Selecting and connecting a heating boiler safety group

Trigger algorithm

Let us briefly summarize the principle of operation of the entire group. From the very beginning of commissioning, an automatic air vent operates, removing all air from the system. However, if it overheats and reaches critical pressure levels, it is powerless. To avoid an emergency, the safety valve is activated, releasing excess coolant, thereby reducing the pressure in the system.

To monitor the operation of the system, the safety group includes a pressure gauge that shows the pressure at the moment: low pressure indicates depressurization, a malfunction of the expansion tank or make-up valve; increased - about expansion of the coolant or excessive release of steam due to overheating.

Self-assembly

There should be no difficulties during the manufacture of the security unit. To start the process, you need to prepare the following tools and materials:

• pressure gauge;
• relief valve;
• wrench and gas wrench;
• air vent;
• two squares;
• crosspiece;
• union;
• sanitary linen;
• sealant;
• adapters.

The angles are screwed into the cross. For a tight connection, plumbing flax is wound onto the thread, evenly distributing it over the surface. A small layer of sealant must be applied on top. Then, using a wrench, screw the squares into the crosspiece perpendicular to each other.

Then you need to install an air vent, a safety valve and a pressure gauge. If the parts have different thread sections, adapters are used. After the final assembly of all elements, the operation of the product must be tested under pressure - the unit should not leak, and all parts must be in working position.

What does a heating system safety group consist of?

The safety group for the heating system consists of a housing on which three devices are installed: a pressure gauge, a safety valve and an automatic air vent:

Safety group for heating: from left to right - safety valve, automatic air vent, pressure gauge

Let's consider these devices each separately.

Safety valve

The purpose of the safety valve is to protect the heating system from too much pressure.

The safety valve is designed for a certain pressure and when this pressure is exceeded, it is activated, i.e. it releases excess.

In fact, the expansion tank is responsible for compensating for excess pressure in the heating system: water expands when heated - its excess is forced into the expansion tank, which keeps the pressure in the system constant and the system intact. At the same time, the total amount of coolant in the entire heating system remains the same.

But it happens that for some reason the expansion tank did not work. For such a nuisance, a safety valve is installed through which excess water will be discharged from the system. To prevent water from flowing out onto the floor, we attach a tube to the thread on the side and lead this tube into the sewer.

Conclusion: sewerage in the boiler room is very desirable.

And further:

important! Antifreeze must not be disposed of down the drain!

On top of the safety valve there is a handle (red, similar to a water tap valve). Using this handle we check the operation of the safety valve. The functionality of the valve is checked very simply: turn the handle in the direction indicated by the arrow - water flows, release the handle - it stops flowing, which means the valve is working, we can sleep peacefully. If the water continues to leak, open and close it a second time, a third time... usually the flow stops.

But if the valve stubbornly does not hold water, you will have to replace it. And the faster, the better, because its performance is important.

The coolant may leak through the safety valve due to the valve not fitting tightly into the seat (for the uninitiated it sounds like nonsense, but it is true).

They produce safety valves designed for different pressures; you need to select them based on the pressure for which our boiler is designed. For the heating system of a private house, we buy a 3 atm valve.

Let's say there is no safety group with the required valve on sale. Then we buy the listed devices separately and assemble the security unit with our own hands.

Pressure gauge

A pressure gauge is a device for monitoring pressure in a heating system.

Like safety valves, there are pressure gauges designed for different pressures; you need to select one that is convenient to use: one glance at the device should be enough to determine its readings, without any calculations.

Conclusion: since the pressure in the heating system of a private house should be between 2 and 3 atm, then select a pressure gauge no more than 4 atm:

The pressure gauge has two arrows: red – control, black – working. The red one is set manually to the desired level (usually 2 atm, for floor-standing boilers it is no longer recommended, but in general, we check in the boiler passport). If during heating operation the working arrow deviates further than red - alarm! Something has “flyed”!

Automatic air vent

The entire safety group is placed on top of the boiler because of the air vent: it should be at the highest point where air bubbles rush.

Read more about this device in the article about the purpose, design and installation of an automatic air vent.

Connection to the heating system

First of all, it is necessary to correctly determine the installation location of the security group.

There are certain requirements that must be met:

• this should be a horizontal section of the pipeline next to the heat generator;
• on the supply line after the boiler;
• some boilers provide for installation of a safety unit directly on the unit itself; for this purpose there is a special connector on top of the heat generator;
• the distance from the heating device to the protective block should not exceed 1.5 meters, less is possible;
• for a pipe running vertically upward from the boiler, for example, to the next floor, it is necessary to arrange a branch. This is done using a corner so that the safety group can be positioned in a horizontal plane and the units look “heads up”;
• for a very powerful boiler, it may be necessary to install another protective unit.

