What is the safety valve on a water heater used for? How to choose a safety valve

Why is a safety valve needed in a water supply? How does this valve work? What other types of fittings are used in water supply and heating systems? Let's figure it out.

Device and types

A typical valve has two pipes - for connecting to the water supply and for drainage. In this case, the drainage pipe can be smooth or equipped with a thread.

The housing contains a spring with a hermetically sealed normally closed seat (that is, in the absence of external influences, located in closed position) valve. Water presses on the valve from the seat side.

At a certain pressure level, the valve opens and remains open until it drops below a threshold value. The water is drained all this time through the drainage pipe.

It’s curious: most inexpensive valves do not allow you to change the factory setting and operate at a pressure of 1.5 - 7 kgf/cm2 specified by the manufacturer. However, they can be opened manually. However, there are also adjustable devices, allowing you to set the response pressure in the range of 1-16 atmospheres.

What else is useful to know about this type of fittings?

• The difference between valves of the same type (adjustable and non-adjustable) comes down mainly to differences in the diameter and type (external or internal) of the thread for connecting to the pipeline;
• The typical price of an unregulated device of size DN15 is 300-400 rubles, an adjustable one is 50-80% more expensive;
• Some manufacturers offer models with a built-in pressure gauge that allows you to visually monitor the current pressure in the pipeline.

A special case

The so-called safety group for a boiler consists of two different valves mounted in one housing - safety and non-return. This device is easily recognized by two threads for connecting to the water supply and by an arrow on the body indicating the direction of water flow.

Functions

Safety valves for water supply and heating systems prevent pressure from rising above their activation level and protect pipelines, fittings and other fittings from damage.

It is worth clarifying: they are not used in cold water supply systems, centralized hot water supply systems with water supplied from heating mains and central heating. Club members - hot water supply with water preparation in a storage water heater (electric boiler or indirect) and autonomous heating.

DHW

Any type of storage water heater must be equipped with a check valve at the inlet.

Yes, simply because without this valve, water will pour out of the boiler when the main water supply is turned off and reset. You see, its inlet pipe opens into the tank just above the bottom level: such a device allows you to achieve stratification of water according to temperature.

Please note: in addition to financial costs, discharging water from the tank will mean a high probability of leakage from the heating elements of the electric boiler.

Now imagine what will happen after filling and turning on the boiler, separated from the cold water supply by a check valve.

• The water temperature will begin to rise;
• As it heats up, its volume will begin to increase, in full accordance with the laws of physics;

• An increase in the volume of almost incompressible liquid in the confined space of the tank will cause a rapid increase in pressure.

This is where a safety valve installed on the water supply comes to the rescue: it will release excess water into the drainage and thereby reduce the pressure level.

Heating

On heating, our hero is part of the boiler safety group and performs the same function as on hot water supply: it releases part of the coolant when the pressure rises dangerously.

The valve works in tandem with a membrane expansion tank and duplicates its functions: in normal mode, excess coolant is contained by compressing air separated from water by an elastic membrane, expansion tank. If the pressure continues to rise due to incorrect calculation of the volume of the tank or overheating of the coolant, the valve is triggered.

By the way: the installation is also practiced with boilers of significant volume. It significantly reduces water supply costs: without an expansion tank, each time the water in a 300-liter indirect tank is heated from 10 to 70 degrees Celsius, a little over 6 liters will be drained into the drainage hot water.

Installation

Are there any subtleties to installing a safety valve yourself?

• On DHW it is mounted in front of the boiler inlet pipe and after the check valve (of course, if the valves are not united by a common housing);

• On heating, the safety group that turns on the safety valve is on minimum distance from the boiler outlet pipe - where the pressure first begins to increase when the coolant overheats;

However: most electric heating elements and wall-mounted gas boilers are equipped with their own safety group located inside the housing.

• To seal the threads at the connection to the water supply, you can use any heat-resistant winding - flax with paint or sealant, FUM tape or polyester thread with silicone (for example, Tangit Unilok);

• The drainage pipe is directed to the outlet internal sewerage or any plumbing fixture connected to it. If necessary, drainage is extended with a tube.

