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MarGo Plumbing Heating Cooling Inc. Blog

The Expansion Valve: A Critical AC Component


Air conditioners are complex and fascinating machines. When we use them in our homes, we simply turn them on and enjoy the cool air. The part we’re probably most aware of is the fan, which pushes that cool air through our ductwork to come out our vents. But there’s a lot more going on in the system.

Knowing more about your air conditioner can help you understand how to take better care of it. We’d like to explain some of the lesser-known workings of the AC system. In particular, we’ll tell you all about a component called the expansion valve.

Indoor and Outdoor Units

The way your air conditioner works involves using two units, indoors and out, to do two halves of the critical job of cooling your home. The indoor unit is where heat is drawn out from the air in your home. The outdoor unit is where that heat ends up. From there, it has to be released into the air outside your home. 

Connecting the two units is a system of coils, tubes that contain a chemical called refrigerant. This chemical is spectacular at thermal transfer, the process of absorbing and releasing heat. As it flows through the coils, pressurized by the compressor in the outdoor unit, it moves heat from inside your home to outside. Before it flows back into your home, it must be cold enough to absorb more heat.

Releasing Heat

This is where the expansion valve comes in. You see, in the indoor unit, the refrigerant evaporates into a gas as it gets hotter. In the outdoor unit, it condenses back into a liquid. Some heat is released in this process. But the refrigerant is still not cold enough to soak up much more heat. How does the outdoor unit chill the refrigerant sufficiently?

Contents Under Pressure

There is an interesting relationship between pressure and temperature in physics. When something is under high pressure, it will be hotter. Simply imagine molecules being squeezed and pushed together like overheated music fans at a crowded concert. What this means for the AC system is that lowering the pressure of the refrigerant will, in turn, cause the temperature to drop.

The expansion valve lets that highly-pressurized refrigerant expand. The pressure drops. The temperature is lowered. And now the refrigerant is cold enough to flow back into your home and absorb some more heat. The cycle continues, and your home stays cool and comfortable.

As you can see, your air conditioner is a lot more than a fancy fan. This is why it’s so important for routine maintenance and repairs of any AC troubles to be done only by trained, qualified technicians with the expertise to diagnose problems quickly and get them fixed. If you have any concerns about your AC outdoor unit in Livingston, NJ, or any other part of your air conditioner, don’t hesitate to get qualified help

Contact MarGo Plumbing Heating Cooling Inc. today with AC concerns or any questions about your HVAC system!

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