A very important rule that must be followed is that shut-off valves are not installed between the safety group and the boiler. It would be advisable to install a protective block up to the first shut-off valve located on the line.

To avoid injury when checking or when the safety valve is activated in the presence of a person, it is necessary to connect a drainage tube to the device and drain it into the sewer

It is worth checking the functionality of the safety valve in a timely manner. This procedure is performed using the following method - after installation, open the cap in the direction indicated by the arrow on the device.

After installing the protective device, it is necessary to check the correct operation of all modules. To start using the air vent, you will need to unscrew the top cap and bleed the air. Now the lid is returned to its original position, but the device must remain slightly open.

How to connect a solid fuel boiler

The canonical connection diagram for a solid fuel boiler contains two main elements that allow it to function reliably in the heating system of a private home. This is a safety group and a mixing unit based on a three-way valve with a thermal head and a temperature sensor, shown in the figure:

The always open output of the mixing valve (the left pipe in the diagram) must be directed to the pump and heat generator, otherwise there will be no circulation in the small boiler circuit

The presented diagram shows how to connect the unit correctly and is used with any solid fuel boilers, including pellet ones. You can find various general heating schemes - with a heat accumulator, an indirect heating boiler or a hydraulic arrow, in which this unit is not shown, but it must be there. The method of protecting against moisture loss in the firebox is discussed in detail in the video:

The task of the safety group, installed directly at the outlet of the supply pipe of a solid fuel boiler, is to automatically relieve pressure in the network when it rises above a set value (usually 3 Bar). This is done by a safety valve, and in addition to it, the element is equipped with an automatic air vent and a pressure gauge. The first releases the air appearing in the coolant, the second serves to control the pressure.

How the scheme works

The mixing unit, which protects the heat generator from condensation and temperature changes, operates according to the following algorithm, starting from kindling:

1. The firewood is just starting to burn, the pump is on, the valve on the side of the heating system is closed. The coolant circulates in a small circle through the bypass.
2. When the temperature in the return pipeline rises to 50-55 °C, where the attached remote-type sensor is located, the thermal head, at its command, begins to press the three-way valve stem.
3. The valve slowly opens and cold water gradually enters the boiler, mixing with hot water from the bypass.
4. As all the radiators warm up, the overall temperature increases and then the valve closes the bypass completely, passing all the coolant through the heat exchanger of the unit.

This piping scheme is the simplest and most reliable; you can easily install it yourself and thus ensure the safe operation of the solid fuel boiler. There are a couple of recommendations regarding this, especially when piping a wood-burning heater in a private house with polypropylene or other polymer pipes:

1. Make the section of the pipe from the boiler to the safety group from metal, and then lay plastic.
2. Thick-walled polypropylene conducts heat poorly, which is why the surface-mounted sensor will openly lie, and the three-way valve will lag. For correct operation of the unit, the area between the pump and the heat generator, where the copper flask is located, must also be metal.

Connecting with copper pipes will not protect polypropylene from destruction in the event of overheating of the TT boiler. But it will allow the temperature sensor and safety valve on the safety group to work correctly

Another point is the installation location of the circulation pump. It is best for him to stand where he is shown in the diagram - on the return line in front of the wood-burning boiler. In general, you can install the pump on the supply side, but remember what was said above: in an emergency, steam may appear in the supply pipe.

The pump is unable to pump gases, so when the chamber is filled with steam, the impeller will stop and the coolant circulation will stop. This will speed up a possible explosion of the boiler, because it will not be cooled by water flowing from the return.

Way to reduce the cost of strapping

The condensate protection circuit can be reduced in cost by installing a three-way mixing valve of a simplified design that does not require connecting an overhead temperature sensor and thermal head. It already has a thermostatic element installed, set to a fixed mixture temperature of 55 or 60 °C, as shown in the figure:

Special 3-way valve for solid fuel heating units HERZ-Teplomix

Installing such an element definitely allows you to save on piping the TT boiler. But in this case, the possibility of changing the temperature of the coolant using a thermal head is lost, and its deviation at the output can reach 1-2 °C. In most cases, these shortcomings are insignificant.

Installation of homemade automation

High-quality products from well-known manufacturers are quite expensive. For example, the cost of a safety group for boilers of the Italian brand Icma is 40-43 USD. e. If you buy components from the same manufacturer and assemble the safety automatics yourself, the price will be significantly lower:

• safety valve – 6 cu. e.;
• pressure gauge - 10 cu. e.;
• automatic air vent – ​​5 cu. e.;
• brass crosspiece DN 15 as a collector – 2.2 cu. e.

