Explosion valve ARMAK. Valve for a water heater: which one is needed and why Why do we need a safety valve

The safety valve for a water heater only from the outside seems like a simple, insignificant device. Inside, it's a pretty advanced boiler protection tool.

How a safety valve works

So, we take an ordinary valve from an ordinary boiler.
Not all valves have a pressure release handle. It does not play any special role in the operation of the valve. So, periodically, once every six months, open and close to check the performance.

Let's take a closer look at what's inside. And inside there are 3 (three) independently working valves.
1. The safety valve itself
2. Check valve
3. Bypass valve

Safety or blast valve

Its purpose is to prevent an accident. The safety valve consists of a metal stem with a plug at the end (1), a powerful spring (2) and a water discharge fitting (3).

How does he work? Yes, simple.
Let's say 6 bar is written on our valve. When heated, the water inside the boiler begins to expand. Since she has nowhere to go, the pressure inside the tank begins to grow. As soon as the pressure rises to 6 bar, the rod will compress the spring and excess water will flow out through the fitting. In reality, all this happens smoothly and water simply digs out through the fitting.

check valve

Water flows into the boiler, but not back. It consists of a rubber plug (1), a plastic rod (2) and a spring (3). The spring in the check valve, unlike the safety valve, is weak. She only needs to fix the plug on the valve seat.

Do not expect from this valve the same precise operation as on plumbing check valves. It does not have the task of keeping the reverse flow under pressure. It protects the boiler from unauthorized water leakage. Simply put, so that water does not leave it in the event of an accident or lack of water in the supply line.

bypass valve

An inconspicuous and very important valve. Bypass valve, this is a stem check valve(1) with a small spring (2). Opens in the opposite direction from the check valve. Sounds absurd, but it's true.

Let's try to figure out what is so important in it. There is a safety valve. Its task is to relieve pressure above 6 bar.
And what happens to the boiler tank up to 6 bar? The water heats up and expands. The pressure is growing, albeit not critically: 4 - 4.5 - 5 - 5.5 bar. The boiler is not a rubber ball and its tank is welded from sheet steel, and not from tank armor. Naturally, deformation occurs. Buck is trying to bloat. Microcracks appear on the enamel and welds. If only this extra pressure could be blown off somewhere on occasion.
This is where the bypass valve comes to the rescue. How does he work? Flat. The boiler is heating up. The pressure is building up. Turn on the washing machine. She starts taking water. The water pressure in the pipes drops a little, the bypass valve sees this, opens and relieves excess pressure from the boiler into the line. The pressure in the tank equalizes to water pressure. The boiler continues to heat up. Not necessarily a washing machine, it can be a toilet bowl or any faucet.
What can we sum up?
The safety valve is the most important part of the water heater. Its presence and performance directly affects the life of the boiler.

Boiler equipment, whether it is a boiler in a private house or a large boiler room in an enterprise, is a source of danger. The boiler water jacket under constant pressure is potentially explosive.

To ensure safety, boilers and other heat generators manufactured today are equipped with many protective systems and devices. One of the simplest and most affordable - installed. It is sometimes also called an explosive valve.

Causes and consequences of overheating of the coolant

The problem of boost is especially important for solid fuel boilers. An emergency situation, as a rule, occurs when the water in the heating boiler circuit overheats. As soon as the coolant heated above the norm boils in the boiler tank, it instantly turns into steam. This is followed by a sharp increase in pressure in the heating system of such a steam boiler.

As a result of overheating of the heating boiler, the risk of destruction of fittings and polymer pipes increases. Leaks can begin at the system's piping connections, up to pipe ruptures. The worst thing is a boiler explosion or an electrical short circuit in boiler equipment.

What is a safety valve for?

The troubles associated with excess pressure in the heating system are extremely dangerous for people and buildings. Explosive valves are installed to prevent the severe consequences of overheating. Since the boiler itself is the source of the critical pressure increase, the valve should be located as close to it as possible. It is mounted on the supply heating pipeline.

Manufacturers heating equipment often produce their products already equipped with safety groups - a pressure gauge, and a relief valve. This group is usually built into the jacket of the heating boiler. If such a complete set is not provided for in the purchased boiler, then it is necessary to install it yourself.

When is a safety valve needed?

Unlike solid fuel boilers, when using electric or gas, explosive safety valves are not installed. These devices have their own automation, and there is almost no inertia. This means that as soon as the temperature of the coolant reaches the set point, electrical element or geyser turn off on their own. At the same time, heating is also stopped, which eliminates the risk of overheating, and, accordingly, pressure increase to critical values.

Solid fuel boilers, as well as furnaces with a water circuit, are systems in which the use of safety valves is mandatory. Whatever automation is in solid fuel heat generators, after heating the liquid in the network to the nominal value, the furnace will continue to raise the temperature for some time, although access to the chamber is closed by the sensor, and the flame began to die out. This is how the effect of inertia manifests itself. When the temperature in the furnace reaches 90-95 degrees (limit values for most boilers), vaporization is inevitable. The consequence may be a depressurization of the heating system or an explosion of the boiler.

If a safety valve is installed on the boiler in the system, then the pressure increase after the coolant boils will be prevented. The valve will automatically release excess steam to the outside, reducing the pressure in the system to normal. After that, the valve will close and work the next time only in case of a repeat of the abnormal situation.

Safety valve device

The valve is made of plumbing brass using hot stamping technology. It consists of two parts that have a semi-solid state.

The main element of the valve is a special spring. Depending on its elasticity, the power of pressure is determined, which is applied to the membrane that closes the outlet. The standard position of the membrane is in the saddle, preloaded by this spring.

With its upper part, the spring rests against a metal washer, which is mounted on a rod, the end of which is fixed on plastic handle. It is she who allows the adjustment of the explosive valve. The sealing parts and the membrane itself are made of polymer. The spring is steel.

Valve principle

Being in standby mode, the entrance to the inner chamber is closed by a membrane. In the event of an emergency, the mixture of steam and water begins to rest against the membrane, opening it at peak pressure. As a result, the steam-water mixture enters the chamber and then exits through the hole on the side.

After the pressure is reduced, due to the release of a certain amount of water from the system, the membrane falls into place and blocks the water outlet. Sometimes such valves operate frequently, especially when the boilers are operating at maximum power. This is undesirable, since the boiler may lose its tightness and leak accordingly.

If traces of leakage from the safety valve are found, it is necessary to urgently inspect the boiler and the heating system, since its operation is a sign of the heating system operating in extreme conditions. However, sometimes the expansion tank can also be the cause of emergency pressure relief. Therefore, you should definitely check it out.

In addition to the valve under consideration, the PGVU valve can also be used for dust and gas air pipelines. It has the same operating principle. However, in the case of its use, it does not matter at all whether the boiler is a steam boiler or solid fuel, and also what exactly will be thrown out - water, steam or gas.

How to choose a safety valve

If a valve is not supplied with the boiler, it will have to be purchased separately. The choice is made based on the characteristics. The thermal power and the maximum possible pressure of the coolant in the heating system matter.

For reference. Most well-known brands of solid fuel boilers have a maximum allowable pressure of about 3 bar, with the exception of STROPUVA products. They have a limit of 2 bar.

It is best to install a valve that provides adjustment in several ranges. Naturally, the values of the boiler installed in the boiler room must be included in these ranges. After that, the valve is selected by power - the passport to the boiler will help here, in which the power limit of the unit in terms of heat is always indicated.

It is strictly forbidden to install an explosion valve after the pump responsible for the circulation of the coolant in the system. There is another rule. Do not install shut-off valves between the boiler and the relief valve.

Not only the life of the equipment, but also the safety of residents depends on the correct piping of an electric storage-type water heater (boiler). That's how serious things are. And its correct piping is a safety valve for the supply water heater cold water.

What is it needed for

Installing a safety valve prevents the pressure inside the device from rising above the norm. What causes pressure to rise? As you know, when heated, water expands, increasing in volume. Since the boiler is a sealed device, there is nowhere for the excess to go - the taps are closed, there is usually a check valve on the supply. Therefore, heating water leads to an increase in pressure. It may well happen that it exceeds the tensile strength of the device. Then the tank explodes. To prevent this from happening, put a safety valve for the water heater.

Maybe you don't need to install a safety valve, but just remove the check valve? With a sufficiently high and stable pressure in the water supply, such a system will work for some time. But the decision is fundamentally wrong, and here's why: the pressure in the water supply is rarely stable. Often there are situations when water barely runs out of the tap. Then the hot water from the boiler is forced out by pressure into the plumbing system. At the same time, the heating elements will be exposed. For some time they will warm the air, and then they will burn out.

But burned out heating elements are not the worst thing. It is much worse if they become hot, and at this time the pressure in the water supply system will rise sharply. The water that has fallen on the hot heaters evaporates, there is a sharp increase in pressure - by a jerk - which leads to a guaranteed rupture of the boiler flask. At the same time, a decent volume of scalding water and steam escapes into the room under high pressure. What it can threaten is understandable.

How does it work

It would be more correct to call a safety valve for a water heater a valve system, since there are two of them in the device.

