Many people may ask a question that seems simple: Why can the air conditioner cool once it connects to the power supply? And what happened inside of the copper pipe?

The answer is the refrigerant circulation. The key point of cooling is not the cold air itself, but the continuous flow, phase transition, and energy transportation process of the refrigerant inside the copper pipes.

 

I. An air conditioner is not to "create cold" but to "transfer heat."

 

Here is a common misconception to clarify: the basis of the air conditioner is not to produce cooling but to remove heat from interior to exterior. While the "deliveryman" is the refrigerant that flows inside the copper pipe. The tube is just the vessel; what actually contributes to the cooling process is the absorption and releasing of the energy at the different states of the refrigerant.

 

II. Why is "copper" pipe necessarily needed?

 

Being selected as the piping material of the cooling system benefits from its three advantages:

 

Good thermal conductivity: it conduces to the heat exchange of refrigerant and air.

High-temperature and corrosion resistance: it adapts to the frequent exchange of the refrigerant in high- and low-pressure conditions.

High reprocessability with reliable hermeticity: it is easy to weld and bend, reducing the risk of leakage.

 

III. 4-steps circulation of the refrigerant in copper pipe

 

1. Compressing: convert low-pressure gas into high-pressure, high-temperature gas

 

At a state of low pressure and low temperature, the refrigerant is sucked in by the compressor; after being compressed, it becomes high pressure and high temperature. At this time, the temperature of the refrigerant is much hotter than outside of the room.

 

2. Condensing: release heat outside, convert refrigerant from gas to liquid

 

The high-pressure, high-temperature refrigerant (gas state) goes into the condenser (copper pipe + fins), changing from a gas state into a liquid state and releasing heat to the air outside through copper pipes.

The key point here is the process from gas to liquid will release much heat.

 

3. Throttling: sudden decrease of pressure, preparing for the heat absorption

 

Being condensed, the refrigerant becomes high pressure with a medium temperature but in a liquid state.

After passing through a small part (capillary or electronic expansion valve), the refrigerant pressure decreases suddenly, and together with the temperature, it becomes a low-temperature, low-pressure state mixed with gas and liquid.

 

4. Evaporating: absorb heat inside, create "cooling"

 

The low-pressure, low-temperature refrigerant (gas state) goes into the evaporator (copper pipe + fins). At this time the indoor temperature is higher than the refrigerant, which absorbs heat from the refrigerant through copper pipes and changes from a liquid state into a gaseous state.

Evaporating is the process of absorbing heat, so that's why the indoor air has been cooled.

 

 

IV. Why is the phase transition so important to the refrigerant?

 

If the refrigerant uses normal liquid or gas, then the cooling efficiency will be very low.

Absorbing or releasing a large amount of potential heat during the phase transition is the biggest value for the refrigerant. With the same temperature difference, it will transfer more heat than normal substances.

That's why, by flowing backwards and forwards in the copper pipe, a little refrigerant could cool and heat the whole room.

 

V. Heat exchange efficiency depends on the design of copper deeply

 

Whether the refrigerant could work efficiently, it not only depends on itself but also on if:

 

The copper pipe size is reasonable;

The piping length is suitable;

The fins structure and the distance between pipes;

The inside surface of the copper pipe is clean and oil-free;

Those details will directly affect the cooling speed, COP/EER, systematic stability, and lifespan.

 

In every winter, many users will face a phenomenon that when the air conditioner operates in heating mode, the outdoor unit will blow a batch of smoke, and sometimes there are sounds of water flow and shutdown of the motor. It seems the machine has malfunctions.

Actually, most of the time this is not a failure but the operation of the auto defrost mode of the air conditioner. Here we will explain why it smokes in winter, how the defrost mode operates, and if it is harmful to the equipment.

 

I. How does the air conditioner heat in winter?

 

Under heating mode, the room air conditioner indoor unit performs as a condenser to release heat, while the outdoor unit acts as an evaporator to absorb heat. It brings energy from exterior to interior. Though the exterior temperature is 0℃, the air still contains energy, and the compressor could extract this part of the heat through refrigerant circulation.

 

II. Why does frost form on outdoor surfaces?

 

When the temperature is low and the humidity is heavy outdoors, the surface temperature of the outdoor unit heating exchanger will be lower than 0°C. The steam in the air will condense under lower temperatures and form frost on the exchanger surface gradually.

Particularly during 0℃ to 8℃ rainy days in high-humidity areas, it is easier to frost.

The frost covering on the heat exchanger fins will lead to lower heat-exchange efficiency and weaker heating ability as a result of high energy consumption. If it remains without action, the heating performance will be worse and worse.

 

 

III. What's the Defrosting Mode?

 

When the detected frost reaches a level, the air conditioner will start the defrost process automatically.

This function is easy; the air conditioner compressor will temporarily convert the rotating direction and the cooling cycle.

This means the normal heating mode in the room will convert to heat the outdoor unit, melting the frost by using the high-temperature refrigerant in the copper pipe.

