The Thermal Expansion Valve: A Feature Worth Considering When You’re Shopping for an A/C
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The Thermal Expansion Valve: A Feature Worth Considering When You’re Shopping for an A/C


Air conditioning is the largest single consumer of electricity in your home this summer, accounting for as much as half of your entire energy bill. A thermal expansion valve is a feature that helps keep these costs down.

What is a thermal expansion valve?

This type of valve measures refrigerant flow through the system, automatically adjusting as cooling conditions change. When cooling demand is high, the thermal expansion valve opens wide. Likewise, when demand is low, the valve closes partway to reduce refrigerant flow.

The valve senses cooling load by measuring the refrigerant’s temperature when it exits the indoor coil. It senses that temperature increases indicate higher cooling load. In short, the thermal expansion valve creates a more efficient air conditioner.

Why this feature is worth looking for

If you’re shopping for an A/C, make sure the new unit has a thermal expansion valve. The reasons are many:

  • Efficient cooling no matter what: Cooling loads vary constantly due to outdoor temperature changes, sunny versus overcast conditions, indoor heat gain fluctuations and other factors. A thermal expansion valve helps the air conditioner respond to these changes with great efficiency.
  • Protection for the compressor: When cooling loads skyrocket during the dog days of summer, A/Cs with a fixed orifice or capillary tube (alternatives to a thermal expansion valve) may starve the evaporator coil of refrigerant. Conversely, on milder days, too much refrigerant can enter the coil and get into the compressor, potentially damaging it and shortening its lifespan. In this way, a thermal expansion valve protects the compressor.
  • Energy savings: Tests show that air conditioners with a thermal expansion valve maintain a higher level of efficiency in a variety of conditions than those without this feature. This fact holds true even in situations where the air conditioner is charged improperly. (To make sure your air conditioner is charged correctly, have it installed and serviced by a trustworthy HVAC professional.)

To learn more about how a thermal expansion valve makes your air conditioner perform more efficiently all summer long, please contact us at Roth Heating & Cooling in Portland today.

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