They are located in a brass or nickel-plated case, which looks like an inverted letter "T" (see photo). At the bottom of the housing there is a check valve that prevents the outflow of water from the water heater when the pressure in the system decreases. In the perpendicular branch there is another valve, which, when the pressure is exceeded, allows some of the water to be released through the fitting.

The mechanism of operation is as follows:

As long as the pressure in the boiler is less than that in the water supply (when filling or when the tap is open), the poppet plate of the non-return valve is pressed out by the flow of water. As soon as the pressure equalizes, the spring presses the plate against the protrusions of the body, blocking the flow of water.
When the heating is on, there is a gradual increase in the temperature of the water, and with it the pressure also increases. Until it exceeds the limit, nothing happens.
When the threshold level is reached, the pressure compresses the safety valve spring, and the outlet to the fitting opens. Some of the water from the boiler is bled through the fitting. When the pressure drops to normal, the spring closes the passage, the water stops draining.

According to the principle of operation, it is clear that water from the fitting will constantly dig in. This happens when the water is heated, when the pressure in the water supply decreases. If you periodically see water on the fitting, then everything is working fine. But the draining liquid must be diverted. To do this, put a tube of suitable diameter on the pipe, be sure to fix it with a clamp. The normal working pressure of the boiler is from 6 bar to 10 bar. Without mechanical fastening, the tube will be torn off in no time, so we select a high-quality clamp, tighten it well. Take the tube to the nearest sewer drain.

One more thing: the tube on the fitting needs a transparent and preferably reinforced (the so-called "herringbone"). Why reinforced is understandable - due to pressure, and transparent - to be able to control the performance of the device.

Species and varieties

If we are talking about conventional safety valves for a water heater, then they look almost the same, only the nuances differ. But it is these small details that are responsible for the convenience and safety of operation.

In the photo above, there are two safety valves with release levers. They are needed for periodic performance checks. The lever flag is lifted up. He pulls the spring behind him, freeing the let to dump water. This check should be done about once a month. You can also empty the boiler tank - raise the flag and wait until everything drains.

Design features

The difference in the presented models is that the model in the photo on the left has a lever fixed with a screw. This eliminates the possibility of accidental opening and complete discharge of water.

Two other differences stand out. This is an arrow on the body, indicating the direction of water movement, and an inscription showing what pressure the device is designed for. Seemed like minor details. But if you can figure out the direction of water movement (look in which direction the poppet valve is deployed), then it’s more difficult with the face value. How to distinguish, for example, at 6 bar or at 10 bar? Only checks. And how will their sellers be distinguished? No way. By boxes. What if they put it in the wrong box? In general, it is better not to take a valve without marking on the body. These are usually the cheapest of the Chinese designs, but the price difference isn't big enough to make it worth the risk.

Safety valves - serviced and not

Also pay attention to the shape of the water outlet. The model on the left has a long, non-linear fitting. A hose fits on it quite easily and the length is enough to install a clamp. The shape of the fitting on the model on the right is different - with an extension towards the end, but more importantly, the fitting is short. You can still pull a hose on it, but the clamp is in question. Unless you crimp it with wire ...

In the next photo, safety valves without a forced pressure relief flag. The one on the left has a screw cap at the top. This is a serviced model. If necessary, you can unscrew the lid, remove blockage, scale and other contaminants.

The model on the right is the worst of the options. No markings, forced reset or maintenance. These are usually the cheapest available, but this is their only merit.

For large boilers

All the above models are suitable for water heaters up to 50-60 liters. There are other models for larger boilers, many of which have additional devices built in. Usually this is a ball valve and / or a pressure gauge - to control pressure.

The fitting for water discharge here is with a regular thread, so there will be no problems with the reliability of fastening. Such devices already have a rather high price, but their quality and reliability are much higher.

Not for everyone appearance love these devices. For those who give aesthetics great importance very attractive devices are produced. Their price, however, is comparable to the price of an expensive water heater, but it is beautiful.

Can other valves be installed?

Sometimes, instead of a special safety valve for the boiler, they put a subversive one, which is intended for emergency discharge of water for heating. Although their functions are similar, the basic mode of operation is fundamentally different. Demolition should only work in emergency situations. It is designed for salvo discharge of a large volume of liquid. It is not suitable for continuous bleeding of small portions of water. Accordingly, it will not work correctly.

Another case is the installation of only a check valve. It will not allow water to drain when the pressure in the water supply decreases, but it will not save you from increasing pressure in the boiler. So this option doesn't work either.

How to choose and install

The safety valve for the water heater is selected according to the pressure for which the unit is designed. This number is in the passport. Also, the choice is influenced by the volume of the tank. They produce devices with a response limit of 6, 7, 8, 10 Bar. Basically, all units are designed for such pressure. So everything is simple here.

Installation is simple: linen tow or fum tape is wound on the thread, after which the valve is screwed onto the pipe. It is twisted by hand until it stops, then another one or two turns with the help of keys. It is much more important to choose the right place for its installation. This valve is installed directly on the cold water inlet pipe.

Next, there may also be a check valve, which is also called a shut-off valve. But this is already reinsurance - the same device is available in the safety, and often after the water meter at the inlet. The installation diagram is shown below. This is one of the normal options.

The diagram has a ball valve. It is necessary to empty the tank before conservation for the winter (in summer cottages) or before dismantling for maintenance and repair. But more often they put it on a tee, which is screwed directly onto the inlet pipe of the water heater. A safety valve is screwed onto the tee from below, and a ball valve is placed in the side outlet.

Actually, these are all normal options.

Breakdowns, causes, elimination

In principle, the safety valve for a water heater has only two failures: water either often flows from it or does not flow at all.

First of all, it must be said that water bleeding during heating is the norm. This is how the system should work. Water can also be drained when the boiler is turned off, if the pressure in the cold water supply pipes is higher than the valve actuation limit. For example, a 6 bar valve, and 7 bar in the water supply. Until the pressure drops, the water will bleed off. If this situation is repeated often, it is necessary to install a reducer, and it is best on the water in an apartment or house, but there are compact models of reducers that can be installed at the entrance to the boiler.

How to check if the valve is working? If there is an emergency reset lever, this is easy to do. With the boiler switched off, it is necessary to raise the lever several times, releasing the excess pressure. After that, the dripping stops and does not resume until heating starts.

If the water continues to drain, the spring may be clogged. If the model is serviceable, the device is disassembled, cleaned, and then put in place. If the model is not collapsible, you just need to buy a new valve and install it.

This is how the gearbox looks like - to stabilize the pressure on the boiler

Constantly dripping water is unpleasant and “hit” the wallet, but not dangerous. It is much worse if, when heating the water, you never have water in the pipe. The reason is that the valve is clogged or the outlet fitting is clogged. Check both options. If it doesn't work, change the valve.

If you do not limit the heating of water in the boiler and pipelines, then it boils and passes into the vapor phase, causing the pressure in the network to rise to a critical level. The result is a rupture of the line or casing of the heat generator and complete steam room. To prevent the described emergency situation, a safety valve is used to relieve pressure in the heating system in advance. So the selection of this important element should be given Special attention in which this material will help you.

Operating principle

Most ordinary users who are faced with closed water heating systems are familiar with only one type of safety valve - a simple spring-loaded valve with a fixed setting, shown in the photo. The reason is clear - these products are installed everywhere on any boilers, since they are part of the safety group along with a pressure gauge and an air vent.

Note. Wall-mounted heat generators operating on electricity and natural gas are equipped with safety elements from the factory. They are placed inside the case and are not visible from the outside.

Let's understand how a conventional emergency valve, shown in the diagram above, works:

Under normal conditions, the diaphragm, attached to the stem and supported by a spring, sits tightly in the saddle and hermetically closes the passage.
If the coolant overheats, it expands and creates excess pressure in the closed system, partially compensated by the expansion tank.
When the amount of water backwater reaches the threshold of the valve (usually - 3 Bar), the spring is compressed under its influence and the membrane opens the passage. The automatic discharge of the boiling coolant is carried out until the spring has enough force to close the flow area again.
In the event of an emergency, the owner of the house can relieve excess pressure himself by turning the handle on the top of the product.

A few words about where the relief valve is placed along with the safety group in a closed heating system. Its place is on the section of the supply line in the immediate vicinity of the boiler (recommended no further than 0.5 m).

An important point. It is forbidden to install taps, valves and other blocking devices on the pipeline leading from the heat generator to the safety elements.

It is not worth it to tightly connect the pipe of the product to the sewer - wet spots or puddles will indicate valve operation and problems in the heating network. For example, the expansion tank failed or the circulation pump failed when working with a solid fuel boiler (perhaps the electricity was turned off). Often the device begins to leak due to debris getting between the seat and the plate. Learn more about his work in this video:

Clarifying information. Relief spring valves are called subversive by craftsmen and installers, because the pressure of the coolant compresses the spring and causes the membrane to undermine. Do not confuse them with explosive elements installed on the chimneys of industrial boilers burning natural gas.

