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Evaporator Coil - Copper vs Aluminum

Copper has always played an important role in the air-conditioning industry. The two main components of an air conditioner, the condenser and the evaporator coil, are usually made up of copper. In fact, the efficiency of an air conditioning system is highly dependent on both the coils, as these components are the heat transfer devices that make heat removal possible. Of course, some manufacturers use aluminum coils in their air conditioners instead of copper. Actually, the debate over whether a copper or an aluminum coil is better for an air conditioning system has been discussed for several years. Aluminum does have some impressive properties like high thermal & electrical conductivity, greater malleability, low cost, etc. But still there are several reasons that make copper a better choice than aluminum for coils in AC systems. A few such reasons are mentioned below.

1. Thermal conductivity, the ability of a material to conduct heat, is much higher in copper than in aluminum. Copper has around 60 percent better thermal conductivity than aluminum. This means copper enables the heat to pass through it rapidly, which is very important for the efficient operation of an air conditioning system.

2. The specific heat of copper is much lower than aluminum. Having low specific heat means it’s very easy to heat up or cool down the material whenever the system is switched ON and OFF. This makes copper coils more feasible than the aluminum coils in air-conditioning applications.

3. Along with high thermal conductivity, copper also has impressively high electrical conductivity. This in turn helps to enhance the electrical energy efficiency of electric appliances. On the other hand, aluminum has just 61% of the conductivity of copper, which can lead to high energy losses.

4. Copper has a very low coefficient of thermal expansion, which means it changes very little when the temperature rises or falls. On the other hand, aluminum expands nearly 1/3 more than copper under rising temperatures. Such a high degree of expansion results in severe electrical problems when bolted connections are incorrectly installed.

5. Copper coils are usually hard to damage and very easy to repair, whereas aluminum coils are easy to damage and it needs a heavy duty coil cabinet for protection.

Conclusion:

Some feel a copper coil is better than an aluminum coil for air conditioners. However, it is also a fact that these days aluminum coils are widely used in some air conditioning systems. The arguments in this matter fall on both sides of the street. Some of the reasoning can be demonstrated scientifically. Some of the reasoning is merely personal dealer favoritism. From a scientific viewpoint, the following statements are true – providing that all tubing measurements are identical between the components:

   Copper is superior in strength to aluminum

   Copper is more reliable than aluminum

   Copper is more durable than aluminum

   Copper is easier to maintain than aluminum

   Copper provides better heat transfer characteristics than aluminum

   Aluminum coils damage easier than copper coils

   Aluminum coils are more difficult to clean than copper coils.

However, due to the expense of manufacture and an effort to keep up with the reduced unit pricing associated with units that use aluminum tube coils, the manufacturers of copper-based coil systems have resorted to downsizing the thickness of the copper tubing wall. Thus strength, reliability and durability are relative to the actual components used during the air conditioning construction stage.

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