Service

The only type of maintenance required by our hero is a periodic (monthly) performance check. The fact is that the valve may stick to the seat, which will increase the response pressure. The testing instructions are extremely simple: just open the valve forcibly for a couple of seconds.

Who else

Let's get acquainted with several more varieties of the most popular plumbing fixtures.

Title and photo	Description and functions
	Shuts off the water with a ball valve when the rod is turned. It has only two operating positions - “fully open” and “fully closed”. Head and shoulders above its predecessors - plug taps and screw valves - in terms of fault tolerance.
	A throttle, also known as a balancing valve for water supply and heating, allows you to limit the throughput of the pipeline to equalize the temperature of heating circuits or water flow on water supply branches. Structurally similar to a screw valve, but with a needle valve and a wear-resistant stem seal.
	Mechanical or electronic thermostat controls the position of the control valve shutter depending on the temperature working environment or indoor air. The valve moves when the volume of the thermostat working fluid (liquid or hard material with a high coefficient of thermal expansion) or when starting the servomotor.
	A mechanical device for reducing water pressure to standard values ​​(1.5-4.5 kgf/cm2). The most common piston gearboxes operate due to the difference in area (and, accordingly, in the force of influence of the working environment on them) of the valve that shuts off the water and the piston located downstream of it along the water flow.
	Comb with multiple outlets for parallel connection heating or plumbing fixtures. The so-called manifold wiring allows you to independently adjust the coolant flow through several heating circuits. In addition, it equalizes the pressure on plumbing fixtures when water flows through the water fittings of one of them.
	Performs coarse filtration of water, trapping large suspended solids on a stainless mesh. Filtration is especially important if you use plumbing fixtures with ceramic valves: the ceramics chip when you try to close a cartridge jammed with sand in a single-lever mixer or faucet.
	The device we are already familiar with is a steel tank with an elastic pear-shaped membrane separating it into water and air compartments. The tank holds excess expanding water as it is heated in a closed circuit.
	Twin brother of the expansion tank, designed for cold water. Used as a reserve tank and to stabilize pressure during pump operation.
	Limits the movement of water or coolant in one direction. Most common spring valves They shut off the water with a brass or plastic valve with a return spring.
	Takes away from circulation systems DHW and heating systems air jams and steam generated when the boiler overheats. Mounted at the highest points of the circuit or after circulation pump. It works by changing the liquid level in the working chamber: the valve opens and closes with a float.

Conclusion

Of course ours mini review fittings does not pretend to be complete: we have described only some of the most popular types of fittings. The video in this article will help you learn more about why you need to install a safety valve on your water supply. Good luck!

Since in various designs electric water heaters water is adjacent to current, used special means protection. One such device is a boiler safety valve. The performance of the system and the safety of users depend on the correct installation of this equipment. There are several types of safety valves. After selecting the appropriate product, it must be installed and adjusted correctly. In addition, it is advisable for owners of such equipment to know frequent breakdowns and ways to eliminate them, as well as completely replace the valve.

First, let's figure out why a safety valve on a boiler is needed. When the liquid is heated, water vapor is formed in the sealed boiler tank, causing the pressure in the system to increase. Since all valves are closed, pressure cannot be released through the drain into the system. Because of this, excess pressure accumulates in the unit itself.

When the water heats up to 60-65 degrees, the pressure relief valve for the boiler should operate and turn off the device. At this moment, the pressure in the water supply system reaches 2.7-3 bar, and in the heating tank, due to the presence of water vapor, it is higher and equal to 4 bar. These are normal values.

Video of what a safety valve is needed for

If the valve does not work, the boiling point will increase in proportion to the pressure. At a pressure of 10 bar, the water temperature is 180°C. As a result, all the liquid in the tank will turn into water vapor. Due to such high pressure, the housing will not withstand it and the boiler will explode.

The main functions of the safety valve on the boiler:

• protection against spontaneous flow of liquid into the water supply system if there is no water in it yet;
• reset overpressure in manual and automatic mode.

