Heating with air conditioning: the advantages of inverter systems

Any air conditioner is designed to cool the air in the room. But in the cold season, for many users, this device works for heating. However, before you start operating the equipment in this way, you need to understand how to properly start the heating with an air conditioner. This information will help prevent errors in the operation of expensive equipment.

Basic understanding of the heating function of the air conditioner

The principle of operation of a split system for heating is a decrease (!) in the temperature of the air taken from the street. Air will be taken, for example, with a temperature value of -16, and given back in an even colder state, reaching up to -25. The difference is used for heat transfer: The resulting warm air enters the room.

However, will the device have enough power for the full implementation of such a task? It is important to know: if the temperature on the street turns out to be significantly below zero, then the compressor simply does not have enough strength to heat the air — wear and tear will begin. And if the equipment works at its maximum, it is already fraught with the risk of breakage.

So the first condition is outside temperature. Using an air conditioner as a heater is appropriate for regions with a mild climate. And for most of our country, such equipment should be used only in the off-season, in autumn or spring.

Running an air conditioner for heating in winter can be dangerous and frozen drain hose. In this case, condensate will begin to drain into the building. Today, manufacturers are trying to solve the problem by installing a 20-watt heater in the technique. The blocking system also works well: the equipment turns off when the temperature drops sharply.

Advantages and disadvantages of a split system for heating

To heat or not with the help of an air conditioner — each user decides for himself in private. But if the decision turned out to be positive, then you can be sure that the air will not dry out, as when using heaters. There are other advantages:

• environmental friendliness of application (no CO2 emission);
• heat will be produced three times more than electricity consumed.

But besides improving the microclimate, there are also «pitfalls». You should definitely be aware of them with constant use.

1. Device wear happens 3-5 times faster. This will happen due to thickened oil, which will lose its properties.
2. There is a trend to replace the refrigerant — R410, which is safer for the ozone layer, will be in use. This requires the installation of more advanced compressors.
3. The performance of the device will be two times less than the nominal.
4. Air conditioning for heating in winter often fails.

Advantages of inverter air conditioners

When heating the room, the classic air conditioner operates linearly. Its compressor starts, enters the normalized mode, when the temperature set in the climate control system is reached, the device turns off.

An inverter air conditioner works a little more complicated. Applied here engine speed control systemand, consequently, the performance of the compressor. In inverter devices, the so-called double conversion system is used. This means that two circuits work in the electronic power circuit.

The first steps down the 220V AC voltage to a low DC value. At the same time, beats and changes in the power level are drastically reduced with corresponding surges in the mains, where the device is turned on. The second circuit does the reverse transformation. Back to high voltage. The task of this circuit is to control the output frequency.

With this adjustment, the compressor motor is monitored. The lower the frequency, the lower the speed and performance. And vice versa. Such a double conversion scheme with the transition to the principle of motor frequency control provides a set of significant advantages:

• sharp surges in mains voltage disappear almost to zero when the air conditioner is turned on, a smooth start occurs with the absence of significant starting currents;
• thanks to the soft start, the motor resource of the compressor and the mechanical parts of the device increases;
• achievement of higher degrees of compression, consequently, a decrease in the permissible ambient temperatures for the efficient operation of the air conditioner.

Average inverter models in heating mode can work in frosts down to -15 degrees. High-class air conditioners are effective when the temperature drops to -25 … -30 Celsius. Last but not least, this is achieved thanks to the frequency control of the compressor. It can operate at low speeds, the oil in the system does not freeze, circulating constantly.

Selection and Installation Tips

A model that is considered as a candidate for the role of a heating system must be able to direct the air flow vertically downwards. After all, it makes no sense to heat the ceiling. When warm air moves down, the entire volume of the room warms up, correct circulation flows are created.

There are recommendations for installing the indoor unit of the air conditioner used as a heater. This height is not more than 0.5 m from the floor. But here you need to find a reasonable compromise. Yes, when heating, such an installation will be rational. But if the air conditioner is used in two modes, the flow of cold air over the legs will not please.

If we consider budget segment models, they show performance in frosts of -5 … -7 degrees. When trying to turn on such a device at -20, one of several basic situations may occur:

• the device will not start when the environmental sensor is triggered;
• the device starts, but its efficiency will be zero;
• the appliance will cool the air in heating mode.

Important! Running models designed for a certain temperature limit in severe frosts is highly discouraged. It’s like playing roulette. It is possible that the oil has thickened or partially frozen in the system, after which the compressor will simply burn out.

Choosing an air conditioner by parameters

In the list of technical characteristics of the air conditioner, there are a couple of interesting parameters that can say a lot about the device in terms of heating efficiency and saving money.

The first is called COP performance ratio. It describes the ratio between the consumed electrical power and the thermal power supplied to the premises. On average, the value of this parameter is 3.5-4.0. An air conditioner of this class, with an hourly consumption of 1 kW of electricity, will supply 3.5-4.0 kW of thermal power to the room. The best models have a COP value of 5.

Similar to COP for heating, the air conditioner has a parameter cooling performance descriptions. This is ERR, the ratio of thermal energy removed from the premises to the electrical energy spent. However, it is necessary to focus on the COP and ERR parameters with an eye to average air temperatures. The fact is that they are given under ideal conditions.

This means that COP and ERR are measured at 20 Celsius indoors and 7 outdoors. That is, when the room is heated up to +30 COP will fall. Similarly, ERR decreases in the summer heat. Practice shows that even the best Japanese air conditioners with declared COP = 5 in -25 frosts achieve only double or one and a half efficiency. That is, COP=1.5…2.0.

The feasibility of heating with an inverter air conditioner

From the previous section, it is relatively clear why, with the efficiency declared in the passport, the air conditioner saves only 15-20% of electricity compared to classic heaters. The point is in the fall of parametrics, and in the increase in the duration of defrosting cycles, defrosting in a strong minus overboard. In addition, the oil pan and compressor block need to be heated.

Therefore, the answer to the question of whether or not to buy an inverter air conditioner as a heater depends on many factors. Definitely, you should not purchase a household model that is forced to work at the border of its allowable temperature range. It is worth considering the pros and cons of the inverter in regions with low electricity prices.

But if the average annual low temperatures last for a long time, it is reasonable to pay attention to expensive air conditioners. These are devices with a COP of 4 or higher. At the same time, it is highly desirable that the average annual frost be in the middle or closer to the upper limit of their permissible operating temperature limit.

Operating tips

It is important to know such nuances: the first few minutes the device should work as an air conditioner, not a heater. This is necessary in order for the outdoor unit to warm up and thaw out the ice that may have formed in the drainage. The next time this moment will regulate the ventilation speed. Also, many models have a special DeIce functionwhich will allow you not to confuse the mode of correct inclusion.

And here are some more tips to help improve the performance of the technique.

1. Heated drainage will allow water not to freeze and remove condensate.
2. With the compressor stopped, the heater can be switched on to warm up the oil and prevent it from thickening. In this case, the refrigerant will not be able to flow into the crankcase.
3. If the outdoor unit has fan controllerthen it will catch up with the current temperature and prevent freezing of the indoor unit.