Heating, ventilation, and air conditioning (HVAC) systems are manufactured of many electrical and mechanical parts that move heat energy from one place to another. Refrigerant is the vehicle used to transport heat energy, but it can’t do the job all by itself in your home’s central HVAC system. Read on to learn how a small thermostatic expansion valve is vital to your HVAC unit and gives big benefits.

What Are Thermostatic Expansion Valves?

Thermostatic expansion valves are precision metering devices that separate the high-pressure and the low-pressure sides in HVAC systems. The device accomplishes this by precisely controlling the amount of liquid refrigerant that is injected into the evaporator coil. The device measures and adjusts to the refrigerant’s temperature and pressure (i.e., superheat) at the evaporator outlet to determine how much refrigerant to release.

How Thermostatic Expansion Valves Work

Some of the primary components of thermostatic expansion valves used for HVAC systems are the sensing bulb, capillary tube, diaphragm, and the superheat setting spring. These parts work together to create and adjust to three forces at work, which determine whether the valve will open or close:

  • Bulb pressure is based on refrigerant temperature.
  • Spring pressure is constant, and it is set by the manufacturer or installer.
  • Evaporator pressure is based on refrigerant pressure, which varies according to load, air temperature, and other variables.

Benefits of Thermostatic Expansion Valves

These devices give your HVAC unit three big benefits. By precisely measuring the amount of refrigerant to release into the evaporator coil based on your home’s cooling and heating load, these devices help your HVAC unit optimize output while minimizing energy usage.

The third benefit of these devices is they help protect the compressor, which is a very expensive part to replace in any HVAC unit. These valves help prevent liquid refrigerant from entering the compressor, which could damage it.

At Mowery Heating, Cooling and Plumbing, our technicians are trained to precisely calibrate the thermostatic expansion valve and other HVAC components for optimal efficiency. Contact us when it’s time for your next HVAC maintenance call for the best service in the Indianapolis area.

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