Water heater pressure relief valve where to put

Safety valve for the water heater

On the correct piping depends the life of the storage tank, as well as the safety of using the appliance. One of the important components is a safety valve for the water heater, installed on the inlet spigot of cold water.

To understand what the valve on the water heater is installed for, it is worth remembering the school program. It is a law of physics that water expands when heated. The liquid is inside a sealed container. If there is no water separation, the pressure rises and the tank can burst. To prevent an accident will help safety valve for the boiler, bleeding excess liquid from the tank.

You can find information on forums, where it is advised simply not to put a check valve. Then there is no need to install the valve to release excessive water pressure. According to them, when there is excess pressure, some of the water will go back into the pipeline. Part of the advice is correct, but the system will work as long as the plumbing is stable. There are three reasons why this advice is wrong:

  • There is no stable working plumbing without breakage;
  • without a check valve in an empty pipeline all the water from the tank will go;
  • A bare heating element will heat the air inside an empty tank.

Now consider the end result of the problem. Water pipes are left empty in case of a plumbing breakdown. There is no check valve on the inlet pipe, and the water from the storage tank flows freely into the system. The thermostat will turn on the heating element when the temperature drops. Without water the heater will simply burn out, but this is only half of the problem.

There is another danger. The heating element heats up, and water appears in the water supply. Inside the tank suddenly forms a large amount of steam and excess pressure that does not have time to escape 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 be wise, and simply install a relief valve for water.

water, heater, pressure, relief

Types of valves

By the mechanism of its action, bypass valves are divided into the following types:

In the first type of check valves on the boiler, the main working element is a spring, while the second type has a built-in lever that controls the state of the system in the test mode. The models of the magnetic-spring type belong to the combined devices, combining the advantages of field and mechanical structures.

Depending on the type of locking mechanism, the following types of check valves are distinguished:

The disc mechanism platter in the first models moves up and down. When the pressure is in the forward direction the valve opens, and when it is no longer or is weakened it closes through the spring or its own weight.

The device is triggered to close and holds the pressure also at a change in the direction of the fluid flow.

The butterfly valve, the swing or non-return version, is designed as a hinged butterfly valve that rotates and opens under the pressure of the liquid. It is closed by a spring force.

The ball version refers to a mechanism in which the fluid flow is shut off by a ball pressed to the seat by a return spring. The pressure of the fluid from the other direction pushes the ball in the opposite direction, opening the passage for it.

The design of the inter-flange valve is similar to the lifting mechanism, but in it the pallet moves in the direction of flow. Its modification contains two flaps folding towards each other. Bivalve design in open form has minimal resistance to fluid flow.

If we classify valves according to the material of which they are made, we distinguish between the following designs:

  • Brass products, reliable and wear resistant. They are most commonly used in the home.
  • Cast-iron valves. quite inexpensive devices, which have one characteristic disadvantage. They are not protected against rust and are installed only on pipe lines.
  • Stainless mechanisms, which are high quality and reliable products with high price.

It is reasonable to use the latter models only in critical sections of pipelines.

According to the method of fixation on the working object, all water return valves are divided into the following types:

  • Socket mechanisms installed in the pipe break by means of two appropriately sized threaded couplings. This type is most common in terms of households, in some cases it is used in industry.
  • Flanged devices, where the gate mechanism is connected by means of connectors of special design. Used most often in combination with cast iron counterparts on large pipes.
  • Shut-off valves installed between two flanges that are tightened for strength by means of through studs. This type is most often installed on the same main pipelines.

Tankless water heater Pressure Relief Valve replacement

Places of installation

In domestic water supply and heating systems there are many sections and runs, where it is allowed to mount a safety valve.

  • At the outlet of an apartment or detached home from the centralized hot water supply line (DHW).
  • Downstream of the flow meter, providing it with protection against water hammer.
  • At the inlet of a gas or electric water heater (boiler), thus avoiding the outflow of heated and expanded water into the mains with a DHW.

Protective elements are installed in places provided by their design features and direct purpose.

How is the safety relief valve constructed?

The design of this safety accessory is quite simple. It consists of two perpendicular cylinders of different volumes, with a common plane. The larger cylinder has a disc valve inside, which is compressed by a spring. Thanks to it, the water moves in one direction, as with an ordinary return element. This cylinder is at the inlet to the water heater and connects it to the pipe that brings cold water. It has threaded connections on both sides.