Valve operating principle

The operating principle is as follows:

1. As long as the pressure in the boiler is lower than the pressure in the system, the valve plate is kept open due to the influence of water flow. When the pressure is equalized, the spring presses the valve against the body and shuts off the water.
2. If the heating is turned on, the water temperature gradually increases. The pressure also increases proportionally. If it does not exceed the limit values, then nothing changes in the operation of the valve.
3. As soon as the pressure reaches a threshold value, the spring of the safety valve is compressed under its influence. In this case, the exit to the fitting opens. A small amount of water from the unit is drained through the fitting. As soon as the pressure decreases, the spring closes the passage and the water no longer flows.

Video of safety valve device

It becomes clear that the liquid from the fitting must be dripped up periodically. This happens when the pressure in the water supply system decreases and during water heating. Periodically appearing water at the fitting indicates normal operation of the device. To drain liquid, a flexible tube of suitable diameter is installed on the pipe and secured with a clamp. Without fastening, the tube will break off, because normal pressure in the system 6-10 bar. The other end of the tube is discharged into the sewer.

Important! Use reinforced transparent tubing. She will endure high pressure and will allow you to monitor the performance of the unit.

Types of safety valves

Externally, all valve models do not differ significantly; the difference is only in the nuances. So, there is a safety valve for the boiler with a release handle. Such devices allow you to periodically check the performance of the device. To do this, the lever is lifted up, it opens the spring and water is discharged. This check is carried out once a month. Also, using the release handle, if necessary, you can completely empty the storage tank.

In some models, the lever is fixed with a screw, which protects against accidental opening and complete loss of water. Some models differ in the shape of the fitting. Some are linear and elongated, which makes it easier to install the clamp, while others are shorter and have a flare towards the end. In the latter case, it is problematic to install the clamp; you will have to use wire.

Valves without a water release flag have a threaded cap. They belong to the category of serviceable models because the cap can be unscrewed and the valve can be cleaned of scale, blockages and dirt.

Important! The cheapest and most popular models do not have any collection handles, maintenance covers or markings on the body.

For larger boilers, safety devices with pressure gauges and a ball valve are used. The fluid drain fitting has a standard thread, so you don’t have to worry about the reliability of the fastening. These are expensive, high quality and reliable devices.

Valve design

Myself safety device consists of two valves. They are housed in a T-shaped nickel or brass body. A check valve is installed at the bottom, which protects against spontaneous outflow of water from the heater when the pressure in the system decreases. In a branch of the housing, located perpendicularly, there is a second locking mechanism that releases a small amount of water through the fitting when the pressure is exceeded.

How to choose a safety valve

A suitable product is selected depending on the design pressure in the water heater, which is indicated in the device passport. In addition, when choosing, take into account the size of the tank. Usually you can find devices on sale whose response limit is 6-10 bar. This is the pressure that many water heaters are designed for.

Valve installation and adjustment

Installing a safety valve on a boiler is quite simple. Follow these guidelines:

• The product is mounted on the inlet pipe of the heater.
• During installation, consider the direction of water movement. Many valves have a designation on the body that allows you to judge the direction. The arrow should point towards the boiler.
• If the model has an internal installation stop, then screw it until it stops. If there is no limiter, then make no more than four turns while tightening.
• Before screwing, fum tape or flax tow is wound onto the thread.
• After installing the product on the heater, inspect it from the cold water supply side. The check valve seat should be visible through the hole. When you press it with a blunt object, the sash moves forward, and after release it returns back. If the sash does not move, then the installation was performed incorrectly.

Attention! It is prohibited to replace the safety product with a non-return valve. In this case, excess pressure will not be released.

It will take several hours to check functionality. At this time, it is forbidden to open hot water taps.

It is performed in this order:

1. After connecting the unit and filling with water, select a temperature within 80 degrees on the control panel.
2. When the temperature of the liquid in the unit reaches the specified value, water will drip or gradually flow out of the fitting. If this does not happen, wait until the thermostat turns off the water heater.
3. After this, increase the temperature limit, taking into account the capabilities of the model.
4. Water should now drip from the fitting. If this does not happen again, have the valve checked by a repair shop or replace it.
5. After checking the fitting of a properly working device, put a flexible hose on it and secure it with a clamp. Lead the other end of the hose into the sewer system.
6. Set the thermostat to 60-65 degrees.

