Owners who have installed a storage water heater in their home often have questions about the operation of its safety valve. Is water leaking from this device normal or a breakdown? And if the water circulation must take place, then in what quantities and how often? We have already looked at the design and operating principle of a safety valve for a boiler. Now we will tell you how to determine the malfunction of this device and how to solve the problem of its leakage.

Why is the safety valve leaking?

As you already know, the safety valve for a water heater is used to relieve excess pressure from the tank that occurs while heating the water. In this case, a leak can occur in several cases, each of which we will consider in more detail.

Leaking when the boiler is off

Let's simulate the following situation: the water heater is disconnected from the network, the water supply from the water supply is turned on (the tap on the pressure line is open). Water is flowing from the boiler drain hole. The cause of this phenomenon may be either a malfunction of the safety valve or increased pressure in the line.

To find the cause of a leaking safety valve, you need to know the water pressure in the water supply

To determine the culprit of the leak, you need to measure the cold water pressure in the water supply. The fact is that if the main pressure exceeds the accepted SNiP, the valve will open and perform its functions of discharging excess water into the sewer. Most water heater safety valves that manufacturers equip their products with are set to a pressure of 6 to 8 atmospheres.

The maximum pressure allowed by SNiP in main water pipelines should not exceed 6 atmospheres. In fact, it often happens that actual indicators exceed standard values ​​by 1 - 2 atmospheres. Naturally, the safety mechanism will work.

The possibility of particles of scale or debris getting under the locking mechanism plate, which can happen during an emergency pressure release or after draining water from the boiler during maintenance or repair work, cannot be discounted.

If the safety valve leaks, do not under any circumstances remove this part from the water supply system to the water heater. Remember that operating a storage water heater without a safety valve is prohibited and can lead to its explosion.

Video: What does operating a boiler without a safety valve lead to?

Valve leakage during water heater operation

If the water heater is connected to the network and heats water for a long time without significant water intake, then the cause of the constant leakage is most likely a faulty safety valve. The fact is that during the initial heating of cold water, its volume in the boiler will increase by about 2-3%. This excess liquid will be discharged from the tank. In the future, the boiler simply maintains the temperature of the hot water, so there should be no leaks, so the cause should be sought either in a breakdown or in a clogged safety valve.

A completely different picture should be observed with increased water consumption, for example, while taking a shower: the constantly leaving volume of hot liquid will be continuously replaced by cold water.

But when it heats up, the excesses indicated above will begin to appear. Therefore, the flow of a certain amount of water from the drainage hole in this case is quite logical.

Safety valve device for water heater

And the third option is for a small, extended water withdrawal. For example, washing dishes or cooking. With such a flow rate of hot water, there should not be a constant leak from the drainage tube, but the periodic leakage of liquid drops will indicate the correct operation of the water heater.

If the cause of the leak is a faulty valve, then it is replaced with a working part adjusted to the same operating pressure. When replacing, or better yet, while installing a water heater, try not to use cheap Chinese products. Remember that the safety of your family directly depends on the valve. Good Italian safety valves with the same non-separable design, although they cost several times more, are purchased once. As practice shows, there are no problems with them in the future. Connect a flexible transparent hose to the drain outlet of the device. This will help to visually evaluate the performance of the part. Lead the end of the hose into the sewer or a suitable container.

Products from well-known manufacturers are reliable and durable

To remove the valve for replacement or cleaning, you will need a plumber's wrench and an adjustable wrench. The work is performed in this order:

• Disconnect the boiler from the network;
• Turn off the cold water supply tap to the water heater;
• Open the hot water taps and completely drain it from the container;
• Press the lever on the safety valve and remove any remaining liquid from the tank;
• Disconnect the cold water pipeline from the safety valve;
• Remove the valve.

After cleaning or replacement, the part is put back in place in the reverse order.

Important note: you can connect the water heater to the network only after its tank is completely filled with water, otherwise the tubular electric heater may fail.

If the input pressure of your water supply system exceeds the nominal pressure for which the storage water heater is designed (this can be found in the technical data sheet for the device), a pressure reducer is installed at the water inlet to the apartment.

Installing a reducer at the inlet of the water heater will not only reduce the water pressure, but will also prevent the occurrence of water hammer, which adversely affects the coating of the internal tank of the boiler.

