The phrase in the name of the mechanism indicates what function it should perform in water circuits. Indeed, a safety valve for heating (shut-off valves) serves to relieve unexpected loads that may arise under certain circumstances, as well as to regulate the water flow in the pipes. But it is installed in different places, although its purpose remains the same.
Types of safety valves
Types of check valves for bypass or boiler
- Coupled brass fuses threaded on both sides and entrance side an EPDM gasket, and the mechanism itself works on a spring that holds a rod, which, at a certain pressure, is recessed, opening the passage. Any pressure from reverse side only strengthens the blocking. Considering the simplicity of such a fuse, the price for it is rather symbolic, but it lasts quite a long time, since it always undergoes pressure testing after assembly.
- But, unlike a conventional valve, there are pressure relief devices, like what you see in the photo above. Such a mechanism, as a rule, is also made of brass, with a stainless steel spring and a rod plate made of heat-resistant plastic, and is mounted in the circuit after the circulation pump.
- In the cut image shut-off valves the principle of its operation is visible - water presses on a plastic plate, which, in turn, compresses the spring, opening the passage. But if the pressure reaches a critical point (20 bar), then the plate is pressed against the safety rod and it opens the exit to the outside. The maximum operating temperature for this mechanism is 120⁰C.
- In addition to the circulation pump, a heating bypass valve can also be installed for high pressure tanks, for example, it could be an electric boiler. Its operating principle will remain the same, only there is a device for draining water. This is done using a flag, which moves the rod and clears the passage.
- Such reverse devices are most often used in sewerage systems to protect against backflow pressure. This can happen during the snow melting season or heavy rains, When groundwater fill the city sewer system and the water level rises above the drain pipes.
- The essence of the lifting locking device thing is when the water supply presses on the valve, it rises and allows the flow to pass. If the pressure drops, the rod is lowered onto the seat and flow return is eliminated. Such a check valve in a heating system is most often used in industrial facilities and for centralized boiler houses.
- In such mechanisms the locking element is a disk that is perpendicular to the flow and moves along the axis. The mechanism can be made either as a coupling or with flange mountings. Used for systems with low pressure and relatively clean coolant.
Advice. Check valves can be spring-loaded (spring-loaded), where the flap is returned into place due to the pressure of the spiral. Or springless, where the damper returns under the pressure of the mass itself. When choosing, you should always take into account the degree of water contamination, since without force the stem may not close due to blockages.
Three way valves
- If we consider a three-way valve for heating, then its operating principle, as well as its purpose, is somewhat different from conventional safety devices. The need for such a mechanism in heating circuits is determined by the need for cooling. Such units can be with manual switching modes or with a servo drive powered from a 220V network.
- The three-way valve is quite simple in design and has one inlet and two outlets, the flow into which is regulated by a damper. The damper can be either a rod or a ball, which, when rotated, redirects the flow into one of the holes. Such fittings also belong to the category of safety valves, since they are installed on low-temperature circuits, for example, where radiators are adjacent to a “warm floor” and at the same time operate from one source (boiler).
- The fact is that the instructions for combined heating systems do not provide for different heaters, so the water enters the circuit the same and in order to reduce its heating, the supply pipe is fed from the return pipe (“return”). Thus, the water temperature is lower than for radiators.
- Mixing of the coolant can occur automatically and for this purpose, sensors are installed on the low-temperature circuit, signaling servo and motivating him to action. When purchasing such a mechanism, you should not forget that the servo drive itself may be complete with the valve, but you can also purchase it separately and install it yourself by choosing the manufacturer that suits you.
- Such a device, complete with electronics, can be very expensive, but, to paraphrase the well-known saying about the sheepskin, we can say that an expensive three-way mixing valve with a servo drive is worth the money, or the money spent on it. Using electronic shut-off valves, you will save yourself from the need to constantly monitor the system and will be able to leave the house with the heating on for a long period.
