The Thermal Expansion Valve: An A/C Feature That Can Shrink Your Energy Bills

Unless you’re up on HVAC lingo, the term “thermal expansion valve” may not be one you’ve heard before. As obscure as it may sound, though, it’s a term you should get familiar with if you’re looking for a high-efficiency air conditioner to keep you cool during our hot Houston area summers.
A thermal expansion valve is a type of refrigerant metering device. Metering devices control the flow of refrigerant, holding back condensed refrigerant and directing refrigerant into the evaporator (indoor) coil. Older air conditioners use either fixed orifice or capillary tube devices. Because these types of devices can’t change size, they can’t provide precise control.

A thermal expansion valve, or TXV, automatically changes size in response to different cooling conditions. When the device senses an increase in the temperature of the air passing over the coil, indicating an increased cooling load, it widens to allow more refrigerant into the coil. More refrigerant lets the coil absorb more heat. When the air temperature decreases, the TXV narrows to let in less refrigerant. The result is a more efficient air conditioning system.

If you’re shopping around for a new high-efficiency air conditioner, there are a few features to look for besides a thermal expansion valve. These include:

• An Energy Efficiency Ratio (EER), also called a high-temperature rating, higher than 11.6.
• An electronically commutated motor, also called a variable-speed motor, in the air handler.
• A scroll compressor, which is more energy efficient than the older reciprocating compressors.
• An automatic-delay fan switch and fan-only switch, which can be used to improve comfort and reduce energy consumption.
• A “check filter” light that alerts you to when your filter should be inspected and possibly changed.

A system with a TXV will cost slightly more than one with an older type of metering device. Because of the increase in efficiency, though, you should recoup your investment within a year or two.

For guidance on finding an air conditioner with all the features you need, contact us at Davis Air Conditioning & Heating, Inc. We offer reliable air conditioner installation and maintenance throughout the Houston, Angleton,  Ft. Bend, Galveston, Sugar Lane and Brazoria areas.