The total amount for a security group assembled with your own hands is 23.2 USD. That is, the benefit is obvious.

When choosing components, be sure to take into account the advice of our expert, based on many years of practice:

1. Do not go for absolute cheapness when purchasing safety valves. Chinese products begin to leak after the first actuation or do not release pressure at all.
2. Pressure gauges “originally” from the Middle Kingdom often lie. If, when filling the system with coolant, the device underestimates the readings, then after heating the pressure in the network will jump to critical and an accident will occur.

   
   Assembling a homemade block

3. Select a safety valve according to the boiler operating pressure specified in the technical data sheet.
4. Do not buy an angular type air vent, only a straight one. The first creates increased resistance to the outgoing air.
5. The crosspiece should be made of high-quality thick-walled brass. When choosing, compare the weight of a cheap and expensive part in the palm of your hand and feel the difference.

For reference. The vast majority of gas and wood heat generators operate with a maximum water pressure of 3 bar. The exception is Stropuva long-burning cylindrical heaters (max - 2 Bar) and completely cheap boilers with thin walls (max - 1.5 Bar).

Setting up a homemade security group is quite simple. Screw the air vent into the upper terminal of the cross, and install a pressure gauge and safety valve on the side terminals in any order. Cut the finished element into the main line next to the boiler according to the diagram (see the previous section).

If you want to maximize the safety of your solid fuel heating unit, pay attention to thermal relief valves. They work in tandem with the main group and, in case of overheating, release the coolant from the water jacket of the boiler, running cold water from the water supply inside. Product types and connection diagrams are described in our earlier publication.

How and where to install the expansion tank

So, we are going to design and assemble a heating system with our own hands. If it also starts working, our joy will know no bounds. Are there instructions for installing the expansion tank?

Open system

In this case, the answer will be prompted by simple common sense.

An open heating system is, in essence, one large vessel of complex shape with specific convection currents in it.

The installation of a boiler and heating devices in it, as well as the installation of pipelines, must ensure two things:

1. Rapid rise of water heated by the boiler to the top point of the heating system and its drainage through the heating devices by gravity;
2. Unhindered movement of air bubbles to where they will rush in any vessel with any liquid. Up.

The conclusions are obvious:

1. The installation of a heating expansion tank in an open system is always carried out at its highest point. Most often - at the top of the accelerating manifold of a single-pipe system. In the case of top-fill houses (although you hardly have to design them) - at the top filling point in the attic.
2. The tank itself for an open system does not need shut-off valves, a rubber membrane, or even a lid (except to protect it from debris). This is a simple water tank open at the top, into which you can always add a bucket of water to replace the evaporated water. The price of such a product is equal to the cost of several welding electrodes and a square meter of steel sheet 3-4 millimeters thick.

This is what an expansion tank for an open heating system looks like. If desired, a water tap from the water supply can be brought into the hatch in it. But much more often, as the water evaporates, it is topped up with an ordinary bucket.

Closed system

Here both the choice of tank and its installation will have to be taken quite seriously.

Let's collect and systematize the basic information available on thematic resources.

Installation of the expansion tank of the heating system is optimal in the place where the water flow is closest to laminar, where there is a minimum of turbulence in the heating system. The most obvious solution is to place it in the direct filling area in front of the circulation pump. In this case, the height relative to the floor or boiler does not matter: the purpose of the tank is to compensate for thermal expansion and dampen water hammer, and we can bleed the air through the air valves.

Typical tank installation diagram. Its location in a single-pipe system will be the same - in front of the pump along the flow of water.

• Factory equipped tanks are sometimes equipped with a safety valve that relieves excess pressure. However, it is better to play it safe and make sure that your product has it. If not, buy one and install it next to the tank.
• Electric and gas boilers with electronic thermostats are often supplied with a built-in circulation pump and heating expansion tank. Before you go shopping, make sure you need them.
• The fundamental difference between membrane expansion tanks and those used in open systems is their orientation in space. Ideally, the coolant should enter the tank from above. This subtlety of installation is designed to completely remove air from the compartment of the tank that is intended for liquid.
• The minimum volume of the expansion tank for a water heating system is taken approximately equal to 1/10 of the volume of coolant in the system. More is acceptable. Less is dangerous. The volume of water in the heating system can be roughly calculated based on the thermal power of the boiler: as a rule, 15 liters of coolant per kilowatt is taken.
• A pressure gauge mounted next to the expansion tank and the feed valve (connecting the heating to the water supply) can provide you with an invaluable service. The situation with a stuck safety valve spool, alas, is not so rare.
• If the valve releases pressure too often, this is a clear sign that you have miscalculated the volume of the expansion tank. There is no need to change it at all. It is enough to purchase another one and connect it in parallel.
• Water has a relatively low coefficient of thermal expansion. If you switch from it to a non-freezing coolant (for example, ethylene glycol), you will again need to increase the volume of the expansion tank or install an additional one.

