Safety drain valve. Important thing to do for the boiler: safety valve
Water heaters are the most common devices for organizing hot water supply in a private home; sometimes they are also installed in high-rise apartments.
For installation on a water pipe, you will need some tools and additional materials. One of the required fittings is a safety valve for a water heater. As a rule, this protective element is supplied with the main device, but some budget models may be sold without a valve.
Purpose of the fuse
There are three main tasks that a safety valve performs:
- ensures safe operation of the water heater;
- protects heating elements from dry heating;
- if necessary, allows you to drain water from the water heater.
A safety valve is installed on storage water heaters (boilers). To better understand its principle of operation, you need to know how the boiler is designed and how it works.
The storage water heater contains water throughout its entire operation. The heating element turns on depending on the temperature to which the thermostat is adjusted.
Cold water enters the water heater through a pipe at the bottom of the tank. Hot water flows out of the tank through a pipe that is built into the bottom and installed inside, so that its upper end almost reaches the top of the tank.
This allows you to first select the top layer, which has a higher temperature, while cold water flows from below.
If there is not enough backwater in the main, the water can be drained through the pipe, which is designed for filling.
If there is no water, the heating elements will simply overheat and burn out. Even if they do not have time to burn out before filling, the water, when it hits the hot metal, will quickly boil and form a large amount of steam, which will create very high pressure. This pressure will be enough to destroy the device.
To prevent an explosion from occurring, it is necessary to install a check valve for the water heater, which must be located on the inlet pipe for cold water. In this case, when the pressure in the cold pipeline decreases, liquid will always remain in the container, preventing overheating of the heating elements.
But installing a check valve alone is not enough. Moreover, if you install only it, the consequences may be even worse than without it.
The water entering the water heater will stop as soon as the pressure in the boiler becomes equal to the pressure in the cold pipeline. After heating begins, the water will expand inside, and with the hot water taps closed, it simply will have nowhere to go and the pressure will begin to increase. All this is fraught with an explosion, the consequences of which can be the most unpredictable and tragic.
Obviously, for normal operation you just need to provide a drainage device that will produce an emergency release of water when the pressure reaches a certain threshold (excess value). It is implemented as a safety relief valve for the boiler.
Device and principle of operation
The device for preventing a serious accident looks surprisingly simple, and its dimensions are small - it fits in the palm of your hand. It is a small mechanism consisting of two perpendicularly located spring-loaded valves, enclosed in one metal body. Essentially, these are two cylinders (tubes), one of which is slightly larger than the other.
The first larger diameter tube, usually 1/2 inch, with two threads at the ends, has a check valve installed that allows fluid to flow in only one direction. The flap in it is located across the pipe and can move along it by several millimeters, opening or closing the passage.
Under the influence of pressure directed towards the water heater, the flap opens, compressing the spring. As soon as the pressure in the pipeline and behind the valve is equalized, the valve closes under the action of a spring.
In a tube of smaller diameter, located perpendicular to the first, a second valve is installed, the spring of which is adjusted to open at a certain pressure, exceeding the pressure for the first valve. This is a fuse that protects against explosion.
Thus, when the pressure rises and the check valve does not allow water to escape into the cold supply pipe, the second valve opens and it is discharged through the drain pipe.
The nozzle may have special notches that make it easy to put on a hose of a suitable diameter. This hose must be secured with a clamp and led either into the sewer or into a container that will have to be emptied from time to time. This will have to be done infrequently, since the amount of water squeezed out during operation of the water heater will be small.
Very often, a plastic flag is provided in the design to force the opening of the drain device. You can use it to check the functionality of the fuse. To do this, you just need to open it and make sure that the piston stroke is free, it is not clogged with rust and scale, and the spring force is enough to return the valve to the closed state.
The safety valve body is often marked with an arrow indicating the direction of water flow to facilitate installation. The small pipe is usually marked with a marking indicating the pressure in pascals at which the emergency valve opens.
Installation
The safety valve for the water heater is installed on the pipe that supplies cold water to the container. Due to the presence of threads at the ends of the device, it is installed without welding or soldering, its installation is simple. Be sure to follow the direction of the arrow on the body, indicating the direct flow of cold water. To seal the thread, you must use flax with packaging paste or FUM tape.
It is recommended to install a tap or drain valve between the inlet pipe and the safety valve. This is necessary because if you often drain water using a safety valve, the elasticity coefficient of the spring will decrease and the nominal opening pressure of the valve will change. Drainage will be needed when repairing a boiler, for example, in case of replacing heating elements or when preserving a house in winter, when liquid is drained from all systems to prevent it from freezing and destruction of pipes.
The tap must be placed on the side outlet of the tee in such a way that it is impossible to shut off the pipe between the water heater and the safety valve, otherwise the latter will not work. To ensure that air enters the water heater and does not create a vacuum that prevents draining, you can open one of the hot taps on the mixers.
It is not practical to install a drain valve with a tee on a hot water pipe. It will be impossible to drain water through it, and there is no need for extra detachable connections in the water supply.
If you want to hide the safety valve, you can slightly lengthen the vertical section of the pipe. But the distance from the tank to the valve should not exceed 2 m.