The traditional demolition design described above is not perfect. The spring mechanism, driven by excessive pressure, is not accurate and may work late when the temperature in the boiler tank has reached 100 ° C and above, that is, boiling has begun. Of course, you can try to adjust the product with a screw or change the settings (there are versions with an adjusting cap), but this does not always give the desired effect.

Moment two: the safety valve for the boiler protects it from destruction, but not from overheating. After all, the discharge of the coolant does not allow to cool the heating unit if combustion in the furnace continues. And finally: in heating systems open type such devices are generally useless, since the water in them can boil without increasing pressure.

Leading manufacturers of heating fittings offer products of modern design, devoid of the listed disadvantages - thermal relief valves. These protective elements do not respond to an increase in water pressure in the system, but to an increase in its temperature to a critical level. There are 3 types of products:

reset with a remote temperature sensor;
combined device with a temperature sensor and a make-up circuit;
the same with direct installation in the pipeline.

For reference. Here are the names of reliable brands, whose emergency fittings can be safely bought and used in private homes. These are the manufacturers ICMA and CALEFFI (Italy), Herz Armaturen (Austria) and the world famous European brand Danfoss.

The principle of operation for all varieties is the same: a spring mechanism with a membrane (or two) is driven by a bellows with a heat-sensitive liquid that expands significantly when heated. In this way, the thermal relief valves react quite accurately when the critical temperature is reached. We propose to consider each of them in more detail.

Element with remote sensor

The product is the same spring mechanism built into the body with two nozzles for connection to the supply line and discharge into the sewer. The rod that opens the plate and the way to the coolant is moved by bellows (2 groups - main and reserve). When the water overheats (from 95 to 100 °C), they are pressed by a thermosensitive liquid coming from the sensor flask through a capillary tube. The design of the safety element is shown in the figure:

The temperature valve is included in the piping of a solid fuel boiler in three ways:

with cooling through the water circuit of the heat generator;
the same, through a special emergency heat exchanger;
coolant discharge with automatic make-up.

The first scheme, shown below, is used for double-circuit heating installations that heat water for domestic hot water. When the sensor, mounted under the casing of the TT boiler, acts on the mechanism, the hot water from the circuit is drained into the sewer, and cold water from the water supply takes its place. Whatever the cause of the accident, such a flow system will quickly cool the boiler jacket and prevent the consequences.

Note. The publication uses diagrams from the CALEFFI brand, taken from the official resource of the manufacturer.

The second scheme is intended for heat generators with built-in emergency heat exchanger for cooling in case of overheating. Such units are produced by European brands Atmos, Di Dietrich and others.

An example of connecting a waste element through a standard heat exchanger, see the video:

The latter scheme is implemented only together with an automatic make-up system, since here the valve discharges the coolant, and not the cooling water.

As you can see, the manufacturer allows the installation of two emergency means - for pressure (safety group) and for temperature (relief valve)

Warning. It is not recommended to use automatic make-up for wood-burning heaters with a cast iron firebox. The latter is afraid of temperature changes and can crack from supplying a large amount of cold water to the return line.

Combined products with make-up system

This bright representative of emergency valves is similar in principle to bypass valves and performs 3 functions at once:

Discharge of superheated coolant from the boiler tank by a signal from a remote sensor.
Efficient cooling of the heat generator.
Automatic make-up of the heating system with cold water.

The picture above shows the design of the product, where it can be seen that 2 plates are installed on one rod, simultaneously opening 2 passages: the boiling coolant is discharged through the first, water flows through the second in the opposite direction and replenishes the losses. The connection diagram for a combined bypass valve with a solid fuel boiler looks like this:

Note. If it is necessary to use a similar device for cooling a TT boiler with cast iron heat exchanger, then the flow must be organized through an open expansion tank or indirect heating boiler.

The bypass valve with a triple outlet works according to the same combined principle, only it is built directly into the coolant supply pipeline near the heating unit. The bellows is located in the part of the body placed in the pipe. The discharge is made through the lower branch pipe, and the water supply and the make-up line are connected to the two upper ones. Such products are used when there is a lack of free space in the boiler room.

How to choose emergency fittings

Of course, at the price of purchase and installation, a traditional blast valve will cost less than temperature devices. It will easily protect a closed heating system tied to a gas, diesel or electric boiler, because in the event of an accident they stop heating almost instantly. Another thing is a wood-fired and coal-fired heat generator that cannot go out immediately.

To successfully select a thermal relief or overpressure valve, follow these guidelines:

When using any energy source other than solid fuel, feel free to buy a conventional demolition device.
Study the documentation of your heat source or boiler (depending on what needs to be protected) and select safety fittings according to the maximum allowable pressure indicated in it. Most of heating technology designed for a limit of 3 Bar, although there are exceptions - Lithuanian Stropuva boilers can only withstand 2 Bar, and some Russian units (from inexpensive ones) - 1.5 Bar.
For effective cooling of wood-fired heat generators in the event of an accident, it is better to install one of the heat relief valves. Their maximum working pressure is 10 bar.
AT open systems with a TT boiler, pressure relief is useless. Choose a safety product that operates at a coolant temperature of 95-100 ° C, suitable for your unit and make-up method.

Advice. Refrain from buying cheap safety fittings from China. Not only is it unreliable, it also leaks after the first explosion.

In addition to products with fixed settings, there are adjustable valves on the market. If you are not a professional in the field of heating, then you should not buy them, and there is no special need.

If you are keenly interested in the safety of the boiler room and the reliable operation of heating equipment, we recommend that you carefully study the range when buying fittings. The point is that there are new healthy foods, which cannot be reviewed within the framework of this article, but they may be useful to you.

operational moment. Monitor the condition of safety valves in order to detect the operation in time and understand the causes. Direct the heat release devices into the sewer funnel with a jet break - an unexpected splash of water in the boiler room and wet footprints will make it clear that an emergency has occurred.

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types, selection and installation rules

A safety or relief valve is an engineering device designed to regulate the operating water pressure in a closed or open heating system.

The device prevents undesirable phenomena associated with an uncontrolled increase in temperature or pressure.

Why you need an overpressure relief valve

The relief valve is used to remove excess coolant when the operating pressure in the system is exceeded. The device was developed in accordance with the Mendeleev-Clapeyron law, when water begins to expand when heated and in a closed system exerts critical pressure on the walls of pipelines and other equipment.

Overheating of water and its boiling is an undesirable phenomenon in heating systems. An increase in pressure to critical levels leads to depressurization of joints and gates, disruption of valves and taps, and bursting of pipes in vulnerable areas.

The valve is designed to prevent an emergency. It is a mechanism designed to drain a small amount of hot water, due to which the working pressure in the system is normalized.

To do this, the device is connected to the pipeline at the supply section as part of the so-called. safety groups together with an air vent and a pressure gauge. To discharge excess fluid, a discharge pipe is connected to the valve, through which water is discharged into the sewer.

What does it consist of and how does it work?

The relief valve is a device in a metal case made of brass or stainless steel. Inside the device there is a rod with a spring connected to a special membrane, which is directly pressed by the working medium, but under normal hydrodynamic parameters, it is opposed by a spring that keeps the membrane closed.

The equipment works on the principle of direct action: the working medium, when the temperature rises and the volume increases, presses on the spring, which opens the hole and releases excess hot water until the pressure returns to normal. After that, the spring presses on the membrane in the opposite direction, blocking the outflow of the working medium.

Thus, as soon as the water pressure in the system rises above a critical point, the spring compresses, opening the through hole to dump excess water. After a short drain of hot water, the pressure in the system is normalized, and the spring is activated, closing the valve.

In addition to the automatic mechanism based on the actuation of a spring, the valve has a handle for manual discharge of water, which allows the user to independently drain a small amount of heated coolant when the pressure gauge approaches critical.

Important! The reset device is installed only on the supply section of the heating system no further than 50 cm from the boiler. No foreign devices (faucets, valves, taps, etc.) can be inserted between the boiler and the valve.

Varieties of overpressure relief valves

There are several generally accepted classifications of safety valves. Depending on the mode of action, there are:

direct-acting valves - devices are triggered by direct action of the working medium on the spring mechanism;
indirect action - work when exposed to an external source of pressure (hydraulic fluid or electric drive).

According to the type of load on the membrane, the device is divided into the following types:

cargo - the most common mechanism for adjusting the working pressure in the system;
spring - resistance to the pressure of the working medium is exerted by a lever that presses on the stem, holding it in the closed position;
lever-spring - hybrid devices equipped with a spring and a lever mechanism;
magnetic-spring - these are valves of indirect action, equipped with an electromagnetic drive.

Modern manufacturers offer other types of overpressure relief valves.

For example, there are thermal relief valves on the market that do not react to an increase in pressure, but to an increase in the temperature of the working medium. They may have a remote or built-in temperature sensor that operates on the basis of a temperature-sensitive fluid located in the bellows.

When the water temperature is heated to 95-100 degrees, the liquid in the capillary tube of the sensor flask puts pressure on the bellows, which open the stem and drain the overheated water to normalize the pressure.

