October 20, 2021
Thermostatic Expansion Valve in Lakeside, CA

Understanding how your air conditioning system works can help you make better maintenance decisions. The following explanation will show you how a thermostatic expansion valve, or TXV, works. The TXV controls how refrigerant moves inside of your air conditioning unit.

Pressure Principles

Before you learn about the TXV, you must know a little about the forces that drive it. Pressure changes power the TXV. When the temperature rises within the system’s evaporator, it causes the pressure to increase. Conversely, pressure decreases as the temperature decreases.

The Thermostatic Expansion Valve in Action

The first part of the TXV we’ll cover is the sensing bulb. This refrigerant-filled bulb is next to the evaporator output. As the evaporator heats up, so does the sensing bulb. This causes a pressure increase that eventually pushes refrigerant out of the sensing bulb.

The refrigerant next goes through a capillary tube. This is a metallic pipe that leads from the sensing bulb to the TXV. It is coiled on the TXV side.

Once the refrigerant reaches the TXV’s powerhead or top portion, it begins to push an internal diaphragm downward. The diaphragm is made of thin sheet metal. As the diaphragm drops, the valve gradually opens to allow refrigerant to flow from the condenser to the evaporator.

As the evaporator begins to cool, the pressure that drives the valve open begins to fade. As this happens, the valve begins to close due to pressure from the evaporator and the pressure spring. The pressure spring is on the other side of the valve from the diaphragm. Eventually, the temperature rises enough to increase sensory bulb pressure and release more refrigerant into the system.

Rely on Your Local Experts

Knowing how your home cooling system works is one way to maximize the comfort of your home. Another way is to get a home comfort analysis to find your best heating and cooling upgrade options. For this or any of our other services, reach out to us at Hi-Tech Air Heating & Cooling in Lakeside. Our technicians provide a complete range of both residential and commercial heating and cooling installation, maintenance and repair to customers throughout San Diego County, and we’ve been doing it for more than 20 years. Call us today.

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