Build Daily


August 12, 2017 18:06

Check valve to the water heater

Permanent availability of hot water in the house or apartment - for most people this is a long- become habitual norm, without which it is difficult to imagine a normal, comfortable life.If the water supply to housing stretched or organized autonomous uninterrupted water supply, for example, from a well or wells, there is nothing to think - you need to install the water heater of a particular type.

Check valve to the water heater

-return valve for the water heater

Probably leading position on the popularity of among water heating appliances for household use are electric boilers.They are extremely easy to use, their installation does not require any additional the negotiation procedures, or compilations of individual projects.Installation of the boiler is quite posilen and for self-holding.That is why the information is needed, which will be presented in this publication - each house masters should clearly understand how important safety check valve to the water heater.

As would neither warned the workers of h

ousing and communal services, emergency and rescue services, controlling Gostekhnadzor authorities, any would stories with consequences accidents or showed on television, all wellwith alarming regularity are "geeks" that all these technical recommendations and a good advice - not a decree , they "know how to simpler and better."Alas, but ignoring the very small size, low cost, easy to install, and at the same time - extremely important object strapping an electric water heater can result in very big trouble, and it is not excluded that even in tragedy.

Design and principle of operation of the valve

Article Contents

  • 1 Design and principle of operation of the valve
  • 2 How does a safety valve in different situations
    • 2.1 Video: the need to install a safety valve
  • 3 recommendations on the selection and installation of the safety valve
    • 3.1 Video: typical boiler piping arrangement
  • 4 Frequently Asked questions (FAQ)

First of all, you must immediately make a very importantreservation. Although very often in order to obtain information Interest is driven search term "non-return valve for the water heater", a much more accurate , it is more correct to speak of the safety valve, which combines several functions.These devices have a certain similarities, but there is a huge difference, which predetermines main task - ensure safe operation of the electric heater.

comparison - consider normal check valve device:


That's the way a normal non-return valve.But it for the boiler - enough!

It - metal cylinder , both sides of which are threaded sections for "zapakovki" in a straight pipe of the corresponding diameter portion.Inside stopped poppet valve - drive with a rubber seal around the circumference of the central axis - stock ( on display at figure green arrow).The disc is constantly in a state of a spring-loaded, overriding an internal channel for the passage of water.

When the water supply in the direction of the arrow (the direction of fluid flow permitted is always indicated on the valve body - below this mark is shown a red arrow), the pressure in the pipe through the "plate" compresses the spring and opens the passage.As soon as the pressure decreases, the valve again enters the closed state independently.

This precaution is certainly necessary to constantly in the water heater, under any circumstances, the tank was filled.However, this measure is not enough to ensure safety - it bude described below.

relief valve is arranged somewhat more complicated:

Safety valve device for a water heater

safety valve device for a water heater

In fact, this two valves in one body, arranged perpendicular to one another.

used in the larger cylinder (pos. 1), which is water run, set all the same valve to prevent reverse flow of water.On the supply side - the threaded portion of "Dad" (. Item 2) for tie-in plumbing (in particular, here it will be convenient to connect the flexible hose water disposals).On the opposite side - the nut "Mama" (item 3.), Which in some cases is wound directly on a regular cold water supply pipe to the electric heater.

The figure is very well marked "plate" of the check valve (pos. 4) with a sealing ring in the circumferential direction, and the spring (pos. 5), which holds the valve in the closed position.

And now - the main difference.Perpendicular to the cylinder with check valve is still one, several smaller (pos. 7).In fact, it posted same poppet valve spring but he is much more powerful - this is the most precautionary "stall" valve.Normal and even slightly increased pressure in the water pipe system is not able to compress spring and open it - it requires a much more serious efforts.

in the cylinder of the "plate" of the safety valve is required to have a hole with a pipe (pos. 8), which is triggered when the valve will be reset excess liquid.

Jilin etc. etc. edohranitelnym with "Stall" valve can be completely drowned out by , and sometimes it ends with the threaded cap (cap), for which there is the adjusting screw (usually - under the "internal" hexagon).But the most common safety valves with lever:

Many models are equipped with a valve to allow manual lever bleed fluid

Many models are equipped with a lever valves to allow manual venting liquid

The figure clearly visible features of this device.The lever (pos. 9) for manual opening of the safety valve with water discharge through the pipe (pos. 8).Note that the nozzle may have a special performance of the relief, allowing to wear it thin hoses to drain the water in the drainage (sewer).manual valve control function is useful, for example, to drain the contents of the boiler during repair or maintenance work. Nevertheless , «to get involved in" the use of such a manual should not be - it may be in some cases even dangerous (this will be discussed more below).

on any safety valve is always an arrow indicating the direction of the flow of cold water in the direction of the electric water heater.(On scheme - red arrow).Very often on the body indicated by the limit set pressure "Stall" valve - in this case is 0,7 MPa or 7 atmospheres ( yellow circle in the figure).

How does a safety valve in various situations

To finally confirm the importance of the safety valve, it is best to consider the cases in which it works, as well as those situations, that can arise, if atfor some reason the valve is damaged or missing.

For clarity, yet again - the simplest, but most understandable boiler piping arrangement with a safety valve.Blue and red arrows show the direction of flow, respectively, cold and hot water. green arrow shows the place of installation of the safety valve .

