It’s hard to imagine modern human life without hot water at any time of the year. An electric type water heater is able to create comfortable living conditions, providing residents with hot water. Therefore, in many houses that are not connected to the central heating system, residents install special water heating devices - boilers. Installation of such equipment can be done with your own hands, but special attention must be paid to the safe operation of this unit.
Installation of a protective system is impossible without studying the principle of operation and the purpose of the check valve for the water heater. The main characteristics, installation rules, as well as all the pros and cons of operation, the manufacturer indicates in the technical documentation of the heating device.
Purpose of the check valve
Having bought a boiler, anyone asks whether a check valve is needed on the water heater. The non-return valve is also called a safety valve, therefore manufacturers of household appliances and persons controlling the operation of the equipment require installation of the boiler in compliance with safety rules.
To understand why a check valve on a water heater is necessary, remember the lessons of physics in a school course. Any substance expands when heated. So water, heated to a temperature of 90 ℃, increases its volume by about 3%. Therefore, in a boiler with a capacity of 50 liters of hot water it becomes 1.5 liters more.
The water tank is a sealed device, but when the water is heated, the vapor pressure inside the tank will inevitably increase. And this phenomenon promises a boiler explosion, which not only can cause great material damage, but also become a threat to the health and life of the owner. It is to eliminate this threat that a non-return valve is installed on the water heater, which performs safety and protective functions:
- prevents the entry of hot water back into the plumbing system;
- when the pressure rating is exceeded, water is discharged;
- eliminates the possibility of water hammer, normalizing the pressure inside the tank;
- provides an opportunity to drain water from the tank during maintenance.
Simple check valve device
The check valve device on the water heater is quite simple. Structurally, this element is two cylindrical parts that are located in the same cavity. Such cylinders are perpendicular to each other.
A larger cylinder contains a poppet valve inside, which is pressed by a special spring. By the principle of an ordinary check valve, such a device allows the fluid flow to move in only one direction. On both sides of the large cylinder there is a thread through which it is connected on one side to the inlet of the water heater, and on the other, to the cold water pipe.
The second cylinder of a smaller cross section is located at an angle of 90 ° to the main body. On the outside, it has plugs as well as drainage drain pipes. A similar check valve is placed inside the small cylinder, which functions in the opposite direction to the main one.
Valve operating principle
The backpressure safety valve for the water heater is mounted at the inlet to the boiler and is regulated in accordance with the maximum allowable pressure.
In the closed position, two forces act simultaneously on the sensitive plate-type membrane - the water pressure in the tank and the compression force of the spring. During water withdrawal, the liquid pressure decreases, under the action of a spring, the membrane opens cold water, filling the tank at the same time.
When the pressure force of the liquid column is aligned with the compression force of the spring, the membrane closes the water supply opening, while the action of the check valve prevents the liquid from pouring back into the water supply system.
When the force of water pressure increases, which occurs when it is heated to a given parameter, the check valve of the small cylinder is activated. As a result, excess fluid is drained through the side pipe.
If water starts to drip slightly from a tap with a check valve for a water heater, do not worry - this is the correct operation of the safety device. To prevent water from spilling onto the floor, it is necessary to substitute a special container for collecting water or to make a drainage drainage hose into the sewer or toilet.
Classification of locking devices
Manufacturers offer a huge selection of different protective devices. Therefore, choosing the right check valve for the water heater, it is necessary to take into account many parameters of the water heating device, as well as its installation location and connection method. The usual non-return valve is made in different designs. The principle of operation and the appearance of the locking devices can be almost the same, but with the presence of special nuances in the design and the possibility of its application, on the basis of which the classification of the main types of safety valves takes place.
Device types
Check valves by type of device can be divided into check valves and the valves themselves. Their difference is that the non-return valve has a baffle in the form of a spool, and the shutter has a membrane in the form of a round disk. Depending on the design of the valve, the valves are divided into types:
- lifting view, where the valve moves up and down under fluid pressure, weakening or straining the action of the spring;
- in rotary devices the shutter is made as a flap;
- the ball type has a ball as a locking element, which, when the water flow stops, falls, closing the water supply opening;
- the wafer type is equipped with a disk-type shutter.
Classification by tank volume
There are various models of taps with a non-return valve for a water heater, which are suitable in volume for the following boilers:
- small ones are installed on tanks up to 50 liters;
- middle valves are mounted on boilers with a volume of 50-200 liters;
- tanks with a capacity of more than 200 liters are equipped with large valves.
Valve designs of small and medium sizes are characterized by not very high pressure indicators and a low price. Therefore, the replacement of failed shut-off equipment of these types is not difficult.
