Abstract: in the 1940s, radiator thermostatic control valve appeared in Europe. In the early 1980s, China began to develop its own radiator thermostatic control valve
Thermostatic radiator valves in the 1940 s in Europe, in the early 80 s in our country started the self-developed, thermostatic radiator valves into, late in the 90 s, with the deepening of heat metering technology and to meet the majority of the people of the bedroom temperature personalized requirements, a variety of domestic and imported products arises at the historic moment, thermostatic radiator valves and is used in many engineering projects in China.
The room temperature control of radiator heating can be controlled by radiator thermostatic control valve, or by manual temperature control valve with better resistance characteristics. The advantage of using radiator thermostatic control valve is that it can make good use of "free heat" to achieve the purpose of energy saving, and at the same time avoid the user to carry on cumbersome and repeated adjustment.
1. Classification and working principle of radiator thermostatic control valve
Radiator thermostatic control valve is composed of thermostatic controller and valve body. Its working principle is that the user turns the thermostat to the required set temperature. When the indoor temperature exceeds the set temperature, the internal temperature package of the thermostat (the heat-sensing medium filled with internal heat) is heated and expanded to increase the volume, push the valve stem, make the valve smaller, reduce the inflow flow of radiator, and make the room temperature reach the set temperature. When the indoor temperature is lower than the set temperature, the temperature package will contract when it is cooled, and the volume will decrease. The reset spring in the valve core pushes back the valve stem, making the valve open wider and increasing the water inflow of the radiator until the room temperature reaches the set value.
1.1. Thermostat
The thermostatic controller can be divided into built-in type and remote type according to the location of the temperature packet. Because the temperature packet feels the temperature of the surrounding air, and the regulating action of the temperature control valve is generated by the volume change of the temperature packet, the position of the temperature packet is very important for the correct use of the temperature control valve. In most cases, when the indoor temperature of the room in which the radiator is located needs to be adjusted, the built-in temperature control valve should be used. In some specific cases, such as this group of radiator is covered by the radiator cover, the temperature control valve is located in the cover, or in the temperature control valve near the other hot (cold) source, such as kitchen, strong lighting fixtures, at this time, the temperature package experience is the local high temperature around, rather than the accurate room temperature, should use the remote thermostat controller. In some special systems, such as horizontal single-tube downstream system, temperature control valve can only be installed in the first set of radiators, and the user mainly adjusts the temperature between the living room or main bedroom, or the remote type temperature control valve can be used to collect the temperature sensor in the living room or master bedroom for adjustment.
1.2 thermostatic control valves can be classified into the following four categories according to the different sensitive temperature media filled by their temperature packets:
1) steam temperature package
Temperature bags filled by medium is a kind of low boiling point liquid, when the outside temperature, part of the liquid gas, temperature increased package size to promote stem, close the valve opening, reduced into the radiator water flow, when the outside temperature lower part of the gas and liquefied liquid, bulb volume decreases, and valve opening increases, thus increasing the radiator water flow. The temperature sensitive medium in the temperature packet is often in the mixed state of gas and liquid, and its advantage is that the acting time is fast, but it has very strict requirements on the sealing of the temperature packet.
2) liquid temperature packet
The temperature sensitive medium filled in the temperature packet is special liquid, generally methanol or toluene. This kind of temperature packet is widely used in China because of its large volume and short acting time.
3) solid temperature packet type
Inside the temperature packet is filled with a higher coefficient of expansion of solid, paraffin wax, etc. Due to the small change in the volume of solid compared with gas and liquid when heated (cooled), its temperature sensing action is slow, but the volume is small compared with the liquid temperature packet, which is also used in some domestic applications.
4) metal plate type
The temperature sensing device of the thermostatic controller is a special alloy metal sheet with memory function, which expands and contracts by heat and drives the temperature control valve to act. This kind of product needs to carry on the strict experiment and the inspection to its temperature sensing device before leaving the factory. At the same time, because the metal has the fatigue fracture and so on characteristic change after the frequent expansion and bending, and the metal has the malleability, this kind of temperature sensing device life and the precision will affect. Some domestic manufacturers produce this kind of temperature control valve products, its foreign products are rarely seen.
2, thermostatic valve body
Thermostatic valve body is generally made of copper, surface nickel-plated, according to the inlet and outlet water and the installation of temperature controller valve core Angle can be divided into the following several.
1) straight-through thermostatic valve body: temperature control valve inlet and outlet Angle of 180°
2) angular thermostatic valve body: temperature control valve inlet and outlet Angle of 90°
3) three-dimensional temperature valve body (three-dimensional temperature control valve) : temperature control valve inlet, outlet and valve core into a 90° Angle, similar to the X, Y, Z coordinates.
4) special combination temperature control valve body: for some new type of radiator (such as bathroom radiator, etc.) and some connections (such as single-pipe straddling), many manufacturers also launched some special combination temperature control valve body. I won't enumerate them here.
3. Kv value and Kvs value of temperature control valve
The water resistance characteristics of foreign control valve products are generally expressed with Kv value, and many domestic temperature control valve products also use Kv value to indicate the water resistance characteristics. Kv value is defined as the flow rate through the regulator when the pressure drop before and after the regulator is 1bar. The Kvs value represents the Kv value at the maximum opening of the regulator. Can be applied to the following formula Kv equivalent value of the local resistance coefficient of commonly used in domestic factor value.