The expansion tank in the photo is installed according to all the rules: the coolant is supplied from above, the tank is equipped with a pressure gauge and a safety valve.

Main types of heating safety groups

The configuration of security blocks, as noted above, can be very diverse. There is, for example, this option.

Or here’s another option, in which all the elements are enclosed in a single housing.

A few more options.

There are many other options for implementing a security group on sale, but external indicators in this case do not matter, since the principle of operation is the same for all of them. You should, we repeat, choose one or another model according to the pressure indicator for which the pressure gauge and safety valve are designed.

Now, having understood the main types of groups, let’s get acquainted with popular manufacturers and the approximate cost of such products.

Connection diagram

A floor-standing boiler, unlike a wall-mounted one, does not have a built-in circular pump, an expansion chamber or a safety group. All this needs to be installed outside it. The supply pipe is connected to the top of the boiler and the safety group is mounted there.

Correct installation of the safety group, where it is located at a distance from the crane and does not interfere with it

There should be no shut-off valves, filters or other elements between the boiler and the safety group. For example, if the tap is closed, an accident will occur.

Note! The safety group is always mounted only in a vertical position and above the boiler. The security group can be presented in a corporate form

The main element in it is an emergency valve that relieves pressure. In some cases, instead of the entire safety group, it is possible to install only one emergency valve on the tee

The security group can be presented in a corporate form. The main element in it is an emergency valve that relieves pressure. In some cases, it is possible to install only one emergency valve on the tee instead of the entire safety group.

Very often, a safety group is placed immediately above the boiler, and at the moment the pressure is released by the valve, liquid enters the boiler, which is unacceptable if it is electric. Therefore, if the safety group is installed above the boiler, then a tube is connected to the emergency valve and taken to the side. A container for liquid is placed under it.

Connection diagram for a safety group in a heating system with an expansion tank

The return circuit is carried out as follows (in the direction from the boiler) - a shut-off valve, a circulation pump, a dirt filter, a second shut-off valve, a tee with a valve for connecting the expansion tank and a valve for filling the network. For systems with such a simple circuit, installation of a check valve is not required. The dirt filter is mounted with an oblique outlet downwards. The pump rotor must be horizontal and the terminal box in the upper position.

Note! The expansion chamber must not be installed in front of the first shut-off valve. Expanzomat compensates for pressure fluctuations in the heating system

When water heats up, it expands. To prevent pressure from being released through the emergency valve, the expansion tank reduces it. The volume of the expansion chamber must be at least 1/10 of the entire system

The expansion valve compensates for pressure fluctuations in the heating system. When water heats up, it expands. To prevent pressure from being released through the emergency valve, the expansion tank reduces it. The volume of the expansion chamber must be at least 1/10 of the entire system.

For example, if the boiler volume is 80 l, and the heating system is 140 l, then the total volume is 220 l. Therefore, an expansion tank of 22 liters is required for stable operation. Experts recommend taking a larger expansomat - 1/7-1/8 of the volume of the entire system.

Expansion tank in a closed heating system

As a sealant for threaded connections, it is recommended to use FUM tape, flax, pastes or other sealing agents that will ensure a tight connection of all elements even during heavy loads.

Review of the best models

Among the most popular manufacturers that produce protective fittings are companies such as Valtec and Watts.

The Watts company has become famous for its huge range of different devices for the heating system, among which the protective block has an important place. The KSG model range has different threaded body devices, which differ in size and material of production.

Additionally, certain devices are sold with a thermal insulation casing. Products of the KSG model range are typically equipped with a relief valve, which is designed for a maximum value of 3 bar. Installation into the heating main is carried out using a special connector with a thread inside.

Valtec is not inferior in quality to this brand. The company presents a model range of devices for boiler equipment and expansion tanks - the VT495 and VT460 series. VT460 products are designed to work with domestic heating boilers with a power of no more than 45 kW and a pressure of no higher than 3 bar.

But the cost of factory-made devices is quite high, so it is advisable to make this unit yourself.

Before assembling the security group yourself, do not forget to prepare the appropriate tool

Where is the expansion tank installed for heating?