Important! If water flows from the fitting immediately after filling the tank, then the valve is defective and needs to be completely replaced.

Frequent breakdowns of safety valves and methods for eliminating them

You can deal with common device malfunctions on your own if you know what to do. Most often, boiler owners are faced with constant leakage of water from the safety product or, conversely, a complete cessation of the outflow of liquid.

Valve clogged

If water does not drip from the fitting when the maximum temperature is reached. Check the serviceability of all taps in the system, as well as the presence of leaks in the water supply system of the house. If no such problems are found, it means that the mechanism is clogged. It needs to be removed and washed or completely replaced.

To flush the device, open the drain valve by pressing the lever on the device. Let the running water thoroughly rinse the mechanism. Since the drain hose is transparent, contaminated water is clearly visible. When will it go clean? clear water, the exit is closed again with a lever. If the leak does not stop after this, the safety device needs to be replaced.

Water dripping from valve

If the boiler drips from the safety valve, this indicates a weakened pressure spring. This calibrated part cannot be replaced, so you will have to buy a new product.

Video on how to fix a valve if it is dripping

Sometimes leakage occurs when the pressure in the cold water supply system is exceeded. In this case, it will be noticeable when using other plumbing fixtures. Less commonly, the reason is associated with insufficient volume or complete absence of the expansion tank in the water heater. To solve problems, an expansion tank is installed at the outlet of the device.

How to replace a broken safety valve on a water heater

Valve replacement work is carried out in the following sequence:

1. First, drain the water from the heater and disconnect it from the power supply.
2. Shut off the supply of cold and hot water to the device. To do this, close both valves on the water heater. If they are not there, then they simply shut off the water supply to the apartment.
3. Next, open two different taps in the house. We open the hot water tap on one mixer, and cold water on the other.
4. Now open the taps on the boiler and drain the remaining water.
5. Disconnect the flexible hose from the return discharge fitting.
6. We unscrew the old valve and install a new product in its place.
7. We close all the taps in the house and connect the unit to the power supply system.

If there is no hot water supply system at all in a private house, then draining the liquid and turning off the device is carried out in the same order, with the exception of the point with opening the hot water mixer and turning off the tap on the hot water pipes.

On the quality of the storage water heater piping electric type Not only the duration of its operation will depend, but also the level of safety during operation. This is one of the most serious moments when installing a boiler and requires special attention. Correct strapping for a water heater is called a safety valve built into the cold water supply system.

The integration of a safety valve protects against a sudden increase in pressure in the internal part of the unit, significantly exceeding the norm. The question arises, what is the reason for such a jump? As we were able to establish, during heating the liquid increases in volume and, therefore, expands. Due to the tightness of the heater reservoir, the resulting excess simply has nowhere to go - the tap is turned off (as a rule, a check valve is installed on the supply).

Further heating of the liquid may cause increase in pressure. At this moment, there is a danger of exceeding the tensile strength of the unit and rupturing its walls. To avoid such an explosion, a safety valve is installed for the boiler.

Some owners may ask: is it worth the hassle of installing a fuse when you can simply remove check valve. Experts answer this in the following way: at a relatively high and uniform pressure in the water supply system, such a scheme will function, but for some time. This does not mean that such actions are a way out of the situation. The fallacy of this scheme is due to a number of reasons:

1. The pressure in the water supply system is not stable.
2. Excess water is removed from the boiler into the water supply, exposing a heating element.
3. By heating the air, the boiler will fail after a while.

Burnt out heaters are not the most a big problem. Much more important is that there is a danger of unexpected changes in pressure in water pipes. The liquid, falling on the heated heating element, quickly turns into steam, sharply increasing the pressure. Under such conditions, the walls of the boiler are guaranteed to rupture. A large number of boiling water and steam, pushed by pressure, will fill the room, threatening everyone in it with serious injuries.

Principle of operation

Safety valve for a water heater, in addition to the main structure, it consists of several more elements. They are housed in a brass or nickel housing. In most cases, the device looks like an inverted letter T. It is attached to the bottom of the tank on the water heater check valve, capable of preventing liquid from leaking out of the tank when the pressure in the pipes drops.