If water drips through the valve for no apparent reason (without heating), this may indicate high pressure in the system (above normal). In this case, it is recommended to install a reducer on the water supply system and adjust the pressure. If the water in the tank is cold, the pressure is not higher than 4 bar, and the valve continues to drip, then this is most likely a defect and the device must be replaced.
Functionality check
After installing the safety valve, you must check its functionality. To do this, fill the container with cold water. You need to fill with the tap open so that air comes out of the boiler. After water flows from the hot tap, you need to turn off both taps.
Water should not drip from the safety valve, but when opened by hand, it should come out under pressure approximately equal to the pressure in the water supply. There is no need to measure it, since it is easy to determine visually.
After heating has started, you should not turn on the hot water taps for some time. This will create increased pressure in the tank. Droplets will appear in the drain tube or simply from the valve hole (if there is no tube) as liquid begins to be displaced from the tank. This means that the safety valve is in working order and the water heater can be safely used.
The need for selection occurs in the event of a fuse failure, leakage or loss for some reason. If you need to buy a new safety valve, then pay attention to its response pressure. It is necessary to compare with the boiler pressure, which is indicated in the passport. Another indicator is the setup step. Typically it is 0.5 bar. You can choose a safety device with a slightly lower pressure than the boiler, but in no case with more.
A valve for a boiler should not be confused with a similar device for heating, since the latter is designed for lower pressure. It is also impossible to install a check valve instead of a safety valve, as it will not perform its functions and the heater may explode.
It is advisable to pay attention to the material of the case and choose brass, since it is more ductile, does not crack, lasts longer, although it is more expensive.
Buying your first electric boiler is a significant event. It is impossible to forget it, if only because for the first time you have to figure out why the water heater needs a power cord, as well as how to connect and install the entire system.
Subsequently, as a rule, no questions arise, so when replacing the boiler with a new one, reading the accompanying instructions is often skipped. Today we will talk about why a safety valve for a water heater is needed and what will happen if you “forget” to install it.
Laws of physics
Every person knows from childhood that when heated, objects expand, increasing in volume. The value depends on the material of the object, temperature and environmental conditions - these are the laws of physics. And water is no exception. If there is an increase in volume in a sealed enclosed space, then mechanical damage to the boundaries is quite possible - they will simply be torn apart. The safety valve for the water heater, which is necessarily included in the boiler installation kit, serves to protect the walls of the tank from destruction.
If it is missing, it must be purchased and installed separately. To understand the operating principle of a water heater safety valve, let's mentally assemble a model of the tank and connect it to the system.
Experiment
Two pipes are connected to the boiler: the supply of cold water and the return of already heated water. While the taps on the outgoing line are closed, the volume of the tank will be filled with cold water, which will begin to be heated by the heating element to the set temperature. As soon as you open the tap, hot liquid rushes out of the tank, squeezed out by portions of cold liquid coming from the system. However, there are several points that do not allow the boiler to be operated with this switch on. Firstly, since the entire mass of cold water (in the tank and pipe) is not divided by anything, the heating element will constantly work, trying to heat the entire available volume. Secondly, if for some reason the water disappears in the supply pipe or the pressure drops significantly (not uncommon in domestic systems), then the stored and heated liquid from the tank will partially flow by gravity back into the supply pipeline. To prevent this from happening, a check valve is installed on the connection pipe. The spring-loaded plate allows water to flow in only one direction, mechanically separating the two media - a simple but incredibly effective solution. Why do you need a safety valve for a water heater? Let’s mentally complicate the task by adding to the design the usual one installed on the feed. In this case, heating will occur without losses, and the disappearance of water in the supply pipeline does not threaten anything.
But what happens if the heating value is set not to 20-30 degrees, but to 60-80, as often happens? In accordance with the well-known law of physics, the water will begin to expand, and since all the taps are closed, the internal pressure will increase. If the walls of the tank are of poor quality, they will be locally damaged (burst). And if the tank material is chosen correctly, then the following happens: the pressure and temperature increase, but the water does not boil, since at high pressure the point moves. As a result, it turns out that the boiler may well contain water with a temperature of over 100 degrees. But then someone opens the water tap. The pressure drops sharply, returns to the usual 100 degrees, an avalanche-like release of steam occurs, which sharply increases the pressure and the tank bursts. If you manage to avoid injury, it can be considered lucky.
Safety valve for water heater "Ariston"
To prevent such accidents, they are designed in such a way that when a certain value of internal pressure is exceeded, part of the water is automatically discharged (usually a few milliliters). The layout of these elements is the same, so there is no difference whether they are installed on an Ariston, Termex, or other boiler. There are two spring-loaded plates inside: one of them functions as a simple check valve in the supply, and the other holds water in the tank until until the pressure exceeds a certain limit.
For modern people, hot water is the norm, ensuring a comfortable life. If there are problems with hot water supply, you can install heating devices. The most popular designs are electric boilers. The safety valve for the water heater is an important component when installing the unit. The level of safe operation and service life of the device depend on this detail.
The operating time of system elements depends on this device
Purpose of the part
A non-return safety valve for a water heater prevents sudden changes in pressure inside the device. The reason for such jumps is due to the fact that the liquid increases in volume and expands during heating. Due to the tightness of the tank, the resulting excess has nowhere to go, because the tap is turned off.