So, the installation of the tank depends on the type of heating system and the purpose of the tank itself. The question is not why an expansion tank is needed, but where it should compensate for the expansion of water. That is, in the heating network of a private house there may be not one such vessel, but several. Here is a list of functions assigned to various expansion tanks:

• compensation of thermal expansion of water in closed heating systems;
• in open networks, the reservoir performs 2 functions - it absorbs excess coolant volume and removes air from the system into the atmosphere;
• under certain conditions, the membrane tank serves as an addition to the standard expansion tank of the gas boiler;
• absorb excess heated water in the hot water supply network.

Being at the highest point of an open type system, the tank acts as an air vent

In open heating networks, the water in the reservoir comes into contact with atmospheric air. Therefore, the installation of the expansion tank is provided at the highest point - on the riser coming from the boiler. Often these systems are made gravity, with increased diameters of pipelines and a large amount of coolant. The capacity of the tank should be appropriate and be about 10% of the total volume of water. Where else if not in the attic to put such a large tank?

Alternative homemade open tanks made from a plastic canister (photo on the left) and an air receiver

Closed-type heating systems are distinguished by the fact that the membrane expansion tank for water is completely sealed. The optimal installation option is in the boiler room, next to other equipment. Another place where it is sometimes necessary to install a closed expansion tank for heating is the kitchen in a small house, since the boiler is located there.

In closed systems operating on non-freezing coolant, the volume of the tank should be increased to 15% of the total amount of liquid. The reason is the increased coefficient of thermal expansion of glycol antifreeze.

Making a security group at home

Many people are interested in whether it is possible to make such a group with your own hands? It is possible, but to do this you need to purchase each of the elements separately, and then connect them using adapters, tees, and so on. You can weld the block body from pieces of fittings and pipes made of polypropylene - this will cost much less than the “store-bought” version made of brass.

At the same time, do not forget that the polypropylene safety group can only be installed in those lines where the temperature of the working fluid is low (for example, in “warm floor” systems), but in no case in radiators! This is explained by the fact that if the liquid heats up to 95 degrees, it will lead to the destruction of polypropylene, and the consequences of this can be the most unpredictable.

Video – Security Group

Principle of operation

Each heating system has its own specific maximum pressure values. This is directly affected by the degree of heating and cooling of the liquid that is in the network. As described above, due to the fact that the pressure begins to exceed the norm, significant damage can occur. To understand how the safety unit helps to avoid the consequences of emergency situations, it is worth considering the principle of its operation.

The set of parts of the safety unit may vary depending on the purpose for which the main unit is used, but in the basic configuration the system contains only three modules that are built into the housing. This is a pressure gauge, an air vent (Maevsky tap) and a safety valve.

Let us examine in more detail the purpose of all three elements.

A pressure gauge is a measuring device that can be used to quickly monitor pressure readings. Its most important function is to determine the most accurate data. But, like any device, it has certain errors. The measuring units in pressure gauges are either bars or atmospheres, but the first option remains the most popular.

As can be understood from the descriptions, each part of the security unit performs its own specific functions. The elements can either be located separately, in different parts of the pipeline, or be in a single bundle. There is also another option for completing the system. It has a hydraulic shock absorber added to it, protecting the pressure gauge from the effects of the environment.

The equipment as a whole operates according to a certain simple scheme. If for some reason the expansion tank cannot compensate for the expansion of the coolant, and the closed system is subjected to high pressure, then the pressure in the bowels of the equipment also increases. At this moment, the safety valve comes into operation. Its spring compresses and the valve opens. This way, the excess coolant gets the opportunity to escape, the excess air exits through the air vent.

This is due to the fact that in such systems there is often too little draft inside the chimney. In the pipeline itself, the pressure can also become either too low or too high. Due to such problems, gas contamination of the room is possible.

Operating principle of the safety unit

The security group works according to an extremely simple scheme, where each of the modules is responsible for maintaining the standards of certain indicators in a private boiler room:

1. Thanks to a convenient pressure gauge, the user can monitor the pressure readings at the moment the line is filled with coolant, as well as during the operation of the boiler.
2. The safety valve protects the heat generator from critical pressure drops.
3. The main functionality of the air vent is based on the automatic release of air entering the pipeline during its initial filling or during operation.

All safety modules are represented by a single unit and are equipped with a special housing - a manifold.

Provided that the boiler room circuit uses an open type expansion tank, installing a safety group does not make sense - the pressure in the pipeline is equal to atmospheric pressure, and excess air leaves the system through the tank capacity.

Regardless of the type of boiler used (solid fuel, gas, diesel), the protective unit is considered the main emergency element of a closed heating system, which tends to work with excess pressure

How to tie solid fuel boilers

The connection diagram for a wood-burning heat generator is designed to solve 3 problems (in addition to supplying the batteries with coolant):

1. Preventing overheating and boiling of the TT boiler.
2. Protection against cold “return” and excessive release of condensate inside the firebox.
3. Work with maximum efficiency, that is, in full combustion mode and high heat transfer.