The perpendicular branch contains another valve, which is activated after the pressure increases and discharges excess liquid through the fitting. The operating principle occurs in several stages.

1. If the tank pressure is lower than that occurring in the pipes, when filling or opening the tap, the poppet plate in the check valve is pressed out by the water pressure. When the pressure level returns to normal, a spring mechanism presses the plate against the protrusion of the housing, limiting the flow of liquid.
2. During active heating, the temperature of the liquid slowly increases, and at the same time the pressure increases. Until it reaches the maximum value, the mechanism is not activated.
3. After reaching the limit level, the pressure compresses the fuse spring, opening outlet channel of the fitting. Excess liquid from the reservoir is removed through this channel. After the pressure drops to the normal level, the spring closes the flow and water removal stops.

Based on the above, it can be understood that liquid will periodically drain from the fitting channel. This phenomenon occurs when water is heated and pressure in the water supply system decreases. If you regularly notice water at the fitting, this means that the safety valve for the boiler is operating normally.

However, at the same time there is a need to drain the flowing liquid. To carry out the procedure, a tube of a suitable size is attached to the nozzle: it must be tighten with a clamp to ensure secure fastening. Regular operating pressure in the water heater tank from six to ten bar. Without reliable fastening, the tube will simply break off, so the choice of clamp must be approached with special care. Tighten it tightly and lead the tube to the nearest sewer drain.

The tube to the fitting must be transparent, ideal option there will be a reinforced hose. This helps control the performance of the system, and the reinforcement provides additional protection against pressure.

Valve operating principle

Features of different types of valves

If we talk about a standard safety valve for a boiler, they are not very different in appearance. However, there are small nuances, responsible for the ease of use of the device.

The image shows valves equipped with release levers. Their purpose is to periodically check serviceability:

• the lever is moved to a vertical position;
• it activates the spring mechanism, pulling it along with it;
• As a result, a channel opens through which water flows.

Release lever on valve

The differences between the models shown are that the valve located on the left has a fixed lever special bolt. This eliminates the possibility of involuntary opening and complete removal of liquid.

The following image shows valves without a positive fluid release lever. The left model has a threaded lid at the top. It is intended for Maintenance fuses. If necessary, it is unscrewed to remove blockages, scale and other contaminants.

Valves without lever

The right model is the least preferred option. It does not have any markers, a water release lever or a service hole. This is the cheapest and lowest quality product coming from China. There is no need to talk about reliability and durability. You can use it only as a temporary replacement at your own peril and risk.

Pressure rating note

There are a few other notable differences. The arrow shown on the body indicates water flow direction, as well as an inscription informing about maximum pressure, which the device can withstand. At first glance, the details seem insignificant. But if you can easily figure out the direction of liquid flow (to do this, just look at the location of the poppet-type valve), then the situation with ratings is more complicated.

By what signs can you distinguish between a six and ten bar valve? Only by experience. You may ask, how do suppliers differentiate them? No, only according to the inscriptions in the documents. Experts do not recommend purchasing devices without any markings on the case. Of course, the cost of labeled products may be higher than that of analogues, but it is better not to save on this issue.

Fitting shape

In addition, it is worth paying attention to the shape of the fluid removal fitting. In the left model this element is quite long and has a nonlinear shape. It will be easy to attach the tube to it, and the length is quite enough for secure fastening with a clamp.

The shape of the similar element in the right model is different. It has a characteristic expansion at the end, but the most important thing is the length of the fitting. It will be quite difficult to install a tube on it and even more difficult to ensure reliable fastening. The use of artisanal methods will not guarantee a good result, and difficulties with drainage may arise in the future.

For large volume boilers

Each of the devices described above is designed for a storage water heater with a volume of fifty to sixty liters. To tanks bigger size use other systems, each of which integrates special equipment. Most often this ball pressure gauge or a valve that controls pressure.

Ball pressure gauge

They are equipped with a fitting for removing liquid standard thread to increase the reliability of fastening and solve the problem with clamps. This type of device has a high price, but the level of quality is significantly higher than other systems.