According to the control method, the valves are divided into two groups: manual and automatic - they are controlled, respectively, manually or are triggered automatically when the pressure of the working medium increases. In addition, there are regulated and unregulated. Adjustment allows you to set any threshold water pressure.

According to the type of working medium, there are water and air. The former remove excess liquid, the latter discharge excess gases from the system, preventing the airing of circuits in closed heating systems.

There are also control valves equipped with a built-in thermostat, which changes the throughput of the device, slightly opening or completely blocking the outflow of the working medium. Such devices are usually installed at the entrance to the heating radiator in the room.

How to choose a safety valve

The main criterion for choosing a safety device is the technical parameters of the heating system specified in the project documentation.

In most modern closed systems heating, standard brass direct acting safety valves are used.

They are suitable for installation in systems operating on diesel, gas or electric boilers. When the critical temperature and pressure are reached, the safety valve almost instantly stops further heating of the working medium and prevents an accident.

Simple brass safety valves are designed to exceed the pressure of the working medium up to 3-6 bar.

When choosing a valve for diesel, gas and electric boilers, it is necessary to choose safety devices that can withstand a pressure of 20-25% higher than the normal working pressure in the system.

For solid fuel boilers operating on peat, briquettes or coal, you need to more carefully choose the type of vents, because. solid fuel cannot stop burning instantly and continue to heat the water for some time after turning off.

They are suitable for modern thermal relief safety valves, designed for a maximum working pressure of 10 bar. The same applies to solid fuel boilers in open heating systems where relief valves operate most efficiently by responding to an increase in operating temperature rather than pressure.

Important! When choosing a safety device, be sure to study the technical documentation for the boiler equipment. Manufacturers usually indicate the required technical parameters for maximum pressure and temperature, according to which relief valves are purchased.

It is undesirable to choose cheap engineering equipment from Chinese manufacturers: it is usually not of high quality and quickly fails. An indicator of wear is an increase in the number of valve actuations.

Installation rules

In closed heating systems, the safety valve is installed at the highest point of the supply circuit.

Between it and the boiler there should not be any functional elements (valves, valves, gate valves). A mandatory requirement for the installation of the device is a strictly vertical position. Installing even at a slight angle will cause water to leak.

A drain hose is connected to the discharge pipe of the valve, which is sent to the sewer drain. It is advisable to choose a location where the device is to be installed so that it can be easily accessed in the event of a need for service or replacement.

Like all types of engineering equipment in direct contact with the working medium, safety valves are subject to contamination.

For normal operation of the equipment, it must be periodically cleaned. Otherwise, the device begins to leak water even at normal operating pressure. A metal device can be cleaned with ordinary table vinegar or alcohol.

Important! Even if the valve has begun to leak, it is impossible to install a plug on it, because. this most often leads to an emergency. It is advisable to replace the device with a new one as soon as possible, choosing the appropriate one in accordance with the operating water pressure.

infotruby.ru

Safety relief valve: varieties and principle of operation

Safety relief valves (PSV) are devices that are used in various gas pipeline structures and perform the function of dumping excess gas into the atmosphere or an auxiliary pipeline. Gas release is necessary in order to get rid of excess pressure in the communication. UCS are also used in other types of pipeline structures (heating, plumbing), however, everywhere they perform the same function.

Excessive pressure in any system is extremely dangerous, so relief valves are installed on almost all types of pipelines

Why are PSCs needed?

Relief-type safety valves are necessary to equalize the pressure in the system, with its short-term increase. During operation, such devices are in the closed position, so they are referred to as closed pipe fittings. Such devices are mounted at the communication point, which is located behind the regulator, and work in the event of an increase in pressure in the gas pipeline. After the release of excess gas, the valve returns to its original state.

In the absence of PSK, various emergency situations are possible, among which the most common is the mechanical destruction of the gas pipeline. Excessive pressure that occurs in the system is automatically removed by means of the PSK.

Note! PSK remove excess gas to the environment or to a branch of the main pipeline with a low pressure indicator.

PSK is an indispensable device that is responsible for the safety of pipeline structures, as well as pumps and fittings. Consider the main factors that precede the occurrence of excess pressure in the system:

various malfunctions that occur in the equipment during its operation;
increase in the temperature indicator in communication;
various physical processes that take place within the network;
errors in the thermal-mechanical scheme.

An increase in pressure can occur different reasons and the only way to prevent an accident is to reset it

The main advantages of PSK

Shut-off safety valves may have different design, however, they all have common advantages, which are recommended to pay attention to. Consider the advantages of these devices:

in addition to providing automatic control of pressure indicators in the system, these safety devices provide sealing in the pipeline;
one of the main advantages of PSK is that they have a simple design;
PSK are easy to install;
the versatility of these products allows them to be used in any type of communications;
are equipped with sealing elements and are resistant to wear;
have an optimal construction height;
resistant to temperature changes;
resistant to corrosive influences. PSK can be used even in pipelines transporting aggressive chemicals;
able to carry heavy loads.

Shut-off valves can be sealed with a bellows. Thus, the wear resistance of the safety device is increased.

Varieties of PSK

To date, all PSKs are classified into types depending on the design and features of functioning. Consider the main types of safety relief devices, depending on their design features:

membrane;
spring.

By design features valves are divided into two types, one of them uses a spring as a locking element

Membrane. The main advantage of such devices is that they are equipped with a special membrane. Such a membrane is characterized by high elasticity and performs the function of a sensitive part. In membrane devices, the spool performs only one function - shut-off. Thanks to the presence of such structural element, like a membrane, the CPS sensitivity indicator is enhanced. Such an increase contributes to the expansion of the operational range of shut-off and safety valves, since it becomes possible to use them in pipeline structures with low pressure of the working medium.

Note! As a rule, diaphragm valves begin to work in the event of a pressure increase of no more than 15%.

Spring. This type of PSK is equipped with a spring, which is necessary in order to open the valve when the pressure in the system rises, as well as to purge the device. Blowing out the PSC is a necessary measure that allows you to reduce the risk of sticking of the spool to the seat, remove foreign particles that clog the sealing elements.

In addition, PSCs are subdivided into:

low-lift products;
full lift products.

In the first case, the shutter opens slowly (in proportion to the increase in pressure inside the communication). In turn, the safety full-lift relief valve opens in the event of a sharp increase in pressure.

Relief valves are most often made of metals that do not rust.

Device, dimensions and principle of operation

Safety relief valves are mainly made from materials that are resistant to the harmful effects of corrosion (aluminum, brass). The body of the product, as a rule, has the shape of a truncated cone, equipped with a saddle. There are two threaded holes on the body, which can have different diameter(1" or 2" depending on valve type). To date, you can find two types of valves, which are classified according to the cross section - PSK-25 and PSK-50. Characteristics of PSK are presented in table No. 1.

Table 1

PSK have a forced opening mechanism, which is necessary in order to check the operational affiliation of the device. Checking the device for operability is carried out as follows: it is necessary to pull on a special element of the forced closing mechanism - traction (such manipulation should be carried out 3-4 times).

The principle of operation of the PSC is quite simple: excess gas from the network enters the valve cavity and acts on the membrane, which helps to retract the spring. Thus, the membrane is lowered and the gas is released into the environment. After removing excess gas, the pressure in the communication returns to normal, and the membrane returns to its normal position by renewed action on the spring.

Before the valve without fail a check valve must be installed. This is necessary in order to stop the valve if necessary.

Valves must meet all the requirements of GOST, performance testing is carried out without fail

Requirements for PSK

Safety relief valves must comply with the necessary physical and technical parameters, which are described in the relevant documentation. Consider the main requirements that are put forward to the PSC:

the shutter of the device must open fully at the maximum pressure that was set during the adjustment;
the shutter returns to its original position automatically after the pressure in the network reaches the nominal value or is lower by 5%;
after normalization of pressure, the valve should close without loss of sealing performance.

Helpful information! It is more difficult for devices of a low-lift type to ensure proper tightness of the shutter after removal of gas. This is due to the fact that such valves require more effort to achieve the desired tightness.

If the shutter closes with some delay, the pressure inside the communication may drop to unacceptable levels. The consequences of such a decrease will lead to disruption of the system.

trubamaster.com

use of safety devices in heating

With uncontrolled heating of water in the boiler and pipelines, the coolant can boil and go into the vapor phase, creating a critical pressure rise in the system. Because of this, breaks in the contour or sheathing material of the heat generator may occur. To prevent such an emergency situation, it is necessary to use a pressure relief valve that performs its function in advance.

The operation process of the emergency device

Many users of closed heating systems know only one version of safety fittings - a spring-loaded water pressure relief valve equipped with a fixed setting. These devices are used for installation on different boilers, as they belong to the group of safe use of heating together with pressure gauges and air vents.

Units that work with electricity and gas are supplemented with safety components directly from the factory. They are inside the case and are not visually detected. It is necessary to understand the operation of the emergency pressure relief valve:

The so-called safety group, including the relief valve used in a closed heating circuit, is located on the supply line at a distance of no more than 0.5 m from the boiler. Installation of taps, valves and other blocking devices is prohibited in this area.

