Thermal expansion valve: principle of operation, device and characteristics

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

One of the main applications of a thermostatic expansion valve is to control the temperature in a residential building or room. For the correct use of this device, it must be installed on a heating radiator in the room in which it is important to maintain the desired temperature.

Select device

When choosing this device, it is important to consider three parameters such as:

• device type;
• technical parameters of the valve;
• product cost and manufacturer.

If we talk in more detail about each of these selection criteria, then it is always worth starting with determining the type of device. On this basis, products can also be divided into several groups:

• The first group includes those types of devices that differ in the way they are mounted on the pipe. Among these types, the following can be distinguished: a direct expansion valve, which is installed on pipes running parallel to the ground. The angle valve is intended for installation on those pipes thatare removed from the floor, axial products are installed on pipes coming out of the wall.
• The second group includes devices that differ in such a feature as the type of heating system. Thermostatic expansion valves for one-pipe system have a higher flow capacity than valves for two-pipe.

Thermocouple

It is important to say that the valves are divided into several groups, not only by the types of systems with which they work. Different groups of these products differ in such a thing as a thermoelement, as well as a working fluid. If we talk about filling, then the devices can operate on gas, liquid or paraffin. Gas types of elements are considered the most high-class, liquid occupies an average niche, and thermoelements working with paraffin became the worst in terms of their characteristics.

There are also slight differences in the way the fuser is adjusted. In total, there are two categories of element adjustment. The first category includes those devices that are adjusted to general average parameters by specialists in production. This is called element presetting. The thermostatic expansion valve with open adjustment is the second category, the peculiarity of which is that each user can independently adjust the thermocouple.

Performance

After the type of device was determined during the selection process, you can proceed to its selection bytechnical parameters. The expansion valve must provide the following parameters:

• Maximum operating temperature should be up to 200 degrees Celsius.
• The pressure this device must withstand is between 16 and 40 bar.
• It is important that the valve is made entirely of materials that are not susceptible to mechanical or corrosive attack. Parts made of bronze, brass or steel are considered the best for these qualities.
• The diameter of the heating pipe in the house and the diameter of the control valve must be the same.
• The last most important characteristic for a valve is the ability to mount it on the desired system. For example, if the regulator is mounted using a thread, then the parameters on the valve and pipe must match.

Manufacturers and cost

It is logical that the cost of the product is formed not only from the characteristics that were listed above. This parameter also fluctuates depending on which manufacturer has released a particular valve. Currently, there are several companies whose products are considered the best on the market:

• The first representative is the German company Oventrop. The main advantage of their product is, of course, high quality. The price of a thermostatic valve from this manufacturer starts at 1,000 rubles.
• The second well-known manufacturing company is Danfoss. The company is Danish, and the cost of their products starts from 1,500 rubles. What sets their product apart is that they use the latest manufacturing technology to extend the life of the valve.
• The last of the three well-known representatives was the Italian company Luxor, which stands out from the rest with its prices - from 250 rubles, and is also characterized by the fact that the products from the manufacturer are quite reliable.

Installation recommendations

Installation of this product is best done by following these guidelines:

• The most appropriate place to install the valve is the entrance to the heating radiator.
• It is important to know that there is such a parameter as the optimal installation height of this device. It is located in the area from 40 to 60 cm from the floor. Most often, all valves are initially calibrated to exactly this height. If you can’t follow this rule, then after installing the device, you will need to reconfigure it.
• In order to ensure the normal operation of the sensor, one more recommendation must be observed - the valve head must be in a horizontal position after installation. If you position the device so that the head is in a vertical position, then the warm air flowing through the pipes will interfere with the normal operation of the valve.
• Another of the rules is the arrangement of a bypass if the valve is mounted in a one-pipe system. A bypass is a pipe through which a liquid will circulate if, for any reason, its movement in itselfradiator will be difficult.

Valve connection

You can connect a thermostatic radiator valve as follows:

• The first thing to do is to drain the fluid from the heating system. It is not difficult to do this in a private house, but in an apartment building you will have to contact a service company, since the drain valve is located in the basement of such a house.
• Next, the process of tapping into the pipe is carried out at a pre-selected location.
• At the ends of each of the pipes you need to cut the threads of the required parameters.
• If the thread of the valve was originally processed with a sealed thread, then using an adjustable wrench, you can mount the device in a prepared place.
• It is important to note that each valve has directional arrows that indicate the movement of the fluid. When mounted on the reverse side, proper operation of the device will not be ensured.
• After installing the components, it is important to check the system for leaks.
• The last step is to set up the system fuser itself.

It is worth noting that if you have the necessary knowledge and skills, you can carry out the installation on your own.

Features of Danfoss, Eagle products

The Danfoss thermostatic expansion valve is distinguished by its design and other features from other valves. In terms of design, this device includes a thermostat, which is separated fromthe valve itself with a membrane. In addition, one of the important elements of these valves is the spring. It carries out the superheat control process.

If we talk about Eagle products, we can single out the following regulator. Radiator expansion valve Eagle 302-1608. It has internal as well as external threads. It is characterized by such pressure as 1.6 MPa or 16 kgf/cm2. The type of this regulator is direct.

All Danfoss products are divided into several categories:

• TE5-TE55. These devices are designed to control the flow of liquid refrigerant into the evaporator devices installed in refrigeration units.
• TGE. This group of products is distinguished by the fact that the design of the valve units of the device is indispensable, and they were made specifically for the air conditioner. This category thermostatic expansion valve is designed for commercial air-conditioning systems with high capacity.

Danfoss Benefits

Temperature control devices AKV from this manufacturer deserve a special mention. They have found the most active application among refrigeration units, which are located in shopping centers. Among the most important advantages of this product are the following:

• The type of this design is collapsible, which makes it possible, if such a need arises as the replacement of a valve assembly, to easily cope with this task.
• One of the main advantages is the absence of the need for constant adjustmentregulator during operation.
• This device is not only a thermostatic valve but also a solenoid at the same time.

AKV regulators are also distinguished by the fact that they have a functional electric drive. The principle of operation of this valve is based on the pulse-width control of parameters.

Working principle

Installing an expansion valve is considered to be the best solution for regulating the flow of refrigerant to the evaporator. The principle of operation of the expansion valve is based on the regulation of the refrigerant supply in such a way that overheating is observed at the outlet of the evaporator almost all the time. When the evaporator superheat increases due to heat load, the controller increases the refrigerant flow until the superheat value is below the setpoint. This adjustment method allows the unit to maintain the evaporator fill level at that which is limited by the onslaught of the setpoint.