What is an Aircon Expansion Valve and How Does it Work?

The air conditioner is a powerful machine capable of providing maximum cooling for every office and household. Since everyone swears by an air conditioner to keep them cool and comfortable all day, these units must always be kept in great condition, both internally and externally. 

The air conditioning system relies on different parts in order to continue providing families and businesses with maximum cooling and ventilation for all seasons. But in a country like Singapore, where dry weather is prevalent all year, this is especially important as most Singaporeans turn to the machine to save them from the effects of intense heat and humidity. From compressors to filters to coils, each part counts in making sure that the air conditioning unit is able to perform at the best of its capacity. However, apart from these essential aircon parts, few are familiar with the function — and in most cases, the existence — of the aircon expansion valve.

As one of the most important and crucial parts in an air conditioner, expansion valves are devices used to control the refrigerant flow in a refrigeration system.  In this article, we will discuss in detail the functions of an expansion valve, its different types, and how they all function to make the AC unit work.

How Does An Aircon Expansion Valve Work?

To better understand how an aircon expansion valve works, you must first have the basic understanding of the direct relationship between temperature and pressure. When the refrigerant pressure increases, the temperature also rises. This results in the molecules of both elements packed more tightly together. The increase in both elements is what happens once the refrigerant makes its way through the compressor.

The relationship between pressure and temperature also works in the opposite direction. By a reduction in the pressure of the refrigerant, one can also cool the refrigerant off effectively. In simpler terms, as the refrigerant’s pressure gets reduced, the refrigerant can also be effectively cooled off. What the expansion valve does is to accomplish this process by inhibiting the refrigerant from flowing into the evaporator coil.

So without the expansion valve, there is the big possibility that the refrigerant would flow and rush into the evaporator coil without any reduction in its pressure. What the expansion valve does is to only permit a small amount of the refrigerant to pass by and go into the coil. As the refrigerant makes its way inside, it’s only able to spread itself out in the empty evaporator coil. This reaction of expansion causes its pressure drop, also taking the temperature down with it.

The Different Types of of an Expansion Valve

1. Automatic Expansion Valve - This expansion valve type works by using a pressure-actuated diaphragm that regulates the refrigerant flow from the liquid line down to the evaporator. Its usual disadvantage lies in the fact that it’s counterproductive if the load fluctuates. This type is strongly recommended to not be used in air conditioners as the load is likely to fluctuate a lot.

2. Thermostatic Expansion Valve - The thermostatic expansion valve or TEV is known to use a valve mechanism that controls the liquid refrigerant’s flow into the evaporator coil. Afterwards, the flow is controlled by the evaporator by way of its pressure. This type of device operates well even during different cases of fluctuations, making it suitable for an air conditioning system. Once the evaporator warms, the valve is able to provide a higher flow rate. Once it cools, this flow rate is then reduced. Additionally, there is a sensor bulb located at a higher temperature in the evaporator that detects the coil’s temperature.

3. Capillary Tube - The capillary tube is a tube with a small internal diameter. This tube can be coiled for its length and usually installed to the suction line. To remove dirt and moisture from the refrigerant, a filter-drier is commonly fitted before the tube. To ensure that the devices performs exceptionally well, the refrigerant found in a system must be properly calibrated at its factory level. Compared to the thermal expansion valve or TXV/TEV, the capillary tube is generally cheaper and used in room or window air conditioners.

4. Float Valve - The float valve is a valve that is operated by a float immersed in the liquid refrigerant. To control the flow of this liquid refrigerant, both low-side and high-side floats are used. The low-side float functions by helping the liquid refrigerant be maintained at a constant level inside the evaporator. When there is no liquid inside the evaporator, it opens and closes when there is some. On the other hand, the high-side float, located at the system’s high-pressure side, maintains the refrigerant at a constant level in the condenser. Once the compressor works, the float chamber receives a flow or condensed refrigerant inside and the valve is opened. This reaction allows the refrigerant to make its way into the evaporator. Once the liquid level found in the float chamber goes down, the valve opening will close. It is during this process that the liquid is further prevented from flowing into the evaporator.
   

Maximizing Your Aircon’s Performance

It is worth noting that like any component inside the AC system, the expansion valve isn’t immune to any repairs and damages. It can malfunction like any other air conditioner part, resulting in a unit that fails to give any cooling. That’s why understanding the way an aircon expansion valve works is important as it contributes to how your air conditioning unit operates and functions. The valve plays a key role in the overall system of an air conditioner and thus, deserves to be taken care of through proper maintenance and check-ups.

Apart from doing regular maintenance for your aircon valve, it pays to check for your overall aircon system occasionally to help you save from potentially bigger maintenance and repair costs in the long run.

For quality maintenance and repairs for every major air conditioning brand, contact us at Oasis Aircon Singapore. Our team of highly skilled air con technicians are here to assist you for all your aircon needs. With our honest pricing, we ensure that your home, office, or business will receive the best service, for the best price.