Advice. Three-way valves can be made of cast iron, steel or brass and are desirable for use in systems with varying flow rates and pressures. Thus, steel and cast iron devices are better suited for centralized and industrial facilities, and brass is very effective for home heating systems.
A safety valve in the heating system is installed to relieve possible excessive pressure on inner part lines or individual components of the heating circuit. Pressure surges can occur not only during normal operation of equipment or recharging the system, but also in cases of equipment failure, which leads to emergency situations. One of the most common reasons is incorrect operation expansion tank or make-up unit. In addition, installation of the described valve will provide the opportunity to control the flow of water in the pipes, optimize it in cases of recharging the system, eliminating failure of the expansion tank.
The main body of the valve is made of brass by hot stamping. The design of this device is relatively simple and consists of the following components:
- Frame;
- Control valve (manual regulator);
- Locking membrane;
- Central working rod;
- Spring.
The principle of operation of the valve consists in the operation of a central spring and a membrane, which, at excess pressure levels, is compressed and ensures the release of excess steam-water mixture through a special release hole. At normal pressure levels, a locking membrane made of elastic polymer materials, fits tightly to the connecting hole with the supply pipeline. The regulator located at the top of the device allows you to accurately set the required valve performance. In a sense, the principle of operation of the valve is similar to the functionality of an expansion tank. The presence of water leaks in the area where the safety valve is installed indicates its operation.
H2_2There are several types of safety valves, which differ not only in their operating mechanism, but also in their scope of application. Thus, to eliminate excess pressure in the pipeline, the following types of valves are used, the selection and calculation of the number of which must be carried out taking into account their functionality: 
In order to correctly carry out the calculation and select the type of valve, it is necessary to clearly define the functions that it must perform. Connection diagram for these devices, as well as calculation of their number and technical characteristics are provided common project. The selection of the type should take into account the calculation of the power indicator of the main heating boiler and the volume of the heat exchanger, the number of heat-generating equipment and its location, as well as the features of the system’s make-up unit and the type of expansion tank. It is worth noting that the most universal is the bypass valve protection mechanism.
Installation diagram and features
Installation rules, selection and necessary calculation of characteristics of safety valves are contained in technical regulatory documents.
The main requirements that should be taken into account when installing these devices are:
- Installation in the supply circuit in close proximity to the heating boiler and make-up unit. In certain cases, with massive wiring, several such devices must be provided to maintain an acceptable pressure level;
- The installation of regulators, expansion tanks, shut-off elements, make-up units or other devices is prohibited between the installation sites of safety valves. In addition, pipes whose diameter will be smaller than the diameter of the valve itself should not be allowed to narrow.
Calculation and installation of discharge mechanisms must provide for the presence additional pipeline, which would provide a connection between the valve and, for example, the waste channel.
During operation of the heating system, it is possible to change the direction of movement hot water. This leads to destabilization of the heat supply and can cause failure of individual components. To avoid this phenomenon, a check valve for heating is installed. Its connection diagram depends on the design of the system and its parameters.
Purpose of the check valve
Structurally, it is a pipe of a certain diameter, inside of which a locking element is located. A non-return valve is integrated into the heating pipeline in areas where there is a possibility of reverse flow of water. It should not negatively affect heat supply parameters - create zones of uneven pressure, reduce the intensity of coolant flow.
Main characteristics of the device:
- Nominal bore diameter. It must correspond to the same parameter of the pipeline where the device will be integrated.
- Operating and maximum pressure in the system. If the last value is exceeded, the locking mechanism may fail, which will cause a lack of circulation in the system.
- Material of manufacture.
- Design: ball, lifting, petal or spring disc.
The latter needs to be addressed Special attention. Some models are not structurally designed to work in the autonomous heat supply of a private house or apartment. Therefore, you need to approach the selection of a check valve professionally.
Types and design features
At the first stage, the heat supply characteristics are determined - pressure value, approximate flow rate under various thermal conditions. Then, based on this data, the most suitable suitable models check valve.