Hot water is a useful and pleasant function in a person’s home. But there are cases when there is no such central communication, or the liquid flows barely warm. We have to buy a water heater. This apparatus combines near-boiling liquid and electricity. Therefore, measures must be taken to prevent danger.

The storage type heater tank is a hermetically sealed tank in which water is heated. During this process, steam is generated and pressure increases. That is why among the technical characteristics of the unit there is an indicator of maximum pressure. For household appliances it is usually 10 bar.

When in the evening all family members took a shower, bath and washed the dishes, the hot water was used up, and the tank was filled with cold liquid. While people sleep, the water heater heats the water, and the pressure inside the housing increases. All taps are closed, there is no return flow into the system. This means pressure accumulates in the boiler itself.

Having reached the set heating parameter, usually 60° - 65°, the thermostat should turn off the device. At the same time, the pressure in the water supply system is 2.7-3 bar, plus the steam from the water heated in the tank, for a total of about 4 bar in the heater housing. The situation is within normal limits.

Let's imagine that the sensor did not work. According to the laws of physics, the boiling point increases in proportion to pressure. For water at 10 bar, this parameter will be 180o C. The volume of liquid in the tank is about 80-100 liters, now all this mass has turned into steam. If the housing fails, an explosion will occur. A boiler safety valve can protect you in such a situation. This mechanism performs two functions:

1. Prevents spontaneous drainage of liquid from the heater into the system when there is no water in the communications.
2. Relieves excess pressure from the tank in automatic and manual modes.

Operating principle

Two valves are placed in one body.

• The first, check valve, is located on the cold water supply side. As the tank empties, the pressure in the water supply becomes higher than in the reservoir and the inflow pressure pushes the seat away from the inlet. The path through which water enters the boiler is cleared. When the device is filled and the pressure in it and the pipes is equalized, the spring returns the seat to its place, thereby blocking the outlet from the boiler back to the water supply network.
• Second, safety valve for the boiler , during normal operation of the device is closed, and in the event of excess pressure, the jet from the unit acts on the valve, the calibrated spring is pressed out and the outlet channel opens, allowing the excess liquid to be discharged.

Installation

1. The device is mounted directly on the inlet pipe of the water heater.
2. When connecting, the direction of fluid movement must be observed. To do this, there is an arrow on the valve body, which should point towards the boiler.
3. Some models may have an internal position stop. Such safety valve for boiler You can screw it all the way. If this option is not available, then when tightening the mechanism, you should make no more than 4 turns. Violation of this rule can lead to a narrowing of the safety channel.
4. After mounting the mechanism on the heater, look inside its body from the side where the cold water enters. The check valve seat should be visible. Try to press it lightly with a blunt object. If the installation is done correctly, the obstacle should move forward and return to its place after being released. If the saddle does not move, then the work was done incorrectly.

Attention! Cannot be replaced boiler safety valve simple check valve. In this case, only the tank empty warning function will work. Excess pressure will not be released.

Examination

This procedure will take several hours to complete. During the entire test period, do not open hot water taps.

• After fully connecting the water heater and filling it with water, set the heating limit on the control panel to about 80 O .
• As the temperature rises, closer to the maximum, a trickle or drops of escaping liquid should appear from the fitting.
• If this does not happen, wait until the thermostat turns off the water heater.
• Depending on the characteristics of your model, increase the limit to the maximum possible.
• When the heating process is completed, liquid should drip. If there is no leakage, or the device is able to reach a level of more than 80 O It is recommended to have the valve checked by a workshop or replace it with a new safety mechanism.
• Place a hose onto the fitting of a working mechanism and secure it with a clamp. The second end must be taken to the sewer.
• If water begins to flow immediately after filling the tank, the device is defective, it must be replaced with a new mechanism.

If the safety valve is not installed on the boiler, operation is prohibited.

Selection

The basic rule that should be followed when choosing this device is that the response pressure of the mechanism corresponds to the characteristics of the heater. This parameter is indicated on the case or in accompanying documents. It is better not to buy models from which you can set action limits.

Please note that there is a forced fluid release lever. Inspect the threaded connections and make sure that they are of good quality and that there are no thread defects.

The drain fitting should be placed so that it is convenient to put the hose on it.

