What Is an Expansion Valve?

While learning the anatomy of your air conditioner might not appeal to your interests, knowing the different parts of your AC and how they function can help you in the long run. Your air conditioning system is an intricate one, containing hundreds of individual parts—like an expansion valve for example. Although small in size, the expansion valve is ultimately an essential part on your AC system.

So, What Does an Expansion Valve Do?

In simple terms, the expansion valve is a component in the refrigeration process of an HVAC system. In order to warm or cool a home, AC systems generally use a liquid known as refrigerant. Refrigerant travels throughout the AC system and undergoes a series of changes along the way—mainly, transitioning from a liquid to gas.  The expansion valve works to remove pressure from the liquid refrigerant and allows it to expand. As the refrigerant expands, it changes its state and turns into a vapor thanks to the expansion valve.

Internal Vs. External

There are two types of expansion valves—internal-equalized and external-equalized. The valves both work to remove the pressure from the refrigerant so it can expand and turn into vapor, but are used within different units.

Internal Valves These are typically seen on low pressure and single circuit evaporator coils. Refrigerant enters as a high-pressure liquid and the flow of refrigerant is restricted through a small orifice. As the flow is passed through, it becomes a low-pressure liquid before turning into a vapor.

External Valves These valves are generally used on multi-circuited evaporators. These differ from internal valves as the evaporator pressure travels through the underside of the evaporator tail pipe. This works to balance the expansion and help remove the pressure.

How to Tell if the Expansion Valve is Broken

It’s possible that the expansion valve can break or be damaged, leaving you to deal with the repair. While air conditioning issues can be the result of many things, there are a few telltale signs that your expansion valve is broken. If there are mysterious noises emitting from the system, this may be a sign that valve is faulty. Ever notice that your air conditioner seems to be continuously running? This could also be a sign that your expansion valve is damaged or has stopped working.

Expansion valves are an important component of AC anatomy but are ultimately just a little piece of the puzzle. To ensure your expansion valves are working harmoniously with the rest of your air conditioning system, it’s important to have regularly scheduled maintenance checks. The experienced technicians at Engineered Air are skilled in both diagnosing and repairing whatever AC issue you may have. At Engineered Air, we want your home to be comfortable year-round! To learn more about us and what we can do for your AC, click here, or to learn more about our products click here.

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