The presented wiring diagram for a solid fuel boiler with a three-way mixing valve allows you to protect yourself from condensation in the firebox and bring the heat generator to maximum efficiency mode. How it works:

1. While the system and heater are not warmed up, the pump drives water through the small boiler circuit, since the three-way valve is closed on the radiator side.
2. When the coolant heats up to 55-60 degrees, the valve set to the specified temperature begins to mix in water from the cold “return”. The heating system of a country house is gradually warming up.
3. When the maximum temperature is reached, the valve completely closes the bypass, all water from the TT boiler goes into the system.
4. A pump installed on the return line pumps water through the jacket of the unit, preventing the latter from overheating and boiling. If you put the pump on supply, the chamber with the impeller can fill with steam, pumping will stop and the boiler is guaranteed to boil.

The principle of heating using a three-way valve is used for piping any solid fuel heat generators - pyrolysis, pellet, direct and long-term combustion. The exception is gravity distribution, where the water moves too slowly and does not provoke condensation. The valve will create high hydraulic resistance, preventing gravity flow.

If the manufacturer has equipped the solid fuel unit with a water circuit, the coil can be used for emergency cooling in case of overheating. Please note: the fuse on the safety group is triggered by pressure, not temperature, and therefore is not always able to protect the boiler.

A proven solution is to connect the DHW coil to the water supply through a special thermal relief valve, as shown in the diagram. The element will be triggered by a temperature sensor and at the right moment will pass a large volume of cold water through the heat exchanger.

Using the Buffer Capacity

The best way to increase the efficiency of a TT boiler is to connect it to heating through a buffer tank. At the inlet of the heat accumulator we assemble a proven circuit with a three-way mixer, at the outlet we install a second valve that maintains the required temperature in the batteries. Circulation in the heating network is ensured by a second pump.

A balancing valve on the return line is needed to adjust the performance of the pumps

What we gain thanks to the thermal accumulator:

• the boiler burns at maximum and reaches the declared efficiency, fuel is used efficiently;
• the likelihood of overheating is sharply reduced since the unit dumps excess heat into a buffer tank;
• the heat accumulator plays the role of a hydraulic arrow; several heating branches can be connected to the tank, for example, radiators of the 1st and 2nd floors, floor heating circuits;
• a fully heated tank maintains the operation of the system for a long time when the wood in the boiler firebox has burned out.

TT boiler and storage water heater

In order to load an “indirect” boiler using a wood heat generator, you need to embed the latter into the boiler circuit, as shown in the picture. Let us explain the functions of individual elements of the circuit:

• check valves prevent the coolant from flowing in the other direction along the circuits;
• the second pump (it is enough to take a low-power model 25/40) provides circulation through the spiral heat exchanger of the water heater;
• the thermostat turns off this pump when the boiler reaches the set temperature;
• An additional air vent prevents the supply line from becoming aired, which will be above the standard safety group.

In a similar way, you can connect the boiler to any boiler that is not equipped with an electronic control unit.

How to choose a security group for a boiler

To make it easier to understand, I will make recommendations for selection in the form of a list:

• First, find out what pressure your boiler capacity is designed for. Otherwise, you risk causing a flood or explosion at home.
• Thread diameter - if you have a regular storage water heater, then you need a group with a diameter of 1/2 inch. On indirect heating boilers it will be 3/4.
• Availability of connection for drainage - many group models are made with a threaded connection for connecting a sewer corrugation or come with a siphon included, as shown in the figure above.
• Additional features - manufacturers love to delight customers with all sorts of “goodies” such as shut-off valves and pressure gauges.
• Material - The GBB should be made of brass. Do not consider other materials.
• Manufacturer - it's up to you. I prefer European ones and find high-quality specimens.

Features of choice

When selecting a security group, pay attention to the following technical parameters:

• Maximum power.
• Maximum coolant temperature.
• Connecting diameter.
  Safety groups of domestic boilers with a power of up to 50 kW have a pipe with a 1" internal thread.
• Nominal pressure.
  It must correspond to the parameter specified in the boiler passport.
• Coolant compatibility.
  Some devices cannot be installed in heating systems with non-freezing liquids.

Installation and maintenance rules

According to modern safety requirements, each radiator must have a shut-off valve in front of it in case it fails and repair work is carried out without stopping the entire system. Which is especially important in the cold season. The safety group for the heating system should be installed similarly - the tap that shuts off the coolant MUST BE AFTER the safety system.