Possible faults and solutions

1. If, when the boiler is cold, water flows out of the emergency release hole, this means that, most likely, foreign elements have entered the valve. Open the drain channel completely using the lever and allow the liquid to flush thoroughly through the mechanism. When clean, transparent liquid flows through the hose, close the outlet with the lever. The leak must stop, otherwise the device must be replaced.
2. Water is constantly flowing from the valve. This malfunction indicates that the spring pressing the seat has weakened. Since this part is calibrated, a new valve must be purchased. An extraneous cause of such a nuisance could be a significant increase in pressure in the cold water supply system, but this is unlikely and will be noticeable when using other plumbing fixtures. Unfortunately, there is another possibility for this defect - the absence or insufficient volume of the expansion tank in the boiler. The best option to resolve the problem would be to replace the water heater with products from a different manufacturer. If this solution is not possible, install an additional expansion tank at the outlet of the heater.
3. If no liquid comes out of the fitting at all, and all the taps are working properly and there are no leaks in the hot water distribution system, wash the device as described in paragraph 1 or replace the mechanism.

Adjustment

Safety valve for boiler, adjustment

Having purchased a safety valve for a boiler, the adjustment of which is done manually, install the mechanism as described above.

• Complete installation, connection and filling of the water heater.
• Turn on the device in a mode close to maximum in accordance with the manufacturer's instructions.
• Immediately after reaching the set temperature, turn the adjusting screw or knob, depending on the valve model, until water begins to flow out of the fitting.
• Drain some of the liquid from the tank. There will be space in the tank that will be filled with cold water. Accordingly, the temperature inside the heater will drop. Turn on the boiler's maximum operating mode again. Now water will flow from the discharge channel automatically. If this does not happen, loosen the spring until a thin stream appears. Check with another drain and reheat cycle.
• Set the operating mode to about 60 O . You should not constantly use higher temperatures unless absolutely necessary. This can cause increased wear on the heat exchanger.

Service

During use, depending on the intensity of hot water consumption, it is necessary to rinse safety valve for boiler from scale, rust fragments from pipes and other foreign matter in the water. To do this, you just need to sometimes open the emergency discharge channel of excess liquid using a lever.

This mechanism should not be used to empty the water heater. Particles settling at the bottom of the tank passing through the bleed spring will get stuck and interfere with its further normal operation.

By following all the rules for using the water heater and ensuring that the safety valve is working properly, you will confidently and safely use hot water.

Safe operation is exactly the factor that firefighters, employees of the Ministry of Emergency Situations, housing and communal services, police and other utility companies tirelessly tell us about. You may be surprised by the fact that a large percentage of people simply ignore safe installation, do not pay attention to basic safety rules, and a safety valve for a water heater is generally an unnecessary innovation from the realm of science fiction.

But what happens if the electric boiler simply explodes? This is a huge danger for residents and the building itself. And the cause of the explosion is often the refusal of careless boiler owners to buy and install an inexpensive and easy-to-use safety valve.

Why is the safety valve on your water heater so important?

To better understand and understand the importance of the valve, let's understand its design and system.

How does a safety valve work?

Let's start with the fact that the boiler safety valve is very simple. The design consists of two cylinders located parallel to each other and with a common cavity.

The large cylinder contains a poppet-shaped valve that is supported by a spring. It produces water flow in one direction. In general, this is a well-known check valve. The ends of both cylinders are threaded so that the valve can be connected to the heating system and pipes.

The second cylinder has a much smaller diameter and is located perpendicularly. There is a plug on the outside, and a pipe is made in the body for draining and discharging water (drainage). There is also a poppet-type valve located inside, only with the opposite direction of action.

Often on such a device there is a handle or lever that helps open the drainage mechanism at any time.

What is the principle of operation of the mechanism?

The valve also operates on a simple principle. Cold water creates pressure in the water supply and squeezes out the poppet check valve, due to which the heater tank is completely filled.

If the tank begins to fill, then the internal pressure exceeds the external one, the valve begins to close, and when water flows out, it ensures filling.

A more powerful spring is installed in the second valve, which is designed for increased pressure in the cylinder, which will begin to increase when it is filled. If the pressure in the cylinder begins to exceed the norm, this acts on the spring, which, compressing, opens a drainage hole where excess water flows out.

Frequently asked question: Why is proper operation of the water heater valve so important?

Perhaps, with our description of the valve structure, we did not convince you that this is a very important thing. Then let's simulate the situation that his absence could lead to.