Classification by design features:
- Spring-loaded. The best option for heating a private house or apartment. A rod with a spring is installed in the pipe. It rests against a disc-shaped limiter. During normal fluid movement, pressure on the disc opens the valve. If a change in direction occurs, under the action of a spring, the disk part blocks the working section of the pipe.
- Petal or spring-disc. They are used for central heating. A restrictive curtain whose diameter is equal to the working cross-section of the pipe. The spring fixes the petal in the closed state, but under the influence of pressure it opens. Advantages - maximum throughput.
- Ball. The pipe has a complex zigzag shape. In the working part there is a sphere, which rises upward under the influence of pressure, ensuring the normal passage of the coolant. Disadvantage - it is used only for large diameter pipes.
For autonomous heat supply the best option there will be a spring check valve. Most often it is made of brass, the cost is from 120 rubles.
A check valve is installed to prevent changes in the direction of fluid flow in pipes. He is mandatory element in and gravity heating. Installation on the pipe is required before connecting to the boiler pipe. It is mounted after the circulation pump.
Besides protective device installed in the pump piping - on the reserve pipe. This is necessary in case of a power outage or pump failure. In this case, the circuit with forced circulation is closed using taps, and the liquid flow is directed into a pipe with a check valve.
Another application option is the arrangement of a heating make-up unit. It is necessary to automatically add water to the main line when its volume or pressure critically decreases. The check valve for this circuit performs protective functions - it prevents the movement of coolant into the water supply system when the pressure in it critically decreases.
The protective device can be used to install underfloor heating systems and mixing units. In some cases, it is recommended to install it in the radiator piping on the bypass. The main thing is that it should not destabilize the operation of the heat supply. To do this, it is necessary to check it periodically in case of deterioration. performance qualities make repairs or replacements.
The bypass valve of the heating system thermostat is a simple mechanism designed to discharge the working medium (heat-conducting fluid) operating in heating systems into the return line when the pressure in the fluid supply circuit increases significantly.
Causes and Effects
Often, an increase in the pressure level in such systems is associated with the normal functioning of thermal valves that are installed on radiators or a thermal head. When reaching the set value in manual mode maximum temperature, the supply of hot coolant to one or another radiator is reduced, which ensures an increase in pressure, and in some cases even the whistle of the radiator shut-off valves.
Of course, this affects, in addition to the level of comfort in the room, also the performance and durability of the heating system and its individual components. To avoid such situations, professionals recommend equipping heating systems with thermostatic valves.
Equipping the system with bypass valves will make it possible normal functioning, and is guaranteed to ensure stabilization of the pressure inside it.
Where to mount and why
The thermostatic valve is mounted by inserting it into the system at a short distance from the liquid supply pump, between the return and supply circuit. The mode for setting the maximum permissible pressure limit of the working medium allows the owner to make the settings manually.
Currently, the range of these products offered trading network big enough. But as practice shows, it is better to pay attention to such well-known trade marks like Mankenberg, Valtec, DANFOSS. They have proven in practice efficiency, reliability and durability in operation.
Purpose
Regulating thermostatic bypass valves are designed to ensure a stable pressure difference between the return and supply pipes in heating systems closed type. When the heat load decreases, the thermostatic radiator valves close. This leads to an increase in the pressure drop between the return and supply pipelines.
Usage bypass valve provides the following benefits:
- reduces the load on the pump;
- protects the boiler from rust;
- prevents the occurrence of unnatural normal operation noise;
- increases the temperature of the working medium in the return pipeline.
By closing the thermostatic valves on the radiators, we will increase the resistance of our heating system (increase in the pressure difference between the return and supply pipelines). This will increase the load on the pump and lead to noise.
If the pressure reaches the maximum level, which corresponds to the settings of the bypass valve, it opens, forming an adjustable bypass. Also, a bypass valve is installed behind the circulation pump between the return and supply pipelines.