A significant disadvantage for many owners may be appearance tap. Especially for such people, the production of fuses has been launched, which not only have practical benefits, but can also decorate the interior of the room. Their cost can significantly reach the price of the boiler itself, so everyone will have to assess the feasibility of such a purchase for themselves.

Installation of other valves

There are cases when, instead of the factory pressure surge protection system, a heater tank is installed blast valve. It is intended primarily for emergency removal of liquid into the heating system. Although their functionality is largely the same, the basic principle of operation is fundamentally different.

The blast-type valve performs its functions only during an emergency. It is needed to urgently remove all water from the tank. It is not intended for periodic bleeding of small portions of liquid. Considering all this, you should not expect correct functioning from such a craft.

Another example is mounting only check valve. Its mechanism will not allow liquid to drain at low pressure in the system, but it will not be able to save you from sudden surges in the tank. As practice shows, such an assembly is also not functional.

Diagram of all components safe operation water heater

Selection and installation

The fuse should be selected based on the pressure that the device can withstand. This figure is usually included in the registration certificate. In addition, the volume of the tank may influence the choice. There are systems with a response threshold of six, seven, eight, ten Bars. These are the most common values ​​for tripping the fuse.

The installation process is quite simple.

1. Wrap a special tape or flax tow around the threads for a tight seal.
2. Screw the valve onto the pipe.
3. Continue to tighten it all the way with your hands, and then turn it a few times using the wrench.
4. Don't forget about making the right choice places for its installation. Experts recommend attaching it directly to the cold water inlet pipe.

After this, you can install a check valve system, or as it is also called - constipation. But these are reinsurance measures; a device with similar functions is already included in the fuse system, and it is also often integrated into water meters.

The diagram demonstrates location ball valve . It is used to remove liquid from the tank during winter storage or during dismantling. Drainage may also be required during maintenance or repair. In most cases, it is installed on a tee, which, in turn, is connected to the fuse system.

You shouldn't save money on this important detail, like a fuse. This device will not only help you maintain the functionality of the heater, but may also save you from serious injury. Pressure surges in the water supply are a common occurrence, and no one is immune from tank failure. Spend some time installing safety valves to ensure your safety.

A check valve for a water heater is inexpensive (from 160 rubles), externally unremarkable, and its purpose is simply not known to many. Therefore, the mandatory installation of it seems to some “advanced” smart people to be an optional whim of a drunken plumber. But everything is for the time being. After the water heater explodes one day, simultaneously destroying half of the apartment, the opinion about the need to use a check valve for the water heater will change dramatically, unfortunately, somewhat late. Learn from other people's mistakes, gentlemen!

Why do you need a check valve in a water heater?

A check valve for a boiler is sometimes called a safety valve. There is no mistake in this. Design feature shut-off valves for a water heater is that it consists of two valves located perpendicular to each other. One of them, located in a larger diameter tube, is reverse. Another located in the tube smaller diameter, safety.

The check valve is used to prevent liquid from flowing out of the boiler into the water supply network when the pressure in the tank exceeds the pressure in the cold water supply network (CWS).

A safety valve is essentially a relief, automatic device that is triggered by excess pressure at the inlet in front of the valve.

Both devices have the same design, disc type. They differ in throughput and pressure settings. Simply put, the diameter of the pipes and the stiffness of the clamping springs.

How to choose a check valve for a water heater

These devices differ in:

• Nominal pressure (PN). There are: 0.6; 0.7; 0.75; 0.8; 0.85 MPa. About what the nominal pressure of a particular safety device can be found out from the inscription on the body of the device, but it may not be there. In this case, you should focus on lower value i.e. 0.6 MPa.

It’s hard to see in the picture, but in fact, the difference between the springs of the check valve and the safety valve is clearly visible in the holes of the pipes.

Some manufacturers storage water heaters It is recommended to use a pressure reducing valve () to set the water pressure in the cold water system 20% below the start value of the safety valves. For example, for a device designed for 0.6 MPa, the pressure in the indoor cold water network should be 0.48 MPa.

Of course, the process of organizing such adjustment is quite troublesome. You will need to purchase and install at least one pressure gauge. There is information about how to choose a pressure gauge, but it will be possible to really control and, if necessary, quickly regulate the pressure level, and this is necessary not only for normal operation boiler, but also for other devices. For example, for efficient work.

