Why copper and aluminum are used in HVAC coils

HVAC coils are often made with copper and aluminum, two metals that efficiently transfer heat. That’s because cost and effective heat transfer are often the key deciding factors in choosing materials for HVAC coils. There are pros and cons to both copper and aluminum, which I describe below.

Let’s start with some basics about where the heat transfer takes place in coils. In most HVAC coils, tubes are responsible for 30% of the heat transfer and fins are responsible for the other 70%. That’s because the surface of the fins is larger than the surface of the tubes.
Pros: Copper coils are stronger, easier to maintain, and more reliable than aluminum coils. Copper has a better heat transfer rate and is easier to repair in the field if the coil is damaged.
Cons: The cost of copper continues to rise, and copper coils require more material than aluminum coils.
Pros: Aluminum offers effective heat transfer at a lower cost than copper. Aluminum is more pliable than copper, so less aluminum is required.
Cons: Aluminum coils are difficult to repair and usually need to be replaced. Aluminum coils are also more difficult to clean and maintain. Aluminum fins can corrode, although this can be prevented with the application of a coating.

Given the pros and cons of copper and aluminum, we often sell HVAC coils that combine copper tubes with aluminum fins. Copper tubes offer the best heat transfer and aluminum fins offer good value. Chilled water coils, hot water coils, condenser coils and evaporator coils typically use copper tubes and aluminum fins. However steam coils and steam distribution coils often run at a higher PSI so we recommend stainless steel tubing depending on the pressure and application.

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