What type of valve is best used when compressors are controlled by a thermostat?

When compressors are controlled by a thermostat, the best type of valve to use is the automatic expansion valve. This type of valve is designed to control the flow of refrigerant into the evaporator, based on the pressure and temperature conditions within the system.

The automatic expansion valve is particularly suitable because it automatically adjusts the refrigerant flow according to the demand of the cooling system as sensed by the thermostat. When the temperature rises beyond a set point, the thermostat signals the compressor to engage, and the automatic expansion valve opens to allow more refrigerant into the evaporator, effectively maintaining the desired temperature.

Using other types of valves, such as a high-pressure float valve or a pressure relief valve, may not provide the precise control needed for efficient compressor operation. A manual valve demands manual intervention, which is not practical or efficient in an automated system like one controlled by a thermostat. In contrast, the automatic expansion valve ensures that the system responds dynamically to temperature changes, making it the most effective choice for this application.