When people buy air conditioners, most of them are concerned about the cooling capacity. However, during the actual operations, the same 12000 BTU split air conditioners may differ in cooling performance, apparently. This is because the actual cooling ability does not depends on the product itself; instead, it is affected by the working conditions, installation, operation statistics, etc.

This article is to introduce the key factors that influence the air conditioner's cooling capacity and help people better choose a product that suits their needs and get the best utilization performance.

 

I. What is the cooling capacity of an air conditioner?

 

Cooling capacity is the ability of the air conditioner to remove heat from the interior to the exterior in a unit of time. Common units are BTU/h (British Thermal Unit Per Hour) and kW (kilowatt).

 

Examples:

9000 BTU ≈ 2.5 kW

12000 BTU ≈ 3.5 kW

18000 BTU ≈ 5 kW

24000 BTU ≈ 7.5 kW

The more powerful the cooling capacity, the larger the space the air conditioner will cover.

 

 

 

II. Key factors that influences the cooling performance

 

1. The exterior ambient temperature

The ambient temperature is the most important key factor that influences the air conditioner cooling capacity. The air conditioner releases heat to the outside through the outdoor unit. If the outside ambient temperature rises, the condensing pressure will increase, which will lead to higher compressor load and lower heat-exchanging efficiency. In case of that, the actual cooling capacity will gradually decrease.

 

Examples:

Testing cooling capacity is 100% under the ambient temperature of 35 ℃;

When the ambient temperature goes up to 46 ℃,  the testing cooling capacity may decrease to 85%-95%;

Under the extreme environment of 52°C, it may decrease to 70%-85%.

 

This is why in the high-temperature areas, people tend to choose T3-type air conditioners more.

 

2. The room size and the height

The larger the room, the more heat it needs to be removed. Except for the room size, the height is also important.

Examples:

 

Room 1: 20 m² with a height of 2.8 m;

Room 2: 20 m² with a height of 4.5 m.

 

Their sizes are the same, but room 2 has 60% more air volume, which will require more cooling capacity. For warehouses, shops, and exhibition halls, the cooling capacity depends on the actual volume instead of the floor size.

 

3. The insulation performance of the building

The housing structure of the building will continue to spread heat to the indoor environment. The factors include the thickness of walls, the insulation quality, the rooftop insulation performance, and the material of doors and windows. The buildings with poor insulation performance will bring more cooling load.

 

Examples:

Single-story sheet-metal factory building

Container office

Building with extensive glass curtain walls

 

These conditions normally require an air conditioning system with higher capacity.

 

4. Sunlight intensity

The sunlight will increase the interior heat apparently, particularly for west-facing rooms, south-facing glass curtain walls, and top-floor rooms.

The solar radiant heat can reach up to 20% of the total cooling burden. As for the areas with strong sunlight, it is recommended to increase the cooling capacity.

 

 

5. The number of people in the room

The human body is the source of heat. Commonly, each adult can generate about 100~150W heat per hour. Particularly in the offices, conference rooms, classrooms, restaurants, and shopping malls.

When the occupant density is increased, the air conditioner needs to shoulder the cooling burden from the human bodies additionally.

 

6. Heat from the devices

Many electric devices will release heat during their operations. Such as computers, databases, televisions, lighting equipment, kitchen equipment, etc.

In the spaces like server rooms, monitoring centers, and commercial kitchens, the heat generated by the devices is greater than that of the human body. In such conditions, it is necessary to check the cooling capacity again according to the actual heating burden.

 

7. The piping length and the installation

No matter how perfect the air conditioner is, irregular installation will still affect its cooling capacity.

Common issues are:

Too long copper pipe;

Poor insulation;

Refrigerant leakage;

Insufficient vacuum-pumping;

Too many elbows on the copper pipe.

These problems will lead to:

Loss of cooling capacity;

Increased pressure drop;

Increased energy consumption.

 

Finally, the actual cooling performance does not reach the designed level.

 

8. Charge of refrigerant

Refrigerant is the key medium of air conditioners to transfer heat. If the refrigerant is insufficient, then the heat-exchanging ability of the evaporator will decrease as well as the cooling capacity. But if the charge of refrigerant is too much, then the system pressure will be irregular, which will increase the compressor burden.

 

9. The cleanliness of air filter

Blocks on the air filter will obstruct air circulation. This may lead to lower airflow, frost on the evaporator, and lower cooling ability.

If the air filter has not been cleaned for a long time, the cooling efficiency of the air conditioner will decrease about 10% and more. Regular maintenance will help to keep the air conditioner at the best performance.

 

10. Stability of power supply

Abnormal voltage will directly influence the operation of the compressor and fan motor. When the voltage is low, the power output of the motor will decrease, and the compressing efficiency will decrease as well. In the areas where the power supply is unstable, it is recommended to equip with a voltage regulator or choose the air conditioners that are available with wide voltage (180V-230V).

 

The actual cooling capacity of the air conditioner is not fixed, but it is affected by multiple factors simultaneously. When choosing air conditioners, it is not enough to only be concerned with the number (BTU). Taking the working environment and actual cooling burden into consideration comprehensively, we will gain the best experience in comfort, energy efficiency, and cost advantage on long-term operation. We are a professional air conditioner manufacturer in Guangzhou, China. If you have any questions related to your room cooling solutions, please don't hesitate to contact us.