How to install a bypass in a heating system. Bypass - what is it? You might also be interested

When installing a heating system, it is important to create a design that will operate with maximum efficiency and will not lose efficiency due to failures in coolant circulation.

For this purpose bypass must be used: the element serves to ensure the safety and stability of the hot circuit and does not allow it to fail, even if a leak occurs on the heating radiator.

What is bypass in heating systems

A bypass is a section of the pipeline that acts as a jumper and is mounted between the forward and return pipes in order to control the uninterrupted supply of liquid.

The bypass circuit is made of the same material from which the riser is made, but a pipe of smaller diameter is chosen for this. Optionally, a check valve is installed on the “shunt” to prevent the outflow of liquid against the main circulation.

Why is this element needed in the heating system?

Most often, multi-storey buildings of older series are equipped with single-pipe heating systems, which are distinguished by their simplicity of design and low installation costs. The heating station of the building has supply and return collectors, is equipped with radiators, and in the event of an accident on one of them, the battery must be dismantled.

This situation leads to complete paralysis of the riser operation if the system is not equipped with a bypass: this element makes it possible to block the movement of the coolant using shut-off valves. As a result, the liquid will circulate through other radiators, and damaged elements can be replaced.

With the help of this “shunt” it becomes possible:

Adjust amount of coolant.

Replace batteries, repair them while the system is running without stopping it.

Speed up processes draining and filling heating circuits with working fluid.

Provide circulation coolant in the forced heating system after stopping the pump.

The bypass transports water parallel to areas with shut-off valves. The bypass circuit can also be used to drain and refill the heating pipe.

A forced system equipped with this device will work even when the pump is turned off: after the power supply is stopped, it is enough to turn off the taps leading to the pump and open the central shut-off element.

In a one-pipe system

Experts do not question whether a bypass is needed in a one-pipe heating system. The answer is clear - yes. Bypass allows:

Adjust the degree of heating of radiators if you install a thermostat valve instead of shut-off valves.

Replace battery without draining the coolant and lowering its temperature.

In apartment buildings, before carrying out manipulations with the heating system, you must obtain permission from the management company employees.

In a two-pipe system

Owners of private houses are interested in whether it is necessary to install a bypass if there is a two-pipe heating system. In this case, the jumper is not necessary, since the radiators are mounted in an independent way, which allows you to disconnect the battery or replace it without stopping the heating operation.

Such a system is considered more expensive to install and requires more time to install, but due to its improved efficiency and ease of repair, it is increasingly being installed in modern private and multi-storey buildings.

You should make sure that the system is really two-pipe: some single-pipe designs look similar in appearance, but instead of a parallel pipe, there is a riser for the upper liquid supply. In such systems, it is also necessary to install a bypass.

How is a bypass installed in a heating system?

Installation of the bypass circuit can be carried out according to different schemes:

On radiators of single-pipe systems open or closed type.

Parallel to the pumping device, which operates in a gravitational heating network (gravity-flow system).

Installation as a jumper between the coolant supply and return pipes.

Installation on mixing stations nodes.

If we are talking about a high-rise building, where a heated towel rail is connected to the main hot water riser, the design also includes you need to install a bypass.

How to make a jumper and choose the right cross-section diameter

To install the “shunt” it is necessary choose the right connection point: it should be located as close to the radiator as possible, but further from the riser pipe. If necessary, the bypass can be equipped with an auxiliary tap.

Before installation, you need to carry out calculations and purchase components; It is important that the bypass diameter in a one-pipe system is one size smaller than the cross-section of the main pipes.

To install the pump unit on plastic pipes, it is assembled in advance and connected using soldered tee jumpers, and when installing on metal pipes, you first need to weld the pump bends.

When performing installation work, it is important to remember the following points:

Install mixing valve not required, since it works in collector systems where the coolant speed has already been brought to normal.

It cannot be allowed to shut-off valves overheated, since this reduces its performance properties. For this reason, reinforcement must be welded at a distance at least 20 cm from valves that may burst or become deformed.

The pump is placed so that the working shaft positioned horizontally: This allows you to reduce the gravitational load and extend the life of the device.

