Final answer:
The statement is false. An automatic expansion valve does not use a thermal bulb but instead relies on refrigerant superheat. A thermostatic expansion valve uses a thermal bulb to control refrigerant flow.
Step-by-step explanation:
The statement that an automatic expansion valve uses a thermal bulb to help control the amount of refrigerant being fed into the evaporator is false. An automatic expansion valve, also known as an AEV, regulates the flow of refrigerant into the evaporator based on the refrigerant's superheat. The AEV adjusts the flow to ensure that all liquid refrigerant has evaporated before it leaves the evaporator, preventing liquid refrigerant from returning to the compressor, which can cause damage.
Alternatively, a thermostatic expansion valve, or TXV, uses a thermal bulb to sense the temperature of the refrigerant leaving the evaporator. The temperature information is used to adjust the refrigerant flow to maintain a set level of superheat at the outlet of the evaporator, ensuring effective cooling and protection for the compressor.
The description provided outlines the basics of a heat pump system or refrigeration cycle, where an electrically driven compressor increases the gas pressure and sends it to a condenser coil, where heat is transferred to the surroundings as the gas condenses. The liquid then goes through an expansion valve, which in turn cools it down and sends it back to the evaporator coils.