Selection of an air conditioner for cooling capacity and cooling capacity

The first and main technical characteristic that is paid attention to when buying any air conditioner is its capacity. Distinguish between power consumption and performance in cooling and heating modes. The second indicator, conventionally speaking, is interpreted as the amount of cold or heat that the climatic 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 the power of the air conditioner, making the purchase.

Power consumption and cooling capacity

Consumption power - electricity consumption per unit of time (also in kW). The energy consumed is spent on removing some of the heat from the room to the outside. The value of refrigeration capacity is usually several times higher than the power consumption, precisely because heat is not absorbed by the device, but is removed to the street.

The total ratio of these two values ​​can be used to judge the energy efficiency (EER) of the air conditioner, that is, its efficiency in terms of energy consumption. Manufacturers distinguish seven energy efficiency classes, among which the most profitable equipment is class A devices. They consume the least energy for their work. An important indicator in this case will be consumption per year.

But speaking about the selection of the power of the air conditioner, experts mean precisely its cooling capacity, the values ​​of which correspond to the total amount of heat of all heat sources in the room.

As mentioned, this value has two meanings: BTU and kW. The first is the British thermal unit, which corresponds to 0.293 watts. In the labeling, different brands designate this characteristic in different ways. Usually 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. Experts, respectively, call them "seven", "nine", "dvenashka", "eighteenth".

Rated and optimal power of the air conditioner

The nominal power is understood as the average performance of the air conditioner for operation in the cold. But in each individual case, it is necessary to calculate the optimal power, which, ideally, should coincide as much as possible with the first.

The nominal values ​​are selected by the manufacturers for each type of cooling device:

• Window blocks usually have the following 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;
• The cassettes are in this order: 18, 24, 28, 36, 48, 60. Custom row: 34, 43, 50, 54;
• Channel splits start with a capacity range of 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 from 30 and go up to 100 or more.

This list is not accidental.It has already taken into account the selection of an air conditioner and its capacity by the area of ​​the room, and by the height of the ceilings, and by heat inflows from household equipment, electric lighting, people, roofs with walls, open windows and ventilation.

Power calculation for a domestic air conditioner

Why is it so important to correctly calculate and select an air conditioner in terms of power (cooling capacity)?

Insufficient optimal power entails the operation of the device in non-stop mode - it will try to reach the required temperature in the room. With an overabundance of optimal power, the air conditioner will operate in a constant start / stop mode and produce too strong flows of cooled air, which will not be able to be normally distributed around the entire perimeter. Both the one and the other options instantly wear out the compressor.

Ideally, climate control equipment should operate in such a way that there is no unnecessary heat load, because any air conditioner can only compensate for a limited amount of heat.

Having made the correct calculation of the capacity of the air conditioner, after reaching the set temperature, the compressor turns off, and then only the room unit functions. As soon as the parameters have increased by a couple of degrees, a command is sent to the compressor through the temperature sensors, and it turns on again.

When buying a household split system or monoblock, you can make a lightweight calculation of the power, taking into account only the area of ​​the room.

It is generally accepted that on average 1 kW = 10 m². Therefore, a 17 m² room requires a cooling capacity of 1.7 kW. Air conditioners with a capacity of 1.5 kW or more are produced, 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 large number of equipment, and several people are regularly there, then it is better to give preference to higher values ​​- 2 kW or 7 BTU.

Low power air conditioners correspond to the following table of values:

A typical calculation of the power by the area of ​​the room is done according to the generally accepted scheme:

Q1 = S * h * q / 1000

WhereQ - power during cold operation (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 surpluses from an adult:

0.1 kW - at minimum activity;

0.13 kW - with low or medium activity;

0.2 kW - with increased activity;

Q3 - the total value of heat gains from household appliances.

Heat surpluses from household appliances:

0.3 kW - from a PC;

0.2 kW - from TV;

For other devices, the value is calculated as 30% of the maximum power consumption.

The power of the climate control must be in the range Qrange from -5% to + 15% of the rated power Q.

