The first and main technical characteristic that you pay attention to when buying any air conditioner is its power. It is necessary to distinguish between power consumption and performance in cooling and heating modes. The second indicator, conditionally speaking, is interpreted as the amount of cold or heat that the climate device produces in a certain unit of time. This value is usually indicated either in kW or in thousands of BTU / hour. It is on it that they make the choice of air conditioning power, making an acquisition.
Power Consumption and Cooling Capacity
Power consumption - electricity consumption per unit time (also in kW). The energy consumed is spent on removing a certain amount of heat from the room to the outside. The cooling capacity is usually several times higher than the consumption power precisely because the heat is not absorbed by the device, but is removed to the street.
Through the total ratio of these two values, one can judge the energy efficiency (EER) of the air conditioner, that is, its efficiency in terms of energy consumption. Manufacturers distinguish seven classes of energy efficiency, among which the most appropriate equipment is considered to be devices that correspond to class A. They least spend energy on their work. An important indicator in this case will be consumption for the year.
But speaking of the selection of the air conditioner's power, the specialists have in mind precisely its cooling capacity, the values of which correspond to the total amount of heat of all heat sources in the room.
As already mentioned, this value has two designations: BTU (BTU) and kW. The first is a British thermal unit corresponding to 0.293 watts. In the marking, different brands differently denote this characteristic. Typically, the nominal power values in BTU are multiples of 1000. If the numbers 7 (07), 9 (09), 12, 18, and so on are found in the marking code or in the technical documentation, then these are the values of the nominal power, where 7 = 7000 BTU, 9 = 9000 BTU and further down the list. Specialists, respectively, call them "seven", "nine", "dvenashka", "eighteenth."
Nominal and optimum power of the air conditioner
Under rated power is understood the average performance of the air conditioner for working in the cold. But in each case, it is necessary to calculate the optimal power, which ideally should maximally coincide with the first.
Nominal values are selected by manufacturers for each type of cooling device:
- Window blocks usually have such standard positions: 5, 7, 9, 12, 18, 24;
- Wall splits correspond to the model range in this version: 7, 9, 12, 18, 24. Sometimes some brands produce non-standard models with the following nominal values: 8, 10, 13, 28, 30;
- Cartridges go in this order: 18, 24, 28, 36, 48, 60. Non-standard number: 34, 43, 50, 54;
- Channel splits start the power series with 12 models and sometimes end with 200;
- Console installations have the following variety: 18, 24, 28, 36, 48, 60. In a non-standard version: 28, 34, 43, 50, 54;
- Columns start at 30 and reach 100 or more.
Such a list is not accidental. Here, the selection of the air conditioner and its power according to the area of the room, and the height of the ceilings, and heat gain from household equipment, electric lighting, people, roofs with walls, open windows and ventilation are already taken into account.
Power calculation for domestic air conditioner
Why is it so important to correctly calculate and choose an air conditioner by power (cooling capacity)?
The lack of optimal power entails the operation of the device in non-stop mode - it will try to reach the required temperature in the room.If there is a surplus of optimum power, the air conditioner will operate in a constant start / stop mode and give out too strong flows of chilled air that cannot be distributed normally around the perimeter. Both options instantly wear out the compressor.
Ideally, climate control equipment should work so that there is no unnecessary heat load, because any air conditioner can compensate for only a limited amount of heat.
Having made the correct calculation of the power of the air conditioner after reaching the set temperature, the compressor turns off, and then only the room module functions. As soon as the parameters have increased by a couple of degrees, a command about this is received through the temperature sensors on the compressor, and it turns on again.
When buying a household split-system or monoblock, you can make a lightweight calculation of power, taking into account only the area of the room.
It is considered that on average 1 kW = 10 m². Therefore, a room with an area of 17 m² requires a cooling capacity of 1.7 kW. Air conditioners with a capacity of 1.5 kW are available, but not all manufacturers have such low-power models. And the next value is usually 2 kW. If the side is sunny, the room is equipped with a lot of equipment, and several people are regularly there, then it is better to give preference to the side of high values - 2 kW or 7 BTU.
Low power air conditioners correspond to the following table of values:
| Area, m² | power, kWt | Power, BTU / h |
| 15 | 1,5 | 5 |
| 20 | 2 | 7 |
| 25 | 2,5 | 9 |
| 35 | 3,5 | 12 |
| 45 | 4,5 | 14-15 |
| 50 | 5,0 | 18 |
| 60 | 6,0 | 21 |
| 70 | 7,0 | 24 |
A typical calculation of power over the area of a room is done according to the generally accepted scheme:
Q1 = S * h * q / 1000
WhereQ - power during cold work (kW),S - area (m²),h - ceiling height (m),q - coefficient equal to 30 - 40 W / m³:
q = 30 for the shadow side;
q = 35 for normal light exposure;
q = 40 for the sunny side.
