The latest generation household split-systems equipped with inverters are better than their predecessors in technical specifications, which is quite natural. The essence of the problem: according to the reviews of many ordinary users living in the CIS countries, the main difference between the new models is the high price, the remaining advantages are invisible. Therefore, it is proposed to thoroughly analyze 3 questions: what is an inverter air conditioner, its principle of operation and real advantages.
The algorithm of a conventional air conditioner
To understand the difference between an air conditioner with an inverter, it is advisable to familiarize yourself with the duty cycle in a conventional “split”. How is the climate system in a simplified form:
- 2 heat exchangers - an evaporator and a condenser - are connected by copper tubes into a closed loop, through which freon circulates;
- a compressor is installed on the line with gaseous freon, which raises the pressure in the condenser;
- on the return line there is an expansion valve (thermostatic valve or capillary device);
- both heat exchangers are spaced into different blocks (indoor and outdoor) and are blown by fans;
- control of the units lies on the electronic unit receiving the signals of the temperature and pressure sensors.
Reference. All refrigerators operate according to a single principle: due to the evaporation of the working fluid (freon), thermal energy is taken from the room air. Further, it is diverted outside the premises and is released into the environment during gas condensation in an external heat exchanger. The vapor compression cycle is described in detail in the publication on the manufacture of air conditioning on its own.
The standard “split” operates in the on / off mode according to the following algorithm:
- The user turns on the device for cooling and sets the desired temperature inside the room.
- The compressor starts at full power and raises the pressure in the condenser. After about half a minute, the turbine of the indoor unit turns on and starts to drive cold air into the room from the evaporator.
- When the temperature in the room reaches the set value, the electronics stops the compressor by the signal of the sensor.
- Since the throttle valve constantly passes liquid freon into the evaporator, the cooling process continues until the pressure in the system is equalized. The air temperature drops 1-2 degrees below the set.
- When the room heats up again, the controller switches on the compressor unit again at the signal of the sensor. He again takes 20-40 seconds to increase the pressure, during which time the temperature manages to grow another degree. Then, the chilled air supply resumes.
Key moment. The compressor of a conventional wall-mounted air conditioner always runs at full power or is idle in standby mode. At the moments of stop / start, an inertia effect occurs - at first the air is supercooled, then it has time to overheat. Temperature changes are clearly felt by a person who is near the internal unit of the split system.
Other types of old air conditioners are similarly arranged - mobile, floor and duct. Devices of the "winter - summer" type are able to work for heating until the frost on the street reaches -5 ° C. At lower temperatures, the oil starts to thicken in the stopping compressor, and the condenser fins are covered with ice.
What is the difference between inverter models
The new generation of air conditioners has several differences:
- installed an additional electronic control unit - inverter;
- the compressor engine operates on a different principle;
- power is regulated smoothly, but not stepwise;
- the defrost function of the heat exchanger in the outdoor unit is provided.
Note. The latest modifications of the “splits” are equipped with DC motors, whose speed is easier to regulate.
Now we will understand what the name "inverter" means. This is a current frequency converter that allows you to smoothly change the speed of the compressor electric motor and the performance of the unit for cold / heating. The board is located in the external unit of the split system and is part of the main circuit.
Thanks to the frequency converter in the air conditioner, inverter power control is implemented:
- When turned on for the first time, the compressor operates in maximum mode to quickly reach the set temperature in the room.
- When the sensor detects an approach to the set temperature threshold, the inverter smoothly reduces the engine speed at the command of the controller.
- When the required air temperature is reached, the supercharger does not stop - it switches to the minimum capacity mode.
- Further, the compressor unit works to maintain the microclimate of the room, increasing or decreasing power depending on changes in environmental conditions.
Since the compressor operates non-stop, the lubricant does not freeze in the cold - the device is able to heat room air at minus temperatures overboard (to -15 degrees). The problem of condenser freezing is solved by introducing a periodic defrosting system.
An interesting point. Externally, inverter-type air conditioners are no different from their predecessors. Some manufacturers write INV or INVERTER on the external module case. But in most cases, information about the type of split system is indicated in the technical passport of the product.
We are looking for real pros and cons
We list the advantages of inverter coolers declared by sellers and manufacturers of HVAC equipment:
- profitability of 30-60% in comparison with conventional "splits";
- reliability, long service life;
- reduced noise during operation;
- more accurate maintenance of air temperature;
- the ability to heat the house at negative street temperature minus 15 ° C.
Comment. It must be understood that manufacturers and traders of refrigeration equipment often exaggerate the merits of products. An example of advertising: the resource of an ordinary cooler is 8–10 years, and the inverter one is 15 years old. The goal is clear: the consumer must believe and buy a more expensive air conditioner for an apartment or a private house.
Profitability - a relative concept
Air conditioners with a variable compressor shaft speed really save energy due to the absence of inrush currents and a smooth decrease in performance. No wonder such a technique was invented in Japan and has been widely used in Europe, where the cost of electricity is quite high.
The operating conditions of climatic household appliances in the territory of the post-Soviet states differ from Western European countries. The savings from using inverter air conditioners are small for the following reasons:
- The hot season does not last long, and the price of 1 kW of electricity is much lower than European tariffs. If you save the kilowatts saved during the year in monetary terms, the amount will not impress you.