Typical installation of a safety valve

Typical installation of safety valve

1. After the electric water heater is installed completely "tied with", followed by its filling.To do this, simply open the cold water and hot tap on one of the mixers.Pressure in the water pipe is sufficient to open the check valve for the smooth flow.As the volume of content DHW cylinder air is an attempt to take.Once out of the mixer will stream of water - all container filled to the top of the intake manifold, the supply can be turned off.

pressure in the boiler in the mome nt etc. imerno well pressure in the cold water mains - it seemed to be "propped up" to them.However, it may be even a little higher - for score remained compressed a small amount of air at the top of the tank.Plus, when the power starts heating the water - and it is also , naturally, leads to increased pressure.

2. Consider a situation that the non-return valve - not established , or is out of whack.That balance has been achieved in completing boiler capacity sooner or later breaks down, as the pressure becomes higher than the pressure in the pipe."Hot" on the mixer taps are closed, then heated water will find a way out in a different direction.This can lead to the fact that hot water begins to flow suddenly from the "cold" tap, or it is filled on a toilet cistern.A between boiler thermostat can not understand the situation and not gives a signal to turn off heaters .Expensive electric energy is spent absolutely nothing.

3. But it still - not the most sad.It is no secret that the pressure in the water main, especially in multi-story homes, often reduced to critical values ​​(from the tap, as they say, barely flows ), or even completely disappear.The reasons for this - a great multitude, for example, an accident on the highway, preventive maintenance, planned reduction of pressure, such as at night and etc .What happens in the absence or non-return valve malfunction?Nothing good - boiler simply emptied as all the water will flow out of it completely in the supply pipe.

Well, if the boiler provides for protection from "dry" heat, and she promptly work!And if not?Powerful heating elements be idle to warm the air in the closed volume, and it will end or burnout, or cracking of the enamel - at least, nothing good can not expect in such a situation.

4. One might ask the question - is it possible to confine installation of this non-return valve?It would seem , judging by description, it is able to solve all the problems.

Do not count exaggeration : this attitude - it is implicit in his house bomb!

not count exaggeration: this attitude - it is implicit in his house bomb!

No, not in any case impossible.Installation of the valve is complex, combining the reverse, and safety, is a prerequisite for the safe operation of the water heater.

If somewhere the reader will meet a similar picture - only a check valve at the inlet, it must be understood that it is comparable to a powerful bomb planted which no one knows when explode .

Еще один образец "самоубийственного креатива"

Another example of a "self-destructive creativity»

consider the situation in detail. When the boiler starts heating and rise of temperature, according to the laws of thermodynamics, in a closed volume begins to increase pressure.

Designers of home appliances lay into each cylinder certain service life, allowing the unit to operate to certain pressures in capacity - usually a value specified in the technical documentation.Usually all boilers - it is a very balanced thermodynamic system in which very accurately calculated the optimal ratio of the permissible temperature and pressure levels. Nevertheless , anything can happen.As soon as the pressure level for some reason starts to approach the upper permissible level for the relief valve spring is compressed and discharged into the drain pipe over the resulting liquid.As a result, the system enters again in a state of dynamic equilibrium.

Protruding from the drain pipe water - normal

protruding from the drain pipe water - normal

And now try to imagine what might happen in a situation where the safety valve is not present, and all limited to reverse

heating water should be limited to a thermostatic control, but quite often, these electromechanical devices - far from perfect, and may simply fail.In this case, heating is continued unchecked.

pressure inside the boiler tank grows, but it has no outlet - the mixers are closed and the check valve firmly blocked the supply line.It would seem, temperature reaches only up to 100 degrees, to the boiling point of water?Nothing like this!With increasing pressure in the closed volume rises sharply and the temperature of the boiling liquid.For example, the data shown in the table:

pressure in a closed volume, bar (MPa) temperature of boiling water, ° 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

As mentioned above the word "bomb» - it does not discharge from the hype!In such circumstances, the water heater turns on really explosive terrible destructive power.

Already at 4 - 5 atmospheres of pressure the boiling point reaches almost 150 ° With , and continues to rise.on the wall of the pressure rise can lead to their deformation, chipping enamel or ceramic coating - but it is the smallest of the possible evils.Scary other circumstance - sharp drop in pressure in the closed system, and this can happen with the appearance of cracks in the weld, at the break of the rubber seal, or even just when you open the hot water tap at the mixer.

sharp decline in pressure results in a corresponding sharp decline in boiling point of water.As a result, the entire volume liquid (imagine all at the same time 50, 80 or 100 liters!) Instantly boils, which, of course, is accompanied by the release of enormous amounts of steam.It will not sustain any, even the most robust housing - should be a huge explosion, which is able to carry on all his ways, including even the brick interior walls.A good example on the Internet - a lot.

Hard to believe , but it is - the consequences of the explosion of conventional electric boiler

hard to believe, but it is - the consequences of the explosion of conventional electric boiler

So, will lead a brief summary on the need for a safety valve.

- It prevents reverse leakage of water from the tank into the pipeline supply, in case of decrease in pressure.

-Availability klapa on to input creates additional protection from possible boiler strong pressure surges in the water, from water hammer.

- safety valve to eliminate the possibility of other levels of security flaw - will maintain a temperature-baric regime in the boiler within the allowable values.

- Safety valve, equipped lever allows, in addition, to carry out the discharge of water from the boiler if necessary.This is normal?