Subsequent heating may cause an increase in pressure. In this situation, there is a high probability that the permissible strength values of the device will be exceeded and its walls will rupture. To avoid such moments, a check valve is being installed on the water heater.
Many owners are puzzled whether it is necessary to install a fuse if the check valve can be removed. Experts say that with high and uniform pressure levels in the systems, this scheme will work, but not for long.
This does not mean that such actions are the way out of the situation. The error of the technique is that the pressure in the system is not always stable. Excess water flows from the appliances into the water supply system, thereby exposing the heating element. By heating the air, the unit will break down after some time.
In this video you will find out why the boiler is dripping:
Burnt out structures are not the worst problem. It is important that there is a possibility of a sharp change in pressure indicators in the system. The liquid quickly turns into a vapor state, which sharply increases the pressure. In this case, the walls of the water heater will certainly burst. A large amount of hot water and steam will quickly fill the room, threatening serious consequences for the people in it.
Principle of operation
The safety valve consists of several elements. They are housed in a brass or nickel housing. Often the part looks like an inverted letter T. A check valve is fixed to the bottom of the electric boiler, which prevents water from flowing out of the system when the pressure in the pipes decreases.
The operating principle of this valve is easy to understand The perpendicular outlet consists of another valve, which is activated after an increase in pressure and discharges excess water through the fitting. The principle of operation of a check valve on a boiler is as follows:
- If the pressure in the tank is less than in the pipes, then when the tap is opened, the check valve plate is pressed out by the water pressure. When the readings return to normal, the spring mechanism clamps the plate to the protrusion on the body, preventing fluid flow.
- During the period of active heating, the water temperature slowly rises and the pressure increases. The mechanism is not activated until the indicators reach maximum values.
- When the limit level is reached, the safety spring is compressed under the influence of pressure, opening the inlet channel on the fitting. Excess water flows out through this passage. After the values decrease to standard, the spring closes the channel and the liquid drainage stops.
From what has been described, we can conclude that water periodically drains from the fitting. This occurs during heating of the liquid, when the pressure in the water supply system decreases.
If water is regularly present in the fitting, it means that the drain valve for the water heater is fully functioning. But at the same time it is necessary to drain the flowing liquid. To do this, a tube of the appropriate size is fixed to the nozzle; a clamp can be used as a fastening element. Normal operating pressure in the tank ranges from 6 to 10 bar. Without a strong fixation, the pipe will break, so you need to choose this part carefully. You should tighten it tightly and lead it to the drain in the sewer.
Features of different types
If we are talking about standard safety valves for water heaters, then they are not very different in appearance. But there are a number of nuances on which the ease of use of the part depends.
Do not forget about the nuances of these valves Release lever
Some valves are equipped with a special lever. Periodically you need to check its performance. To do this, you need to carry out the following manipulations:
- Move the lever from horizontal to vertical position.
- Wait until the spring mechanism is activated, because the lever pulls it along with it.
After these steps, a duct will open from which water will flow. This procedure should be carried out at least once a month. This is how water is drained from the water heater tank. After raising the flag, you need to wait a little until the liquid drains completely.
On some valves, the lever is secured using a special bolt. This design eliminates the possibility of spontaneous opening and draining of liquid. In addition, some products come without levers at all; on the top of them, a cap is fixed with a thread, which is needed for servicing the valve. As needed, it is opened and various dirt and scale are removed.
The least preferred option is parts without any levers, holes for removing dirt or markers. These are the lowest quality products produced in China. You cannot rely on their strength and long service life. Such devices can be used as a temporary replacement for more durable parts.
Fitting and pressure value mark
There are a number of other differences between the devices. On the body there is an arrow indicating the direction of water flow, as well as an inscription that informs about the maximum possible pressure for a particular product. Such little things may seem insignificant, but if it is not difficult to figure out the direction of water flow, then with pressure indicators the situation is much more complicated.
At first glance, it is difficult to say what values exist for a particular valve, because they can only be calculated experimentally. Suppliers distinguish them only by documents. Craftsmen do not advise buying products without identification marks. Of course, the cost of marked parts is slightly higher than that of analogues, but it is better not to save in this matter.
In addition, you should pay attention to the shape of the water drainage fitting. On some parts it is long and has a non-linear shape. It is easy to attach the tube to such a device; its size is quite enough to securely fix the clamp. If the products are expanded at the end, then the main thing is the size of the fitting. It is better to refuse such an acquisition. This is due to the fact that it will be difficult to fix and secure the handset on the device. Homemade methods do not guarantee the quality of work, and in the future there may be problems with water drainage.
Don't forget about the pressure mark Products for large appliances
All devices described are designed for small storage water heaters with a capacity of 50-60 liters. For larger tanks, other parts are used, each of which integrates specialized equipment - a valve or ball gauge that controls pressure.
The fluid drain fitting is equipped with a standard thread. This is necessary for better fixation and no problems with clamps. Such devices are not cheap, but their quality level is much higher than that of other systems.
Many consider the appearance of the faucet to be a significant drawback. For such people, fuses are specially produced, which are not only useful in practice, but also decorate the interior of the room. Often their price is equal to the cost of a water heater, so everyone evaluates for themselves the feasibility of such an acquisition.
