premises of any area located on any desired floor.
The system has some drawbacks. Among the most significant is the energy dependence of the structure. Thus, during a power outage, heating stops functioning, which is especially noticeable in areas with interruptions in power supply. In addition, the system requires frequent maintenance and monitoring.
Air heating is very economical. Initial costs for its arrangement are small, operating costs are also low
Another negative feature of air heating is that the installation of the structure must be carried out during the construction process. The installed system is not subject to modernization and practically does not change its operational characteristics.
If necessary, it is possible to install air heating in a constructed building, but in this case only suspended air ducts are used, which is not aesthetically pleasing and not always efficient.
The main elements of the heating system
Before you can equip air heating with your own hands, you need to become familiar with the elements of which it consists.
Air heating devices
The main task of the equipment is to heat the air entering inside to the desired temperature. Almost all known heat sources can be used for this.
Depending on the type of heating device, the air masses are either passed through a heat exchanger with hot steam, water, etc., or heated directly inside the heater.
Heat generators used to heat the air in the air heating system should not heat the air to a temperature over 70º, so that after mixing with the air in the room, it does not lose its properties as the environment, coming in for inhalation (+)
In practice, four types of structures are used in practice as heat generators for air heating systems:
- Direct heating fuel systems. In them, the air is heated by the heat obtained from the combustion of any fuel. This type includes coal, gas, diesel, pellet and other heaters.
- Electrical equipment direct heating. It is a powerful fan heater that connects to the ducts.
- Devices indirect heating. It is assumed that there is a heat exchanger in which hot liquid circulates. The latter can be heated in any way: using a wood stove or any other heating device. Alternatively, you can consider connecting the coolant from a centralized heating system.
- Combined design. It represents two, sometimes three systems of different types, united in a common structure. The most effective and practical option is obtained by combining the electrical and liquid systems.
The latter option is considered the most successful, since such equipment will be able to provide the house with heat even in the event of a power outage or problems with fuel. However, for obvious reasons, such devices are more expensive. Spending money on them is not always justified, especially if power outages are extremely rare.
The main pipelines are made of galvanized metal. These are rigid structures to which flexible bends are connected.
Channels for the movement of air masses
The heating system of the channel type will not be able to work without a duct network. According to them, air masses move to the premises and return to the heat generator. Circular transportation is most often used, since single-tube structures, which can also be used, have limited functionality and a large number of drawbacks. In the drawing, this design resembles two trees.
The role of trunks is played by two rigid main pipelines made of galvanized metal. One of them serves, the second - the return. To them through adapters are connected "branches".
These are flexible air ducts of smaller section extending to the rooms. They must be sealed with aluminum tape and insulated. Insulation in this case not only retains heat, but also absorbs sounds.
Foil insulators of various grades are usually used for insulation. For highways, a coating with a thickness of 3 to 10 mm is selected. For distribution channels suitable material thickness of 25-30 mm.
Inside single-story buildings, heated air is directed from the bottom up, so air ducts can be built into the floor. In two-storey buildings, the air duct network can be laid on the ceiling of the first floor or in the thickness of the interfloor overlap.
Air ducts must be insulated. Insulating material not only saves heat, but also absorbs sounds
In this case, hot air to the first floor is served from the ceiling. The outlets of the air ducts on the second floor are located in the lower part of the internal walls and on the floor. The return ticket is also placed differently.
On the first floor, the openings for collecting cooled air are at the floor level. On the second, on the contrary, at the ceiling. Here, overheated air masses are collected, which go into the return flow.
Fans for air circulation
Air masses inside pipelines are transported by force. This operation is carried out by special duct fans. The equipment is installed on both return and supply ducts. In addition, most often they are also structural elements of the heater.
When choosing a fan, in addition to the technical characteristics, it is desirable to consider the following parameters:
- the ability to work at different speeds;
- minimum noise level;
- lack of sensitivity to voltage drops;
- equipment with soft start system;
- possibility of smooth adjustment of equipment speed.
You need to understand that the fans are responsible for the pressure performance of the equipment, in fact, determine it. Therefore, the technical parameters of the equipment must exactly match the specifics of a particular system.
Installation scheme of the intra-channel fan inside the duct: 1 - axial-type fan; 2 - air heater constructed from copper pipes with aluminum plates; 3 - air distributor with flaps, changing direction
Flow Distribution: Grilles and Diffusers
All ducts connected to the room are connected to ventilation grilles or diffusers. These elements are designed to separate the airflows intended for heating for ventilation and air conditioning, as well as for uniform distribution of air flow inside premises.
Floor, wall and ceiling devices are available, among which you can find models with movable adjustable louvers.
Intra channel dampers and valves
Elements are designed to adjust the capacity of the heating system. Throttle valves must be mounted in the supply ducts. The devices regulate the pressure of the air masses entering the different rooms and make it possible, if necessary, to fix it.
Valves are equipped with different sections of air ducts. It is mandatory to put inlet valves regulating the flow of air from the street.
In addition to valves that control the inflow and outflow of air flow, ventilation systems are equipped with smoke removal valves and fire-fighting counterparts. In case of fires, they prevent the spread of fire and gases that stimulate burning, remove fire and smoke from the premises
Air preparation equipment
Given that air heating is often combined with air conditioning systems, air preparation becomes a popular option. In this case, the design is equipped with various filters: carbon, mechanical, electrostatic.
They clean the air from all sorts of impurities. Additionally, humidifiers, ionizers, ventilating aerostaty, sterilizers, dryers and the like equipment.
It looks like a diffuser, evenly distributing the flow at the outlet of the duct
Automatic control systems
Air heating in itself, and especially combined with ventilation and air conditioning, is considered a rather complex system. To coordinate its operation, automatic control units are used, which make it possible to quickly and accurately change the parameters of the system.
If necessary, the owner can set the characteristics he needs, getting the most comfortable for him microclimate in the house.
Control units differ in functionality and are selected individually for each specific heating system. Properly selected automation allows not only to fully control the air heating, but also to change to distance programmed settings, zoned distribute air flow and include heating in the system smart House.
Features of the competent calculation
Despite the assurances of the unfortunate masters, independently calculate the air heating is very difficult. Such a task is only possible for specialists.
The customer can only check the availability of all items of the project, which include:
- Determination of heat loss of each of the heated premises.
- Type of heating equipment indicating the required power, which must be calculated on the basis of real heat losses.
- The required amount of heated air, taking into account the power of the selected heater.
- The required section of the ducts, their length, etc.
These are the main points of calculation of the heating system. It will be correct to order the project from specialists. As a result, the customer will receive several calculation options from which it will be possible to choose and translate the most liked solution into reality.
An air heating system is a complex structure consisting of many elements. For its calculation, it is better to attract professionals, for acquaintance with the components it is worth studying the scheme in detail (+)
Conclusions and useful video on the topic
Why choose air heating:
How to calculate the air heating system:
Basics of arrangement of air heating in a private house:
Air heating is among the safe, economical, extremely durable and reliable systems. That is why it is becoming increasingly popular. It is quite simple to equip the system on your own, but it is unlikely that you will be able to make competent calculations.
Possible errors will lead to a decrease in the efficiency of the system, constant drafts and other unpleasant consequences. It is optimal to get a professionally prepared project and, if desired, implement it with your own hands.
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