While you are standing in the appliance store, bombarded by gaudy stickers and energy star ratings, it is easy to overlook the behind the outdoor unit condenser has-- the coil. Meanwhile sales salespeople are talking to you about Wi-Fi control and voice commands, the material of this coil—copper or aluminium —determines how well your machine feels, how long it lasts, and how much it costs to fix when things go wrong.
If you are having difficulty choosing between these two metals, don't worry-- you're not alone. The "Copper vs. Aluminum" debate is one of the oldest in the HVAC industry. Here's a detailed look at which material is superior or not, especially in connection with modern inverter technology.
The Science of Heat Transfer
To understand why the metal matters, let's first understand what a condenser does. It’s one job in life is to take away the heat absorbed from your room and toss it outside. The faster it tosses this unpleasantness away, the better your AC will work.
Copper, as all scientists know, has a far higher heat conductivity than aluminum. It has a higher heat transfer coefficient–which means that it allows heat to escape much faster. This is essential for inverter AC. How does inverter technology work? It uses variable compressor speeds to maintain constant temperature. A copper coil makes this possible by rapidly cooling the refrigerant, allowing the compressor to run at lower, energy-saving speeds most of the time. For example, if you have a heavy-duty machine such as a 1.5 ton inverter AC, this efficiency stops the machine from having to work overtime on hot summer afternoons.
Durability and Corrosion Resistance
Aluminum is significantly cheaper than copper, but it's softer too--that can't be so great for running into hard times. This is why so many budget-friendly brands have switched over to aluminum condensers. However, being more vulnerable to physical damage is a drawback. Live in a hailstorm area? Outdoor units hit with debris; the aluminium fins won't withstand bending and thus obstruct air flow with impunity.
Copper is structurally stronger and of a harder nature. It can also withstand higher pressure and easier to wash with a pressure machine without bending the fins.
However, copper does have an enemy that is a twofold curse: corrosion. Salty air in coastal regions can give copper the blues by instinct. To counter this intention, widely used techniques include applying special anti-corrosive coatings over (often blue or gold) to prolong the service life. Brands like Daikin India have founded themselves upon high-quality copper condensers to let the life be long even in bad weather.
The Repair vs. Replace Dilemma
This is the point where different ways to deal with an on-again-off-again decision start eat into your hard-earned money. Condenser coils are under very high pressure. If a leak develops, whether because of moving parts on the condensing section or elsewhere within the sealed system is determined by such an unpredictable factor: the repair methods for these two different metals.
Copper is easy for a technician to fix in the field. Supposing that a copper coil develops the gas leak, the technician just must braze the spot, refill with gas and the unit is back up and running. This is a permanent repair, and costs a fraction of the materials for a new coil. So it's financially lucrative.
Aluminum coils are difficult if not impossible to mend. They require a special welding that typically cannot be done by most local technicians. Furthermore, in the process of welding-heat hell put out surrounding aluminum is often damaged. Consequently, if an aluminum condenser leaks the standard solution is to replace the whole coil--a very expensive operation and indeed in some cases costs nearly as much as the air-conditioner when new.
Comparison Table: So, Which Do You Select?
If you want safety and durability above anything else, pick copper. It does require a small initial capital outlay, but lower energy bills and being easy to fix mean that its total cost of ownership is lower over the machine's life cycle -- especially when you're getting a high-capacity cabinet air conditioner for a large master bedroom or living room set.
The aluminum is Not Completely passed
There are some cases where an aluminum unit for a temporary place (such as the bedroom of a permanent residence -- or a friend's basement) at less initial cost may be just the answer. For example, a 12000 BTU Non-inverter Split AC with an aluminum coil may still be a highly economical choice as the only air conditioning unit in a spare bedroom used intermittently.
Ultimately, Copper is The Best Choice
As the key technology for cooling. Copper is good at heat transfer. It ensures that your inverter technology really saves power--so you'll have windows-sized electricity bills and forever cool.