Other devices
There are situations when, instead of factory safety systems that prevent pressure surges, a blast valve is installed. Its main purpose is emergency drainage of liquid into the heating system. In terms of functional characteristics, such products are very similar, but the principle of their operation is diametrically opposed.
Demolition-type products function in case of accidents. They are necessary for emergency draining of water from the water heater and are not suitable for periodic bleeding of small portions. Such elements should not be expected to function correctly.
In addition, many install only a check valve. Its mechanism prevents fluid from escaping at low pressure, but it does not protect against sudden changes in the tank. Practice shows that such a device is also non-functional.
Selection and installation
It is necessary to select a bypass valve for a boiler based on the pressure value that the product can withstand. Often this figure is recorded in the registration certificate. In addition, the choice is influenced by the capacity of the tank. There are systems whose response threshold varies from 6 to 10 bar. These are the most common indicators for valve actuation. The valve installation process is quite simple, if you follow the step-by-step instructions:
- Wrap FUM tape or tow around the thread for a tight connection.
- Fix the tap on the pipe.
- Tighten the product until it stops by hand, and then make several turns with a wrench of the appropriate size.
- Do not forget about the installation location of the unit. Experts advise placing it on the cold water inlet pipe.
After this, you can install a check valve, otherwise called a lock. Such manipulations are reinsurance measures, because a design with identical functions is already present in the fuse system; in addition, it is often integrated into water meters.
Then you need to position the ball valve, which is used to remove water from the container when dismantling or preserving the product for the winter. These steps will also need to be performed during preventive cleaning or repairs. Often the tap is mounted on a tee - the connecting link between the product and the safety system.
The safety valve is a mandatory part for the proper functioning of the water heating device. It is undesirable to neglect this design, because inattention can be fraught with serious consequences.
If difficulties arise with selection or installation, it is better to entrust this matter to experienced craftsmen who, within a short time, will make the boiler completely ready for proper and safe operation.
The constant availability of hot water in a house or apartment has long become a familiar norm for most people, without which it is difficult to imagine a normal, comfortable life. If a water supply is extended to the housing or an autonomous uninterrupted water supply is organized, for example, , then there is nothing to think about - you need to install a water heater of one type or another.
Probably the leading position in popularity among water heating devices for domestic needs are electric boilers. They are extremely easy to use, their installation does not require any additional coordination procedures or drawing up individual projects. Installation of such a boiler is quite feasible even for independent installation. That is why the information that will be presented in this publication is necessary - each of the home craftsmen must clearly understand how important a safety check valve is for
How would workers of housing and communal services, emergency and rescue services, state technical supervision authorities warned what would stories with the consequences of accidents have not been shown on television, still with alarming regularity there are “smart people” who benefit from all these technical recommendations and simply kind advice is not a decree, they themselves “know what is simpler and better.” Alas, ignoring a very small, inexpensive, easy-to-install, and at the same time extremely important object for piping an electric water heater can result in very big troubles, and, it is possible, even a tragedy.
Design and principle of operation of the valve
First of all, it is necessary to immediately make a very important disclaimer. Although very often, in order to obtain information, those interested enter the search query “check valve for a water heater”; it would be much more accurate and correct to talk about a safety valve that combines several functions. These devices have a certain similarity, but there is also a huge difference, which predetermines the main task - security safe operation of an electric heater.
For comparison, consider the device of a conventional check valve:
This is how a regular check valve works. But it’s not enough for a boiler! This is a metal cylinder, on both sides of which there are threaded sections for “packing” into a straight section of pipe of the appropriate diameter. A poppet valve is stopped inside - a disk with a rubber seal around the circumference, on the central axle - rod(shown in the figure with a green arrow). The disk is constantly in a spring-loaded state, blocking the internal channel for the passage of water.
When water is supplied in the direction of the arrow (the direction of the permissible liquid flow is always indicated on the valve body - this mark is shown with a red arrow in the figure), the pressure in the pipe through the “plate” compresses the spring and slightly opens the passage. As soon as the pressure decreases, the valve automatically returns to the closed state.
This precaution is, of course, necessary to ensure that the tank in the water heater is constantly filled, under any circumstances. However, such a measure is clearly not enough to ensure safety - this will be discussed below.
The safety valve is somewhat more complicated:
Essentially, these are two valves in one body, placed perpendicular to one another.
In the larger cylinder (item 1), which follows the flow of water, the same valve is installed, preventing the reverse flow of water. On the supply side there is a male threaded section (item 2) for insertion into the water supply system (in particular, it will be convenient to connect a flexible water supply hose here). On the opposite side there is a female threaded coupling (item 3), which in some cases is screwed directly onto the standard cold water supply pipe in the electric heater.
The figure clearly shows the check valve “plate” (item 4) with a sealing ring around the circumference, and the spring (item 5) that holds the valve closed.
Now here is the main difference. Perpendicular to the cylinder with a check valve there is another one, somewhat smaller in size (item 7). In fact, it contains the same poppet valve, but its spring is much more powerful - this is the same safety “breakdown” valve. Normal and even slightly increased pressure in the water supply system will not be able to compress the spring and open it - this requires much more serious efforts.