And the second cylinder has the following characteristics:

  • Is perpendicular to the main;
  • is equipped with a plug on the outside;
  • equipped with a small drainage outlet.

There is also a poppet valve on the inside of the small cylinder, but it is actuated in the opposite direction to the large cylinder.

Installation and adjustment instructions

Installation of the safety valve on the water heater begins with the selection of an appropriate model. The permissible pressure in the device must correspond to the operating pressure of the heater. These data are given in the manual.

Connection is made by your own hands according to the instructions.

  • Put a safety valve on the branch of the water supply system that brings cold water to the tank.
  • The device should be placed between the tank and the shutoff valve. If the valve thread fits into the thread of the inlet pipe, simply unscrew the part. FUM-tape or linen fleece shall be used for sealing the connection.
  • The threads must be tightened firmly to prevent leakage. Do not apply too much force, as the bronze body can burst.
  • After wrapping the system, check the operation of the water heater. Draw water into the tank, inspect all connections. There must not be any leakage. If water appears, it is necessary to drain the liquid, disassemble the water heater and reassemble. Check that the valve is working by turning the flap. If water leaks from the nozzle and the leak disappears when the flag is returned to its original position, the device is installed correctly.

If the tank is operated correctly and the tap water quality is high, the unit will seldom fail. Over time, dirt or lime scale can deposit here, so the valve is periodically cleaned. It is easy to do: it is enough to bleed water once a month with the emergency lever. The water pressure will wash out the debris and dirt, and the plate will fit tightly into its seat again.

Adjustment of the safety valve on the water heater is to loosen or tighten the spring in the body. To do this, the assembly should be removed from the tank and completely disassembled. It may be necessary to adjust if the constant water pressure is too low or too high.

The mechanism is originally set by the factory for the standard parameters of the water supply.

How to open the valve on the electric water heater

You will have to exert a lot of force to open the valve, because the pressure will not allow you to press the spring.

The lever is vertical, which means the damper is closed. To open it you need to move the handle upwards. After that the water should start to drain from the water heater.

How to replace a broken fuse

Replacement of the safety valve on the home water heater is carried out in a certain sequence. What we do:

  • Empty the boiler tank and disconnect from the network.
  • Close the water supply to the appliance.
  • Open cold water on one faucet and boiling water on the other.
  • Turn on the water drain from the boiler.
  • Remove the hose from the spigot.
  • Remove the old/broken safety valve and install a new one.
  • Close the faucets and plug in the boiler.

How the valve functions

To learn complete information on selection, operation and maintenance of boilers (water heaters) of all manufacturers, you can.

In addition to specific information on the site, you can also learn specific problems from other people on this topic who have already bought a boiler (storage water heater) and thus avoid them. You will find a regularly updated list of such problems and their solutions.

Replacing a Temperature Pressure Relief Valve (T&P Valve)

To understand the principle of operation, consider its construction. The safety device consists of two perpendicularly placed brass cylinders that form a common cavity. In the inner part of the larger cylinder there is a disc element which is pressed by a spring and allows the fluid to move in one direction only, preventing it from flowing out. The heater inlet and the cold line pipe are connected to the two ends of the larger cylinder, which end with a threaded connection.

There is also a disc element inside the smaller cylinder, which has a reverse actuation. At its outlet there is a handle of forced discharge, at the bottom there is a branch pipe for drainage of excess water which is connected to the sewerage system with a plastic pipe. You can’t use buckets, jars for draining.

How it works? The pressure in the water supply squeezes the spring of the plate, the liquid flows into the tank. When the tank is filled, the pressure in the tank has exceeded the water supply, the valve closes, the flow of water stops. In the process of water flow the pressure changes, the valve opens, the water starts filling the boiler again. When the liquid in the tank gets warm and begins to expand, the protective disk device of a smaller cylinder is triggered, the side drainage hole is drained and the pressure in the tank is equalized.


Sometimes individual elements of the water heater or the entire system stop working properly. This reduces the safety of the construction and can lead to unfortunate consequences. In this case, you need as early as possible to find out the cause and location of the breakdown and either fix it yourself, or call a specialist for this. Thermostats, heating elements and safety valves are the most common failures. And the problem with one of them can instantly affect the rest. Never install elements that do not match the boiler parameters or have different ways of connection.

Malfunctions do not occur by themselves, there are certain reasons for them.

