Video principle of operation of thermostats. Video principle of operation of thermostats Features of choosing the RA-G thermostat valve and its connection
At the end of the last century the lineup radiator valves of the famous Danfoss brand has been replenished with the RTD-G version, adapted to Russian single-pipe heating systems. The result of generalization is the most good options its application was a new modification of the RA-G thermostat valve, which today the company offers for use all over the world.
An example of the permanent update of valves in this series was the appearance on the market in May 2011 of an updated set of temperature control equipment in blister packaging. It consists of a thermal head type RA2940 with a built-in gas-filled temperature sensor and a direct thermostatic valve RA-G20.
RA-G thermostat valves: main technical and operational characteristics.
The entire line of RA-G thermostatic valves has a nickel-plated body and internal threads. Manufacturers offer models in straight and angular versions with nominal diameter from 15 to 25 mm. Valves of the RA-G series are designed for single-pipe pumps heating systems with top/bottom filling. They can also be used in two-pipe gravitational systems heating. They are compatible with any RA series thermocouples.The RA-G thermostat valves are characterized by increased flow capacity. Regulation range temperature regime ranges from 0°C to 26°C. It is possible to completely shut off the coolant supply.
They are distinguished by high strength, which at a maximum temperature of 120 °C allows them to withstand operating pressure 16 bar. This means that even with unstable operation of heat supply systems, it is guaranteed that an emergency situation will not occur.
To identify valves RA-G maybe by caps gray, which only perform protective function and are not intended to restrict the movement of coolant.
Design of thermostat valves RA-G.
The latest RA-G thermostat valve designs consist of the following components:1. Nickel plated body
2. oil seal
3. O-ring
4. plates
5. saddles
6. Chrome steel pressure pin
7. return spring
8. rod
9. Union nut
10. connecting nipple
Features of choosing the RA-G thermostat valve and its connection
When choosing a thermostatic valve of this series for single-pipe heating systems, you should pay attention to the presence of a closing section between the supply and return lines to the radiator. In this case, the diameter of the RA-G valve is selected according to the diameter of the liner, and the diameter of this section is one size smaller compared to the diameter of the liner.In conditions of the same diameter of the connections and the closing section, it is advisable to use a bypass choke of the RTD-BR type. And when completely closed valve To reduce the residual heat transfer of the radiator, it is recommended to install a reverse flow throttle RTD-CB on the return line between it and the closing section. Following these recommendations will ensure that the difference between the coolant flow through the radiator and in the riser is at least 30%.
Connection to pipelines is carried out through a coupling fitting, and to heating devices - using threaded shanks with a union nut.
What are the advantages of RA-G thermostat valves?
A generally recognized advantage is that these are the only valves with such high flow rates. This was achieved by increasing the diameter of the seat and profiling the internal surface, which increases the coefficient of flow into the radiator, as well as reducing the risk of valve clogging.The undeniable advantage of RA-G type valves is the use of modern high-quality technologies for the manufacture of all control components, as well as the use of special materials that eliminate the threat of mechanical wear and corrosion damage
Along with this, they have the unique operational ability to replace the crane axle box, saddle, and cone of the structure on site without stopping the operation of the heating system.
All this makes RA-G thermostat valves leaders in ensuring the most high level energy efficiency among analogues existing in the global heating engineering market.
The RA-N control valve is designed for use in two-pipe pumping systems water heating.
RA-N is equipped with a built-in device for preliminary (installation) adjustment of its throughput within the following range: K = 0.04–0.73 m3/h - for valves DN = 15 mm;
RA-N valves can be combined with all thermostatic elements of the RA and RAX series, as well as with the TWA-A thermoelectric actuator.
To identify RA-N valves, their protective caps are painted red. The protective cap must not be used to block the flow of coolant through heating device. To do this, use the handle (code number 013G3300).
Valve bodies are made of pure brass with nickel plating
The technical characteristics of RA-NCX valves in combination with thermostatic elements of the RA and RAX series comply with European standards EN 215-1 and Russian GOST 30815-2002, and the connecting thread size complies with HD 1215 (BS 6284 1984).