In the cylinder cavity behind the safety valve “plate” there is necessarily a hole with a pipe (pos. 8), where excess liquid will be discharged when the valve is activated.
A cylinder with a safety “breakdown” valve can be completely plugged, and sometimes it ends with a threaded plug (plug), behind which there is an adjusting screw (usually with an “internal” hexagon). But the most common safety valves are those with an additional lever:
The figure clearly shows the features of such a device. The lever (pos. 9) is intended for manual opening of the safety valve with water discharge through the pipe (pos. 8). Please note that the pipe may have a special relief design, which allows you to put thin hoses on it to drain water into the drainage (sewer). The manual valve control function can be convenient, for example, for draining the contents of a boiler during repair or maintenance work. However, you should not get carried away with using such manual control - this can in some cases even be dangerous (this will be discussed below).
Any safety valve always has an arrow indicating the direction of cold water flow towards the water heater. (there is a red arrow in the diagram). Very often, the maximum operating pressure of the “stall” valve is indicated on the body - in this case it is 0.7 MPa or 7 atmospheres (yellow circle in the figure).
How does a safety valve work in different situations?
To fully understand the importance of a safety valve, it is best to consider the cases in which it operates, as well as the situations that may arise if for some reason the valve is missing or faulty.
For clarity, once again - the simplest, but also the most understandable scheme for piping a boiler with a safety valve. The blue and red arrows show the direction of flow of cold and hot water, respectively. The green arrow points to the installation location of the safety valve.
1. After the electric one is installed and completely “tied”, it should be filled. To do this, simply open the cold water supply and the hot tap on one of the mixers. There is enough pressure in the water pipe to open the check valve to allow unimpeded flow. As the volume of the water heater tank fills, air is displaced. As soon as water flows from the mixer, the entire container is filled to the upper intake pipe, the supply can be turned off.
The pressure in the boiler at this moment is approximately equal to the pressure in the cold water main - it is, as it were, “propped up” by it. However, it may even be a little higher - due to the remaining compressed small volume of air in the upper part of the tank. Plus, when the power is turned on, the water begins to heat up - and this, of course, also leads to an increase in pressure.
2. Let's imagine a situation where the check valve is not installed or is in a faulty condition. The equilibrium that was achieved when filling the boiler tank is sooner or later disturbed, since the pressure becomes higher than the pressure in the pipe. The “hot” taps on the mixers are closed, which means that the heated water will look for an outlet in a different direction. This can lead to hot water suddenly starting to flow from a “cold” tap, or to filling the toilet flush tank with it. Meanwhile, the boiler thermostat cannot understand the situation and does not give a signal to turn off the heating elements. Expensive electrical energy is completely wasted.
3. But this is not the saddest thing. It is no secret that the pressure in the water main, especially in multi-storey buildings, often drops to critical values (from the tap, as they say, it barely flows), or even disappears completely. There are a great many reasons for this, for example, an accident on the highway, maintenance work, a planned reduction in pressure, for example, at night, etc. What happens if the check valve is missing or faulty? Nothing good - the boiler will simply empty, since all the water from it will completely flow into the supply pipes.
It’s good if the boiler has protection against “dry” heating, and it will work quickly! And if not? Powerful heating elements will idle heat the air in a closed volume, and this will end either in their burnout or cracking of the enamel - in any case, nothing good can be expected in such a situation.
4. A reasonable question may arise - is it possible? limit myself only by installing this same check valve? It would seem, judging by the description, that he is able to solve all problems.
Do not consider it an exaggeration: such an installation is like a bomb planted in your home! No, under no circumstances is it possible. The installation of a complex valve that combines both non-return and safety valves is a prerequisite for the safe operation of the water heater.
If somewhere the reader comes across a similar picture - only a check valve at the inlet, then he should understand that this is comparable to a planted powerful bomb, which will explode unknown when.
Another example of “suicidal creativity” Let's look at the situation in detail. When the boiler is turned on, heating begins, and as the temperature rises, according to the laws of thermodynamics, the pressure in a closed volume begins to increase.
Designers of household appliances include a certain operational resource in each water heater, allowing the device to operate up to certain pressure values in the tank - usually this value is indicated in the technical documentation. Typically, all boilers are very balanced thermodynamic systems, in which the optimal ratios of permissible temperatures and pressure levels are very accurately calculated. Nevertheless, anything can happen. And as soon as the pressure level, for some reason, begins to approach the permissible upper mark, the spring on the safety valve is compressed, and the resulting excess liquid is discharged into the drain pipe. As a result, the system again enters a state of dynamic equilibrium.
Water coming out of the drain pipe is normal. Now let’s try to imagine what can happen in a situation where there is no emergency valve, and everything is limited only by the return
Water heating should be limited by a thermostatic regulator, but quite often these electromechanical devices are far from perfect and can simply fail. In this case, heating continues uncontrollably.