A common mistake is to install a shut-off valve between the boiler and the security system itself. In this case, if you need to stop the boiler as quickly as possible (especially a solid fuel boiler, for example, if pipes rupture or a radiator leaks), then it will be impossible to do this without consequences. After all, the coolant will continue to heat up for some time and will not find a way out. As a result, pressure increases and either pipes burst in another place or the boiler collapses. Both lead to significant losses.

After the device is installed according to the instructions, it is put into operation by opening a special cap on the automatic air vent. Please pay special attention - it is forbidden to remove it completely

Also, depending on the quality of the coolant and the degree of operation of the entire system, it is necessary to periodically (on average, once a month) inspect the valve for contamination between the seat and the plate. Because if dirt is not removed for a long time, this can lead to further leaks - just turn the device in the direction of the arrow and it will clean itself.

During installation, you must adhere to certain rules that will ensure the safe operation of the entire heating system. Firstly, there should be no foreign objects or pipes in front of the group so that they do not obscure the view of the pressure gauge. The best location is considered to be one in which, upon entering the boiler room, the readings of the measuring device are immediately visible. Secondly, it is prohibited to install other elements on the pipe between the group and the heat exchanger. Ideally, this pipe should be as short as possible in length and located as close to the boiler as possible. The manifold has threads on all outlets. Actually, installing a boiler safety group means screwing all the parts onto the crosspiece and installing it on the pipe. To prevent leaks, FUM tape, sealing paste or flax are applied to the threads before installation. Compliance with these simple rules during installation will allow the boiler equipment to operate without leaks and dangerous situations.

Self-installation steps

You can assemble a safety group for the heating system yourself. This will require a large investment of time and money. If everything is done correctly, the unit will work perfectly and protect the equipment from breakdowns, as well as emergency situations.

Connection rules

Before you begin installing the security unit yourself, you need to study in detail the advice of professionals. They will help beginners avoid a large number of mistakes and make a truly reliable design.

Do not forget to strictly follow the instructions when connecting a security group

General connection tips:

1. It is best to install the protective block on the supply pipeline located at the outlet of the device.
2. The unit can be placed at a distance of at least 50 centimeters from the heat source.
3. There should be no foreign parts (tees with branches, taps) on the section of the pipeline where the protective device is installed.
4. Professionals do not recommend installing a safety group on metal-plastic or polypropylene pipes, as they can be deformed when exposed to heated air. The best option would be to use a metal piece.
5. The automatic air vent is fixed only in a vertical position.
6. A flexible hose can be connected to the safety valve, through which excess liquid can flow into the bottle or onto the floor.

Selection and purchase of components

Ready-made security units are quite expensive, so it is best to purchase individual components. This little trick will help cut your costs in half.

When choosing parts, you should adhere to the following tips:

1. You should not buy the cheapest safety valves that were made in China. Such products will quickly fail and will not relieve pressure.
2. All pressure gauges of Asian origin give incorrect readings. This is due to low quality materials and incorrect graduation.
3. It is better not to use a corner-type air vent, as it creates additional resistance to escaping steam.
4. The safety valve should be selected based on the operating pressure of the installed boiler. Such information can be found in the technical data sheet that comes with the device.
5. It is better to choose a crosspiece from high-quality brass.

During the work you will need some materials and tools. You can buy them at any hardware store or rent them from friends.

Items must include:

• adjustable wrench;
• gas keys;
• union;
• crosspiece;
• adapters;
• angles with external and internal threads;
• any material for sealing connections (plumbing linen, special tapes and others);
• sealant.

Operating procedure

Once all the preparatory steps have been completed, you can begin assembling the security unit. This work is done in a few simple steps:

1. Plumbing flax is carefully wound onto the threads of the angles. It is important to lay the material evenly, without gaps.
2. For better fixation of the connection, a thin layer of sealant is applied.
3. The squares are attached to the crosspiece using a wrench.
4. Then a pressure gauge, a Mayevsky valve and a safety valve are installed. If they have different diameters, then use suitable adapters.
5. All joints are carefully treated with sealant.
6. The protective unit is tested for functionality. During the inspection, detected leaks and other defects are eliminated.

The use of antifreeze in a heating system

To reduce the negative impact of low temperatures on radiators and pipelines, antifreeze is used for the home heating system. Antifreeze usually contains ethylene glycol. It is poisonous and you need to be careful not to get this substance on exposed skin and, especially, in your eyes. Antifreeze vapors, which are formed under the influence of high temperatures and can be released outside if there is a small leak, are also harmful.

Of course, the price of antifreeze for a heating system may vary depending on the composition of the product and the manufacturer. But still, using antifreeze in heating devices will cost more than using ordinary distilled water. True, in some cases, the use of non-freezing liquid is simply necessary to ensure the safe and proper operation of the entire heating system.