Types of valves for boiler and bypass
To understand the installation and selection of an element for radiators, you must first find out what safety bypass valves exist and what function they are intended to perform.
The operating principle of a thermostatic safety valve is quite simple and is as follows. The working medium (water) exerts pressure on the plastic area, which compresses the spring and opens the passage. But when the pressure exceeds 20 bar, the plastic plane reaches the rod, which opens the outlet to the outside.
This valve is mounted for radiators in heating systems on containers in which the liquid is under high pressure. This could be an example electric boilers. The valves installed on electric boilers have a special hole to ensure local drainage.
They are a mechanism that is equipped with a double-sided thread and located with outside gasket. The device operates on the basis of a spring that holds the rod. After applying force, the rod is pressed in and opens the passage. When pressure builds up on the back side, the blocking provides more pressure.
These products are made from brass. The rod plate located inside is made of heat-resistant plastic, and the spring is made of of stainless steel. The mechanism works due to the fact that water under pressure is supplied to the damper, which rises, clearing the way for the flow. When the pressure drops, the rod lowers, eliminating the possibility of flow returning.
Three way valves
A three-way valve in a heating system is necessary to allow the coolant to cool. They may have mechanisms with manual control, electric drive and servo drive. They have enough simple design, outgoing and incoming openings.
Flow regulation is provided by a special damper, which has the form of a rod or ball. When rotating, it orients the flow in in the right direction. Such a valve also belongs to safety valves mounted on circuits with low temperatures. For example, in places where warm floor adjacent batteries operating from the same heat source.
They are used in places where it is necessary to lower the temperature in one part of the circuit. It helps reduce temperature heated floors compared to batteries.
Mixing of the working medium can be carried out in both manual and automatic modes. To operate the valve in automatic mode, it is necessary to equip the low-temperature circuit with special sensors, information from which will be supplied to the servo drive. A three-way valve is produced from different materials, but the main ones for their production are cast iron and steel.
The four-way valve is often made of bronze. It has three holes, one of which is output and two are inlet. The regulating element in it is a corrosion-resistant rod.
When moving in a vertical direction, it does not completely block the flow of water, which makes it possible to redistribute the flows.
A modern heating system is complex, subtle balanced system. Its main task is to provide indoor comfortable conditions regardless of the weather outside the window. This means that a high-tech heating system must be able to adapt to changing weather and change its operating modes. By-effect such flexibility and sensitivity - overloads that can lead to a decrease in heating efficiency or emergency depressurization of the circuit. To ensure that the heating operates without failure, a special type of shut-off and control valves is used - safety valves.
Why is a safety valve needed?
Valves are devices that constantly, or when specific conditions are reached, regulate or completely close the flow of a substance transported in pipelines. Safety valves for heating, as the name implies, must protect pipes, heat exchangers and vessels (device housings) from harmful influences.
For example, the pressure in the heating system rises to following cases:
- When the coolant picks up operating temperature and increases in volume.
- If the water is heated too much, until steam forms (the volume increases several hundred times).
- In case of malfunctions or complete failure automated node recharge. IN in this case the pressure usually rises to the emergency level, but sometimes the valve of the device stops holding, and the coolant flows in the opposite direction, accordingly, the pressure in the heating installation drops sharply.
The boiler valve is a combined device, it prevents backflow and discharges excess water volume
Basically we are talking about pressure increasing to a critical level. But this is far from the only problem that requires an immediate solution. There are also valves that prevent backflow of water or eliminate airing in the system. All safety valves in the heating system essentially perform the same job, but are mounted in different places and can protect individual components and devices/devices. They are installed:
- To protect autonomous heating installations with closed circuit, in which boilers using all types of fuel are used as a heat generator, as well as heat pumps or solar collectors.
- For steam heating.
- In systems with heat storage tanks.
- In DHW circuits that are equipped with flow-through, storage or electric heating element heaters.