We invite you to watch a video demonstrating the rules for installing a bypass in a heating system:

The bypass is an important element for the functioning of a single-pipe heating system, which is indispensable when it is necessary to service, repair and dismantle radiators. Installing this component is quite possible on your own; it is only important to choose the right components, make sure you have the tools and follow the instructions.

Surely each of us has come across the above term. In this article we will answer the following questions:

"What is bypass"?
“What is a bypass for?”
“How is a bypass installed?”
“Automatic bypass - what is it?”

The general meaning of the word is very vague and imprecise, so when you use this term in your speech, it is necessary to clarify the scope and principle of operation.

Bypass Application Areas

In the first case, the device is used in a water supply system. As a rule, this device is used either when installing a circulation pump, the purpose of the latter is to increase the pressure in the system (in this case, installing the device yourself is mandatory), or when installing all kinds of meters and other metering devices. The valve performs only one function - it is a bypass line.
Bypass in a water heating system – this is a special device, which allows you to adjust the water supply to the radiator batteries with very high accuracy. A lot depends on this detail. Each of us hates to be in a room where it is either too cold or too hot. The valve, in turn, solves this significant problem, making your stay in the room comfortable and pleasant. The device creates a pleasant microclimate and avoids sudden temperature changes.

Bypass device and principle of its operation

The simplest part of this structural system is a small piece of pipe in the form of a jumper. However, a full-fledged valve must have at least three taps for water supply, since if at least one of them is missing, the device will not be able to work as intended. This device is installed between the direct and return wiring of a conventional heating radiator.

Bypass types

So, it should immediately be noted that all models of this device, according to their characteristics, can be divided into two large groups. Each of them has its own characteristics, which will significantly affect the operating principle of radiator batteries or water supply system.

The first group includes devices with a check valve. As a rule, such devices are used for circulation pumps. This bypass does not work all the time, but when necessary. The operation occurs as follows: after turning on the pump, the valve automatically opens due to excess pressure, and then begins to let in hot water. water or other heat carrier. After the pump has finished operating, the bypass also automatically stops working. However, you should be careful: if rust gets in, the device may fail.
The second type includes devices without a valve. This type will ensure reconstruction or repair without shutting down the entire heating system.

Do-it-yourself bypass installation

Do-it-yourself installation of such a device as a bypass is a very simple process; it does not require much experience from you and a wide range of tools - it is enough to have only a basic kit.

The bypass and the need for its installation when organizing single-pipe or two-pipe heating systems are due to the improvement in the quality of heating of premises in a private house or high-rise apartment. Why do you need a bypass: this is a metal or plastic pipe in the form of a jumper that bypasses one or another heating device. The installation of a bypass itself creates options for redirecting the coolant bypassing the devices being replaced or repaired without turning off the heating in the house. A jumper from a section of pipe to redirect liquid bypass is designed uncontrolled (open), with a valve, or automatic.

The device can serve various mechanisms - heating system pump, pressure gauge, radiator, manifold, underfloor heating pipeline, etc. Bypass is especially important for the uninterrupted operation of the pump - with the correct slope of the pipes, the principle of natural circulation will temporarily replace the pump being repaired, and the heating will not be turned off. It is important to tie radiators with a pipe jumper, especially in a single-pipe circuit, and when including bypass valves in the circuit, a bypass valve is simply necessary. And the last application of the device is to work in the collector unit of two-pipe circuits when mixing supply and return at the inlet or outlet of the boiler.

The jumper can be installed in pipelines made of metal-plastic, polypropylene, steel, cast iron, brass or copper. You can buy the device or make it yourself, but it is not advisable to use metal steel pipes, as they rust and clog the coolant. The best option is heating and bypass made of polypropylene: such a pipeline will work reliably and for a long time.

What is a bypass for and how does it work?

The single-pipe heating distribution scheme is still in demand in individual construction, but in old multi-storey buildings this solution was often used, so installing a bypass pipe was considered a non-discussable and necessary option.

