What component is used to restrict flow from the condenser to the evaporator?

The correct answer is the capillary tube. In refrigeration systems, the capillary tube acts as a metering device to control the flow of refrigerant from the condenser to the evaporator. Its design consists of a long, narrow tube that creates a pressure drop, which regulates the refrigerant's flow rate based on the cooling requirements of the system. This restriction allows the refrigerant to expand and cool as it moves into the evaporator, where it absorbs heat.

The capillary tube functions on the principle of fluid dynamics and is particularly useful in systems with low refrigerant charge or simpler setups, such as in small refrigeration units and household appliances. It competently manages the refrigerant's flow without the need for moving parts, which enhances reliability and reduces maintenance.

Other components mentioned in the choices serve different purposes. For example, the expansion valve also regulates flow but operates differently, responding directly to changes in system pressure and temperature. The float valve is used in liquid storage applications or water level control and does not directly manage refrigerant flow between a condenser and evaporator. The pressure switch monitors system pressure and can control different components but is not designed to restrict flow. Each of these components serves a distinct role in the refrigeration cycle.