Let's assume that there is simply no safety valve, which is located on the tank and ensures the outflow of standing water.

Even if the pressure in the water supply remains at a stable level, the boiler will not work correctly. This is very simple to explain - if the temperature in a tank with a stable water level begins to rise, then the pressure will automatically increase.

There will come a time when the pressure inside the tank exceeds the pressure of the supplied water and the heated water, on the contrary, goes into the water supply system. Then everything will be disrupted - hot water will flow from the warm tap and from the toilet barrel. In this case, the heat regulator continues to work stably, and the boiler will continue to waste expensive energy.

The situation will become critical if there is a pressure surge in the water supply system, which happens quite often in our country, for example, when the water pressure at a water pumping station drops at night.

Pipes may generally be empty due to an accident or repair work. The water in the boiler will gradually begin to pour out, and the water heater itself will heat the void, which leads to burnout.

What if we take a complex model?

You can say that the water heater has an automatic system that stops the flow of water, or stops heating. But you must understand that the automatic machine is not installed on all models and any mechanism malfunctions.

It seems that to protect yourself from such a situation, you just need to install a check valve.

Our “Kulibins” do just that, not fully understanding that the check valve in this case is a time bomb. I don’t even want to imagine what will happen if the thermostat closes. The water in the tank begins to boil, and since there is no way out of the circle, the pressure will begin to increase, and if the pressure is increased, the boiling point of the water automatically increases. The least that can happen is a crack in the enamel coating inside the tank.

If a crack forms due to a pressure drop, or you simply manage to open the tap, the pressure will return to normal, but the water inside will still exceed 100 degrees. Then the entire volume of liquid will boil very quickly and an explosion will still occur.

All this can and should be avoided if you buy a working valve. So, let's summarize.

Valve main value:

• Prevents water from flowing back from the boiler into the water supply system.
• Optimizes and balances pressure surges inside the boiler, protects against water hammer.
• Discharges excess water when it overheats, thereby preventing pressure from going off scale.
• If the valve has a lever, you can easily drain unnecessary water during maintenance.

About installing a plumbing system

To start using a water heater, it must be connected to the water supply system. You can buy and install polypropylene pipes.

Nowadays, the option of metal-plastic pipes is considered fashionable and most convenient. Before you buy anything, compare prices on online sites.

About installing a valve on a water heater

First, select a model. As a rule, if the boiler is really good, then it already contains valves with the required parameters. If you don’t find it, then in case of replacement you will have to buy it with your own money. Their price is small - a maximum of 400 rubles. If there are usually no questions about the threads, since a conventional valve has a diameter of no more than half an inch, then what you need to pay special attention to is the operating pressure.

Before buying a water heater, check all its parameters in the instruction manual, or consult with the sellers on site.

Do not buy a valve with a low pressure rating - it will start leaking very quickly. If you choose a valve with a large value, it will not save you from trouble if the boiler overheats.

How to properly install a water heater valve?

Before installation, check that the boiler is not connected to the mains and drain all water.

The valve must be installed in the place where cold water enters the heater. The process itself is absolutely not complicated - you wrap it with a key 3-4 turns, and use sealants (tape, tow - whatever you want). The second end of the thread must be connected to the cold water supply system.

Be sure to follow the direction of the incoming water (look at the valve body - there should be an arrow drawn there).

If you notice that the pressure fluctuates or is elevated, then before installing the valve, install a water reducer.

Not everyone likes it when water starts leaking out from under the valve. Remember - this is absolutely normal. This indicates that the mechanism works without deviations. Another reasonable solution is to connect the drainage pipe to the sewer using a hose. It is best to choose a transparent hose so that you can easily assess the performance of the entire system.

If you purchase a valve with a lower pressure, water will constantly flow from it

1. It is PROHIBITED to install a locking mechanism between the valve and the water heater.
2. The pressure on the valve will automatically increase the vertical section of the pipes, and then cold water will begin to leak, which you do not need at all. Make sure that the distance between the valve and the heater is 2 meters.

What should you do if water begins to flow heavily through the pipe and does not warm up?
Check the pressure in the pipeline - it can be very high (but this happens very rarely). To solve the problem, install a gearbox.