Do not firmly connect the nozzle of the waste product with sewer system. In wet places, valve operation is determined if there are problems in the circuit (cessation of the operation of the expansion tank or circulation pump). This situation is possible during a power outage. It happens that the device leaks due to a blockage between the seat and the plate.

Safety valve

Types of safety valves

A spring system that operates at a critically high pressure cannot be absolutely accurate. Sometimes it acts with a delay at a temperature in the boiler tank of 100 degrees and above. It is possible to adjust the product with a screw or change the settings with a cap, but this will not give the desired result.

The emergency product prevents the boiler from breaking down, but not its overheating, and the discharge of the coolant will not cool it if the combustion in the furnace continues. And also in open-type systems, the use of a valve is useless - the pressure in them does not increase when water boils.

There are many proposals of modern product developments free from the disadvantages that have been listed, for example, thermal relief valves. Such means do not work with an increase in pressure in the system, but with an increase in the temperature of the liquid to a critical point. There are three types of such devices:

reset with the addition of a remote temperature sensor;
combined - with the presence of a temperature sensor and contour feeding;
the same device with the function of direct installation in the pipeline.

All types work on the same principle: actuating a spring mechanism with one or two membranes using a bellows with a temperature-sensitive fluid that expands significantly when heated. There is a fairly accurate response of the thermal reset fuses to a critical temperature level.

Overpressure safety valves differ in the way they are controlled: manual and automatic. Therefore, the regulation is carried out manually or automatically when the pressure in the heating circuit rises.

In accordance with the working environment, water and air valves are used. The excess liquid is removed first, the excess gases are discharged second, airing the heating system. They are usually applied at the inlet to the heating battery.

With the help of adjustable devices with built-in thermostats, the throughput changes, it is possible to slightly open or block the outflow of the coolant. These are also used at the radiator inlet.

Bleed (blast) overpressure valve

Waste product selection

The main criterion for choosing a valve for relieving excess water pressure in heating is determined by technical parameters corresponding to the heating system and specified in the design documents.

Modern closed heating circuits are usually equipped with direct acting brass fuses. They are installed in systems for the heating of which diesel, gas or electric boilers are used.

As soon as the temperature and pressure have risen to a critical level, the valve reacts instantly, stopping the heating of the coolant and preventing an accident. Discharge products are designed to exceed the pressure up to 3-6 bar.

When choosing a fuse for a system heated by a diesel, gas or electric boiler, you should pay attention to a device that will withstand pressure in the circuit that is 30% higher than usual. For boilers that are heated with peat, briquettes or coal, you should carefully select the type of vents, since solid fuel is not able to immediately stop burning.

They are well suited for the use of thermal relief safety valves, which perform their functions up to a maximum pressure of 10 bar. The same applies to solid fuel units with open heating systems, in which such products work most efficiently and respond to an increase in temperature, not pressure.

adjust the emergency valve for the autoclave

It is undesirable to purchase inexpensive Chinese-made equipment, which is of low quality and short service life. The wear of the device is determined by the increased number of its operations.

Installation Features

When installing a water relief valve, one should take into account not only its characteristics, but also the work performed by the expansion tank. If it does not respond to the increased pressure in the system, the fuse should operate to release excess fluid. Following the installation rules, the location of the valve should be at a distance of 30-40 cm from the outlet pipe of the boiler, and a pressure gauge is built between them. Its readings serve as information about the state of the heating circuit. Relief valve installation rules:

It is forbidden to install locking equipment in front of the device - valves, taps, etc.
To remove excess water, a drain tube is placed on the outlet pipe of the valve. To do this, you can use a connection with a return or sewer.
The safety valve must be installed at the highest point of the closed heating system.

In addition, the working condition of the mechanism should be checked regularly. For spring models, soldering of the plate with the walls of the body may occur. This acts to exceed the maximum pressure mark, which affects the timely operation of the valve in the heating system, due to which the device may not open the liquid outlet.

Often this concerns the operating conditions of the reset fuse for heating, and not the principle of its operation. However, even with careful installation, the product may not function properly. With frequent operation of the emergency device (6-8 times), it is recommended to replace it. This means that the mechanism has become unusable - the spring and plate have worn out. When installing a safety valve, consider:

to what extent its technical characteristics correspond to operational ones;
correct connection;
during installation, it is worth using traditional tow for pipes, the FUM tape (fluoroplastic sealing material) does not withstand temperature exposure, which may cause a leak.

It is important to know that if the valve is leaking, you can not put a plug on it. This will lead to an emergency. You should purchase a new device that matches the working water pressure and replace the old one.

Installation progress

All products designed to relieve excess pressure are equipped with installation instructions that require careful study before starting installation work. First, disconnect the device from the mains and drain the water. Installation sequence:

Device and repair of the valve 3 bar Ariston Uno

To extend the life of any heating system, you should include a protective group in it, consisting of a fuse, a pressure gauge and a vent valve. It is advisable to install more thermal sensors that turn off the heating equipment or turn on an additional cooling system when the temperature of the coolant rises critically.

A safety device with standard specifications can leak even at low pressure in the system. This problem is eliminated by cleaning the body parts. First, the product should be dismantled, then put in a container with vinegar for 3 hours. Then rinse thoroughly with water and install in its original place, treating the connections with alcohol.

If the valve continues to leak water, the rubber gasket that rests on the seat is most likely clogged. It would be better to make a replacement than to clean it without deforming it.

Some consumers are overcome by doubts about the strength and reliability of locking products using plastic. Indeed, they are marked by a shorter service life, so it is better to purchase with metal components. These fuses are more expensive, but they last much longer.

Relief valve setting

oventilyacii.ru

Safety valve for a water heater: why is it needed, how to install

What is it needed for

This is how the installed valve for relieving pressure in the water heater looks like

How does it work

It would be more correct to call a safety valve for a water heater a valve system, since there are two of them in the device.

Boiler safety valve device

The mechanism of operation is as follows:

As long as the pressure in the boiler is less than that in the water supply (when filling or when the tap is open), the poppet plate of the non-return valve is pressed out by the flow of water. As soon as the pressure equalizes, the spring presses the plate against the protrusions of the body, blocking the flow of water.
When the heating is on, there is a gradual increase in the temperature of the water, and with it the pressure also increases. Until it exceeds the limit, nothing happens.
When the threshold level is reached, the pressure compresses the safety valve spring, and the outlet to the fitting opens. Some of the water from the boiler is bled through the fitting. When the pressure drops to normal, the spring closes the passage, the water stops draining.

According to the principle of operation, it is clear that water from the fitting will constantly dig in. This happens when the water is heated, when the pressure in the water supply decreases. If you periodically see water on the fitting, then everything is working fine. But the draining liquid must be diverted. To do this, put a tube of suitable diameter on the pipe, be sure to fix it with a clamp. The normal working pressure of the boiler is from 6 Bar to 10 Bar. Without mechanical fastening, the tube will be torn off in no time, so we select a high-quality clamp, tighten it well. Take the tube to the nearest sewer drain.

One more thing: the tube on the fitting needs a transparent and preferably reinforced (the so-called "herringbone"). Why reinforced is clear - due to pressure, and transparent - to be able to control the performance of the device.

Species and varieties

If we are talking about conventional safety valves for a water heater, then they look almost the same, only the nuances differ. But it is these small details that are responsible for ease of use.

Safety valve for the boiler with the possibility of forced pressure relief

Two other differences stand out. This is an arrow on the body, indicating the direction of water movement, and an inscription showing what pressure the device is designed for. Seemed like minor details. But if you can figure out the direction of water movement (look in which direction the poppet valve is deployed), then it’s more difficult with the face value. How to distinguish, for example, at 6 bar or at 10 bar? Only checks. And how will their sellers be distinguished? No way. By boxes. What if they put it in the wrong box? In general, it is better not to take it without marking on the case. These are usually the cheapest of the Chinese designs, but the price difference isn't big enough to make it worth the risk.

Safety valves - serviced and not

The model on the right is the worst of the options. No markings, forced reset or maintenance. These are usually the cheapest available, but this is their only merit.

For boilers up to 200 liters

With pressure gauge and original

Not everyone in appearance likes these devices. For those who attach great importance to aesthetics, very attractive devices are produced. Their price, however, is comparable to the price of an expensive water heater, but it is beautiful.

Can other valves be installed?

How to choose and install

Installation is simple: linen tow or fum tape is wound on the thread, after which the valve is screwed onto the pipe. It is twisted by hand until it stops, then another one or two turns with the help of keys. It is much more important to choose the right place for its installation. When installing a water heater, this valve is installed directly on the cold water inlet pipe.

Installation example

Next, there may also be a check valve, which is also called a shut-off valve. But this is already reinsurance - the same device is available in the safety one, and often after the water meter at the inlet. The installation diagram is shown below. This is one of the normal options.

Boiler safety valve installation diagram

Installation of a safety valve after a tee

Actually, these are all normal options.

Breakdowns, causes, elimination

In principle, the safety valve for a water heater has only two failures: water either often flows from it or does not flow at all.