Safety valves in heating installations operate on different principles and decide different tasks. Therefore, it is customary to divide them into several types:
- regulating,
- bypass,
- waste,
- reverse,
- air.
Types of valves for heating and hot water systems
Air valves
The air inside the circuit is compressed by the coolant into “plugs” and interferes with the circulation process, without which the operation of water heating is impossible. It enters the pipes during filling of an empty system, or when replenishment is carried out (the water contains a certain amount of air in dissolved form). It partially penetrates through seals at joints and connections, as well as through diffusion through the walls of pipes and heat exchangers. In any case, it is necessary to prevent the formation of traffic jams.
To do this, “Mayevsky taps” are installed on the radiators - manually controlled valves (you need to unscrew the screw). But there is also automatic air vents, which react without human intervention to the air in the pipes. Air valve for heating, it has a float in its body, which, moving up/down, moves a needle through a rocker arm and opens or closes the discharge hole. Install it in places where air accumulation is most likely (manifold, top point of the riser, pump with air separator).
Check valve
Installed on pipelines to prevent the coolant from flowing in the opposite direction. Check valves are installed at the inlet of a heating or storage tank, and can also be seen on the main bypass line. The device is a mandatory part automatic node make-up, where it stops the flow of coolant into the water supply pipes if the pressure there is too low.
The non-return valve for heating is very simple. The seat inside the body is covered by a spring-loaded membrane. As it moves, the water/antifreeze compresses the spring and lifts the membrane - the flow is open. If the water flows in the opposite direction, the spring will press the membrane against the seat (the liquid itself will also contribute to blocking) - the duct will be closed. In another design, the control element of the device is a hollow ball made of metal or heat-resistant rubber. This “free” ball is buoyant and is easily lifted by the flow above the passage hole, but during the reverse movement it fits tightly into the saddle.
For boilers use special check valves with outlet for water discharge. In fact, the “spout” is another valve that discharges the excess volume of liquid that appears when the water is heated and in the absence of analysis. It can also release water when too high blood pressure in the water supply.
Reset valve
It is triggered when the pressure in the heating system exceeds a set value. The device simply drains the “extra” coolant, thus returning the pressure to normal. The main elements of a relief valve for heating are:
- locking unit (seat + bolt);
- a sensitive mechanism that sets the response pressure (spring or loaded lever device).
In spring and lever valves, the coolant with set pressure exceeding the load/spring force, undermines the pressed membrane and goes into the sewer, collecting container or pit. Then the force of the loaded valve will begin to overcome the falling water pressure, and the valve will close.
Relief valve(left) is part of the boiler safety group
Bypass valves
The design of this type of device is similar to discharge models. Only they do not remove excess coolant from the system, but redirect it to return pipeline. In what cases is this necessary? Nowadays, users actively use automatic and manual thermostats on radiators. But by “squeezing” the flow to reduce the heat transfer of the battery (usually all at once), we reduce the speed of the coolant and increase the pressure in some areas. But circulation pump works without slowing down, which negatively affects its durability. To prevent such problems, a heating system bypass valve is precisely what is needed, which allows water to flow through a short ring. Unlike dumpers, this device functions to drain water long time, not in individual moments when the likelihood of an accident is high.
Control valve
This device designed to control the flow of coolant by changing the cross-section of the passage. It's a two way actuating mechanism, which can be triggered by manual installation or by various types drives (most often electric). According to the type of locking element, control valves are divided into:
- saddle,
- ball
Some types of heating control valves can be used not only to balance water flow, but also to control pressure. There are many applications for such devices, but most often they are installed on radiators and on the DHW circuit with a tank indirect heating.
A valve mounted at the inlet to the battery allows you to limit the flow through the heat exchanger and direct the coolant to other heating devices
Safety valves increase the efficiency and safety of your heating system. These are the same important elements, like batteries, pipes and a heat generator.
Video: safety valve