Check the valve - you may have purchased a low pressure model that is not suitable for your boiler. If everything is in order here, then the problem is in the spring - it has sat down and it’s time to change the valve.

If the valve remains dry in any situation, this should be a cause for concern. If even with strong pressure of water not a drop comes out of it, this means that it is simply faulty - clogged or greasy. Don't take risks either and hurry up and buy a new one.

Buying and installing this simple device is very simple, but you will be sure that you are safe, and your home is protected from fire, and the residents of the house are protected from harm that a faulty water heater can cause.

An electric water heater creates comfort in the home by providing residents with hot water. But those who often come across it know that a boiler can pose a certain danger associated with rupture of the container if it is installed incorrectly. A correctly assembled circuit, including the mandatory installation of a safety unit, will help to avoid this.

To understand why a safety valve on a water heater is needed, you need to remember your physics lessons. Water heated to a temperature of 90 o C expands by about 3%. It is easy to calculate that inside a boiler with a capacity of 50 liters during operation, the volume of hot water will increase by 1.5 liters. If you don't drain it, the container will simply burst. To prevent this from happening, a valve designed for a certain pressure is installed. When a critical point is reached, the mechanism is activated, releasing excess liquid into the sewer.

That's why such a mechanism is needed. Its device protects the boiler from excess pressure that occurs when heating water.

Principle of operation

If you take a closer look at the design of the valve and the principle of its operation, the entire mechanism can be called a valve system. This is because there are two of them in one building. The operation of the first is clear; excess pressure from the boiler is released through it. The mechanism is connected to the side hole of the case. Why is the second check valve needed? The design of the mechanism inside the housing is such that the check valve is located at the bottom opposite the inlet. It prevents cold water from flowing out of the boiler if there is no pressure inside the water supply.

The principle of operation of the mechanism is as follows:

1. As long as the pressure inside the water heater is less than the water pressure, water presses the check valve plate, constantly flowing into the container. After the pressure is equalized, the spring presses the plate against the housing socket, thereby preventing liquid from entering the tank.
2. The further operation of the mechanism consists of waiting. The liquid inside the boiler gradually expands from heating, and until the pressure reaches a critical point, the valve system is closed.
3. Once the permissible limit is exceeded, the hot water pressure compresses the safety valve spring. The plate comes out of the housing socket, opening a hole where excess liquid will drain. Having reached normal limits, the spring presses the plate back to the seat, returning the mechanism to its original state.

Having examined the design and principle of operation of the mechanism, we can draw conclusions why water often drips at the outlet. This will always happen when the temperature of the liquid increases and the water pressure decreases, which indicates normal operation of the device.

Next, the question arises of where to put the liquid flowing out of the side hole. To drain the water, a PVC pipe is connected to the outlet. It must be reinforced and secured with a clamp to the pipe. These requirements must be met, since operating pressure in the range of 6–10 bar will tear and rupture the tube. Sometimes the question is asked, why make a drain from a transparent tube? The answer is simple, for convenience. It is convenient to control the work through the transparent walls. That is, it will be visible whether water is flowing or dripping, which can often indicate a malfunction of the mechanism.

Existing types of valves

A conventional check valve for a water heater is produced in different designs. Although the appearance and operating principle are almost the same, there are still some nuances.

Each modification of the design helps to use the boiler comfortably, and sometimes, on the contrary, interferes with:

• a safety valve with a lever is convenient for checking the mechanism for operability, which must be carried out monthly. By lifting the flag, the lever forcibly opens the drain hole. This also helps to completely drain the water heater in case of an emergency. Some models have flags secured with a screw. It protects the mechanism from accidental opening;
• When installing or replacing a valve, you must pay attention to the presence of a direction arrow and markings of the permissible operating pressure. In the absence of such, the direction of fluid movement can be determined by the location of the plate in the socket by looking inside the housing. How can you find out the working pressure, since it is only tested by tests? No way, and the sellers won’t help with this either. Therefore, it is better not to install such models;
• The fittings themselves through which water is discharged may also have their differences. It is convenient to put the tube on the long herringbone-shaped protrusion and secure it with a clamp. The short fitting also has a thickening at the edge to hold the hose, but there is not enough room for a clamp. The tube will have to be crimped with wire;

• If the safety valve is not equipped with a flag, it is intended for forced discharge only. It is impossible to check its performance with a test drain. It is good if the body has a threaded cap for maintenance. By unscrewing it, you can clean the clogged mechanism. There are cheap, maintenance-free models. Such valves should be abandoned altogether due to the danger of their use.

