Table of Contents
Traditional water systems still remain the main source of heat in houses. However passionless statistics claims that it is much more favorable to heat houses by means of air. Whether so it? Let’s try to understand.
Device and principle of work of system
The air heating services favourably differs from others in the fact that the source of heat energy warms not the intermediary heat carrier, and at once air which moves to the room. However, there are versions which do not use air ducts. Most often air heating services includes the following elements:
- The heatgenerator – the device warming air. It can be gas or diesel torch, the heat pump, water heater, the furnace and other equipment.
- Air ducts. The system of channels giving the warmed-up air to the warmed rooms.
- Fans. The devices intended for the direction of the warmed air stream indoors.
The principle of work of design is rather simple. Cold air comes to the heatgenerator at which surely there is heat exchanger and the fan directing the movement of flow. Here it is warmed till 45-60 °, then comes to air duct, moving on it, warms the room. The air which has given heat on the return air ducts or through special grids in floor returns to the heatgenerator.
If the room too big, then in long air ducts heat waste can appear. In such cases arrangement of several heatgenerators intended for work without air ducts is possible. Specialists claim that the optimum length of air duct should not exceed 30 m, each of branches – 15 m.
Economic calculations show that it is a little irrational to use air heating system only for heating of rooms. Often in construction the design for cooling of air with the portable block of ventilation is established. Thus it is possible to combine conditioning and heating in one system that allows to maintain comfortable indoor temperature practically during any season. Besides installation of additional equipment for creation of healthy microclimate is possible: sterilizer and humidifier for air.
Arrangement of air heating is possible with the help:
- Natural ventilation. The simplest option which is not demanding equipment installation. The system functions thanks to the fact that the air streams heated in the heatgenerator rise up. The cooled-down air falls closer to floor and returns to the heat exchanger. The lack of such system is that additional intake of cold air through doors or windows breaks circulation and, respectively, all operation of the equipment, creating temperature distortion.
- Mechanical ventilation. For ensuring good circulation in system the fan is installed. Thus air movement speed significantly increases and the room gets warm much quicker. Besides in constructions with mechanical ventilation it is simpler to regulate temperature in the heated room. Noise which reaches from air ducts is considered insignificant lack of design.
Why it is worth choosing this system:
- Air heating – the practical decision for heating of rooms. Owners of such systems note their indisputable advantages:
- Relative low cost of the equipment. In general, if to compare to the systems of hot-water heating it is possible to note that boilers for heating of air at cost do not differ from water. But here distributing by means of air ducts and lack of radiators give significant economy.
- Resistance to low temperature impact. Air heating cannot be frozen.
- Small inertance. After start of system of the room get warm, literally, in several minutes.
- Compatibility with ventilation and possibility of air handling.
- Rather easy flush mounting and simplicity of start.
- Full safety. All processes proceeding in system are controlled by the highly sensitive automatic equipment blocking the equipment at the slightest danger. Also owing to lack of the pipes filled with the heat carrier, their ruptures or leaking of hot liquid are simply impossible.
- Profitability. High efficiency, low energy consumption and lack of the intermediate heat carrier do air heating very favorable.
- Durability and reliability. On condition of competent design and mounting the construction will serve at least 20 years.
It is considered to be that air heating practically has no shortcomings. However it is possible to call at least one rather serious problem. This arrangement of air ducts. It is the simplest to place them under ceiling where usually and have ventilation. But heated-up air already rises up therefore inflow of heat has to go from below. Of course, it is possible to force warm air strong flow and from under ceiling, but then on rooms the constant draft will walk. It is unlikely it will be the good decision.
Thus, for receiving inflow of heated-up air from bottom of the room it is necessary to have air ducts or in walls behind decorative coat that will inevitably reduce the net volume of the room, or to stack them between log under finished floor. As the way of solving the problem can be laid air ducts in rather small boxes from gypsum cardboard which will act also as room decor.
We choose heat source
As the heatgenerator for the system of air heating it is possible to choose one of devices:
- Gas boiler. The equipment is used as full-fledged source of heat or as part of multifunction climatic complex which part can be: air conditioning system; humidifier; the filter catching dust; system of recuperation of heat; ultra-violet air purifier. The scheme of operation of the equipment is extremely simple: at combustion of gas in boiler the heat exchanger via which air flow is banished heats up. After warming up he gets divorced on rooms.
It is worth carrying to number of indisputable advantages of the device:
1. opportunity to be switched from liquefied gas to main by simple change of nozzle in torch or from gas on liquid fuel.
2. low cost of fuel provided that the pipeline from gas pipe-line is brought to boiler;
3. possibility of work in completely automatic mode with regulation of supply of gas to torch which amount depends on temperature on the street.
As the main shortcomings of system are considered:
1. Dependence on gas pipe-lines. Such systems are carried out not everywhere, and to heat the building bottle gas is simply ruinous. For liquefied gas and liquid fuel it is necessary to equip special storages.