First of all, it must be said that bleeding off water when heated is the norm. This is how the system should work. Water can also be drained when the boiler is turned off, if the pressure in the cold water supply pipes is higher than the valve actuation limit. For example, a 6 bar valve, and 7 bar in the water supply. Until the pressure drops, the water will bleed off. If this situation is repeated often, it is necessary to install a reducer, and it is best on the water in an apartment or house, but there are compact models of reducers that can be installed at the entrance to the boiler.

Boiler piping with safety valve and reducer

This is how the gearbox looks like - to stabilize the pressure on the boiler

Constantly dripping water is unpleasant and "hit" the wallet, but not dangerous. It is much worse if, when heating the water, you never have water in the pipe. The reason is that the valve is clogged or the outlet fitting is clogged. Check both options. Did not help - change the valve.

stroychik.ru

Safety valve in the heating system: types, purpose, diagrams, installation

Due to improper operation, temperature fluctuations and pressure surges, autonomous heating systems may malfunction. The negative consequences in such situations are critical: from the breakdown of individual components, ending with the destruction of buildings and a serious threat to life.

A safety valve in the heating system will help eliminate dangerous risks.

What is a safety valve for?

Heating systems are filled with water, the temperature of which is approximately 15 degrees. Circulating in a closed circuit, the coolant heats up, significantly increasing in volume. At this time, the pressure exerted on the inner surface of the pipes and the devices installed in the system increases significantly.

Exceeding the permissible norm, in most cases more than 3.5 bar, turns into:

leakage at the junction of pipeline parts;
damage or breaks connecting elements and pipes made of polymers;
boiler tank explosion;
short circuit of electrical equipment in the boiler room.

The highest risk emergencies characteristic of solid fuel boilers, in which it is difficult to regulate the heat transfer power. The performance of the electrical and gas equipment quickly adjusted from starting to maximum performance and vice versa.

Often they have safety automatics that turn off work items when the temperature rises excessively.

The intensity of burning wood, coal and other types of fuel in a solid fuel boiler is adjusted by opening / closing the damper. In this case, the force of heat transfer does not change immediately, but gradually. Due to the inertia of the heat generator, the heat transfer fluid can overheat greatly.

Together with a pressure gauge that calculates pressure and an air vent that removes air from the system, a safety valve is often included in the safety group.

When the firewood in the chamber warms up well, bringing the water in the network to the required temperature marks, air access is blocked, and the active flame begins to die out.

However, in a hot state, the firebox continues to release the accumulated heat. Reaching 90-95 degrees, the coolant boils and starts the inevitable intense vaporization. As a result, a sharp jump in pressure is provoked.

It is in such circumstances that the safety valve comes into operation. When the limiting pressure parameter is reached, it opens the shutter, freeing the way out for the resulting steam. After the values stabilize, the valve closes automatically and goes back to sleep mode.

Its installation is mandatory not only for solid fuel, but also for steam boilers, as well as furnaces equipped with a water circuit. Many modifications of heating equipment are equipped with these devices at the production stage. Usually the device is cut directly into the heat exchanger or installed in the pipeline near the boiler.

Varieties and principle of operation

The design of the drain valve includes two mandatory components: a shut-off part, consisting of a seat and a shutter, and a force generator. There are several types of equipment with their own characteristics. They are classified according to certain criteria.

The difference in the clamping mechanism

AT heating systems private houses, apartments and industrial installations of small power, preference is given to the spring type of the product.

The main working element of the device is a spring. It supports the membrane that covers the saddle. A washer is placed on the rod connected to the handle, against which the upper part of the spring rests. The position of the washer and the pressing effect on the membrane is regulated by the handle

The device is characterized by a simple and reliable structure, compact dimensions, the ability to combine with other elements of the security unit, and an affordable price. The compression force of the spring mechanism depends on the pressure parameter at which the valve operates. The setting range is affected by the elasticity of the spring itself.

The principle of operation of spring fuses is as follows:

the shutter of the device is affected by the flow of water;
the movement of the coolant is limited by the force of the spring;
critical pressure exceeds the compression force, lifting the valve stem up;
liquid is sent to the outlet pipe;
the internal volume of water is stabilized;
the spring closes the shutter, returning it to its original position.

The body of the springy device is made of high-quality high-strength brass using hot stamping technologies and techniques. Steel is used in the production of the spring. The membrane, seals and handle are made of polymers.

Some brands produce equipment with factory settings already set. Also in the range there are models that are customizable at the installation site during commissioning.

Valves are open and closed. In the first version of the design, the coolant is discharged into the atmosphere, in the second it goes down into the return pipeline

Lever-load fuses are not so widespread. In private autonomous systems they are rarely mounted with a boiler. Operation is concentrated in the industrial sector in large-scale production, where the diameter of pipelines is at least 200 mm.

The force on the rod in such mechanisms is not given by a spring, but by a load hung on the lever. It moves along the length of the lever, adjusting the force with which the stem will be pressed against the seat.

The lever-weight valve opens when the pressure of the medium from the bottom of the spool exceeds the values emanating from the lever. After that, the water leaves through a special discharge hole.

The adjustment of the lever-load fuses is carried out by moving the rod along the lever. In order to prevent its unauthorized or accidental change, the load is bolted, covered with a special casing and locked with a lock.

The set pressure, as well as the setting range, is determined by the length of the lever and the mass of the load. Lever fuses are not inferior to spring devices in terms of reliability, but they are more expensive. Devices are installed on flange fittings of pipes with a nominal diameter of 50 or more.

Shutter height views

In low-lift safety valves, the valve lifts no more than 0.05 of the seat diameter. The opening mechanism in such equipment is proportional.

It is characterized by low bandwidth and the most primitive design. Low-lift equipment is used on vessels with a liquid medium.

Full-lift devices are equipped with a two-position opening mechanism. They equip not only vessels with liquids, but also systems in which compressible media circulate (compressed air, steam, gas)

Full lift instruments have a higher bolt lift. This means that their throughput is much better than the previous version, so they are able to discharge larger volumes of excess coolant.

Response speed classification

The shutter cover of the proportional relief valves opens gradually. As a rule, the amount of opening is proportional to the increase in pressure exerted on the inner surface. Simultaneously with the lifting of the mechanism, the volumes of the discharged coolant gradually increase.

The design of the devices does not limit the possibility of their use in a compressible medium, but still they prevail in systems with water and other liquids.

Among the advantages of proportional speed relief valves are low cost, simple design, absence of self-oscillations, batch opening at the level of values necessary to maintain specific operating parameters.

A feature of on-off valves is instantaneous operation with full opening after reaching the boundary pressure marks in the system, at which the safety lock opens.

When installing a two-position valve in a heating system with a liquid heat carrier, it should be taken into account that during a sudden opening of the shutter, a large amount of water will be discharged.

This will cause the pressure to drop too quickly. The valve will instantly close, causing water hammer. Proportional devices do not cause such risks.

Three-way emergency valves

Separately, it is worth talking about a device not so well known to consumers - a three-way valve with a manual or electric switch. It is used in heating systems with low temperature circuits.

The design of the fuses is equipped with three holes, one of which is inlet, two are outlets. The flow of the medium is controlled by a damper made in the form of a ball or a rod. The moving fluid is redistributed by rotations.

Three-way fuses are appropriate for condensing boilers and in cases where several different systems operate from one heating equipment

Let's imagine a situation: a heating scheme with a system of conventional radiators and underfloor heating is implemented in a house. The technical requirements for the operation of the second option provide for not too high coolant temperatures.

The boiler heats water in the same temperature regime for all systems. In such conditions, there is a need for a redistribution device, with the tasks of which the three-way valve does an excellent job.

It is responsible for the following functions:

delimitation of areas;
flow density distribution by zones;
facilitating the mixing of the coolant from the supply / return main branches to send colder water to the underfloor heating pipeline than to radiators.

In order not to constantly control the temperature of the medium yourself, you need to pay attention to valve models equipped with a servo drive.

This device is powered by a sensor installed in the low temperature circuit. When the temperature marks change, a locking mechanism is activated that opens or closes the flow of liquid from the return.

How to choose the optimal model

Before dwelling on specific safety equipment, it is necessary to familiarize yourself in detail with the technical characteristics of the boiler installation.

The operation of the safety valve is negatively affected by sub-zero temperatures. Therefore enough important characteristic for the device is the presence of frost protection

Do not neglect the study of the manufacturer's instructions, which indicate all the limit values. Several criteria play a decisive role in choosing a device for heating:

Boiler performance.
The maximum allowable medium pressure for the heat output of the heating equipment.
Safety valve diameter.

It should be checked that the pressure regulator in the device has a range within which the parameters of a particular boiler are included. The set pressure should be 25-30% greater than the operating pressure required for stable operation of the system.

The higher the operating pressure, the less time the device should spend on operation. The gap between the pressure at the start of movement and when the valve is fully opened should be 15% for a nominal value of less than 2.5 atm, 10% for higher parameters

The diameter of the safety valve cannot be smaller than the inlet connection. Otherwise, constant hydraulic resistance will not allow the fuse to fully perform its immediate tasks.

