Why do I Need a TXV?

Your TXV (or Thermostatic Expansion Valve) regulates the correct flow of refrigerant to your AC evaporator while preventing liquid refrigerant from reaching the compressor. It plays a major role in your AC unit, working hard so you can keep cool and carry on during the hot summer season.

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How Your TXV Works

The TXV in your AC unit measures your system’s superheat and responds by controlling the amount of refrigerant that flows to the evaporator to stabilize the superheat. A TXV is normally made of brass with both a refrigerant inlet and outlet, and a removable cap for adjusting the superheat. The TXV’s power head, capillary tube, and sensing bulb are made of stainless steel and helps maintain optimum efficiency while preventing liquid refrigerant from reaching the compressor.

The condenser releases refrigerant as a high-pressure, saturated liquid to the TXV through its inlet. Once it passes through the body and outlet of the valve, it’s released as a low-pressure and low-temperature vapor mixture.

Hot for Superheat

Superheat is measured by calculating the difference between the boiling point temperature of the refrigerant in the evaporator coil and the actual temperature of the refrigerant gas as it leaves the evaporator.

The superheat in your AC system can be optimised through an adjustable TXV, or by adjusting the quantity of refrigerant in the system in the case of a fixed bore metering device instead of a TXV.

It’s important that your TXV measures superheat to prevent damage to your AC system compressor.

Selecting the Right TXV

Not only does your HVAC system need a TXV, but you want to make sure you have the best one for your system — preferably one that matches the cooling capacity of the unit. Cooling capacity, measured in tons, describes your system’s ability to remove heat from a space in a certain amount of time.

Since a TXV is designed to work in systems with different tonnage ranges, you’ll be able to find:

  • A TXV for 1.5 to 2 ton systems

  • A TXV for 2 to 3 ton systems

  • A TXV for 3.5 to 5 ton systems

In newer AC systems, a TXV is already installed to enhance your system’s efficiency. However, when you need to buy a TXV on its own, it’s important to know what model and size your system needs.

The Right Refrigerant

Along with selecting the right TXV to match the cooling capacity of your system, you’ll want to choose one that’s compatible with (and optimizes) the refrigerant your system uses.

A Stable TXV

If you’re interested in air conditioning, the TXV is a neat little valve. Not so interested in AC systems? It’s still a good idea to get acquainted with the various parts, like the TXV, since each is crucial for proper functioning and the right fit can help you avoid other issues in the future.

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