  • Untimely replacement of damaged parts. For example, a check valve must be replaced at least once a year. It is cheap and will not cost much.
  • Improper installation of the entire system. If the fuse is inserted into the pipe with insufficient waterproofing or at too great a distance from the inlet to the boiler, the system will not function properly.
  • Voltage fluctuations in the electrical network can cause failure of the heating elements of the system.
  • Existence of a factory defect or lack of preventive inspections. In order to choose the right heater and fuses it is necessary to study all the information very carefully when buying. And even the highest quality unit must be checked periodically.
  • The formation of scale or the occurrence of corrosion. Scale and corrosion on the return plug can cause water to leak back into the piping or “eat away” the various connections, compromising their tightness.

The most basic faults can be divided into several types. often than not, the broiler begins to leak. This can be a manufacturing defect, as well as acquired because of corrosion crack. Such a tank can’t be fixed by yourself, you’ll have to replace it completely. Water dripping from pipe joints indicates leakage. From the safety valve, on the contrary, water must sometimes drip. If it is always dry, it should be replaced.

The second common malfunction is most often a lack of heating. Almost always it is due to malfunction of the heating device or thermostat. Sometimes in this way the emergency cutoff device works, when the boiler is constantly turned on at the maximum temperature.

Often the walls, the perimeter of the outlet, and the surrounding area can get hot when the water heater is operating. The most dangerous thing in this case is the heating of the plug or socket. The cause may be a bad contact or a broken heating element. If the water heater does not run on electricity, and from a gas network, the chimney can be clogged with ice, which will block the exit of steam. In this case it is quite simple to clean it.

In case the water heater gives insufficient amount of warm water, it is necessary to check whether the inlet and outlet pipes are not mixed up. And if the hot water comes into the kitchen faucet with little or no pressure, while the faucet is working properly, you need to check the safety valve. It can be clogged with rust or dirt, after cleaning it the water pressure will be restored.

A quality safety valve for boilers not more than 200 liters installed on a standard household heater can serve for at least ten years. It is necessary to regularly clean it from sediment and check the performance of the entire system. Every three to four years it is desirable to dismantle it and wash it with special chemical solutions, which can be purchased in hardware stores.

water, heater, pressure, relief

At installation it is necessary to follow the given rules and conduct a quality check of the system with cold water at head pressure. If there are any doubts in your own abilities, it is better to entrust such responsible work to professionals. After all, not only the property, but also the health of all tenants depends on the quality of work.

To learn why it is necessary to install a safety valve for the water heater and what happens if it is not installed, see the following video.

Causes of breakage of the safety valve

If the valve on the boiler is dripping constantly, regardless of the time of day and the intensity of water use in the house, there is a high probability that the product is faulty. There can be many reasons for this.

  • Factory defect. Generally, weak springs and leaking cylinders. Such products will actuate even at operating head. To face with such trouble are those who seek to save money and buy cheap Chinese fakes.
  • Blockage. Arises from improper cleaning of the tank or because of poor water quality. The essence of the failure is that after compression, the spring cannot decompress, because there is an obstruction of solid particles in its path. With this fault, the product will leak even when the device is turned off and the faucet is closed.
  • High system pressure. This is not uncommon on the top floors of high-rises with an overhead supply of water. Since the pressure is kept at a constantly high level, the valve will leak continuously, regardless of time of day.

If there is a leak, it won’t go away on its own. The situation will only get worse until it reaches a critical state. Therefore, if the safety valve on the boiler leaks, it is necessary to take urgent measures to determine the causes of this phenomenon and restore the performance of the water heater.

Selection and installation

Select a fuse should be based on the values of pressure that can withstand the device. This figure is usually entered in the data sheet. In addition, the choice may be affected by the volume of the tank. There are systems with trip thresholds of six, seven, eight, ten bar. These are the most common values for triggering the fuse.

  • Wrap special tape or linen gauze around the threads for a tight seal.
  • Screw the valve onto the spigot.
  • Continue to screw it in by hand until it stops, and then make a few turns with a wrench.
  • Do not forget about the right choice of place for its installation. Experts recommend attaching it directly to the inlet pipe for cold water.

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

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

Do not skimp on such an important detail as a fuse. This device will not only help you to keep the heater working, but possibly save you from serious injury. Pressure surges in the water supply are not uncommon, and no one is immune to tank failure. Spend some time installing safety valves and be assured of your own safety.

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