All radiator thermostats, manufactured by Danfoss, are manufactured in factories certified to ISO 9000 (BS 5750).
To prevent deposits and corrosion, valves of RA-NCX thermostats should be used in water heating systems where the coolant meets the requirements of the Rules technical operation power plants and networks Russian Federation. In other cases, you must contact Danfoss. It is not recommended to use compositions containing petroleum products (mineral oils) to lubricate valve parts.
High-tech body
Silent operation
The low noise characteristics of the valve are especially important for the consumer. This is why Danfoss valves are equipped with a flow stabilizer special design, allowing you to work absolutely silently even with increased pressure drops.
Less susceptible to valve sticking
“Sticking” is the sticking of the valve cone to the seat due to prolonged contact when the valve is closed. For liquid-filled bellows, the closing force is extremely high. When using Danfoss thermostats with gas filling, there is practically no increase in the closing force with increasing temperature, since in this case all the gas condensate evaporates. This, as well as the careful selection of materials for the valve cone and seat, made of a special alloy of glass and plastic, reduces the possibility of “sticking” to a minimum.
Valve that won't clog
Danfoss RA valves are optimized for working with gas-filled thermostatic elements and therefore their rod stroke is increased by 1.5 times: from 0.46 mm (for liquid thermoelements) to 0.74 mm.
Greater stem movement and larger valve flow area reduce the likelihood of valve clogging.
Easy maintenance
Danfoss RA valves have a single performance adjustment window, with a gradually increasing cross-section.
In valves from other manufacturers, the setting window is a set of round holes of different sections. If dirt clogs this round hole, disassembly is required to clean the valve. Whereas for a Danfoss valve in such a situation, it is enough to turn the adjustment ring - without disassembling the valve and without using any tools.
Easy setup
For settings Danfoss valves RA for radiator performance does not require special tools.
Just lift and turn the adjustment ring. The positions of the tuning ring are marked with numbers from 1 to 7, completely open position indicated by the letter N. So the setting is easy not only to carry out, but also to check.
Precision tuning
The RA valve adjustment ring has 14 precise fixed flow positions. Many other manufacturers offer no more than 6 drills/holes and therefore only 6 possible throughputs.
Replacing the stuffing box under pressure
When replacing the stuffing box, there is no need to disconnect the valve and empty the system - the replacement can be done under pressure.
Thermostatic valves with increased flow rate RA-G are used mainly in single-pipe systems. All RA-G valves are compatible with all RA series thermostatic sensors.
RA-G valves are equipped with gray protective caps. The cap should not be used to block the regulated medium. For these purposes, a special metal handle (code no. 013G3300) should be used. The pressure pin in the stuffing box is made of chrome-plated steel and does not require lubrication throughout the life of the valve. The entire seal assembly can be replaced without draining the system. To prevent deposits and corrosion, type RA-G valves should be used in water heating systems where the coolant meets the requirements of the Rules for the Technical Operation of Electric Power Plants and Heat Networks of the Russian Federation. It is recommended not to use coolant containing mineral oil.
Thermostatic valves with increased flow rate RA-G are used mainly in single-pipe systems. All RA-G valves are compatible with all RA series thermostatic sensors.
RA-G valves are equipped with gray protective caps. The cap should not be used to block the regulated medium. For these purposes, a special metal handle (code no. 013G3300) should be used. The pressure pin in the stuffing box is made of chrome-plated steel and does not require lubrication throughout the life of the valve. The entire seal assembly can be replaced without draining the system. To prevent deposits and corrosion, type RA-G valves should be used in water heating systems where the coolant meets the requirements of the Rules for the Technical Operation of Electric Power Plants and Heat Networks of the Russian Federation. It is recommended not to use coolant containing mineral oil.