The types of valves considered are usually used on boilers with a capacity of up to 60 liters. In a large water heater, the valve goes together with a pressure gauge and a shut-off valve. The fitting has a thread, which makes the drain hose securely attached.

Installation rules

To ensure safe operation of the boiler, the check valve must be correctly installed in the system. Usually it comes with the water heater. If not, the safety device must be selected separately, and the permissible pressure of the valve must correspond to the operating pressure of the boiler. All parameters can be found in the product instructions.

Installation of a safety unit on a boiler can be carried out with or without adapters, but in compliance with certain rules:

The design of some valve models may differ in the presence of a pressure control mechanism. The principle of its adjustment is to loosen or tighten the pressure spring. You need to know that the mechanism has already been initially adjusted by the manufacturer, and you cannot make changes there without experience.

After installation, water is drawn inside the water heater to check all connections. If a leak appears, you can try tightening the thread. Otherwise, you will have to drain the water to repack the connections. You can check the functionality of the valve by turning the flag. If during this action water flows from the fitting, and after returning the flag to its original position, the flow stops, then the mechanism is working properly.

Possible breakdowns and methods for eliminating them

Failure of the safety unit is expressed by constant flow of water or its complete absence. If the liquid flows or drips only when heated, which is convenient to observe through the transparent tube, then everything is working properly. That's what this node is for.

Let's look at the possible causes of the leak:

• Sometimes water drips from a cold boiler. Here you can observe the drop frequency. If it becomes more frequent and then subsides, it is possible that the water pressure exceeds the permissible limits. The check valve is constantly open and excess water pressure passing through the water heater is released. Once the water pressure normalizes, the flow will stop. If such situations occur frequently, it is advisable to install a reducer at the entrance of the water supply to the house;
• Sometimes water drips due to debris getting under the plate seat. The situation can be corrected by periodically bleeding the liquid using the emergency lever. The flowing water will wash away the dirt, the plate will sit tightly in the seat, and the dripping will stop until the boiler heats up. When bleeding does not produce positive results, the spring of the collapsible model is pulled out to clean it from dirt. If this does not help or the body of the safety assembly is not dismountable, you only have to replace it with a new one;
• Usually, leaking water brings additional costs, but there is no danger of the water heater bursting. It’s bad if the liquid doesn’t flow or drip at all. This may be due to scale in the mechanism itself or inside the fitting. Only mechanical cleaning will help here or it is better to change the unit;
• Some valve models may leak due to improper installation. They only need to be screwed in four turns, otherwise the adjustment will be pushed through. Now they sell improved models with a limiter that can be screwed all the way. It is best for an inexperienced person to give preference to this design;
• There are situations when a person sins on the valve, and the boiler itself is to blame. This is due to the rapid increase in pressure at the outlet of the water heater as it heats up. The first reason occurs when the thermostat breaks down, which can be replaced with a new one. The second reason is the worst. Cheap Chinese products inside the container have little room for liquid expansion. This can be corrected by installing a hydraulic accumulator or purchasing a high-quality boiler.

The functionality of the safety unit will protect the residents of the house from burns that can be obtained during a rupture of a boiler with boiling water. The main thing is to remember that instead of such a unit you cannot install a simple check valve. This will only make the situation worse.

In contact with

The service life of the storage boiler, as well as the safety of using the device, depend on the correct piping. One of the important components is the safety valve for the water heater, installed on the incoming cold water pipe.

To understand why a valve is installed on a water heater, it’s worth remembering the school curriculum. According to the law of physics, water expands when heated. The liquid is inside a sealed container. If there is no water supply, the pressure rises and the tank may burst. A safety valve for the boiler, which bleeds excess liquid from the tank, will help prevent an accident.

On the forums you can find information where they advise simply not to install a check valve. Then there is no need to install an excess water pressure relief valve. In their opinion, when excess pressure appears, some of the water will go back into the pipeline. The advice is partially correct, but the system will work as long as the water supply system functions stably. The advice is wrong for three reasons:

• there are no stable operating water pipelines without breakdowns;
• without a check valve, all the water from the tank will go into the empty pipeline;
• a bare heating element will heat the air inside the empty container.

