All air conditioning sytems have one of two types of devices to regulate the liquid refrigerant as it passes into a gas: an orifice (also called piston or flowrater) or a more advanced device, a thermostat expansion valve (TXV).
An orifice (also referred to as a piston or flowrater) is installed in an evaporator coil when the coil is a different tonnage rating than the condenser or heat pump tonnage rating. Installation takes about 5 minutes, and consists of replacing orifice already inside coil. We have an online picture step-by-step guide which shows how to do this.
Thermostatic Expansion Valves (TXVs) are a requirement for some higher efficiency split system heat pumps, and an optional upgrade for other air conditioning systems. However, they are not needed with an Alpine brand system if you purchase a new indoor evaporator coil or air handler, since the TXV is already built into the coil system. Your system will operate more precisely and with greater efficiency with a TXV. These valves offer more control over how much liquid refrigerant enters the evaporator coil. The valves only allow a precise amount of liquid into the evaporator coil to ensure that all liquid that enters fully evaporates. This prevents too little liquid from entering the evaporator making the system run less efficiently. It also prevents too much liquid from entering the evaporator which can cause excess liquid in the suction line.