Many people have a question: is it possible to pour antifreeze into the heating system of a house? You can use such a non-freezing liquid, but you should know a number of rules and follow safety requirements. Sometimes automotive antifreeze is used for the heating system.

In this case, it is important to take into account some features of the operation of the heating system:

• Antifreeze is more viscous than distilled water. Therefore, if a circulation pump is used, it will have to be replaced with a more powerful unit;
• the degree of fluidity is quite high. A small microcrack or loose connection is enough for antifreeze for heating the house to begin to penetrate into the room. Therefore, you need to ensure the tightness of the structure, and instead of rubber gaskets it is better to use paronite gaskets;
• The heating rate of water with antifreeze is slightly lower. This feature should be taken into account when choosing the temperature mode for the heating system;
• Antifreeze cannot be used in a home heating system in concentrated form. The product must be diluted with water.

Thus, many modern models of heating systems are equipped with a safety unit. But if this module is missing, you should install it additionally. This protective mechanism reduces the likelihood of air locks and regulates the pressure in the system. To avoid the negative impact of low temperatures on pipes, use antifreeze. All this allows you to extend the service life of heating devices and make their work better and more efficient.

Scope of application

The complete product described above is not needed in all heating systems. For example, wall-mounted gas boilers already have safety automatics. Pressure gauge and thermometer readings can be displayed on the control panel screen, and the safety valve and air vent are located under the panel. “Beginner” owners of wall-mounted boilers are often scared when a few drops of water come out through the hole in the bottom of the casing. Not everyone knows that this is the result of the overpressure relief valve triggering.

There is no need for a safety group in open gravity heating systems. The pressure in them never rises to unsafe levels, and the air escapes through an open expansion tank.

In accordance with the rules for the safe operation of floor-standing gas and solid fuel boilers connected to a closed heating system, the group must be installed in the piping. In addition to its main task, namely protecting the heat exchanger and pipelines, it is a good tool for diagnosing faults.

An example is the following situation. The operating pressure when the coolant has cooled is below the minimum. The boiler owner turns on the make-up, “catches up” the pressure, and then loads fuel. After the coolant has warmed up, the pressure gauge needle reaches the maximum, and then the safety valve is activated. The boiler operates normally until the load is completely burned out, and then (after a slight decrease in temperature the situation repeats: the pressure is again below the minimum. The reason is the incorrect operation of the membrane tank. Two options are possible:

• The membrane is destroyed.
  After unscrewing the nipple, water comes out of the hole.
• The pressure in the air chamber has dropped.
  It is necessary to check the tightness of the nipple and replace it if necessary. After this, the inner tube can be inflated with a tire pump to the “certificate” pressure.

The operating principle of a system with a membrane tank.

Why is it needed and how does it work?

Any heating system operates within a certain range of pressure values. It changes depending on the degree of heating and cooling of the liquid in the network. When the coolant heats up, it expands, thereby increasing the pressure in it.

A safety group is needed to prevent rupture of pipes, leaks from shut-off valves, or breakdown of other elements of the heating system due to high pressure. With its help, the pressure is controlled, and when its maximum permissible value is reached, it discharges the required amount of coolant from the network.

A security group consists of the following elements:

• Emergency (safety) valve;
• Automatic air vent;
• Pressure gauge.

Heating safety group diagram
All of them are attached to one base - the console. The connection between the console, the emergency valve body and the air vent is made by hot forging. The rotary cover on the safety valve is made of heat-resistant nylon.

There should be no air in any heating systems. Because of it, noise occurs in the network, and some elements of the network, for example, a circulation pump, fail faster. The entry of air into the heating system is inevitable when it is filled with coolant.

It is also released from liquids when they are heated to high temperatures. In order to remove it from the system, automatic air vents are used.

Using a pressure gauge, visual control of the pressure in the network is carried out. The emergency valve releases coolant from the system to reduce pressure. The direction of liquid discharge is shown by an arrow on the device body. This is necessary so that during the release of the coolant it does not fall on a person.

It is best to connect a plastic tube to the safety valve and lead it to the container. This will not only make its use safer, but will also help you monitor its operation and check how much coolant has been discharged and whether it is in working condition.

The air vent is an important part of the heating safety group

If the valve has been inactive for a long time, it may begin to leak due to contamination, thereby reducing the pressure in the network. Therefore, it needs to be cleaned periodically. To open the valve, turn the cap in the direction of the arrow.

Note! The drain hose is selected with the same diameter as the outlet on the emergency valve so that it does not create obstacles during the release of coolant from the heating system.