This procedure will last 3-10 minutes, which is a common protection mechanism for air conditioners.

 

IV. Why can we see white smoke?

 

When the frost is melted by hot refrigerant quickly, it becomes water; some water is heated to evaporate, becoming steam; hot steam and cold air condensate and form plenty of small and slim water fogs, which look like smoke.

 

In the meantime, you will see the outdoor fan stop working, the indoor unit stop supplying air, and hear sounds of water flow, which are all common phenomena.

 

 

V. Why does the indoor unit not heat during the defrost procedure?

 

When defrosting, the system is heating for the outdoor unit, and the indoor unit stops supplying air. This is to avoid blowing cold air indoors in winter and improve defrosting efficiency. Some air conditioners will show "DF" or "H1" or a defrosting symbol. After defrosting is finished, the air conditioner will resume heating automatically.

 

VI. Is frequent defrosting normal？

 

Based on the environmental conditions, in extremely cold and high-humidity weather, it defrosts once every 40-90 minutes normally.

If defrosting occurs every 10 minutes, or the heating is obviously insufficient, or the outdoor unit freezes heavily, it would be a lack of refrigerant, sensor failure, or the blockage of the drainage pipe. At this time, it is suggested to arrange professional examination and maintenance.

 

VII. How to reduce frequent defrosting?

 

1. Ensure good ventilation for the outdoor unit;

2. Ensure drainage unobstructed;

3. Avoid frequent start-ups;

4. Set a reasonable temperature. (22-24℃).

 

We are a professional air conditioner manufacturer in China. Should you have any other questions in the industry, please don't hesitate to reach us!

 

Many people have the experience when using the air conditioner that we set a temperature at 26℃, but the room temperature is still not comfortable. Is that the error of the sensor or the air conditioner itself?

The answer is that when the air conditioner is set to a temperature, it does not mean the temperature at every corner of the room. We are going to explain it clearly based on its mechanism.

 

I. What exactly does the "set temperature" of an air conditioner measure?

 

The air conditioner does not measure the whole room temperature, but it determines whether it needs continuous cool or heat by the sensor.

In most of the wall mounted air conditioners or floor standing air conditioners, the temperature sensor is normally located near the air inlet of the indoor unit or inside the air inlet zone, which measures the air temperature near the air conditioner. This means that whether the air is conditioned to 26℃ or not depends not on the position where you are but on the area around the air conditioner.

 

 

II. Why are there different temperatures in the same room at the same time?

 

The temperature is not completely uniform even in the same room. There are factors that influence it: 

 

1. Air stratification

 

The cold air has high density, which tends to sink, while the hot air has a low density and tends to rise. As a result, the space that is close to the ground is colder, and the space that is close to the ceiling is hotter. That's why some feel cold on the feet and hot on the head and feel uncomfortable. With an air conditioner operating, people still feel uncomfortable.

 

2. Building structure and insulation conditions

 

West-facing walls, glass windows → continuous heat taken in

Wide room space, high floor height → stronger thermal inertia

Leakage in door gaps and window gaps → Continuous coolness loss

All these will mislead the air conditioner to regard the cooling procedure as having reached the setting temperature, but the whole room is not truly stable.

 

3. The relation between airflow and the human body position

 

Direct air blow → More cooling;

Back-wind zone or corners → Higher temperature;

At the same 26℃, people sitting beneath the air outlet will feel cold, while those sitting at the corner will feel hot.

 

III. Why is 26°C sometimes still cold?

 

This is a common misconception among many people. Actually, the air conditioner is working between a temperature range instead of pursuing 26℃.

For example, the setting temperature is 26℃, but the actual control range is 25℃ to 27℃. When the sensor detects the temperature lower than the limit (here 25℃), the compressor will slow its speed or stop working; when higher than the limit (here 27℃), the compressor will start to work again.

If at this time, you sit near the direct air blow area or around the sensor, you will feel colder but with a not-so-low temperature setting.

 

IV. Why do the inverter air conditioners seem more stable?

 

Compared with normal non-inverter air conditioners, the advantages of the inverter air conditioners lie in the following facts:

 

· The compressor speed is continuously adjustable;

· The temperature fluctuation is lower;

· The indoor airflow is more smooth and comfortable;

 

This doesn't mean the inverter air conditioners measure the temperature more precisely, but when the air reaches the setting temperature, it works at a low power continuously instead of stopping working. Finally the indoor temperature becomes more uniform, and the experience of the human body is more comfortable.

 

V. How to adjust the room temperature more reasonably?

 

Instead of struggling over whether the temperature is precisely measured or not, we'd better focus on the comfort and the power consumption.

 

Common advice:

· Summer cooling temperature: 26-28℃;

· Adopt with wind speed adjustment instead of lowering the temperature blindly;

· Avoid long-time direct air blow;

· Slightly close the window, curtains, and doors when there is poor tightness in the room;

 

Noted: The air conditioner is to remove excessive heat, not to "create low temperature".