Special purpose:

Ensuring uninterrupted operation of individual components of the heating system without turning off the heat. Repair or replacement of mechanisms, equipment and individual elements in the heating system is facilitated by the fact that the inlet and outlet shut-off valves (supply and return) of the coolant are closed, and the working fluid is redirected through a jumper pipe, as a result of which the broken unit can be easily dismantled or repaired. This is why a bypass is needed in a heating system, but this is not the only purpose of the bypass;
The functioning of a single-pipe heating system can be improved, since it has a significant drawback: the temperature from the heated coolant is unevenly distributed over the radiators due to their sequential connection scheme. Thus, the temperature in the very last radiator will always be the lowest. To obtain the same temperature on all batteries, install a bypass in front of each heating device - radiator, battery or register. Here, the purpose of the bypass is that a certain volume of media is directed bypassing the radiator sections, and gets hot even into the furthest battery. In this case, the diameter of the pipe jumper in a single-pipe heating system must be equal to or less than the diameter of the pipes of the main circuit;
Maintain the operation of heating systems during an emergency power outage, since the circulation pump does not function, and the presence of a bypass will make the movement of coolant uninterrupted.

Important: Homeowners often wonder if a bypass is needed in a two-pipe double-pipe heating system? With this pattern of movement of the working fluid, the bypass, after closing the valve, will redirect the coolant to those areas that lose heat the most.

Device classification

Bypasses are divided according to the type of shut-off valve and functional purpose. According to the types of locking devices in the circuit of different heating systems, the contours are:

Inclusion in a system with a shut-off valve that manually opens or closes at the right time. It is recommended to install the valve, which can be three-way or ball, in the center of the pipe;
A jumper with a valve is an automatic device that operates autonomously and does not require outside intervention. An automatic heating valve is a rubber or silicone unsinkable ball. Such a bypass valve only works in conjunction with the pump: when the electric motor is turned on, the valve opens under the pressure of the working fluid, and when the pump is turned off, it closes, stopping the movement of the coolant.

Important: in order to install a bypass with an automatic valve in the heating system of polypropylene pipes, it is necessary to monitor the origin of the working fluid: it must be absolutely clean, free of scale, debris, rust, etc. Any solid particles can deform the ball, causing the valve to leak fluid.

According to their functional purpose, bypasses are classified as:

Radiator jumper located at the entrance to the radiator for scheduled or emergency shutdown of the device without stopping the heating;
Pumping bypass: installed simultaneously with the pump to turn off or change its operating mode. If the bypass pipe is installed correctly, then failure of the pump is impossible;

Bypass installation - conditions and methods

To install the bypass bypass pipe in a polypropylene pipe heating system correctly, follow the following recommendations:

The diameter of the bypass pipe is taken to be smaller than the diameter of the pipeline;
The jumper should be located as far as possible from the main riser and as close as possible to the device being served;
The bypass is mounted in a horizontal position to avoid air pockets;
The bypass section of the pipe can only be installed after the coolant has been drained.

The first method of installing a jumper for a radiator is welded. The inclusion of polypropylene in the heating system ensures maximum reliability of the circuit, but steel pipes can also be used, albeit with less efficiency. PVC or metal pipes for the bypass are drilled in the right place, a jumper pipe is inserted into the hole, and the joint is welded. A ball valve is installed in the place where the radiator was previously connected. The last stage is installing the radiator in a new place, fixing the device and connecting it to the heating.

The second method is coupling. The radiator is also dismantled, the jumper is secured in place using factory couplings, and shut-off valves are cut into the edges of the bypass. In the same way, the radiator is attached and connected to the circuit in a new location.

Bypass in the "warm floor" system

How to properly install a bypass in a “warm floor” scheme needs to be described in more detail, since the temperature of the coolant with such a solution should not be more than 45 ° C. Installation of a heated floor involves the installation of a collector, and a bypass jumper on it acts as a bypass section of the heating route and a mixing unit.

The mixing unit in the manifold is a three-way valve with a temperature sensor. The valve divides the coolant flow into two parts, one of which it directs into the pipes of the “warm floor” device, and the second through a parallel line. In this case, the supply and return are mixed, after which the working fluid flows back into the boiler jacket.

Before you make a bypass along a small circuit, you need to understand that a jumper through a three-way valve will connect the supply and return, that is, the collector must be included in the underfloor heating circuit. The bypass works in this scheme as follows: after starting the boiler, the three-way valve shuts off the flow of cold working fluid from the heating main to the heat generator.

After the coolant heats up to the set temperature (45-50°C), the automatic valve will open and allow a certain amount of hot coolant to flow into the return pipe. This technique allows you to avoid the accumulation of condensate in the combustion chamber and on the surface of the boiler jacket.