- The inverter also consumes excess energy. Some parts are very hot during operation, converting electricity to heat. Otherwise, why are aluminum heat sink radiators installed on the board?
- The amount of energy savings is highly dependent on the type of room to be cooled. The effectiveness of the device is clearly visible in the bedroom, a small living room or a children's room. Another thing is an office where employees constantly open windows and front doors, work with office equipment and so on.
Note.Many online resources talk about the efficiency of inverter coolers using an example of a moving car, giving the corresponding picture. Such schemes give a distorted idea of the energy costs of the frequency converter, working in tandem with the compressor.
Intermediate withdrawal. A smooth increase and decrease in power really gives the result - less electricity is consumed (the delta compared to the “non-inverter” will be 15-30%). But the effect is offset by low tariffs, a short heat season and consumption of the inverter unit itself. Against the background of the price of equipment and spare parts, energy conservation is becoming illusory.
Reliability and resource of units
In order not to take away the reader’s precious time, we will present an analysis of these advantages in the form of brief theses:
- The most vulnerable chiller unit is a compressor. In second place is electronics.
- On the one hand, the absence of starts / stops increases the resource of the inverter supercharger. On the other hand, the service life is reduced due to continuous operation.
- Practice shows: new branded inverters (not cheap Chinese) really last a long time. Only another reason is the introduction of modern technologies, for example, scroll and twin-rotor compressors with DC electric motors.
- From the voltage drops in our network, any electronics can fail, regardless of the type of air conditioner. Repair of the inverter will cost much more.
- If the cooler is not serviced for years, is operated with a lack of freon or clogged heat exchangers, the result will be the same - breakdown of the supercharger. The presence of a frequency converter does not play a role.
Hence the conclusion: the standard “split” in terms of reliability and durability does not lose to the inverter, and if the electronics are replaced, it will win at the price of the parts. We are talking about high-quality equipment from trusted brands - Daikin, Mitsubishi, York and the like. Comparing Chinese products is pointless.
Are the inverters noisy?
In any air conditioner, there are three units that make noise:
- compressor;
- axial fan of the external module;
- turbine fan indoor unit.
The first two elements are taken outside the home (excluding window and mobile versions of air conditioners). In addition, modern inverter split systems are equipped with low-noise superchargers, they are almost inaudible behind the wall. The axial impeller starts periodically and does not bother residents with extraneous sounds.
The turbine of the split internal module is clearly noisy. The sound level depends only on its design, the inverter does not play a role. But the machines of the latest generation still have an advantage - they get advanced developments, for example, an impeller with a special blade profile. So the myth about the noiselessness of inverter models is born.
Exact observance of temperature conditions
A cooler equipped with a frequency converter can more accurately withstand a given temperature, this is an indisputable fact. The problem is different: sellers associate this feature with maintaining the health of residents, although in reality it is a comfortable stay inside the room. Accurate maintenance of air temperature eliminates the sensation of stuffiness and cold at the moment of switching off the standard “split” model.
Reference. In the vast majority of cases, people catch a cold from a sudden change in climate. Example: actively moving along the street in the middle of summer, you enter a room with a temperature of +21 ° С. The heated body cools sharply, which often causes a cold.
We again describe the heating with the inverter as follows:
- In the previous generation of units, the street units were frost-bitten, oil was frozen in the compressor crankcase.
- In inverters, this problem is absent - the units continue to work up to minus 15 degrees.
- In a reverse cycle, the heat transfer efficiency decreases sharply with the temperature of the outside air.Inverter devices are able to work, but in severe frost they warm the room rather weakly.
- How it looks in practice: the internal turbine turns on much less frequently, the intervals between starts are longer. The air stream is barely warm.
Conclusion: during the cold season, all air conditioners are able to effectively warm the air, while on the street 0 ... + 5 ° C. In cold weather, the heating intensity decreases markedly, although the inverter can function physically. The device simply does not have enough heat exchange surface area due to the small size of the condenser.
Reference. In air-to-air or air-to-water heat pumps that are descendants of split systems, the issue of efficiency has been resolved by increasing the dimensions of external heat exchangers.
Briefly about the shortcomings
After analyzing the real advantages of inverter climate systems, we can talk about such disadvantages:
- high initial price of equipment, on average 30% more than "non-inverter" devices;
- expensive repair of electronic filling;
- dubious reliability of frequency converters - boards often become worthless from power surges.
The advantages of inverters over classic models in our conditions are minimal. A tangible decrease in electricity consumption is observed with year-round use (heating + cooling) in living rooms.
Which cooler is better to choose
Regarding the choice of a split system, we will give several recommendations:
- The inverter is appropriate in living rooms where no more than three people stay at the same time - a nursery, a bedroom, a living room.
- For a kitchen, a large hall or office, it is better to take a traditional air conditioning.
- If the budget is limited, you should buy a classic model of a reliable manufacturer. A cheap inverter from the Middle Kingdom will bring a lot of problems, ranging from noise to repairs.
- Do not hope that the inverter version of the “split” will replace the full heating of the room in the winter.