Copper tubes are essential to the overall function of heating, ventilation, and air conditioning systems (HVAC). They’re necessary for moving refrigerant through the system, and without them, our air conditioners simply wouldn’t function. Here’s a rundown of everything you need to know about copper tubes, why copper is used over other materials, and the types of tubes you can find in your AC unit.
What is a Copper Tube in HVAC Units?
Copper tubes are used in HVAC systems to move refrigerant, such as Freon. They can be found throughout the system, including in the compressor, condenser, expansion valve, and evaporator.
For example, in the evaporator coils, copper tubing moves the refrigerant so the chemical can absorb heat from the indoor air, evaporate, and cool the environment. In condenser coils, copper tubes release the absorbed heat to the outdoor air. This causes the refrigerant to condense back into a liquid.
Copper tubes have other applications within the home, and are often seen in the plumbing industry. For example, they’re a common option for water supply lines and water systems.
Benefits of Using Copper in HVAC Units
Some homeowners may be wondering: “But why copper?” There are other types of tubes available, so why is copper the go-to in AC units? Well, copper brings plenty of benefits, such as:
It Conducts Heat Well
Copper is one of the best options for heat conduction, which makes it an excellent option for HVAC units. The copper tubes can transfer heat faster compared to other metals, which improves the overall efficiency and performance of the machine.
It’s Durable
Copper can withstand the elements, and as a non-reactive material, it doesn’t easily fall victim to rust, corrosion, or erosion. It’s also capable of withstanding temperature changes. Since HVAC systems are regularly dealing with heated and cooled chemicals, it’s necessary to use a metal that can stand up to the pressure and temperature changes.
It’s Resistant Against Mold, Mildew, and Bacteria
Thanks to copper’s low reactivity, it’s also a fantastic metal for keeping mold, mildew, and bacteria at bay. HVAC units are often found in tight spaces and use water, which can promote the growth of mold, mildew, and bacteria. Combined with the low reactivity, copper has antimicrobial properties that can keep them away.
It’s Energy Efficient and Cost-Effective
Thanks to their higher thermal conductivity, copper tubes are energy-efficient. They require less energy to transfer heat, use less energy overall, and require less maintenance compared to alternatives, making them more cost effective, too.
In addition, copper pipes can be smaller compared to other types of tubing. This results in less material being used with increased efficiency, which cuts the cost. Smaller copper pipes also mean that less refrigerant is needed.
Types of Copper Piping Used in Air Conditioners
Copper pipes for air conditioning and refrigeration are usually called ACR copper tubing, though they can vary in wall thickness, including outside diameters and inside diameters. The typical sizes for copper tubing in HVAC units are 3/8″, 1/2″, 5/8″, 3/4″, 7/8″ and 1 1/8″. Although there are several different types of copper pipes, only three tend to be used in air conditioners:
Type K Copper Pipe
Type K copper pipes have thicker walls compared to other common types of copper tubing. They’re commonly found in HVAC units, but can also be used for water distribution, oil, and more. Type K can be rigid or flexible, and is great for high-pressure applications.
Type L Copper Pipe
Type L copper pipes are the most commonly used. Like Type K, Type L can also be rigid or flexible depending on the application. It’s not as thick walled as Type K, however, and is instead classified as “medium-walled.” It’s found in HVACs, but can also be used for interior plumbing systems, fire protection, and more.
Type M Copper Pipe
Type M can be found in air conditioners and HVAC units, but it isn’t as common as Type L or Type K. Instead, it’s more commonly used for residential water supply pipes. Type M is only available as rigid piping.
What are the Signs of Problems With Your Copper Tubing?
While copper tubing is reliable and durable, it can have problems over time. Hissing, bubbling sounds, and reduced HVAC efficiency could point to leaks or problems with your copper tubing. Proper maintenance can help keep your unit in excellent condition.
One common cause of leaks in copper pipes is corrosion, even though copper has high corrosion resistance. If you notice refrigerant residue around the joints or connections, there’s likely a leak.
In addition, low refrigerant, refrigerant leaks, or poor airflow can cause copper pipes to freeze. As the refrigerant gets low, the pressure in the copper tubing drops. This can cause liquid refrigerant to get into the tubing and freeze. Topping up the refrigerant can fix the issue, but the lines may need to be replaced to prevent it from happening again. If you notice your HVAC’s copper pipes have frozen over, you should turn off your unit right away to give it a chance to unfreeze, check for leaks, and check the refrigerant levels.
Final Thoughts
Copper tubes are essential to the day-to-day function of HVAC units. While there are alternatives, such as aluminum, copper tends to remain a popular choice thanks to its numerous application benefits. In some cases, homeowners may be able to extend the lifetime of their HVAC unit by replacing the copper tubing. If you’re not sure how to tackle this job, however, it’s best left to the professionals.
Frequently Asked Questions About Copper Tubes in Air Conditioners
What is the difference between hard and soft copper pipes in HVAC applications?
“Temper” is used to describe the strength and hardness of a copper pipe. A hard pipe is known as a “drawn temper” tube and it’s rigid. A soft tube is an “annealed” temper tube, and it is more flexible. Drawn temper tubes can be used where rigid copper pipes are needed, and annealed temper tubes are easier to manipulate into the space. Soft copper is the most commonly used type in HVAC units as it’s easier to install and can fit into tight spaces.
Are there alternatives to copper pipes in HVAC systems?
Yes, there are alternatives available for HVAC tubing. Aluminum is a common alternative to copper pipes. Compared to copper, aluminum tends to be less expensive and lighter. It’s also recyclable.
When should you replace copper tubing in HVAC units?
Copper tubing should be replaced if the pipe has been damaged or corroded. It will also likely have to be replaced if you are installing a new HVAC unit, especially if the copper tube size doesn’t meet the recommendations of the new unit’s manufacturer.
When replacing copper tubing in HVAC systems, brazing is necessary. Solder joints won’t hold up to the temperatures and pressure in an HVAC unit. It’s also important to select the tubing with the right pressure rating and wall diameters to fit your air conditioner.
