Why Copper Pipes Are Used in Air Conditioning?


copper tubes

Copper pipes are widely used in air conditioning. I wonder why copper are preferred over other materials , so I did some research.

Copper pipes are widely used in air conditioning because:

  1. Copper is an excellent thermal conductor
  2. Copper pipes are strong and easy to solder
  3. Copper is more economical than other metals with similar properties
  4. Copper is very good at resisting corrosion

Copper is expensive and many people are trying to look for a less expensive material as an alternative to copper pipe. Understanding the advantages of copper over other materials will give us a good sense of why copper is more preferred despite the higher costs.

Advantages of Copper in Air Conditioning

Copper pipes are used in air conditioning to transfer the refrigerant gas between the indoor unit and outdoor unit of the air conditioner. Copper pipes also can be found in the heat exchanger inside an air conditioner. Pipes are pipes, why copper?

1. Copper is an excellent thermal conductor

An air conditioner requires high-efficiency heat transfer in order to be energy-efficient and reduce power consumption Thus, the finned tube heat exchanger in an air conditioner must be high thermal conductivity materials.

finned tube heat exchanger
Finned Tube Heat Exchanger

The finned tube heat exchanger consists of copper tubes and aluminum fins. Copper tubes carry the cold refrigerant and the aluminum fins increase the air contact surface to help transfer the energy faster.

Copper and aluminum are used in many types of heat exchangers such as computer heat sinks, car radiators, and air conditioners where high efficient heat transfer is required.

But, copper is better than aluminum when it comes to thermal conductivity. Here are a list of top 5 thermally conductive materials:

MaterialThermal Conductivity
(W/m.K)
1. Diamond2000
2. Silver429
3. Copper398
4. Gold315
5. Aluminum Nitride310

From the above table, copper is the third-highest thermal conductor. Notice that copper is sandwiched between diamond, silver, and gold which are way more expensive materials.

Considering the significant difference in material cost, copper is the best choice to use as the thermal conductor in air conditioning.

2. Copper pipes are strong and easy to solder

The installation of an air conditioner often requires sharp bending of pipes. Fragile materials simply can’t withstand the kind of bending that is needed for air conditioner installation and the risk of pipe cracks is high.

Copper is not brittle and it is able to be deformed without losing its toughness. Thus, copper pipes are suitable to be used for both the refrigerant pipes and the heat exchangers in the air conditioner.

soldering copper pipe
Soldering Copper Pipe

Besides, copper is easy to solder. During the installation of the refrigerant copper pipe, multiple soldering is required to join all the pipes together. Copper pipes also can be easily repaired by soldering the crack. This give copper a huge advantage over aluminum because it is almost impossible for average people to solder aluminum because it requires the torch temperature to be as high as 300°C or more.

Therefore, copper fits very well in the practical installation of the air conditioner.

3. Copper is more economical than other metals with similar properties

With similar material properties and practicality of application, copper is more economical than any other materials. Although the material cost of aluminum is 4 times cheaper than copper as of writing, the installation of aluminum pipes is far more expensive and difficult.

Welding a Pipe

We already know that joining aluminum pipes by soldering is impossible, so another way is by welding. Welding aluminum is very challenging also due to its softness. Because of that, the cost of skilled labors, tools and preparation is far beyond the budget of the installation of an air conditioner.

All and all, using copper in air conditioning still make the most sense and it has been proven by history.

4. Copper is very good at resisting corrosion

Copper does not tend to react with other chemicals. This means that it is excellent at resisting corrosion.

The copper pipes inside an air conditioner are constantly in contact with air and water at different temperatures. Most untreated metals corrode very quickly in such environment. Copper pipe with its anti-corrosion properties ensures that the air conditioner will not suffer from pipe cracks, gas leakages and other reliability issues and having a longer lifespan.

Therefore, copper is preferred over other cheaper materials that are poor in resisting corrosion.

Is There Any Alternative Material to Copper?

I get it, copper pipes are expensive. So, is there any alternative material to copper? The short answer is yes, but you might want to take a second look.

Aluminum is the closest comparison to copper because of the similarity in material properties. In fact, early days, people had tried using aluminum pipes in air conditioning. However, aluminum posses a few critical flaws that are not justifiable for its lower price. Thus, people end up moving back to copper.

Another alternative material is stainless steel. Stainless steel is extremely good at resisting corrosion. But, stainless steel is way too expensive. Thus, people quickly drop the idea of substituting copper with stainless steel.

Does Copper Pipe Need to Be Insulated?

Yes, you should always insulate the refrigerant copper pipe because copper pipe is an excellent thermal conductor, if it is not insulated, energy will quickly dissipate to places where it shouldn’t be.

Without insulation, your refrigerant copper pipe will be icy cold. This mean it is losing the cold energy to the environment which it shouldn’t be, it suppose to travel to the indoor unit and provide cooling to your room.

A well-insulated refrigerant copper pipe can improve the energy-efficiency of the air conditioner and thus, reduce the power consumption of the air conditioner.

Related Questions

What type of copper is used for air conditioning? Type M and type L are the most commonly used for air conditioning. In some application, a stronger type K is required.

What copper pipe sizes are used in air conditioning? Copper pipe size of 1/4″ and 3/8″ are mostly used for split air conditioner. Larger capacity uses 1/2″ copper pipe while some commercial air conditioners require as big as 2-1/8″ and above.

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Yu Chang Zhen

Yu was working in the air conditioning industry for the past 7 years, covering from design to installation and maintenance. Yu wish to share all the things he learned with the people around the world.

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