• Thread diameter. 1/2″ or 3/4″ inch.

• The presence or absence of a reset function. A small lever or flag intended not so much for draining (very slowly), but for monitoring the operability of the safety valves. Contrary to popular belief, the color of the lever does not carry any information about the nominal pressure of the device. Can be: black, red, blue or yellow.
• Cost. From 160 to 1600 rubles.
• Manufacturers. Italian companies Remer, ITAP. The well-known European concern Ariston and many other nameless Chinese manufacturers.

Nothing is said about the pressure at which the check valve begins to open, but its value can be judged from the water heater operating manual. For example, for the Termex model, RZL series, it is said that the pressure in the cold water system should be 0.05-0.6 MPa.

Why is my water heater check valve dripping?

It is known that water in a closed vessel increases in volume when heated and will inevitably find a way out, even if this requires tearing the metal tank.

Therefore, let's accept as dogma that a workable safety fittings when the water is very hot (from 80°), it should leak (drip slightly) from a specially designed pipe, releasing excess liquid pressure in the tank.

To drain water leaking from the drain pipe, it is convenient to use a transparent hose from the hydraulic level, with outlet to the sewer.

However, if we talk about moderate heating up to 60°, then the safety valve may not drip. Yes, maybe, if the following conditions are met:

• The inlet pressure must be at least 20% lower than the pressure at which the safety valve begins to open.
• The design of the boiler tank must have in its upper, spherical part, a sufficiently large supply of volume filled with air, acting as a hydraulic accumulator.

In fact, the practical search for the optimal compromise between acceptable temperature, pressure and absence of leakage has been carried out experimentally for quite a long time. There is no universal way to solve this problem. It all depends on the specific circumstances.

A water heater safety valve is often called a water heater check valve and must be installed for the safe operation of boilers. A boiler is a container where water is heated. When water is heated, according to the laws of physics, it expands and increases in volume. In a confined space, with rising temperatures, an increasing volume of water creates increased pressure on the walls of the tank and potentially poses a threat factor. Therefore, a safety valve must be installed on this equipment during installation for safety reasons. It protects the product from breakage, and if any emergency situation will relieve excess pressure and remove from the container water heating tank excess water.

• 1 What is a safety valve
  • 1.1 What types of valves are there?
  • 1.2 Device
  • 1.3 Operating principle
• 2 What can happen if there is no boiler protection
  • 2.1 Conclusion
• 3 Installation
• 4 Conclusion

What is a safety valve

Safety valves for boilers are similar in appearance to plumbing tees and combine the following functions:

• Shut-off valve;
• Check valve;
• Safety valve.

They are necessary in the arrangement of water heaters for bleeding excess water, which is formed due to its thermal expansion.

What types of valves are there?

Safety valves produced for household heating appliances are divided into three groups.

1. For water heater capacity up to 50 liters.
2. For containers from 50 to 200 liters.
3. More than 200 liters.

Small heaters are equipped with disposable valves of the first or second group. They are non-demountable structures made in China With short term service and low price.

Therefore, they can be replaced painlessly as the need arises. Valves of the third group are performed at more high level

• executions, they:
• They have a complex design;
• Withstand pressure up to 7 bar;
• They have a nozzle for connecting the sewer;

Allows visual control of water discharge. IN Lately famous manufacturers

electric boilers, always complete their products with high quality branded valves. In case of replacement, safety valves for the water heater can be purchased at the retail chain, and their specifications

recognized visually by the color of the handle. The red color of the handle indicates that this valve operates with a pressure of 0.6 MPa, black - 0.7 MPa, blue - 0.8 MPa.

Device

The safety valve for a water heater has a simple device and consists of two unequal perpendicular cylinders with a common plane. Inside the large cylinder there is a poppet valve, which is pressed by a special spring. It allows water to flow in only one direction, like a regular check valve. Big cylinder is located at the inlet to the boiler and connects it to the cold water supply pipe, therefore it is equipped on both sides.

threaded connections

• Second smaller diameter cylinder:
• Positioned perpendicular to the main cylinder;
• Muffled from the outside;

Has a small drain drain pipe.

