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Thermostatic Expansion Valve Explained

Thermostatic Expansion Valve Explained

October 20, 2021

Thermostatic Expansion Valve in Norcross, GA

Ever wonder what a thermostatic expansion valve is? It’s a component of your home heating and cooling system that controls the temperature. If you have one, chances are that it has been running for years without being tuned up.

What Is a Thermostatic Expansion Valve?

A thermostatic expansion valve, or TEV, is a one-way control device that regulates water flow into your home’s heating system. It maintains the temperature of the hot water in your property and repairs can be costly if it fails to work correctly.

It controls the flow of liquid in a closed system. The key to its ability to maintain heat is the wax inside that absorbs and releases heat as needed. The valve closes tightly to prevent hot water from escaping and opens up when cold water enters its chamber.

The three main parts of a TEV include the capillary tube, the stem and the thermostatic element, which consists of wax, all wrapped in an insulation jacket. The entire device is encased in metal or plastic.

TEVs can contain several different types of waxes, each with distinct behaviors. Wax expands when it’s heated and contracts when it’s cooled.

As the temperature changes, so does the wax—as it expands, it moves a piston inside the TEV. This movement restricts or increases water flow to your heating unit.

How Do They Work?

Depending on the type of home heating system, your thermostatic expansion valve works with your boiler pump to increase or decrease water flow into the system. When the temperature drops below a certain point, it allows more water flow. As the temperature rises, so does the pressure in the piping, so less water enters your unit. In this way, TEVs maintain a proper water temperature in your heating system to keep it from overheating or freezing.

What Happens If They Fail?

Over time, the wax can crystallize and become rigid, making the valve less responsive to changing temperatures. This is known as freeze-up and can lead to a loss of hot water in your home. In severe cases, it can stop the water from flowing at all. A faulty TEV is often the cause of frozen pipes and broken boilers, which require extensive repairs to get them working again.

What Can You Do to Protect It?

Your home heating system is built to last about 15-20 years. If you have an older unit, it’s recommended that you have your TEV valves replaced every five years or so—this will prevent the problem before it starts and save you money in the long run.
To keep your thermostatic expansion valve in good condition, make sure your HVAC technician performs a system tune-up at least once a year.

You can reach out to Bardi Heating, Cooling and Plumbing if you need TEV replacement in Norcross, GA, and its surrounding areas. You can also inspect it yourself while the heating system is running and before you turn off the power supply to it—if there’s water leaking from anywhere in or around this device, it needs immediate attention.

As with any appliance in your home, it’s important to regularly clean your TEV. This will prevent it from getting clogged with sediment over time and ensure the correct operation of your heating system. Once a year, or whenever you’ve had work on the piping or appliances, you should scrub off any built-up sediment and scale and remove any mineral deposits that have formed. You can then lubricate the TEV.

How Do you Know If Your TEV Is Damaged?

Because a thermostatic expansion valve is a common culprit when it comes to an inoperable heating system, knowing how to spot a problem in advance will ensure that you can keep your family warm through the winter. Keep an eye out for early warning signs that your TEV needs service.

If water is leaking from around the thermostatic expansion valve, it probably needs to be replaced. Anytime that water is leaking, it’s a good idea to bring in a professional.

Some water heaters have TEVs too. If you notice that your hot-water pressure has dropped by half or more overnight, it’s likely that there’s sediment buildup in the valve that needs to be flushed out.

You may notice that your home is normally at a comfortable temperature, yet the heat kicks on and off constantly or is taking longer to heat up or cool down than usual. This could be an issue with the thermostatic expansion valve.

When the water coming into your heating unit is discolored, scaling or staining may be present. This is a sign that the water has been overheating or overheated at some point—in other words, it’s evidence of a TEV freeze-up.

Why Are They Important to Have in Your Home?

One of the most important benefits of a TEV is that they help to maintain the proper water temperature in your unit. This prevents overheating—which can result in broken boilers—and losses in efficiency that slow heating and reduce hot water.

In a home with radiators, the TEV will control the volume of water going to each system or radiator, allowing for individual adjustment as needed. This is extremely helpful during periods of high demand, such as when several people take showers close together.

Your thermostat expansion valve regulates the temperature of both your hot water and heating systems, so regular service can keep them running efficiently and prevent damage. A properly working thermostatic expansion valve is necessary for your heating system to operate at maximum efficiency.

Common Myths About Thermostatic Expansion Valves

A common myth about TEVs is that they can control your home’s humidity levels through the circulation of water. Many assume this because TEVs regulate the temperature of both cold and hot water. This is true in some cases but not in others; it really depends on your specific system.

Another common myth is that a leaking TEV can be fixed by simply tightening the valve with a wrench since it’s responsible for loosening itself as you use hot water throughout your home. This might sound like a simple fix, but it’s actually not good for your system, and it can cause more problems in the long run.

People also believe that in some homes a TEV may have to be turned off during the winter months because it is responsible for pushing hot water through your heating system and home pipework. If this is the case in your home, you will need a special key in order to turn it off or on. However, this type of valve regulates the temperature of the water entering your home, so it is not necessary to turn it off since it can pose a danger if you do not have an alternative heating source.

It is commonly said that TEVs should be used in homes with solar panels because they help control the temperature of the hot water used by those panels. This is true for some homes with solar heating, but not every system requires a TEV—and it’s essential to get expert advice before deciding whether or not you need one in your area.

Bardi Heating, Cooling and Plumbing is an air conditioning contractor company that has been serving the Atlanta area for decades. We offer air conditioning and tune-up services, furnace maintenance and tune-up, AC repair and servicing and replacements and installation of heating systems. If you are located around the Norcross area, be sure to reach out to Bardi Heating, Cooling and Plumbing for any of your air conditioning needs.