The optimal material for the manufacture of equipment is brass. It has a low coefficient of thermal expansion, which excludes the destruction of the body from the effects of strong pressure.

The control block is made from heat-resistant plastic materials that retain the desired rigidity even when in contact with boiling liquid.

Installation and setup rules

Having planned self-assembly safety valve for heating, you should prepare a set of tools in advance. In work, you can not do without adjustable and wrenches, Phillips screwdriver, pliers, tape measure, silicone sealant.

Before starting work, you need to determine a suitable place for installation. The safety valve is recommended to be mounted on the supply pipeline near the boiler outlet. The optimal distance between the elements is 200-300 mm.

All compact household fuses are threaded. To achieve complete tightness when winding, it is necessary to seal the pipe with tow or silicone. It is undesirable to use FUM tape, as it does not always withstand critically high temperatures.

In the regulatory documentation that comes with each device, the installation process is usually described step by step. Some key installation rules are the same for all valve types:

if the fuse is not mounted as part of a safety group, a pressure gauge is placed next to it;
in spring valves, the axis of the spring must have a strictly vertical position and be located under the body of the device;
in lever-loading equipment, the lever is placed horizontally;
on the section of the pipeline between the heating equipment and the fuse, it is not allowed to install check valves, taps, gate valves, a circulation pump;
to prevent damage to the body during valve rotation, it is necessary to select with a key from the side where the screwing is carried out;
a drain pipe that discharges the coolant into the sewer network or return pipe is connected to the outlet pipe of the valve;
the outlet pipe is not connected directly to the sewer, but with the inclusion of a funnel or pit;
in systems where the fluid circulates naturally, the safety valve is placed at the highest point.

The conditional diameter of the device is selected on the basis of methods developed and approved by Gostekhnadzor. In resolving this issue, it is wiser to seek help from professionals.

If this is not possible, you can try using specialized online calculation programs.

To reduce hydraulic losses during medium pressure on the valve disc, emergency equipment is installed with a slope towards the boiler plant

The type of clamping structure affects the adjustment of the valve. The spring fixtures have a cap. Spring preload is adjusted by rotating it. The adjustment accuracy of these products is high: +/- 0.2 atm.

In lever devices, adjustments are made by increasing the mass or moving the load.

After 7-8 operations in the installed emergency device, the spring and the plate wear out, as a result of which the tightness may be broken. In this case, it is advisable to replace the valve with a new one.

Conclusions and useful video on the topic

How the safety valve is arranged and what it consists of:

Emergency valve as part of the safety group:

More about choosing and installing the optimal device:

A safety valve is a simple and reliable equipment that will protect your home from unforeseen emergencies that occur in heating systems. To do this, it is enough to choose a high-quality device with suitable parameters, and then perform its competent configuration and installation.

sovet-ingenera.com

Safety valve for a water heater: installation and connection

Storage water heaters are installed not only in private houses that are not connected to central communications, but also in apartments for a comfortable waiting for the completion of repairs planned by public utilities.

For the safe operation of water heating equipment, it is necessary to purchase and install a safety valve for the boiler that protects the household appliance from pressure surges in the cold water supply system. In addition, this valve is also called a check valve, since it prevents water from flowing back from the storage tank in the event of an emergency shutdown.

Therefore, in the absence of water in the cold water supply system, you can not worry about the safety of the electrical heating element. The heating element will not remain “dry” and will not burn out. The presence of a safety valve will allow you to easily drain the water from the boiler if you need to clean the tank from accumulated deposits in the process of heating water or replace a heating element that has served its time.

A serviceable safety valve is able to ensure long and stable operation of storage boilers.

Protective functions of the safety valve

In the process of heating water in the storage tank of the water heater, its volume increases. In a closed system, according to the laws of thermodynamics, as the temperature of a substance increases, so does the pressure level.

To control the water temperature in boilers, manufacturers install temperature controllers and thermostats on manufactured products. If these devices fail, then the water in the tank will boil, which will lead to a noticeable increase in pressure and an even greater heating of the liquid.

The avalanche flow of the described process, in the end, will lead to the formation of a crack in the walls of the storage tank, through which some of the hot water will pour out. The vacated space will immediately be filled with cold water coming from the plumbing system.

This will lead to an instantaneous boiling of all the liquid in the tank, accompanied by the release of a huge amount of steam and, as a result, the explosion of the container, bursting under its influence.

The safety valve will not allow the pressure to exceed the allowable values by dumping part of the liquid into the sewer system.

In addition to ensuring the integrity of the equipment in the event of critical situations, safety valves perform several other important functions, which include:

preventing the return of heated water from the boiler back to the water supply;
smoothing pressure surges of cold water at the inlet to the water heater tank, which prevents the possibility of water hammer;
dumping excess fluid from the tank at the time of a critical increase in temperature and pressure;
providing the possibility of draining water from the storage tank of the water heater for scheduled preventive maintenance and necessary repairs.

Valves that manufacturers currently produce can have a variety of designs. The kit, along with the main product, may include pressure gauges, various shut-off valves, etc.

When choosing a safety valve for a boiler, one should take into account the fact that the purchased device must comply with the parameters of the operating hot water supply system in the house.

The diagram clearly shows the device of a safety valve for a water heater (boiler), all elements of which are provided with pointers with inscriptions

How does such a valve work?

The safety valve of the boiler also performs the functions of a check valve, which is reflected in its design. Schematically, the product can be represented as two thin-walled cylinders located at right angles to each other, having different sizes, endowed with a common working cavity.

If you look inside a larger cylinder, you can see a check valve installed there, the design of which includes a plate, a spring and a seat machined in the body of the product. The thread applied on both sides of this part of the protective device allows it to be connected to the inlet pipe of the electric boiler.

The smaller cylinder also contains a shut-off device similar in design to the check valve described above, but differs from it only in the presence of a stiffer spring.

Most relief valves have a function to adjust the opening pressure by changing the compression ratio of the spring. The drain hole is located directly behind the locking mechanism. It is recommended to connect a transparent tube to this hole, which allows you to observe the water discharged from the tank.

View from three angles of the design of the safety valve used when connecting storage-type water heating equipment

The safety valve operates according to the following algorithm.

With the valve in the open position, mounted on the inlet line, water freely passes into the container through the hole resulting from pulling the check valve disc from the seat. At the same time, the incoming liquid does not have access to the drainage hole, because the safety spring has a stiffness designed for a higher pressure compared to the plumbing value of this value.
At the moment of full filling of the boiler, the pressure level in the tank and in the line equalizes, due to which the check valve closes. An increase in the temperature of the heated water in the storage tank causes an increase in the pressure force on the check valve disc, which is even more tightly pressed against the seat. Therefore, the heated water cannot return to the cold water supply pipes.
When users begin to consume hot water for domestic needs, the pressure inside the water heater begins to drop and reaches a value less than the water pressure value. At this moment, the plate is wrung out from the saddle and the process of filling the tank with water begins.
If the thermostat breaks down, then an uncontrolled increase in temperature will begin, which will cause an increase in pressure to a critical level. Here, as a result of the compression of the safety valve spring, it will be possible to drain excess fluid through the drainage hole into the sewerage system through a transparent hose.

A small lever is needed to force the opening of the drainage hole, through which water is discharged and pressure is reduced.

Waste of electricity without check valve

A hot water supply system with a water heater can function without a shut-off valve, but then, in the event of an increase in pressure, hot water will be squeezed into the supply line. This will lead to an excessive consumption of electricity, because the device will have to be heated. large quantity water.

The extra wound kilowatts will need to be paid for, which will not add joy to the owner of an apartment or house. In addition to the financial side of the matter, there are also practical inconveniences. After all, instead of cold water, warm water can run from the taps.

These problems must be added to the disadvantages that were described above. Therefore, do not agree to the installation of a water heater without installing a safety valve.

The cost of this brass product is incomparable with the costs incurred to purchase a boiler.

The information on the safety valve body helps to choose the right part for the initial installation or replacement during the repair of the water heater

How to connect a water heater

After installing the water heater, proceed to connect it. To do this, they take a tee, try it on, winding it on the cold water inlet, marked in blue. If there is not enough thread, then a few turns are added with a special device so that the tee is set correctly.

Then they wrap the thread with tow, coat it with a paste that provides a tight connection, and wind the tee, tightening it with an adjustable wrench. Next, a tap is screwed onto the side branch of the tee to ensure quick drain water from the boiler in case of replacing a burned-out heating element or cleaning the tank from scale.

Also, the connection is sealed with tow or tape for threaded connections. From below, a safety valve is connected to the tee, focusing on the arrow showing the direction of cold water entering the water heater. The arrow is located on the valve body.

Next, one part of the American is wound onto the safety valve. The second part of the American is screwed onto the tap and a connection is made with the first part. Then, an adapter is screwed into the faucet for connection to the water supply with propylene pipes.

Next, connect to hot water. To do this, they wind the first part of the American on the outlet pipe of the boiler, marked in red. The second part of the American is wound onto the shut-off crane. Perform the connection.

Then, an adapter sleeve is also screwed onto the tap for soldering the propylene pipe. It remains to connect the boiler to the cold and hot water supply system. Propylene pipes can be replaced with flexible pipes.