Most of us have the experience that a small room could be cooled down in several minutes, but for a larger space, the temperature decreases slowly even though the air conditioner has been operating for a long time. It doesn't mean the air conditioner has not enough cooling ability; instead, a most important physical concept contributed to the situation—thermal inertia, which is often being omitted.

 

I. What's thermal inertia?

 

Thermal inertia is the insensitivity level of an object or space to the temperature exchanges. Simply, it means the higher the thermal inertia, the slower the temperature exchanges; and the lower the thermal inertia, the faster the temperature exchanges.

 

It is not simple data, which is determined by three factors: mass, specific heat capacity, and the heat exchange conditions.

Inside the buildings and rooms, the thermal inertia performs mainly in walls, ceilings, floors, appliances, and the air itself. All those items will store heat.

 

II. Why does a larger house have a higher thermal inertia?

 

1. More items which store heat in the house

 

The larger house has wider wall areas, larger air volume, more concrete and bricks used in construction, and more space to put appliances and decorations. These are all heat storages. When the outside temperature is high, those heat storages have absorbed much heat already.

 

2. Air conditioning is to remove heat first, not to lower the temperature

 

The core task of air conditioners is not to blow cold air but to remove the heat from indoors to the outdoors steadily.

In large spaces, the air conditioner needs to remove heat from walls, floors, appliances, and the air steadily. The larger the space, the more heat needed to be removed, so it took a longer time.

 

3. The surface temperature determines the body temperature

 

Though the temperature had been cooled down, if the wall is hot, the floor is hot, and the appliance surface is hot, according to reflection heat transfer, the human body will feel its heat as well.

That's why people still don't feel cool even though the temperature already shows 24℃ in the large house. Thermal inertia makes it much slower for people to get "real coolness."

 

 

III. Why it may not necessarily solve the issue by purchasing a larger capacity cooling device?

 

Most people will choose a larger capacity air conditioner to cool a large house, such as a floor standing air conditioner or a cassette air conditioner. But the common questions are unreasonable gas-liquid distribution, cold air cannot reach the areas with heat burden, unreasonable air-return design, and long-term stays of heat in a partial area. As a result, the energy consumption rises, but the comfort has no significant improvement.

 

IV. For cooling in the large spaces, the key is to deal with the thermal inertia

 

1. Start the air conditioner in advance, rather than operating it when it's hot

2. Focus on the airflow coverage, rather than the cooling capacity

3. Zoning control, separately dealing with the thermal inertia

4. Matching the air conditioning systematically rather than focusing on the unit datas

 

In large houses, villas, and commercial spaces, VRF, ducted air conditioners, and joint-combined systems are more suitable in both comfort and energy savings.

 

In the large houses, it's not harder to blow cold air but to remove more heat, which is the thermal inertia that influences it. What determines the comfort is not only how big the air conditioner is, but also whether the whole system is recognized and allowed to operate by following the physical rules.

Nowadays, the competition in the air conditioning market is becoming more and more fierce, while large-capacity and high-energy-efficiency machines seem to be the mainstream. But in the meantime, a new trend is silently emerging-- the small-capacity machines. They do not mean to be backward to the "lower class," but instead to redefine the balance of comfort and efficiency in more niche and precise application scenarios.

 

I. New demands from spatial fragmentation

 

As the spaces diversify in both residential and commercial use, the large-scale cooling and heating situations will be replaced with fragmented spaces.

 

New types of rooms are constantly emerging, such as homestays, mobile houses, shared offices, and so on. Customers are focusing on local comfort and energy consumption control, looking for coolness where they stay rather than whole-room cooling. Light commercial buildings, particularly the small dining halls, barbershops, and other places where the energy-saving and flexible installation is the first concern.

 

II. Small capacity ≠ Low Performance

 

In the previous years, small capacity machines meant slow cooling, low energy efficiency, and a short lifespan. But now, the technology innovation is giving them a new life.

 

The popularization of inverter technology

The adoption of a low-power inverter compressor allows small models to work with low loads and at high efficiency, achieving precise temperature control and energy savings.

 

High-efficiency heat exchange design

Hydrophilic aluminum foil, internally threaded copper tubes, and other new materials are adopted, allowing its compact structure to have an excellent heat exchange performance.

 

Smart control

Wi-Fi control, remote monitoring, scheduled operation, and other intelligent operations can be achieved on small air conditioners, providing an uncompromising operating experience.

 

III. Unique Advantages of Small air conditioners

 

Low Power Input/Output

9000 BTU (1 horsepower) or less capacity will be sufficient for localized cooling needs. It is better than other large machines in energy efficiency and power consumption.

 

Flexible installation

Small body, quick installation, and without space limitations. It is suitable for any type of building.

 

Easy Maintenance, Low Cost of Use

The compact design and standardized components reduce ongoing maintenance and replacement costs, making it ideal for short-term locations such as rental properties and pop-up stores.

 

We are a professional air conditioner manufacturer; if you have any questions about our products, please feel free to contact us!