A capillary tube is the simplest type of expansion device used in small air conditioners and some budget One Zone units. It consists of a long, thin tube that creates a pressure drop in the refrigerant before it enters the Evaporator Coil. While effective, it is much less efficient than the Electronic Expansion Valves (EEV) found in our Sophia and Olivia series. Capillary tubes are not adjustable, meaning they don't perform as well in varying outdoor temperatures. We focus on providing high-efficiency Heat Pump Systems that use the latest tech for maximum savings. You can find more technical info on our refrigeration cycles in the Technical Data section. Upgrading from a basic unit to an EEV-equipped system is a smart long-term investment. It’s all about getting the most "bang for your buck" on your energy bill.