2. Gas boilers are potentially dangerous. The equipment with open torch has to be placed in the certain room. Designs with the closed torch are safer and are established in any point of the house on the wall, general with the street.
- Solid propellant equipment. Devices in which the heat energy received as a result of combustion of coal, firewood or pellet is used perfectly are suitable for air heating also. The equipment of this type can be the most various. The self-made boilers which are the simplest firebox are widely used. On its perimeter there pass pipes with a diameter not less than 50-75 mm in which there is warmed air.
And nevertheless the most widespread type of solid propellant boilers for air heating is furnace which call pyrolysis furnaces with pipes heat exchangers which provide natural circulation of heated-up air. However, if necessary install the fan for pressure increment in system. For this device it is absolutely optional to equip the certain room under the boiler house: it will not contaminate combustion products the atmosphere in the room and will not spoil design of the room the look.
From advantages of solid propellant boilers it is possible to allocate:
1. Use of the most available and quite cheap source of heat energy.
2. Possibility of independent arrangement and mounting.
Refer need of warehousing and storage of rather large volume of fuel and lack of possibility of independent operation of the equipment without intervention of the person to shortcomings. Firewood in fire chamber should be put independently and daily.
- Electrical systems. The heating devices working from electricity are various. The fan heater belongs to the systems of direct heating. Banishing air through the heated spiral, the device very quickly warms it. However, such system has low energy efficiency and burns oxygen, worsening structure of indoor air. Various electric convectors and heat guns in tandem with the systems of recuperation of heat are more effective. Their use will allow to reduce several expenditure of energy, but anyway direct heating is much more expensive all other ways.
Channel conditioners which spend energy not for production of heat, and for its transfer will become excellent alternative for devices of this kind. In structure of system drives the external block, rather bulky construction which is located usually on the street on specially prepared base. Except it there is also internal block in which the air passing through the heat exchanger is distributed on air ducts. In devices economic compressors with invertor management are usually used. Indisputable advantages of the equipment:
- Profitability. Expenses on heating will remain at the level of heat carrier cost for solid propellant boiler as the conditioner pumps over heat from the street, but does not develop it independently.
- Simplicity and convenience in management of system. It is only enough to specify desirable indoor temperature, all other process is automated.
- The equipment can work not only as the heater, but also as the conditioner.
- Main shortcoming: the most part of systems can function qualitatively only at temperature not below – 10C on the street. At the same time the more cold outside the window, the operation of the device is less effective.
Calculation of system
For the correct selection of the equipment of the necessary power and its competent placement it is necessary to make calculations of system of air heating. In them are defined:
- the volume, necessary for heating of the room, of the warmed air, is calculated taking into account the operating power of heating appliance;
- heat waste in each room of the house where the system will be installed;
- type of the heatgenerator and its power, the last size it has to be comparable to the number of heatlosses in the building;
- head losses of air stream in installation;
- necessary diameter of air ducts, etc.
It should be noted that independently to perform such calculation extremely difficult. Mistakes in calculations lead to the most unpleasant effects: overheating of the heating equipment, its breakdown, strong draft and noise in rooms. Therefore the most correct decision will be to order calculations of air heating from specialists. Only after calculation will be ready, it is possible to buy the equipment, paying at the same time special attention to its quality, range of operating parameters and functionality.
Features of mounting
Being guided by the made calculations, choose air duct type. They can be:
- rectangular which are used most often in constructions with big section;
- round whose design features increase overall effectiveness of system a little.
Regardless of type of the device are fixed by means of anchors. In order to avoid heatlosses if air ducts pass through not heated sites, it is necessary to warm them surely. If designs pass through overlappings, around them the special metal cover bigger, than air duct, the size is mounted. In exit points of devices to the room air distributors and the airintaking equipment have to be installed.
If mounting of the conditioner is planned, the giving air ducts surely are warmed. Thus it is possible to prevent emergence of condensate. The main air duct is mounted from the galvanized steel which is pasted over with the self-adhesive foiled heater 3-5 mm thick. Installation of designs is made prior to the beginning of finishing work. For masking of distributing it is good to use interceiling space behind false ceiling.
The type of air duct is chosen depending on heatgenerator type. It can be flexible, rigid constructions or their combinations. Devices by means of the reinforced aluminum adhesive tape, metal or plastic collars connect. Air ducts can be got in specialized shops or to order at the enterprises which are engaged in release of ventilation equipment. In the same place inserts, throttle shutters and other standard products are got.
Air heating is safe, extremely easy-to-work, economically and at the same time is reliable and long-lasting. It is absolutely no wonder that the system wins the increasing popularity. Independently it is rather difficult to establish it, at great desire it is worth trying. The spent efforts will pay off a hundredfold: the house with the air heating established in it will please owners with heat and cosiness.