Modern heating devices produced by Danish by Danfoss. RA-G interacts with all thermostatic elements of the RA group installed in modern heating devices.
general information
The main feature of the device presented in this article is its increased throughput. Its area of application is single-pipe water heating systems for houses with pump circulation of the heat conductor. The latter must meet the requirements of the “Rules for the technical operation of power plants and heating networks of the Russian Federation.”
The purchaser should be aware that this device should not be used in systems containing mineral oil contaminants in the thermal conductor.
An important advantage of the device is its oil seal (product code - 013G0290), which can be easily replaced from the home heating system at any time. The oil seal pressure pin is made of chrome-plated steel, so it can not be lubricated throughout the entire life of the device.
The device comes with gray protective caps. The user should remember that under no circumstances should they be used to block the flow of coolant. For this purpose, the device is equipped with a special locking handle (product code - 013G3300).
Video: Radiator Danfoss thermostats R.A.
Nomenclature of commodity items
Today it is profitable to order Danfoss products via the Internet. Prices online are significantly lower than on the market or in specialized stores. To place an order online you need to know the product code. Below we provide a table with codes and some technical parameters products presented in this article.
Code numbers and specifications for RA-G corner vertical version
| Device type | Bandwidth | Code number | ||||
|---|---|---|---|---|---|---|
| with thermoelement | without thermocouple | |||||
| RA-G 15 | 0.54 | 1.07 | 1.61 | 2.06 | 4.3 | 013G1676 |
| RA-G 20 | 0.57 | 1.11 | 1.16 | 2.2 | 5.01 | 013G1678 |
| RA-G 25 | 0.59 | 1.27 | 1.77 | 2.41 | 5.5 | 013G1680 |
Code numbers and technical data for RA-G for direct execution
| Device type | Bandwidth | Code number | ||||
|---|---|---|---|---|---|---|
| with thermoelement | without thermocouple | |||||
| RA-G 15 | 0.51 | 0.94 | 1.35 | 1.63 | 2.3 | 013G1675 |
| RA-G 20 | 0.54 | 1.07 | 1.61 | 2.06 | 3.81 | 013G1677 |
| RA-G 25 | 0.57 | 1.16 | 1.71 | 2.27 | 4.58 | 013G1679 |
The maximum pressure drop across the valve at which it is capable is 0.2 bar for models 013G1676, 013G1675, 013G1678, 013G1677. For models 013G1680 and 013G1679 – 0.16 bar.
Maximum coolant temperature, for normal operation valve, should not exceed 120 °C.
Application in single-pipe heating system
As a rule, the series of devices presented in this article are intended for installation in single-pipe building heating systems. Due to the small temperature difference in the radiator batteries of such systems, the range of heat transfer regulation here is insignificant.
Changing the flow rate through the radiator does not affect its heat transfer. Reducing the flow through the radiator to 30 percent relative to the calculated value leads to a reduction in heat transfer by only 10%. Such a decrease will not cause a decrease in the indoor climate, since the heating devices have a reserve of heat-transferring surface.
Some installation features
When purchasing and installing RA-G, the buyer should consider several important points:
- In a one-pipe heating system with thermostats, there must be a closing section between the return and supply connections to the battery. It is recommended to take its diameter 1 standard size lower than the diameter of the eyeliners.
- The valve diameter should be selected according to the diameter of the connections. By observing points 1 and 2, the buyer will be able to create a heat conductor flow through the heating device of only 25–30 percent of the flow in the riser.
- In the event that the diameters of the connections and the section are the same, it is recommended to use, manufactured trademark"Danfoss", to ensure the coefficient of coolant flow into the device.
- To reduce the residual heat transfer from the radiator when the thermostat valve is completely closed, it is recommended to install a reverse flow throttle RTD-CB on the return line between the section and the device.
Device design
The RA-G valve consists of the following parts:
- valve plate
- sealing ring
- stuffing box
- pin
- valve seat
- spring
- union nut
- connecting nipple
- frame
The spare parts that form the basis of the device are made of stainless materials, which allows the device to perfectly resist corrosion and increase its service life.