Principle of operation

The internal arrangement of the smaller cylinder also consists of a poppet valve, but with the opposite operating orientation.

A safety device is installed at the inlet to the boiler and is adjusted to a certain permissible maximum pressure. When closed, two forces act simultaneously on its sensitive poppet valve.

The first is the liquid pressure in the boiler. The second is on the adjuster side in the form of a spring, which prevents the valve from opening. If the fluid pressure decreases, the valve opens and cold water fills the boiler. When the pressure is equalized, the device is locked, and water from the tank, thanks to the check valve, cannot flow out under the influence of liquid pressure into the active. If the pressure force increases when the water is heated to a certain level, the protection of the small cylinder with reverse action begins to operate and then excess water is discharged through the side outlet.

Sometimes people get nervous about water starting to drip from the safety valve. There is nothing wrong with this process. This is normal. This problem can be solved by placing a small container under it, or by connecting a hose to the drainage hole, which then needs to be lowered into the toilet or sewer.

What can happen if there is no boiler protection

Let's consider the option of no protection that blocks the reverse flow of water into the tank. In this case, the water heater, even with stable pressure in the water supply network, will not function correctly. According to the law of thermodynamics, as the temperature of water increases in a constant volume, its pressure will necessarily begin to increase. As a result, a moment may come when the water pressure begins to exceed the supply pressure. Then hot water will begin to be discharged into the plumbing system or even the toilet cistern. In this situation, cold water continues to flow into the boiler, and the operating thermostat commands the heating element to constantly heat, thereby wasting expensive electricity.

A more critical situation may arise when the water pressure of the water supply network drops sharply. This usually happens at night, when the relevant services carry out unexpected repairs or preventative work, turning off the cold water supply. In this case, completely draining the water from the boiler leads to burnout of the heating element.

To avoid such situations, many “woe Kulibins,” not realizing the complexity of the situation, install conventional check valves in the water heater installation system. However, they do not understand that they are planting a “time bomb” in their home.

After all, a water heater is a complex heating device; its automation and thermostat can also fail at the most inopportune moment. Then events can turn out very sadly. If the material from which the water heater tank is made is chosen correctly, then boiling does not occur there, since the boiling point here moves above the usual 100 degrees and the situation is kept under control. However, if the material does not meet the strength characteristics, then if any water tap in the apartment is accidentally opened, the internal pressure of the tank may sharply drop, the boiling point of water will return to 100 degrees, and then an avalanche-like flow of steam will occur at lightning speed, which can lead to mechanical damage boundaries of the tank and a powerful explosion.

Conclusion

When making a conclusion regarding the installation of additional protection for the water heater, it is necessary to take into account the following factors:

• Discharge excess water when it is heated, maintaining the parameters of its safe pressure zone;
• Do not allow water to flow back from the heater;
• Smooth out water hammer and pressure surges in the water supply system.

Installation

Typically, water heaters for installation are equipped by manufacturers with a complete protection system. If the boiler is completely installed, but there is no safety valve for it, you must purchase one. It is better to entrust the installation and purchase of protection to an experienced specialist, although doing it yourself will not be difficult.

The main installation condition is to install a safety valve directly under the tank after the shut-off valve at the cold water inlet to the heater. To carry out installation, it is necessary to prepare the work area.

1. There should be no water in the boiler tank.
2. The main access to it must be blocked.
3. The water heater is completely disconnected from the power supply.

The protection is installed taking into account the direction of the incoming water flow; it is indicated by an arrow on the valve. To ensure complete sealing of the joint joints, the threads are sealed with fum tape.

Conclusion

The safety valve is mandatory element for arrangement domestic water heaters working under pressure. When purchasing and installing this protection, you must make sure:

• In its operating parameters;
• Calculated power;
• Maximum operating pressure.

You cannot install devices that are designed for smaller parameters or whose threaded connections do not fit the installation site.

Ignoring installation rules, simplifying the installation scheme, or independently improving this protection is extremely dangerous.

By entrusting the installation to an experienced specialist, a person will be completely confident that he is safe, and his home is protected from disaster and fire, which can result from a faulty water heater.