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Most air conditioning systems have thermostatic expansion valves (TXV) as a primary component. Knowledge of the valve increases efficiency in the HVAC operations conducted by technicians. The TXV complements other essential parts of a refrigeration cycle.

The Function of the Thermostatic Expansion Valve

The thermostatic expansion valve has a critical role in the refrigeration process. The valve controls the flow rate of the refrigerant fluid into the evaporator. This function is mistaken with the following:

  • Control of air temperature
  • Determining head pressure
  • Controlling the capacity and humidity levels
  • Altering suction pressure

The Main Parts of the Thermostatic Expansion Valve

The TXV is brass material. The valve contains an inlet and outlet, which help entry and exit of refrigerant. The TXV is between the condenser and the evaporator in the refrigeration cycle.

The other parts of the valve include the main body, the powerhead, and the capillary tube.

How the Thermostatic Expansion Valves Works

The thermostatic expansion valve works by regulating the rate of flow of the fluid. The process ensures a continuous flow of the refrigerant into the evaporation coil. The constant flow occurs when the rate of evaporation is equal to the speed of fluid flow.

The valve pins respond to the temperature and pressure of the evaporator. The valves then block, release, and limit the fluid flow to achieve different flow rates.

There are several implications of the pin’s functions in the valve. The following are some examples of expected results when the pins limit flow:

  • Low pressure in the refrigerant flow
  • Evaporation of the refrigerant
  • Boiling of the fluid
  • Absorption of heat from the surrounding
  • Thermostatic Expansion Valve Failure and Its Diagnosis

The TXV can fail from the interior and lead to inefficiency in air conditioning. These failures may arise from blocked holes and other passages. The presence of solid materials in the valve can also lead to its failure. The powerhead may malfunction, and the probability of overheating may also arise.

Upon failure of the valve, we advise that you replace certain parts instead of the whole valve. Some replaceable features include the screen and the powerhead.

Evans Mechanical is very familiar with thermostatic expansion valves. Contact us today for help with your cooling and heating appliances. We also offer services to improve your indoor air quality in your Eureka home.

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We are always happy with the service from Evans. Your service people are always friendly and professional. And we feel your prices are fair and that you do an excellent job of keeping our heating system in working order. We are glad you are in Humboldt County.

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The installers are finishing up. We expect to have great results with the new furnace & the newly installed dehumidifier. We applaud the professionalism of the installers.

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