The pressure inside the boiler tank is growing, but there is no way out - the mixers are closed, and the check valve has reliably shut off the supply line. It would seem that the temperature will only reach 100 degrees, to the boiling point of water? Nothing like this! As the pressure in a closed volume increases, the boiling point of the liquid also increases sharply. For example, the data is shown in the table:
| Pressure in a closed volume, atm (MPa) | Water boiling point, °Ċ |
|---|---|
| 1.0 (0.1) | 99.09 |
| 1.033 (0.1) | 100.0 |
| 1.5 (0.15) | 110.79 |
| 2.0 (0.2) | 119.62 |
| 2.5 (0.25) | 126.79 |
| 3.0 (3.0) | 132.88 |
| 4.0 (0.4) | 142.92 |
| 5.0 (0.5) | 151.11 |
| 6.0 (0.6) | 158.08 |
| 7.0 (0.7) | 164.17 |
| 8.0 (0.8) | 169.61 |
| 9.0 (0.9) | 174.53 |
| 10.0 (1.0) | 179.04 |
| 20.0 (2.0) | 211.38 |
| 25.0 (2.5) | 222.90 |
| 50.0 (5.0) | 262.70 |
| 100.0 (10.0) | 309.53 |
When the word “bomb” was mentioned above, this is not at all an exaggeration! In such circumstances, the water heater becomes really a scary explosive device destructive force.
Already at 4 - 5 atmospheres of pressure the boiling point reaches almost 150 ° WITH, and continues to rise. An increase in pressure on the walls can lead to their deformation, chipping of the enamel or ceramic coating - but this will be the least of all possible evils. Another scary circumstance is a sharp drop in pressure in this closed system, and this can happen when a crack appears in a weld, when a rubber seal breaks, or even simply when a hot water tap is opened.
A sharp decrease in pressure leads to a corresponding sharp decline boiling temperature of water. As a result, the entire volume of liquid (imagine all 50, 80 or 100 liters at the same time!) instantly boils, which, of course, is accompanied by the release of a colossal amount of steam. No one, even the most durable building, can withstand this - a powerful explosion follows, which is capable of demolishing everything in its path, including even brick interior walls. There are many clear examples of this on the Internet.
It's hard to believe, but these are the consequences of an explosion of an ordinary electric boiler So, let's briefly summarize the issue of the need for a safety valve.
— It prevents reverse leakage of water from the tank into the supply pipeline in the event of a decrease in pressure.
The presence of a valve at the inlet creates additional protection for the boiler from possible strong pressure surges in the water supply and from water hammer.
— The safety valve will eliminate possible shortcomings in other safety levels - it will maintain the temperature-pressure regime in the boiler within acceptable values.
— A safety valve equipped with a lever also allows water to be drained from the boiler if necessary.
Video: Is it necessary to install a safety valve on the boiler?
Prices for popular models of indirect heating boilers
Indirect heating boiler
Recommendations for selecting and installing a safety valve
Selecting the right valve is not difficult. Most often, boilers (especially from leading manufacturers) go on sale complete with a valve of the required rating. You will need to focus on the same value if for some reason you have to change the valve in the future.
The maximum pressure value in the boiler tank must also be indicated in the technical documentation of the product. If the water heater is not equipped with a valve, you will have to purchase it yourself, based on the value indicated in the passport. It is important to choose the right rating here - if you install a valve that is too “weak”, water will leak from it almost continuously. A valve with too strong a spring will not create absolutely safe operating conditions.
The valve can be “packed” directly onto the boiler pipe for cold water (always has a corresponding blue color marking. For reliable sealing during installation, it is best to use flax tow with modern sealing pastes. When tightening, 3–4 full turns are usually sufficient. If there is a flexible liner underneath , then a rubber sealing gasket is sufficient.
Sometimes a drain valve is inserted between the valve and the boiler itself - this greatly facilitates periodic maintenance work. Such an installation is quite acceptable, but only under one condition - the valve must be located at the outlet of the tee, but in no case should it interrupt the direct channel from the water heater to the valve. Any shut-off valves on this straight section are strictly prohibited!
Step-by-step instructions for wiring an electric water heater
It makes sense to consider step by step how you can independently connect an electric boiler to the water supply system. The table below shows two options as examples. Despite some differences, in both cases it will still be clearly demonstrated that the safety valve is a mandatory element of the piping of such a water heater.