In large tanks, check valves for the water heater are installed, the pressure of which is designed for 7 bar. Such equipment is equipped with a special nozzle for connection to the plumbing system.
Valve separation according to the principle of operation
This category of locking equipment is conventionally divided into the following types:
- direct-acting equipment is triggered by direct exposure to liquid pressure;
- Indirect valves are often referred to as pulse valves, since they are triggered by an external pressure source.
Valves are also divided by the height of the liquid:
- low-lifting types are characterized by a membrane lifting height of up to 1/20 of the diameter of the saddle section;
- medium lifting membranes move to a height of 1/20 to ¼ of the saddle section;
- full-height - to a height ¼ of the diameter of the saddle.
Varieties of valves by degree of difficulty
According to this principle, check valves on a water heater can be divided into several types.
1. Non-separable devices are the cheapest among protective devices. The cessation of water flow occurs due to the counteraction of the spring or disk. The check valve is installed on a small-volume water heater, since the main function of the device is to protect the heating element from overheating in the absence of water. Such a part does not eliminate excess pressure. For these purposes, a separate safety valve will have to be installed.
2. A sophisticated protection system includes a ball safety valve and a check valve. With such a device, fluid pressure is monitored visually. Therefore, the lack of automatic action greatly reduces the effectiveness of the shutoff valve.
3. Safe hydraulic system includes check valve, safety valve and siphon. Such a scheme is used mainly at industrial facilities. The siphon allows you to remove excess fluid directly into the sewer.
Valve with release handle
Such a protective device is considered the most common in domestic boilers. The operation of the non-return valve of the water heater with the release handle differs slightly from a simple locking device; in its design an additional lever is provided for the forced discharge of water.
The safety valve with a mechanical hand lever is indispensable for the need for a control check of the operability of the entire unit, which is recommended to be carried out every month. He is also the first assistant in an emergency when you need to completely drain the water from the tank.
The manufacturer must always put an arrow on the body of the manual valve, in the direction of which the locking device should be turned.
Valve Mounting Methods
A wide variety of models of check valves provides various methods for their fastening:
- coupling connection is carried out using threaded couplings on pipes of small diameter;
- valves are attached to propylene pipes by welding;
- Wafer mounting is often done on pipes with a large diameter, and this method implies the installation of a valve between two pipeline flanges.
Basic Valve Installation Rules
For safe operation of the boiler, it is necessary to know exactly where the check valve is placed on the water heater. Most often, when buying a domestic boiler, a non-return safety valve is supplied with the equipment. In this case, the device is set by the manufacturer to a certain pressure. If there is not enough experience, then it is better not to change the factory settings.
The installation of the protective device must be carried out according to certain rules:
- install a locking device on a cold water pipe;
- it is necessary to mount the valve between the tank and the stopcock;
- if it is possible to install the valve directly on the tank, then it is screwed into the tank, and a crane is attached to the device itself;
- installation must be done exactly in the direction of the arrow on the product body;
- all threaded connections are sealed with linen thread or special tape;
- Tighten the threaded connection with special care, as too much force can damage the bronze valve body.
After installation, it is necessary to check how the check valve of the water heater works. To do this, fill the tank with water and visually determine the quality of work. If there is a leak, try tightening the thread. In the case when it was not possible to achieve the tightness of the connection, you will have to drain the water and reinstall the valve, paying attention to the high-quality sealing of the joints.
Check Valve Malfunctions
Breakdowns on the locking device are most often characterized by a constant flow of water or a complete lack of fluid. The flow of water only during heating indicates the correct operation of the unit.
The main causes of leakage are the following factors:
- If the liquid flows from a cold boiler, and the rhythm of the drop is unstable, then, perhaps, the pressure in the water supply network is too high. Therefore, in such situations, it is necessary to put a reducer at the water supply inlet, which normalizes the pressure in the network.
- Sometimes fluid may leak due to debris that has fallen under the seat of the product. In this case, you can try flushing the valve with the emergency release lever. But, if nevertheless it was not possible to restore the operability of the device, then the collapsible model can be cleaned, but the non-collapsible assembly will have to be changed.
- If water does not enter the tank, it may be that the internal parts of the mechanism are clogged with scale. In such a situation, it is necessary to clean mechanically the inside of the product.
- And, of course, the locking device often breaks down due to improper installation.
Remember that not only health, but also the life of the inhabitants of the house depends on the proper functioning of the safety device. Importantly, do not forget that the use of a simple check valve can only exacerbate a dangerous situation.