A metal or PVC piece of bypass pipe is necessary in any heating scheme, since its use is an economical option for distributing heat with high efficiency while saving solid, gas, liquid or electrical energy. Simply put, the volume of coolant supplied to radiators and other devices and devices is reduced when a bypass is installed, without violating the norms for calculating heat transfer of both individual elements of the system and the entire structure.

In modern construction, when installing heating systems, a bypass is necessarily used. This element significantly simplifies the maintenance and repair of any elements of the heating system, and also has a positive effect on the efficiency and economy of heating. This article will discuss how to properly install a bypass in a heating system.

Bypass device

A bypass is a bypass part of the pipeline that ensures the coolant moves along a path that bypasses a certain section of the pipeline. One edge of the circuit is connected to the supply pipe, and the second to the return pipe. Various elements of the heating system, such as pumps, are usually installed on the bypass.

At the connection point between the bypass and the inlet pipe of the device that needs to be bypassed, a shut-off valve is installed. Its presence makes it possible to direct the flow of liquid parallel to the device itself and regulate the intensity of the coolant supply. A valve is also installed on the return pipe, which allows you to exclude a section of the pipeline from the system without the need to stop it.

Types of bypasses for heating

When installing a bypass, shut-off valves are installed not only on the pipes of the connected device, but also on the bypass itself. The type of fittings used allows us to classify several types of bypasses, each of which is suitable for certain operating conditions.

The following types of bypasses exist:

Unregulated;
With manual control;
Automatic.

The characteristics of devices with different types of shut-off valves have significant differences, so before installing a bypass in the heating system, you need to carefully consider each type.

Unregulated bypass

The device of unregulated bypasses is a simple pipe that does not have any equipment. The pipe is constantly in an open state, and the liquid moves through it arbitrarily, that is, there is no opportunity to influence the intensity of the water flow. Unregulated bypass pipes are most often used to connect heating appliances.

When designing a heating system, it is necessary to take into account the fact that water always moves primarily through those areas where the hydraulic resistance is minimal. In the case of a bypass, this means that the internal diameter of its vertical section must be smaller than the internal cross-section of the main pipeline. If this requirement is not met, the coolant will simply gravitate towards the bypass.

When designing horizontal heating distribution, other rules apply that must be taken into account before making a bypass into the heating system. The heated coolant has a reduced specific gravity and always tries to move upward. In order for the system to operate normally taking into account this rule, the diameter of the lower part of the bypass must match the diameter of the main line, and the cross-section of the pipe leading to the radiator must be smaller.

Bypasses with manual adjustment

Bypasses that are adjusted manually (manual bypasses) are equipped with ball valves. The use of ball valves is determined by the fact that they do not change the pipeline capacity at all when switching, since the hydraulic resistance in the system does not change. This quality makes the ball valve an optimal option for bypass.

Shut-off valves of this type allow you to regulate the volume of liquid that passes through the bypass section. When the tap is closed, the coolant moves in full along the main line. The operation of ball valves has one important nuance - they need to be turned regularly, even if there is no need to adjust the system. This is due to the fact that if left stagnant for a long time, the taps may become tightly stuck and will have to be replaced. Sometimes a heating system feed valve is also installed, which plays a significant role.

Manual bypasses in heating systems can be used in several ways. Most often they are used to connect batteries to a single-pipe main, as well as for piping circulation pumps.

Automatic bypasses

Bypasses with automatic adjustment are usually installed in the piping of a pump installed in a system with natural coolant circulation. Such heating systems can operate independently, but thanks to the pump, the speed of fluid movement along the circuit increases, which reduces heat losses and increases heating efficiency.

The presence of an automatic bypass in the pump piping allows the system to independently regulate its operation, i.e. no human intervention required. When the pump is running, the coolant passes through it, and the bypass is closed at this time. When the pump stops, the bypass opens and the liquid moves in it, while the stationary pump impeller cuts off the coolant flow.

Automatic bypasses are divided into two types:

Valve;
Injection.

The design of the first type of device contains a check ball valve. The hydraulic resistance of the valve is minimal, so the liquid easily moves on its own. When the pump is turned on, the coolant begins to move faster, is transported into the main line and diverges in two directions.

