With the onset of light colds in autumn and relative warming in spring, apartment dwellers often think about an additional source of heat. Indeed, in the fall central heating has not yet been turned on, and in the spring it has already been turned off. Not understanding how air conditioning works for heating, many do not even consider it as a means of providing comfort. At the same time, a modern device can help even those who feel discomfort in their homes in winter frosts.
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In simple words about complex things
To understand what the principle of the heat pump is, on which the operation of the air conditioner for heating is based, it is enough to answer the question: which heater has a coefficient of performance in excess of 100%? For most people, the answer will be unexpected. This is a household refrigerator. The following happens in it:
- heat is transferred from the compressor unit, blowing fans;
- heat is taken from the products and enters the environment.
Thus, the refrigerator generates heat, not only using electricity, but also taking it away from food and air, which periodically enters the cooling chambers. The heat pump works on the same principle, into which an air conditioner with a heating function is converted.
What happens in the climate system
When the heating mode is activated in the air conditioner with the remote control, it starts working, for ease of understanding, on a mirror basis. The device begins to cool the environment. The following happens:
- the second freon circulation circuit is activated;
- in the outdoor unit is the expansion structure of the coolant. When it enters it, freon sharply loses its temperature, and the air turns out to be warmer than the tubes with gas;
- Freon in the expansion chamber is heated from the environment;
- the compressor pumps the gaseous coolant into the grate of the compression system, where it condenses with the release of heat taken from the air.
In general, there is nothing difficult in understanding such a scheme of work. The air-conditioning with heating has two freon circulation systems in order to extract heat from the room in summer and from the external environment in winter. In winter, the heat transfer pattern also changes.
Simple air conditioners for heating in the winter take air outside, more complex and sophisticated - partly mix it with the flow from the room to achieve better returns.
Why do air conditioners have different operating temperatures?
Air conditioners with heating differ both in technical indicators of power and heat efficiency, and in the permissible temperature range of use. Devices with a classical compressor circuit (non-inverter) are not recommended to be switched on when, so to speak, the weather parameters are outside the permissible limits.
This not only leads to loss of warranty, but can increase the chance of failure of the air conditioner to 100% - it will burn directly in the first seconds after the start command.
Consider what happens in the design of a classic heating circuit.
- Grease circulates in the system, which is not in a closed circuit, in contact with the coolant - freon.
- When the temperature drops, the grease thickens.
- When the air and, accordingly, the outdoor unit of the air conditioner are cooled below a certain limit, the separation of grease and freon in the liquid state begins, the latter begins to rise up and can enter the oil circuit.
The main drawback of the classic compressor cooling system is the intermittent oil circulation.At that time, when the air conditioner reached the specified microclimate in the room and turned off, the oil flows into the drive. When heating is required and the engine has to start in winter, the selection of thickened grease is slow, and the compressor is forced to work with a sharply increased load.
If, as a result of the separation of freon and oil, the first enters the lubrication circuit, the air conditioner supercharger can burn out immediately at the time of start-up. Negative temperature also plays the role of a brake: ball bearings and seals can freeze. To avoid problems, many cunning sellers advise you to purchase a special winter kit for retrofitting an air conditioner. We will dwell on the usefulness and rationality of such a decision later.
Things are better with inverter air conditioners. Here, the permissible lower temperature limit is greater, since the compressor does not turn off, changing speed and forcing the oil to ply constantly. At the same time, it maintains a relatively stable temperature of the entire system, mixing with freon and taking away part of the heat from it.
What determines the lower temperature limit?
The lower operating temperature limit depends on several factors. For cheap models of air conditioners it can be -5 degrees Celsius, for more advanced ones -7 ..- 10, for market leaders it can reach -20 ..- 25 for household models. To understand how everything works in a single scheme, it is necessary to explain several basic principles.
- The heat extraction system in a classic type air conditioner works like a refrigerator. One mode, one number of produced calories per minute. By turning the compressor on and off at varying speeds of the fan motor, the desired temperature of the air entering the room is reached. In this case, before starting blowing, the heat exchanger must be warmed up.
- The heat extraction system in inverter models can change the rate of calorie extraction. Therefore, it is realistic to achieve smoother control without having to preheat the heat exchanger before starting.
From these two principles it is clear why air conditioners with a classic circuit cannot work at low temperatures. The greater the minus overboard, the more the heat transfer efficiency decreases and spurious losses increase. In the end, the system enters zero efficiency mode, the compressor stops turning off and may burn out.
For inverter models, the situation is better. Energy extraction is more efficient, therefore, even when implementing the standard procedure for blowing the heat exchanger with outside air, heat can be obtained by working in more severe frost.
There is another mechanic with which help raise the efficiency of the air conditioner. This is a mix of outdoor air flows and selected directly from the room. As a result, during heating, it is necessary to compensate for the lower temperature difference, and the air conditioner operates in even more severe frost. However, you cannot take too much air out of the room - the ventilation efficiency is lost.
The third principle, thanks to which the leaders of the air conditioning market wins, is the use of special refrigerant. If the standard freon used in refrigeration units boils at about -18 ..- 25 Celsius, then special - at -30 ..- 35. Even more heat can be taken from the environment by simply providing a significant temperature difference.
In addition, the principles of reducing parasitic losses are implemented. They have the highest performance in inverter air conditioners, so most of the elite models from Mitsubishi Electric, Mitsubishi Heavy Industries (MHI), Toshiba are just this type. These brands are ready to offer products that work easily in -20 degrees below zero. At the same time, the energy efficiency of heating is very high - for one kilowatt of electricity spent, you can get as much as 4 - heat.
The obvious benefits of winter kits
In conclusion, it is worth talking about special equipment with ambiguous advantages.Vendors recommend using winter sets of air conditioning equipment to guarantee performance in cold weather. They include:
- heating the drain system, the outer tube;
- separate TENOV system for compressor and fan;
- engine speed change system in accordance with the temperature drop.
Speaking directly and frankly, winter kits are not able to fully protect the air conditioner, unless the system is poorly mounted and thought out. They can only avoid the output of the external unit of the climate system, which turns on at a temperature not recommended by the manufacturer.
But in practice, the usefulness of the winter kit is only that it can help prevent the formation of an ice plug in the drain pipe. However, with proper installation, it is not used, and the air conditioner designed for operation in frost already has all the necessary protection systems.
Therefore, the question of whether or not to purchase a winter kit depends, first of all, on the depth of the wallet of the future owner. It will not have any effect on the operation of the device, which is operated within the temperature limits recommended by the manufacturer.
As a measure that allows less frequent maintenance of the external unit of the split system and tries to turn on the heating in frankly severe frost (which will be extremely inefficient), winter sets are useful for air conditioners only in the classic compressor circuit. But no more than that.
