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2 Key Advantages of Electronic Expansion Valves

An Airconditioner
An air conditioner achieves its cooling power by reducing the pressure of the refrigerant as it flows into the evaporator coil. The component responsible for this pressure reduction is the throttling device. A throttling device lowers pressure by limiting the amount of refrigerant that can pass into the evaporator coil.

Most home air conditioners contain a type of throttling device known as a thermal expansion valve, or TXV for short. Yet many homeowners have recently switched over to a type of throttling device known as an electronic expansion valve, or EEV. If you would like to learn more about what makes EEVs so effective, keep reading. This article outlines two key advantages of EEVs.

1. Better Superheat Regulation

Both TXVs and EEVs control the flow of refrigerant into the evaporator coil according to the refrigerant's superheat temperature. Superheat simply refers to the number of degrees above boiling point. To promote ideal cooling efficiency, superheat must fall within a certain range. If too low, the refrigerant risks turning back to a liquid as it flows to the compressor.

This phenomenon, known as refrigerant flooding, can cause serious damage to the compressor. Problems may also ensue if superheat temperatures grow too high. In that case, the refrigerant may lead to compressor overheating, which puts the compressor's motor at risk of burnout and other issues.

TXVs and EEVs monitor superheat using sensors located near the output end of the evaporator coil. TXVs use a type of sensor known as a sensing bulb. This bulb contains a small amount of refrigerant. As superheat increases, this refrigerant boils, flowing back to the TXV through a special tube and opening the valve.

While reliable, a TXV simply doesn't respond to changing superheats as quickly as possible. As a result, a slight delay exists between reaching the desired superheat limit and additional refrigerant flowing into the evaporator coil. Over time, this delay can drive up the operating costs of the system while also exposing it to more mechanical stress.

An EEV monitors superheat using an electronic sensor. Electrical waves relay information from this sensor instantly back to the valve. An EEV can regulate valve position within a split-second of superheat reaching the upper limit. As fresh refrigerant flows into the evaporator coil, superheat falls back within acceptable limits in the shortest possible period of time.

2. Lower Start-Up Losses

Every time the compressor turns on to initiate a new cooling cycle, another common cause of inefficiency in an air conditioner occurs. If your air conditioner has already been running, then your home's air probably only needs to be cooled down an additional degree or two every cycle.

In this case, your system doesn't need to ramp up to its maximum cooling power if all it needs to do is maintain a constant temperature. TXVs, unfortunately, can't distinguish between different types of cooling demands. A TXV either opens all the way or remains shut all the way.

This leads to wasted energy during start-ups, since the compressor will have to refresh a larger volume of refrigerant. Excessive refrigerant flow to the evaporator coil may also lead to flooding. Thermostatic expansion valves may lead to start-up energy increases as great as 23 percent.

An electronic expansion valve, on the other hand, promotes better efficiency at start-up. An EEV can regulate the amount of refrigerant flowing through it at any given time with the help of a special step motor, which opens and closes the valve incrementally. As a result, start-up losses generally never exceed more than 8 percent.

For more information about whether an electronic expansion valve would make a good choice for your home's air conditioning system, contact the cooling experts at Powers Heating & Cooling.