Now let's look at the end result of the problem. When there is a water supply failure, the pipes are left empty. There is no check valve on the inlet pipe, and water from the storage tank flows freely into the system. When the temperature drops, the thermostat will turn on the heating element. Without water, the heater will simply burn out, but this is only half the problem.

There is another danger. The heating element is hot and water appears in the water supply. A large amount of steam and excess pressure suddenly form inside the tank, which does not have time to bleed back into the pipeline. The tank is guaranteed to burst in several places. Boiling water will pour into the apartment. For this reason, it is better not to overthink it, but simply install a water relief valve.

Design and operation

There is nothing complicated about the design of a safety valve for a water heater. Most often, the safety unit is made as a single piece. A safety and check valve is contained within one housing.

The standard product diagram looks like this:

• The bronze case inside has two chambers. The design resembles the letter "T". There are two threads cut on the body of the check valve chamber for fastening to the water supply. The safety valve chamber body is equipped with a water drain fitting.
• Inside the check valve there is a spring that holds a rod on which a round plate is attached. When closed, it prevents water from flowing back from the tank into the empty water supply.
• A safety valve similarly has a stem with a spring and a round plate. Most models are equipped with a forced water release lever. This element is directly connected to the stem.

The water heater usually comes with the cheapest safety valves without a lever. It’s better to throw them away and buy a quality product.

In general terms, the operating principle of a safety valve looks like this:

• As water is drawn, the pressure inside the tank drops. The safety valve is closed. Due to the pressure difference, the check valve opens and the tank begins to refill. When the pressure in the water supply and inside the container is equal, the check valve closes.
• The boiler thermostat turns on the heating element. The liquid begins to heat up, increasing in volume. If the pressure reaches a critical level, but there is no water supply, the safety valve is activated. Hot liquid is drained through the fitting. After normalizing the pressure, the spring returns the mechanism to its original position.

The thermostat constantly monitors the set temperature and periodically turns on the heating element. If there is no analysis, the pressure will constantly increase with each increase in water temperature. During this period, liquid drips from the fitting. This is normal operating time. To prevent water from pouring onto the floor, a transparent reinforced hose is fixed to the fitting with a clamp, diverting its end into the sewer.

Types of security groups and the principle of choosing the appropriate model

A standard safety valve for a boiler may differ in design in several design features. These nuances do not change the functionality of the device, but only simplify use and maintenance. To choose the right safety unit, you need to know what safety valves for boilers are and how they differ.

Lever models

The most common type of standard safety assembly is the lever model. This mechanism can be activated manually, which is convenient when checking or draining water from the boiler tank. They do it like this:

• a horizontally located lever is installed vertically;
• direct connection to the stem activates the spring mechanism;
• the safety valve plate forcibly opens the hole and water begins to flow from the fitting.

Even if the tank is not completely emptied, a control drain is performed monthly to check the functionality of the safety unit.

The products differ in the design of the lever and the fitting for discharging water. If possible, it is better to choose a model with a flag fixed to the body. The fastening is made with a bolt that prevents children from manually opening the lever. The product has a convenient herringbone-shaped fitting with three threads, which ensures reliable fixation of the hose.

The cheaper model does not have a flag lock. You can accidentally catch the lever with your hand and unnecessary drainage of water will begin. The fitting is short, with only one threading ring. It is inconvenient to fix the hose onto such a protrusion and can tear it off under strong pressure.

Models without lever

Safety valves without a lever are the cheapest and most inconvenient option. Such models often come complete with a water heater. Experienced plumbers simply throw them away. The units operate similarly to lever models, but there is no way to manually perform a control drain or empty the boiler tank.

Models without a lever come in two versions: with a cover at the end of the body and blind. The first option is more convenient. If clogged, the cover can be unscrewed to clean the mechanism. A blind model cannot be tested for functionality and cannot be descaled. The fluid discharge fittings for both valves are short with one threaded ring.

Safety components for large water heaters

Water heaters with a storage tank volume of 100 liters or more are equipped with improved safety valves. They work in a similar way, only they are additionally equipped with a ball valve for forced drainage, as well as a pressure gauge.

Particular attention should be paid to the fluid drainage fitting. It's threaded. Reliable fastening prevents the hose from being torn off by strong pressure and eliminates the inconvenient use of the clamp.

