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New Technology

NREL Develops New Joining Technology for AC

By Mary Kate McGowan, Associate Editor, News 
From ASHRAE Journal Newsletter, June 2018

The National Renewable Energy Laboratory has been developing a new technology that initially focused on replacing less efficient window air conditioners (ACs) in residential buildings.  Since that invention, the joining and connections concept modeled in the new version of the technology has the potential for broader impact, even for commercial applications.

Two NREL senior engineers in the Building Energy Sciences research group, Chuck Booten and Jon Winkler, have been refining a joining technology to create a system that is easier and cheaper to install, called EcoSnap-AC. It can be applied to mini-split heat pumps, or other split-systems, to dramatically reduce installed costs.

“From a heat pump perspective, it’s still your standard heat pump. Where the innovation really lies is where the indoor and outdoor units are integrated with one another, and really simplifying the process to join them and make the connections,” said Winkler, Ph.D., Associate Member ASHRAE and member of the Society’s Residential Buildings Committee.

The technology’s indoor and outdoor parts snap together with a connection through a wall to provide the convenience of a room air conditioner but with higher efficiency, lower noise, improved aesthetics and fewer air leaks and water intrusion, according to NREL.

With EcoSnap-AC, there are only a few AC components that need to communicate with each other inside and outside of a building. By drilling a small hole or two, a user could install a heat pump system with a line connecting the two parts. In short, a simple snap-together system—with an indoor and outdoor part that snap together with a connection through a wall.

With regular mini-split or any heat pump system, the refrigerant, electrical, condensate and potentially mechanical connections are made between indoor and outdoor units, said Booten, Ph.D., Associate Member ASHRAE.

“This is really about how to integrate those together as seamlessly as possible to make the installation as quick as you can make it, while maintaining reliability and safety. You take the functional components, integrate them with the mechanical components….and you do that in such a way that you don’t need any tools. All you have to do is kind of snap these together, and you’re ready to go,” he said.

The innovative connection system is suitable for any application that uses standard mini-heat pump systems, said Winkler.

The system’s components and materials might have comparable costs to window units and portable units or mini-splits, but the innovative system decreases installation costs, said Booten. The system also eliminates other costs such as by reducing the refrigerant charge and eliminating dedicated electrical wiring, said Winkler.

EcoSnap can have substantial energy benefits, which primarily come from reducing infiltration, said Booten. Replacing the less efficient systems such as window units and portable units with more efficient systems, people should see energy savings, he said.

“From an energy perspective, it’s really about increasing market uptake of efficient systems and getting rid of the window air conditioners as much as possible and that includes the air infiltration and things like that,” Booten said.

The newer technology enables reduced noise levels and does not sit in the middle of rooms, like window units, he said.

For the residential market, Winkler said parts of the system can be applied to packaged terminal air conditioners, which are commonly used in motels and multifamily developments.

Although the project started with a residential focus, the team realized the joining and connections used in the EcoSnap-AC prototype have a much larger opportunity across the vapor compression industry, particularly in commercial applications that require connection and reconnection after initial installation.

The team is looking at other applications while keeping in mind the “biggest bang for the buck,” said Booten.

The U.S. Department of Energy has been identifying HVAC&R joining technologies that cover residential and commercial HVAC&R systems. The focus is on three cross-cutting topic areas:

  • Brazing and joining technologies and processes
  • Advanced component design and materials
  • Installation, operation, and maintenance.

More information on DOE’s efforts can be found here.