Further movement of the liquid occurs without any obstacles, and the reverse flow is blocked by the valve. The operating principle of the valve itself is extremely simple - the hydraulic pressure on the outlet side exceeds the inlet pressure, so the ball is pressed closely against the seat of the structure and does not allow the fluid to move.

Valve bypasses are quite convenient and simple, but they are very demanding on the quality of the water with which the heating system is filled. If the water contains various impurities, such as rust or scale, the valve very quickly becomes dirty and becomes unusable, as a result of which it has to be replaced.

Injection bypasses are devices similar in principle to a hydraulic elevator. A pumping unit is installed in the main line, which is connected to the main circuit using pipes of smaller diameter. With this scheme, both pipes are inserted into the main pipeline.

When the pump starts, some of the liquid enters the nozzle and is passed through the apparatus, accelerating many times in the process. The outlet pipe, which is slightly narrowed and visually resembles a nozzle, which ensures efficient pumping of liquid, also works to increase speed.

A vacuum is created behind the outlet pipe, due to which the coolant begins to be sucked out of the bypass. The flow, moving under pressure, pulls all the liquid with it, and it continues to move along the main highway with noticeable acceleration. This effect allows you to completely prevent the possibility of reverse flow of liquid.

The technology described above only works when the pump is turned on. If the pumping equipment is turned off, then the coolant in full passes through the bypass under the influence of gravitational forces.

Bypass purpose

The main function of any bypass is the ability to keep the heating system in working order even if one of its elements breaks down or there is a power outage. Devices connected via bypass can be disconnected from the system without any problems - to do this, you just need to turn off both taps, and the coolant will flow around the circuit.

Thanks to the bypass, heating can continue to operate in any case, and damaged elements can be repaired, spending any amount of time. The reliability and ease of maintenance of the heating system with a bypass increases many times over.

In autonomous heating circuits, the bypass is used to solve the following problems:

Connecting heating devices to single-pipe wiring;
Pumping equipment piping;
Connecting the water heated floor distribution manifold;
Formation of a small circulation circuit when using solid fuel heating equipment.

The bypass installation method may vary depending on its purpose in a particular heating system.

Bypass for radiator

In single-pipe heating systems, batteries are best connected using a bypass. For two-pipe circuits and manifold distributions, bypasses are not needed, since all heating devices are connected in parallel, and each of them receives coolant at the same temperature. If one of the batteries fails, it can always be removed without turning off the heating system (of course, if there are shut-off valves).

In systems with single-pipe wiring, the batteries are connected in series, so the coolant in each subsequent device cools down. The result is obvious - distant devices receive much less heat, and there can be no talk of any uniform distribution of thermal energy.

Bypasses can solve the problem. The supply and return circuits are connected by a jumper, which ensures independent flow movement. The hot coolant enters directly into the radiator, while the other part of it passes further and at the outlet is mixed with cooled water from one radiator. This scheme allows you to deliver much more heat to subsequent heating devices.

Connecting the pump via bypass

It is advisable to connect the circulation pump via bypass only in those systems that were originally designed for natural circulation, i.e. they must have an accelerating manifold, pipe slopes must be observed and their diameters must be correctly selected. The pump in such systems is not intended to ensure their operation, but to increase efficiency.

For systems that were designed for forced circulation at the design stage, a bypass is simply irrelevant. Such systems operate only due to the pump, so when it is turned off, the circulation of the coolant simply stops. Bypass in this case will not solve the problem.

When connecting the pump via a bypass line, it becomes possible for counterflow in the bypass. In addition, a closed circulation loop is formed between the pump and the bypass itself. In order for such a circuit to function normally, the bypass device must be equipped with a ball valve or check valve.

When the pump is running, the device blocks the flow of liquid through the bypass pipe. The valve does this work automatically, but the tap has to be adjusted manually. When the pump stops, the bypass opens, which allows coolants from different circuits to mix. A similar scheme is not applicable in the case of injection bypasses - they completely eliminate the possibility of reverse coolant flow.

For heated floors

When installing a heated floor, it is imperative to install a mixing unit, in which a bypass pipeline is always built in. The bypass in this case will be used to ensure the normal operation of the heated floor, and without this element the heating will not be able to function.

