Copper vs Alloy (Aluminum based) Coils
Copper has a higher thermal conductivity than aluminum alloy, meaning it can transfer heat more efficiently due to its greater ability to conduct heat. This translates to a faster cooling rate and improved energy efficiency. Additionally, copper is more resistant to corrosion and has a longer lifespan, which reduces maintenance requirements and increases the reliability of the coil.
Aluminum alloy, on the other hand, has a lower thermal conductivity than copper but is lighter in weight and less expensive to produce. It is also more flexible than copper, allowing for easier shaping into the required form for the coil.
In terms of energy efficiency, copper coils have a higher heat transfer coefficient and a higher overall heat transfer rate than aluminum alloy coils. This means that a copper coil can transfer heat more efficiently than an aluminum alloy coil, resulting in improved cooling performance and energy efficiency.

However, the difference in energy efficiency between copper and aluminum alloy coils is relatively small and may not have a significant impact on the overall energy consumption of the air conditioning system. The choice between the two materials ultimately depends on the specific requirements of the air conditioning system, the cost considerations, and the desired trade-offs between performance, durability, and cost.
For most of home uses the cost difference would be negligible and higher durability is needed. Therefore it is recommended to buy an air conditioner with Copper coils.
Outdoor Unit Case
In an air conditioning system, the outdoor unit contains the compressor, condenser, and fan and a PCB which work together to remove heat from the indoor air and dissipate it outside. The materials used for the outdoor unit can have a significant impact on its durability, performance, and maintenance requirements of a air conditioner.
Here’s a comparison between plastic encased and metal outdoor units:
Metal outdoor units are typically constructed using galvanized steel or aluminum, which provide greater strength and durability compared to plastic. These materials also offer better resistance to damage from external factors such as weather, debris, and physical impact, leading to a longer lifespan and reduced maintenance requirements. Additionally, metal units have better heat dissipation properties, which help to improve the efficiency and overall performance of the air conditioning system.
Plastic outdoor units are usually constructed using high-density polyethylene (HDPE) or other thermoplastic materials. Plastic units are typically lighter in weight and less expensive than metal units. They also offer better resistance to corrosion, reducing the need for maintenance and increasing the lifespan of the unit. However, plastic units are more susceptible to damage from UV exposure, extreme temperatures, and physical impact, which may result in decreased durability and performance over time. Furthermore, the heat dissipation properties of plastic are typically lower than that of metal, which may negatively impact the overall efficiency and performance of the air conditioning system.
The choice between metal and plastic outdoor units ultimately depends on the specific requirements of the air conditioning system, including factors such as the expected lifespan of the unit, environmental conditions, and the desired balance between cost, durability, and performance.
It has been observed that most 1.5 Ton and higher capacity air conditioners have Metal encased ODU while some brands use plastic encased ODU for 1 Ton and smaller units. Metal is the preferred choice and should be sought after for reasons given above.