Original models

For lovers of aesthetics and comfort, manufacturers offer safety components in original designs. The product is equipped with a pressure gauge, chrome plated, and given an elegant shape. The products look beautiful, but their cost is high.

Difference in body markings

High-quality products must be marked on the body. The manufacturer indicates the maximum permissible pressure, as well as the direction of water movement. The second marking is an arrow. It helps determine which side to place the part on the boiler pipe.

On cheap Chinese models there are often no markings. You can figure out the direction of the liquid without an arrow. The check valve plate must open upward in relation to the boiler pipe so that water from the water supply flows into the tank. But it’s impossible to determine the permissible pressure without markings. If the indicator does not match, the safety unit will constantly leak or will not work at all in an emergency.

Other types of valves

When they try to save money on a safety group, they try to install a blast valve designed for the heating system on the water heater. The nodes are similar in functionality, but there is one nuance. The blast valve is not capable of releasing liquid little by little. The mechanism will work when the excess pressure reaches a critical point. The blast valve can only release all the water from the tank in the event of an accident.

Separately, it is worth considering installing only a check valve. The mechanism of this unit, on the contrary, locks the water inside the tank, preventing it from draining into the pipeline. If there is excess pressure, the working plate with the rod is not able to work in the opposite direction, which will lead to rupture of the tank.

Installation and adjustment of the safety unit

Anyone can install a safety valve on a boiler without the help of a plumber. The correct installation diagram indicates that the safety unit is attached to the cold water inlet pipe of the water heater. Below are taps, filters and other piping elements.

The valve is installed on the water heater in the following sequence:

• The safety valve is installed directly on the cold water inlet pipe going inside the water heater. Often a detachable adapter is placed between them - “American” for ease of dismantling during maintenance.
• Fum tape is wound onto the threads of the pipe or adapter to seal the connection. The safety assembly is screwed on so that the arrow on the body is directed towards the boiler.
• When screwing the safety valve onto the water heater, you need to stop when you feel a stop. On cheap models there is no mounting fuse. The part is screwed four turns. You can't turn it anymore. The thread of the pipe will close the channel of the fitting for draining water.

After installation, it is worth looking inside the housing from the check valve side. Inside the hole you can see the seat and the locking mechanism plate itself. To check the functionality, press the plate with a finger or pencil. It should move inward, and when released, return to its original place.

When the entire circuit is assembled, begin adjusting the security unit:

• The water heater is filled with water, voltage is applied and the thermostat is set to the maximum temperature. You have to wait until complete heating occurs, and the automation will turn off the heating element.
• Drops of liquid should appear from the fitting. If they are not there, turn the adjusting screw until a positive result is obtained.
• After adjustment, use the lever to bleed some water from the tank, after which the mechanism is returned to the closed state. The drip from the fitting will stop. A new portion of water will flow inside the tank. The heating element will heat it up, and the liquid will again begin to drip from the fitting.
• The mechanism, adjusted to the maximum temperature, will always work when the permissible limit is exceeded. Now you can set a lower operating temperature on the regulator, for example, 50–60 o C. When this threshold is reached, liquid will not drip from the fitting.

The safety group is checked for functionality of the forced drain lever and operation at maximum temperature once a month. If the adjusting screw is missing and the mechanism does not operate according to the required parameters, the part is replaced.

Malfunctions and solutions

A faulty boiler safety valve is detected by liquid constantly flowing from the fitting or when there are no drops at the maximum heating temperature. A failure is considered to be the absence of forced drainage when the lever is raised.

Let's consider possible malfunctions:

• Liquid constantly flowing from the fitting appears at high pressure in the water supply. If the safety group is designed for 6 Bar, then at 7–8 Bar the excess will be constantly released into the line. You can check by forced draining using the lever. If the dripping stops after bleeding, then the problem is in the high pressure of the water supply. It is necessary to install a gearbox at the entrance to the house.
• When water continues to flow after releasing the pressure, the cause is a clogged working spring. If the safety group can be disassembled, all elements are cleaned of dirt and put in their place.
• The absence of a drip and forced drainage indicates a clogged fitting or the entire working mechanism. There is only one way out - disassemble and clean.

If the part is not removable or cannot be repaired, it should be replaced immediately.

The water heater safety group is not a component that you skimp on. Repairing a boiler will cost more.