A thermostatic expansion valve (TXV) is used in most air conditioning systems and functions to regulate the amount of refrigerant released to the evaporator. This valve holds back the superheated high-pressure liquid refrigerant and controls how much liquid enters the evaporator. The thermostatic expansion valve prevents the refrigerant in liquid form from entering the compressor and causing a malfunction in the cooling system.

Components of a Basic Thermostatic Expansion Valve

Whether in air conditioning or vapor-compression refrigeration systems, a thermostatic expansion valve is located before the evaporator. A typical thermostatic expansion valve is made up of the following components:

  • Valve body
  • Diaphragm
  • Pin or needle
  • Spring
  • Sensing bulb
  • Capillary line

The valve body holds the components and contains an orifice inside that controls the flow of liquid refrigerant. The diaphragm is a small thin material made of metal that flexes to apply pressure. The pin in the thermostatic expansion valve moves up and down to restrict the flow path of the refrigerant while the spring functions to counter the force of the needle. The sensing bulb and the capillary line cause the valve to open and close.

How a Thermostatic Expansion Valve Works

Due to the small orifice of the thermostatic expansion valve, the high-pressure liquid passing through the valve decreases in pressure. The reduction in pressure of the refrigerated fluid causes it to boil at a lower temperature. Part of it will vaporize as the liquid passes through the thermostatic valve, and some will remain in a liquid state. The liquid-vapor refrigerant from the thermostatic expansion valve then passes through the evaporator, absorbing heat from water or air surrounding the pipe. Boiling the liquid refrigerant is an essential step for the cooling system as it will reabsorb heat from the air or surroundings and transfer it to the compressor.

The more the refrigerant is exposed to thermal energy passing through the evaporator, the more it changes and becomes a saturated vapor. During this change of state of the refrigerant, there is minimal to no change in temperature due to the latent heat. The refrigerant passing through the evaporator will continue to pick up heat, and eventually, the temperature rises to superheat the refrigerant while the sensing bulb monitors the temperature to control the refrigerant.

Significance of the Thermostatic Expansion Valve

Thermostatic expansion valves are found in many refrigeration systems such as big chillers, heat pumps, or simple AC units at home. Regardless of where it’s found, the thermostatic expansion valve is located before the evaporator. Thermostatic expansion valves come in different designs depending on the cooling coil of the cooling system. AHU units have two thermostatic expansion valves because they have a large cooling coil.

What Happens if the Thermostatic Expansion Valve Fails?

A thermostatic expansion valve is an essential component in cooling systems, and like any other machine, it may malfunction.

If a thermostatic expansion valve fails, the liquid refrigerant will pass through the evaporator into the compressor. Since liquids cannot be easily compressed into vapor, the compressor will fail due to the malfunction of the thermostatic expansion valve.

When your air conditioning system fails, you will need a technician to troubleshoot the problem to determine whether it requires servicing, repair or replacement. A technician well versed with different makes and models of thermostatic expansion valves can provide a solution for you. At Campbell Comfort Systems, we offer solutions for repairing, servicing, or maintaining thermostatic expansion valves.

Your Go-To When Your Cooling System Fails Due to a Malfunction of the Thermostatic Expansion Valve

If you are located in West Deptford and the surrounding areas of New Jersey, Campbell Comfort Systems is your go-to for repair, service, or maintenance for your malfunctioning thermostatic expansion valve. Our certified technicians have served the broader New Jersey area since 1993 and are your trusted choice for servicing, repairing, and maintenance of malfunctioned TXV in cooling systems. We pride ourselves on offering high-quality service and always putting our customers first.

Call Campbell Comfort Systems if you’re having any sort of problem with your thermostatic expansion valve. Other services we provide include boilers, heat pumps, mini-splits, drain cleaning, on-demand water heaters, and more. We are available 24/7 to provide you with reliable customer service. If you need more information about our services or need to schedule your air conditioning or heating maintenance appointment, contact us today!

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