| Illustration | Brief description of the operation performed |
|---|---|
 | To begin with, a few words about installing the water heater itself on the wall. Of course, the location is thought out in advance, before purchasing the device, so that the boiler fits in the space allocated to it and does not interfere with the normal operation of the room. A power cable connected to a separate machine is usually installed in advance at the installation site. Insertion points into the water supply system are also immediately provided. To accurately hang the boiler on the wall, its height is measured. |
 | Knowing the height of the water heater, it is easy to determine the lowest point of the position of the device that it will occupy after installation. |
 | On the back side of the water heater body there are devices for mounting on the wall. In this case, it is a regular mounting strip (bracket) that will cling to the hooks. There may be other options - the device’s instruction manual usually describes all this, and often 1:1 templates are also included to simplify the marking process. |
 | In this case, it is necessary to determine the location of the line on the wall along which the hooks will be mounted. To do this, measure the distance from the lower end of the water heater to the mounting plate. |
 | The same distance is marked on the wall vertically from the previously designated point of the planned lower edge of the boiler. |
 | With control over the building level, a horizontal line is drawn along which the hooks will be located. |
 | The next step is to measure the required distance between the hooks. In this case, 200 mm will be optimal - the hooks will be placed closer to the edges of the mounting strip, but there will still be the possibility of a slight play left and right to align the water heater. |
 | This distance is transferred to the intended horizontal line - the centers of the holes for the hooks are marked. In the example shown, they landed rather poorly - exactly on the seams between the ceramic tiles. If there is such a possibility, then it is better to mark the holes away from the edge of the tile - the likelihood of a crack appearing when drilling holes is much less. |
 | Powerful hooks were chosen to hang the boiler: the outer diameter of the polymer dowel plug is 14 mm, the length of the dowel is 80 mm, the diameter of the metal hook is 8 mm. Often, the electric water heater kit already includes the fasteners recommended for installation. |
 | At the designated points, the corresponding holes are drilled with a hammer drill, into which dowel plugs are driven. Then the hooks themselves are screwed in. |
 | The hooks are screwed in to such a depth that a reliable, stable fit of the water heater is ensured, without play, but also without jamming. |
 | That's it, the boiler is hung on the wall. From below you can clearly see two pipes through which the device will be connected to the home water supply system. The pipes are color coded: blue – cold water supply, red – hot water outlet. |
 | The appropriate connection has already been made into the water supply system - here are two polypropylene pipes to which the water heater pipes need to be connected. On the left is the hot water supply pipe, on the right is the cold water supply pipe. |
 | In the example under consideration, the master decided to equip the entrance to the boiler with an optional element - an additional tap, which will be used if it is necessary to empty the boiler. To do this, a tee will be installed on the inlet pipe of the water heater. The recommended preliminary “fitting” is carried out - how many revolutions are needed for the swarm outlet to take the required position. In general, it is advisable to carry out such fittings before assembling any fixed assembly - there is less chance of making a mistake. |
 | After this, the tee is packed onto a tow winding coated with Unipak sealing paste. |
 | The tee is packed and given its intended position. |
 | A compact tap will be mounted on the side pipe of the tee. |
 | The tow is wound up and sealing paste is applied. |
 | The tap is screwed in, tightened with a key, at least three turns, and given the planned position for easy access to the handle. |
 | But now it’s time to install a mandatory element - a safety valve. Be sure to pay attention to the arrow showing the direction of water flow. |
 | The safety valve will be installed on the lower pipe of the already installed tee. The basic rule is fully observed - there are no locking devices between the valve and the water heater. The valve installed on the side branch of the tee does not have any effect on the safety of operation of the device. |
 | The valve is packed onto a tee - in the illustration this entire assembly is assembled. |
 | It is advisable to make the boiler piping dismountable - this will make it possible to turn off the device to remove it, for example, for maintenance or to replace the heating element or anode rod. Therefore, the foreman decided to install shut-off ball valves with an “American” union nut at both inputs. An example of such a tap is shown in the illustration. |
 | The tap itself will be tightly packed onto the lower branch pipe of the safety valve. And a fitting for transition to a polypropylene pipe will be mounted on the fitting with the union nut itself. That is, it will not be difficult to disconnect the boiler from the pipes. |
 | A second similar tap is installed for hot water, but directly on the outlet pipe of the water heater. And it is also assumed that a fitting for transition to a polypropylene pipe will be packaged with the removable fitting with the “American” one. |
 | Here the fitting mounted to the tap fitting is tried on at the installation site. In this case, a 90-degree elbow fitting was used to immediately lead the pipe closer to the wall. |
 | Next, another bend will be welded in - and the pipe will go down along the wall. |
 | A regular fitting for switching to polypropylene is mounted on the fitting of the second tap for hot water. But this was done solely for reasons of aesthetics in the appearance of the piping - so that the “step” of transition to a level closer to the wall on both pipes is located at the same height. Next, the usual welding and installation work with polypropylene pipes is carried out. |
 | This is how neat the overall water heater piping unit turned out to be. |
 | And this illustration shows how the supply pipes are welded into the previously left water supply pipes. The water heater installation is complete. You can open all the taps (except the drain), fill the boiler with water, and connect to the power supply. If there is a need and opportunity, a transparent PVC pipe is placed on the drainage pipe of the safety valve, which is diverted into the sewer, toilet flush tank or some container - the excess water released will not fall on the floor. |
 | Now let's consider a possible option for piping the boiler with the installation of a flexible line. The illustration shows that the water heater is already hung on the wall. The arrow shows one of the “water outlets” - pipes hidden in the wall under the finishing of cold and hot water pipes. |
 | Conventional ball stop valves will be packaged onto these connections. In this case, there is no particular need to use taps with a union nut - the piping will be dismountable due to the use of a flexible connection. |
 | The nozzle is wound with flax tow. Some craftsmen use FUM tape, but there are still many more supporters of reliable sealing using tow. |