Q2 - the total amount of heat surplus from people.
Heat surplus from an adult:
0.1 kW - with minimal activity;
0.13 kW - with small or medium activity;
0.2 kW - with increased activity;
Q3 - the total value of heat gain from household appliances.
Heat surplus from household appliances:
0.3 kW - from PC;
0.2 kW - from TV;
For other devices, a value of 30% of the maximum power consumption is used.
The power of the climate control should be in the Qrange range from -5% to + 15% of the rated power Q.
It should be noted that this is an approximate calculation, which has errors. Even when choosing a low-power air conditioner for an apartment or office, it is advisable to use the services of professionals and calculate everything for sure, since the simplified method of calculating power involves a minimum amount of equipment, ceiling height and number of people.
What is an online calculator for?
Today, many online storefronts offer a service such as a calculator for calculating the power of an air conditioner, which can easily determine the exact amount of refrigerating capacity, taking into account all the features of the room. This is very convenient - even a simple layman can use it without much knowledge in the field of air conditioning systems. Why might such a skill be needed? So that an unscrupulous seller does not try to mislead a person, trying to sell him an appliance of an inappropriate capacity that has been stored in a warehouse.
At the end of the article, you can watch the video with detailed instructions on how to use the calculator for calculating the power of an air conditioner for an ordinary buyer.
It is worth remembering that such types of standard calculations are suitable only for domestic and administrative buildings with an area of not more than 70-80 m², without additional technical equipment and a large crowding of people in the territory. Equally important is the types / types of compressor. This is also taken into account when selecting an air conditioning system in an apartment or office.
Thus, with the calculation of the capacity of the air conditioner by the area of the room, everything is clear - its results are rather arbitrary, but for multi-systems or centralized air conditioning systems in industrial buildings they are unsuitable.
Calculation of cooling capacity of multizone systems and central air conditioners
When buying and installing multi-zone air conditioning systems, in any case, you will have to contact representatives of climate technology companies, since it is impossible to do this yourself. What do you usually take into account when calculating the power of central air conditioners or multi-split systems? It:
- the maximum value set by the manufacturer at which the device can operate for a long time at maximum load without interruptions;
- allowed capacity that allows consumers to connect to their communications;
- maximum length and height of the pipeline.
From these three points, the total power with which VRV or VRF installations can operate is already being derived.
First, the central air conditioning system always calculates the power for each individual indoor unit according to the principle described above for split systems or monoblocks installed in small rooms. Here, accordingly, there will be more heat gain from appliances, people, walls, roofs and windows. It all depends on the design of the building, its purpose and the crammed equipment.
After that, external installations are already selected taking into account the power of all indoor units and the absolute maximum outdoor temperature, which is set by the manufacturer in the technical documentation. If the values are exceeded due to the installation features of the external module, then use protective screens and shields.
Some premium manufacturers have the opportunity to exceed the permissible power of the external module by about 30%. At the same time, the functionality of the entire layout does not suffer from this in any way.
The selected current determines the operating current and its maximum operating values with a certain margin. This is necessary to select the rated value of the circuit breaker. Protection should be triggered if the permissible values for pressure, current and other parameters are exceeded.
For central air conditioning, it is always wiser to use the calculation of the air conditioner's power online and expert advice, since the selection of the unit for cooling power does not give exact guarantees regarding the served area without taking into account all the heat load. And this can only be determined by a professional.
Air conditioner compressor power calculation
If the power was calculated incorrectly, or the device was already too old, and the compressor broke down, you will have to replace it with a new one. The question is how to find out the power of the air conditioning compressor so as not to repeat mistakes.
For all the processes associated with the movement of the coolant along the refrigeration circuit in the air conditioning devices, the compressor is responsible - the main element of the internal device (structure) of the external module. He is also responsible for the cooling capacity, therefore, under abnormal load, it fails.
As a rule, the power characteristics of this part are determined at the factory, so it is necessary to build on the data in the manual. There is absolutely no need to calculate the power of the air conditioning compressor to pick up a new one. What size the old unit had, this is necessary and taken as a basis. But this is applicable in the event of a breakdown due to the end of the operational life of the device.
If the malfunction is associated with improper selection of permissible values of cooling capacity, then it is necessary to contact specialists.Do not try using an air conditioning compressor to independently calculate the power, which will depend on many factors:
- type of compressor;
- number and diameter of cylinders;
- refrigerant used.
It’s better to calculate the power of the air conditioner online to install a new device, since replacing the compressor is cost-effective only in household systems with cold characteristics of 10 kW and for semi-industrial models.
Buying an air conditioner with a frequency converter (inverter control type) will help keep the main unit longer. This device has a minimum number of on / off cycles and compressor power control - upon reaching the set air parameters, the air conditioner switches to work with reduced cooling capacity.
Then you can watch a video on how to calculate power on a calculator yourself.