Please note that this is an approximate estimate that 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 the power provides for the minimum amount of equipment, the height of the ceiling and the 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, by which it is easy to determine the exact value of the cooling capacity, taking into account all the features of the room. It is very convenient - even a simple layman can use it without much knowledge in the field of air conditioning systems. Why such a skill might be needed? So that an unscrupulous seller does not try to mislead a person, trying to sell him a device of inappropriate capacity that is stuck in a warehouse.

At the end of the article, you will be able to watch a video with detailed instructions on how to use a calculator for calculating the power of an air conditioner for an ordinary buyer.

It is worth remembering that these types of typical calculations are suitable only for household and administrative premises with an area of ​​no more than 70-80 m², without additional technical equipment and a large crowding of people on the territory. The types / types of compressor are also of great importance. This is also taken into account when choosing an air conditioning system for 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, and they are unsuitable for multi-systems or centralized air conditioning systems in industrial buildings.

Calculation of cooling capacity of multi-zone systems and central air conditioners

When buying and installing multi-zone air conditioning systems, in any case, you will have to contact representatives of HVAC firms, since it is impossible to do this on your own. What is usually taken into account when calculating the capacity of air handling units 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 interruption;
• the permitted capacity that consumers allow to connect to their communications;
• the maximum length and height of the pipeline.

From these three points, the total power with which VRV or VRF installations can operate is already deduced.

First, the central air conditioning system always calculates the capacity for each individual indoor unit according to the principle described above for split systems or monoblocs installed in small rooms. Here, accordingly, there will be a greater heat gain from appliances, people, walls, roofs and windows. It all depends on the design of the building, its purpose and stuffed with technology.

After that, external installations are already selected, taking into account the power of all indoor units and the absolute maximum outside temperature, which is set by the manufacturer in the technical documentation. If the values ​​are exceeded due to the peculiarities of the installation of the outdoor unit, then use protective screens and barriers.

Some premium manufacturers have the option to exceed the capacity of the outdoor unit by about 30%. At the same time, the functionality of the entire layout does not suffer from this.

The selected power determines the operating current and its maximum operating values ​​with a certain margin. This is necessary to select the nominal value of the circuit breaker. The protection should operate when the permissible values ​​for pressure, current and other parameters are exceeded.

For central air conditioning, it is always wiser to use the online calculation of the air conditioner capacity and the advice of a specialist, since the selection of a unit in terms of cooling capacity does not give precise guarantees regarding the serviced area without taking into account the entire heat load. And this can only be determined by a professional.

Calculation of the power of the air conditioning compressor

If the power was calculated incorrectly, or the device was already too old, and a compressor breakdown occurred, then it will have to be replaced with a new one. The question arises of how to find out the power of the air conditioner compressor so as not to repeat mistakes.

For all processes associated with the movement of coolant along the refrigeration circuit, in air conditioning devices, the compressor is responsible - the main element of the internal device (structure) of the outdoor module. It is also responsible for the cooling capacity, therefore it breaks down under abnormal load.

As a rule, the power characteristics of this part are determined at the factory, therefore, it is necessary to build on the data in the manual.There is absolutely no need to calculate the capacity of an air conditioner compressor in order to select a new one. What size the old unit had, this must be taken as a basis. But this is applicable in a situation with a breakdown due to the end of the operating life of the device.

If the malfunction is associated with an incorrect selection of the permissible values ​​of the refrigerating capacity, then you must contact the specialists. You should not try to calculate the capacity of the air conditioner compressor yourself, which will depend on many factors:

• compressor type;
• number and diameter of cylinders;
• used coolant.

It is better to calculate the power of the air conditioner online for the installation of a new device, since replacing the compressor is cost-effective only in household systems with cold characteristics from 10 kW and in semi-industrial models.

The purchase of an air conditioner with a frequency converter (inverter type of control) will help to save the main unit longer. This device provides a minimum number of on / off cycles and regulation of the compressor power - when the set air parameters are reached, the air conditioner switches to operation with a reduced cooling capacity.

Then you can watch a video on how to calculate the power on the calculator yourself.