 | The winding is coated on top with Unipak sealing paste. |
 | Then the tap itself is screwed on - first it is baited by hand... |
 | ...and after that, it is tightened with a wrench, so that the “lamb” is located in a place convenient for use – at the top. |
 | A similar operation is completely repeated with the second tap. That's it for now. |
 | Let's move on to operations directly on the boiler itself. Its two pipes are ready for further installation. |
 | A sealing winding is performed at the inlet pipe - a safety valve will be installed here. |
 | In this case, the master decided to limit himself to only the valve, that is, to do without installing a drain valve on the tee. A completely normal solution - you can drain the water from the boiler through the valve - a special lever is provided for this. Draining will take a little longer, but installation is simpler and cheaper, and you still don’t have to resort to emptying the boiler very often. |
 | The valve is screwed on and then tightened with a wrench so that the lever and drain pipe are in a position convenient for the user. In fact, this was the last connecting node, requiring winding of tow. |
 | The safety valve is installed in its original place. |
 | Flexible hoses are connected. In this case, the master used high-quality corrugated stainless steel hoses, which, according to their characteristics, are considered “eternal.” A flexible hose made of a rubber or plastic hose in a metal braid is, of course, significantly inferior in reliability, and is attractive only due to its low price. The installation principle is completely identical. Hoses in length are purchased taking into account the distance from the boiler to the “water outlets”. The gasket that comes with it is inserted into the union nut of the hose, then the nut is inserted onto the thread of the pipe (in this case, the outlet). No winding is necessary if the end of the pipe along the entire circumference is in normal condition - the gasket will provide the required level of sealing of the connection. The union nut is first screwed on by hand until it stops... |
 | ...and then tightened literally another ¼ ÷ ½ turn with a wrench. There is no point in over-tightening the connection - you can pinch the gasket and thereby achieve just the opposite result. |
 | The second end of the flexible hose is connected in the same order to the threaded pipe of the faucet on the corresponding “water outlet”. |
 | The installation of the second hose is carried out in a similar way, with the only difference being that its upper end is connected to the safety valve branch pipe. Now you can turn on the water and check all connections for leaks. If a “tear” is detected, you can slightly tighten the connection with a wrench, without applying much force - the leak should disappear. |
 | If there are no leaks, you can proceed to full operation of the water heater. The illustration shows the “lower node” of the boiler piping: a flexible line is connected to the taps of the “water outlets”. |
 | And these are the same hoses, but connected from above to the safety valve (for cold water) and to the hot water outlet pipe. The boiler installation is complete. |
Video - Check valve on water heater
Frequently Asked Questions (F.A.Q.)
And finally, it makes sense to answer some of the most frequently asked questions regarding the operation of boilers with a safety valve.
- People often ask how to deal with annoying drops of water protruding from the drain pipe?
But there is no need to fight them - they only indicate that the valve is functioning normally. The easiest way is to put a transparent tube on the pipe (so that you can visually control it) and lead it either into a sewer pipe or, for example, into a toilet flush cistern.
- Is it possible to place the valve so that it is not visible?
By and large, if he is so annoying, then it’s okay. But at the same time, certain conditions must be met:
— No additional elements are allowed between the valve and the boiler - shut-off valves, tees, etc.
— The length of the section from the valve to the entrance to the boiler should not exceed one and a half to two meters. The fact is that the vertical column of water in the pipe will put additional pressure on the safety valve spring, and it will begin to work incorrectly, with severe undercutting.
- Leakage from the valve is too frequent and abundant, even at low water heating temperatures. What can be done?
The reasons for this phenomenon may be different.
— The valve rating does not correspond to the characteristics of the water heater.
— the spring in the valve simply weakened over time.
In both cases, the valve should be replaced with a new one with the required actuation force.
Another reason may lie in the instability of pressure in the water supply system. For example, frequent pressure surges with a large amplitude lead to valve activation even in the absence of heating. In this case, it is recommended to install a pressure reducer at the entrance of the water supply to the house (apartment).
- Can I try to adjust the valve myself using adjusting screws?
Definitely no! Adjustment of such devices requires " calibrated» pressure, and carrying out such procedures on your own is prohibited. The valve is not such an expensive product that it is impossible to purchase a new one of the required rating.
- I never saw even a drop of water come out of the valve. This is fine?
And here this is a very worrying sign. Who knows, perhaps the valve is simply “calming” with its appearance, but is completely inoperative. For example, the chamber behind the disc spring is overgrown or clogged with scale, the pipe is clogged, etc. If the valve is equipped with a lever, then you can try to check it manually (only better - at low heating temperatures, about 40 degrees, so as not to get burned).
It is possible that the valve rating is too high - it does not correspond to the water heater model. In addition, manufacturing defects cannot be completely ruled out.
The best way out of this situation remains the same - replacing the safety valve with a new one.
It will be calmer this way!
Never skimp on your own safety!
Video - Tricks for connecting an indirect heating boiler
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 also sometimes called a safety valve. There is no mistake in this. The design feature of the 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. The other, located in a tube of smaller diameter, is safety.
The non-return 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. You can find out what the nominal pressure of a particular safety device is from the inscription on the device body, but it may not be there. In this case, you should focus on the 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 of storage water heaters recommend using a pressure reducing valve () to set the water pressure in the cold water system 20% below the start value of the safety valve. 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 on how to choose a pressure gauge, but it will be possible to actually control and, if necessary, quickly regulate the pressure level, and this is necessary not only for the normal operation of the 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 an efficient safety valve, when the water is very heated (from 80°), should leak (drip slightly) from a pipe specially designed for this purpose, 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.