The connection diagram of the water heater (boiler) to the hot and cold water supply systems shows the sequence in which the device is installed

Alternative way to mount a non-return valve

This method was invented by a craftsman who was faced with the problem of contamination of the safety valve with sediment from a tank with hot water under pressure. If a piece of rust gets under the piston plate on the seat, then the valve can no longer work correctly. It remains open all the time.

To prevent such a development of the situation, it is necessary to mount the valve at the level of the middle of the tank. That is, in the same way as described above, a tee is connected to the inlet pipe of the boiler, and then the connection is made a little differently.

The drain tap is screwed on from below, and the pipe is taken to the side, corners are placed, again the pipe, and somewhere at the level of the middle of the tank a safety valve is installed. After it comes a shut-off valve and a fitting through which already underway direct connection of the device to the water supply.

With this method, the valve always remains clean and the poppet piston does not “hang” above the seat. In addition, in the absence of water in the system, such a curved connection serves as a kind of water seal.

You can learn more about this installation method from the video.

During operation of the boiler, make sure that the drain hole on the safety valve is not clogged or blocked. The drain can become clogged with rust, small solids and other impurities found in tap water.

To check its working condition, a small amount of water is periodically discharged by pressing a special lever or turning the handle. The instructions supplied with the water heater safety valve describe how the valve's forced opening mechanism works.

Installing a cleaning filter tap water solves part of the problem. It is undesirable to change the factory settings of the spring stiffness in valve models endowed with such an adjustment.

Such interference may lead to the destruction of the water heater tank due to the excess of the permissible pressure values inside the household appliance.

Forced discharge of water from the boiler in order to reduce the pressure in the tank is carried out by pressing the lever

Constantly dripping water - what to do and how to fix it?

Some boiler owners are faced with the problem of constant seepage of water through the drain hole. Water can drip from the drain for two reasons:

incorrect valve setting;
too high pressure in the cold water supply system.

The first problem is fixed by replacing or adjusting the device, which must be done with a hex wrench. At the same time, the clamping nut located at the inlet inside the valve is slightly tightened.

You can get to this nut by partially disassembling the device, in which the lever, nut and sealing washer are removed. In general, you can solve the problem faster by buying a new valve.

The second problem related to high pressure in the system, disappears when the pressure reducing valve is installed.

The connection of a tube with transparent walls to the drainage hole was made without bringing it into the sewerage system

Connection of a branch in the form of a transparent tube from the drain hole of the safety valve to the sewerage system through a branch pipe with an oblique inlet

Problems and ways to solve them

The cause of the incorrect operation of the water heater should be searched for immediately, as soon as the first signs appear. It is advisable to test all elements of the household appliance, starting with the thermostat, safety valve and heating element. Most often, it is these parts of the boiler that break.

In the event of a valve breakdown, the masters advise not to save money by repairing the part, but to immediately purchase a new analogue. The model is selected according to the pressure level for which the valve is designed, indicated on the body of the product. This information is also indicated in the safety valve instruction manual.

There are situations when the valve does not function due to a hidden marriage, which is not possible to identify. It is not worth spending time searching for a defect in the design of the part, since the boiler must be operated for its intended purpose.

Therefore, the defective valve is replaced with a new device. If the resource of the installed safety valve is exhausted, then it is also dismantled and a new device is installed. By changing the valve, you can not worry about how the water heater works.

The supplied part will ensure reliable and safe operation of water heating equipment.

The disassembled safety valve allows you to see the screw, which adjusts the degree of spring stiffness with a screwdriver

Install the water heater and properly tie it under the power of any novice master. After reading the article and watching the videos, you can do everything yourself, saving on paying for installation work done by third parties.

If you think that everyone should do their job at a professional level, then invite specialists. Experienced craftsmen will help you choose suitable model safety valve, buy the missing fittings, connect the boiler to cold and hot water in accordance with the norms of construction work.

Do not listen only to those unfortunate masters who consider safety valves to be unnecessary links in the piping chain of a water heater connected to the water supply. Never skimp on your safety!

Any boiler equipment installed in a private house or enterprise is a source of danger. The water jacket of the boiler is the same vessel under pressure, and therefore it is considered explosive. To minimize the danger, modern heat generators, as well as their piping schemes, provide for many protective devices and systems. One of the simplest and at the same time common devices is a safety valve in a heating system. It will be discussed in this article.

Where is the safety valve installed?

To answer this question, we must first understand what it serves. The purpose of installing this simple device is to protect heating systems, prevent high blood pressure coolant in them. This can occur as a result of overheating of the water in the boiler, especially for units that burn solid fuels. When the coolant in the boiler tank boils and vaporization begins, this is followed by a pressure jump in the system. The consequences may be:

leaks and breaks in heating pipelines, most often at joints;
destruction of polymer pipes and fittings;
explosion of the boiler tank, danger of electrical short circuit in the boiler room.

One small valve of a simple design can protect against all these troubles. Based on the fact that an increase in pressure to a critical limit occurs in the boiler, the safety valve must be placed as close as possible to it, on the supply pipeline. Some manufacturers of boiler equipment complete their products with a so-called safety group, which includes a relief valve, a pressure gauge and an automatic air vent. The group is mounted directly into the water jacket of the unit.

It should be noted that safety valves for heating are not always used in circuits. For example, when the source of heat in the house is a gas or electric boiler, then a relief device is not required. The reason is the presence of safety automation in these types of heat generators and the absence of any inertia. That is, when the set coolant temperature is reached gas-burner or the electrical element is turned off and the heating stops almost immediately.

Another thing is a solid fuel boiler or a furnace with a water circuit, here the installation of a safety valve is mandatory. When the firewood in the firebox flared up and the water in the network reached the required temperature, it is necessary to reduce its heating. The access of air to the combustion chamber is closed and the flame dies out, but the red-hot firebox by inertia continues to raise the temperature. If the process goes near the limit values (temperature 90-95 ºС), then vaporization at such moments is inevitable.

As mentioned above, boiling is followed by an increase in pressure, which can be prevented by the safety valve of the heating system. It will automatically open the way to the outside for the formed steam and release it, thereby lowering the pressure to normal. Then the device will automatically close and will be in standby mode again.

The device and principle of operation of the valve

The design of the valve is extremely simple. The body is made of high-quality plumbing brass using hot stamping technology from two cast parts in a semi-solid state. General device safety valve shown in the figure:

The main working element of the valve is a spring. Its elasticity determines the force of pressure that must act on the membrane that closes the passage to the outside. The latter in the normal position is in the seat with a seal, preloaded by a spring. The upper stop for the spring is a metal washer attached to the rod, whose end is screwed to the plastic handle. It is used to adjust the valve. The membrane and sealing elements are made of polymeric materials, the spring is made of steel.

This whole simple mechanism works like this. In the normal (standby) mode, while the coolant parameters are within the specified limits, the membrane closes the entrance to the inner chamber. As soon as a situation close to an emergency arises and the pressure in the heating system of a private house increases, the steam-water mixture begins to support the membrane. At a certain moment, the pressure force of the coolant overcomes the elasticity of the spring, opens the membrane, enters the chamber, and out of it through the side hole.

When some water leaves the system, the pressure will decrease so much that it cannot resist the spring and the membrane will close the passage again. It happens that the operation of the mechanism occurs cyclically, especially if the thermal unit operates at the limit and the temperature of the coolant is close to the maximum (90-95 ºС). In practice, when the blast valve for the boiler is activated very often, it loses its tightness and begins to leak.

If you find fresh traces of drips from the safety mechanism, then this is a clear sign of the heat generator operating in extreme mode or the presence of malfunctions in the heating system, for example, in the expansion tank.

Since far from all manufacturers of heating equipment complete their products with a safety group, you often have to make the choice of a safety valve for a heating system yourself. To do this, it is necessary to study the technical characteristics of the boiler plant, namely, to know its thermal power and the maximum pressure of the coolant.

For reference. Most well-known brands of solid fuel heat generators have a maximum pressure of 3 bar. Exception - boilers long burning STROPUVA, whose limit is 2 bar.

The best option is to purchase a pressure-controlled valve covering a certain range. The control limits must include the value for your boiler. Then you need to choose a product according to the power of the thermal installation, but it is difficult to make a mistake here. The instructions from the manufacturer always indicate the limits of the thermal power of the units, with which a valve of one or another diameter can work.

On the section of the pipeline from the boiler to the place where the overpressure relief valve is installed, it is strictly forbidden to install shutoff valves. In addition, you can not put the device after the circulation pump, do not forget that the latter is not able to pump the steam-water mixture.

To prevent splashing of water in the furnace room, it is recommended to connect a pipe to the outlet of the valve, which discharges the discharge into the sewer. If you want to visually control the process, then a special drain funnel with a visible jet break can be placed on the vertical section of the tube.

Conclusion

The pressure relief safety device is considered to be very reliable due to its simple design. When making a choice, you should pay attention to the quality of the material and not chase a cheap product. No less important is the correct setting of the valve for the maximum pressure of the boiler plant.

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