Thermostatic Expansion Valves (TXVs) Explained

Especially in the intense heat of summer, many people rely on their air conditioning systems more than ever. It can be useful to understand some of the specifics of how your unit works. A vital element to the functioning of your air conditioning system is the thermostatic expansion valve (TXV).

This is the standard metering device found in air conditioning systems, and it is essential for an HVAC technician installing your home’s air conditioning unit to understand the design and operation of this type of valve.

If, after learning what TXVs are and how they work, you have additional questions related to the installation of air conditioning units, call the commercial refrigeration and air conditioning professionals at Five Star Refrigeration & Air Conditioning, Inc., located in Florida.

What are TXVs?

Because the TXV is a valve, it’s helpful to understand what a valve’s overall function is. A valve is a device that controls the passage of fluid through a pipe or duct, especially in an automatic device allowing movement in one direction only. A TXV controls the rate at which liquid refrigerant flows into the air conditioning unit’s evaporator.

The TXV does not control air temperature, head pressure, capacity, suction pressure or humidity. Attempting to use it to control any of these variables will result in poor system performance, as well as possible compressor failure.

Why are TXVs necessary?

The rate at which refrigerant flows into your air conditioning system’s evaporator is important because it keeps the evaporator functioning efficiently while preventing floodback (which occurs when excess liquid refrigerant returns to the compressor).

One of the design features of the TXV is to separate the high pressure and low pressure sides of an air conditioning system, another process that is essential to the successful functioning of your air conditioning unit.

How do TXVs work?

The TXV controls the flow of the refrigerant into the evaporator by responding to the temperature of the refrigerant vapor as it leaves the evaporator and the pressure in the evaporator. As the pressure on the refrigerant lowers, a small amount is converted to gas. This gas represents an energy transfer, as the heat from the refrigerant is converted to latent heat.

Then, the low pressure liquid and vapor combination moves into the evaporator. There, the rest of the refrigerant “boils off” and absorbs heat from its surroundings.

To maximize your efficiency and cost savings on commercial refrigeration and air conditioning units in Florida, contact the experts at Five Star Refrigeration & Air Conditioning, Inc., at 352-345-4813 today!