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Each year, the AHR Expo acts as a window into the future of the HVACR industry. In 2025, that window opened wide to reveal a transformation not only in technology and refrigerants, but in the very bones of the systems we rely on to keep buildings, equipment, and people comfortable and productive.
While much of the industry buzz at this year's Expo centered around new refrigerant blends, cold-climate heat pumps, and innovations in smart controls, one of the most impactful shifts was the simple design of copper tubing.
Many manufacturers are now building heat exchangers and coil systems around 5mm and 7mm copper tubes, moving away from traditional 3/8-inch and larger formats. What started as an engineering tweak has become a structural shift—one that's reshaping performance, sustainability, and product design across HVAC, refrigeration, and even data center infrastructure.
On the Show Floor: A Pattern Emerges
Held in Orlando, the 2025 AHR Expo brought together more than 50,000 attendees and nearly 1,900 exhibiting companies worldwide. There was a clear and consistent trend across the 500,000+ square feet of exhibit space: small-diameter copper tubing is a mainstream design strategy.
The message was unmistakable, from Midea's "M Thermal Arctic" ATW heat pump using 7mm copper to Daikin's commercial rooftop units incorporating 5mm coils. OEMs across the residential, commercial, and industrial sectors embrace smaller copper as a standard.
Why Small-Diameter Copper Is on the Rise
1. Efficiency Through Geometry
Smaller tubes offer a greater surface-area-to-volume ratio, which improves heat transfer. As the refrigerant flows through these narrower tubes, it maintains better contact with the tube wall, enhancing overall thermal exchange.
Residential Multi-zone system using R454B.
2. Lower Refrigerant Charge
With global regulations shifting toward low-GWP refrigerants like R32 and R454B, system designers are under pressure to reduce charge volumes. Smaller tubes mean less internal
volume, allowing OEMs to meet regulatory requirements while delivering high-performance systems. Residential Multi-zone system using R454B.
3. High Strength, Small Scale
Copper maintains excellent mechanical properties even at reduced diameters. In CO₂ systems requiring high-pressure performance, 5mm copper tubes like those in LU-VE Group's gas coolers are rated up to 130 bar, with no need for high-strength alloys.
Small Rooftop units use 7mm copper tube in condensers and 3/8 in. tube in evaporators.
Aluminum Microchannel: Challenges Remain
While aluminum microchannel coils have gained attention, particularly for their weight and cost advantages, the 2025 report clarified that challenges remain, especially for evaporator applications.
Sanhua and Climetal, two major players in aluminum coil technology, acknowledged ongoing difficulties in developing vertical fin evaporators. Despite multi-million-dollar R&D investments, their prototypes have not achieved widespread success.
Copper, by contrast, continues to deliver consistent performance, formicary corrosion resistance, and superior brazability—especially in hybrid applications like dual-fuel systems and cold-climate heat pumps.
The Data Center Boom: Another Driver of Change
Beyond traditional HVAC applications, another force is accelerating the shift toward high-performance heat exchangers with compact copper coils: the rapid rise of data centers.According to projections shared on the show floor, data center cooling will grow at a 23% compound annual growth rate (CAGR) through 2030. As computing density rises, so does the need for compact and robust thermal management solutions.
Here's where small-diameter copper makes an impact:
- Super Radiator Coils now offers 7mm coils for data center cooling applications.
- Motivair and Stulz are developing hybrid systems relying on compact coil designs for rear-door air and chip-level liquid cooling.
- Xylem is focused on water reuse and energy efficiency, and copper coils are used in adiabatic dry cooler systems that save up to 90% of water use compared to tower systems.
As sustainability mandates and urban infrastructure constraints shape the future of data centers, copper's thermal performance, material recyclability, and space efficiency will continue to make it the material of choice.
Examples from Leading Brands
- Daikin uses 5mm and 7mm coils in VRF and rooftop units.
- Gree's "Ultra Heat" systems combine 7mm and 3/8" copper coils for performance down to -35°C.
- Samsung's EHS Eco series heat pumps now feature 7mm tubing across models.
- GE Appliances and Rheem incorporate 7mm and 8mm copper in new cold-climate and inverter-driven heat pumps.
- Eco2 Systems and Enertech are applying 7mm copper in high-efficiency heat pump water heaters, supporting decarbonization and electrification goals.
A Strategic Opportunity for OEMs
This trend presents a rare opportunity for manufacturers and design engineers: A way to deliver better performance and sustainability without reinventing the wheel.
Small-diameter copper tubes enable:
- More compact coil design
- Reduced refrigerant costs
- Smoother integration with next-gen refrigerants
- Compatibility with modular, scalable system architectures
Whether you're developing VRFs, residential heat pumps, or data center solutions, now is the time to evaluate your approach to heat exchangers.
Copper's Compact Future
It's often the smallest design choices that unlock the most significant results. As the HVAC and cooling industries evolve under the weight of global decarbonization, electrification, and digitalization, copper continues to rise, not just in durability or efficiency, but in elegant adaptability.
CDA is helping OEMs, engineers, and product teams navigate this shift with technical support, material expertise, and real-world data on 5mm and 7mm copper coil performance.
CDA also offers tailored support for your projects. To learn more about what it means to partner with CDA, visit https://info.copper.org/how-to-partner-with-cda.
