EVI stands for Enhanced Vapor Injection and is a technology used on our cold climate heat pumps to achieve higher performance at lower temperatures. An EVI heat pump uses a 3rd smaller internal plate heat exchanger called an Economizer within the refrigeration cycle. By utilizing a bypass valve some of the hot refrigerant vapor on the condenser is bypassed to an HX which combines with the colder gas on the Evaporator expansion side. The heat energy is transferred, raising the gas temperature further, which is then injected at mid-range pressure into the head of the scroll compressor through a separate vapor injection port. Using EVI heat pump technology, we can overcome the limitation of maximum flow temperature that other cold climate heat exchangers encounter. EVI Heat Pump technology allows more heat to be delivered resulting in a better COP at much lower temperatures. The EVI technology increases performance efficiency by 27-30%.