It's all about the operating temperature, which must be maintained in heated floors. The coolant in the supply circuit can heat up to 80 degrees, but in a heated floor its temperature should not exceed 45 degrees. The liquid is brought to the required temperature in a mixing unit, which passes only the required volume of hot water. The entire remaining flow is directed to the bypass, where it is connected to the coolant from the return circuit, and returns to the boiler.

For systems with solid fuel boiler

When used in combination with solid fuel heating equipment, the bypass allows the formation of a small circulation circuit. To do this, the bypass pipe is installed in the supply, where there is a coolant heated to the limit, and is connected to a three-way valve located on the opposite side of the structure.

Thanks to the valve, hot water from the bypass and cold water coming from the return circuit are mixed. As a result, a coolant whose temperature exceeds 50 degrees is returned to the boiler for the subsequent heating cycle.

The need to return warm liquid to the boiler is determined by the fact that otherwise condensation will appear on the metal walls of the combustion chamber, which will provoke corrosion and cause damage to the unit. If you supplement the system with a bypass, then these problems can be easily avoided.

Bypass installation

Including a bypass in different types of systems has its own nuances, so before making a bypass for heating, you need to understand these points.

For example, when connecting radiators via bypass, the following rules must be observed:

The internal cross-section of the bypass should be one step smaller than the diameter of the main pipe;
The bypass must be installed at a minimum distance from the radiator;
When used in apartment buildings, the bypass cannot be equipped with a tap.

Installation of a heating system bypass can be carried out both when installing a new system, and when repairing an existing structure. In the latter case, before work you need to prepare a set of pipes of suitable diameter, two tees and shut-off valves.

The inlet pipe of the structure is equipped with one of the following devices:

Ball valve, which has minimal hydraulic resistance and completely allows coolant flow;
A valve that allows you to manually adjust the intensity of liquid flow;
A combination of a ball valve and an automatic thermostat - this combination can adjust the operation of the system automatically.

The outlet pipe is always equipped with a ball or shut-off valve. To connect individual elements, welding or threading can be used. Regardless of the type of connection, it must be airtight. Before putting the system into operation, you need to check it for leaks.

A bypass with a pump in the heating system is installed taking into account the following points:

The bypass on which the pump is planned to be installed is usually part of the main line. The internal diameter of the bypass must be large enough to ensure normal natural circulation in the system. The pump is mounted on a separate pipe, the internal cross-section of which may be smaller than the diameter of the main pipeline.
To simplify your work, it is best to buy a pre-assembled pump unit with the necessary parameters. It is very simple to install such a structure, since all the elements are already correctly assembled and the connections are quite reliable.
When installing it yourself, the pump must be positioned so that the impeller axis is horizontal. The surface with the terminals to which power is supplied should be directed upward - firstly, this will simplify access to the contacts, and secondly, it will eliminate the possibility of liquid getting on the contacts if the system’s seal is broken.
The area with a bypass must be equipped with a check valve or ball valve, which prevents the flow of coolant in the opposite direction - this optimizes the operation of the system. Of course, before installing the bypass, you need to purchase all the components.

Before installing a bypass with a check valve for the circulation pump, you need to think carefully about the design of the future system and take into account all possible nuances.

Conclusion

The bypass is a simple design that allows you to solve a wide range of problems. The presence of this element in the heating system allows you to make all its elements independent of each other, which is very useful during setup and maintenance. Knowing how to properly make a heating bypass will allow you to create a reliable and efficient design.

A bypass is a jumper installed on the thermal route parallel to the main line. This simple detail in the form of a piece of pipe helps solve various problems and is therefore considered an important element of any scheme. Why a bypass is needed in the heating system of an apartment and a private house is described in detail in our material.

Bypass installation options

Once we have determined what a bypass line is, we will consider the question of why it is needed and where it is installed. Depending on the problem being solved, the element takes the form of a bypass pipeline or a straight section connecting the supply line to the return line.

Reference. The English word bypass literally means “bypass”, “bypass”.

There are several options for installing bypasses in heating systems:

On radiators of closed and open single-pipe systems.
Parallel to the circulation pump operating in a gravity (otherwise known as gravitational) heating network.
A jumper between the supply and return, forming a small circulation circuit for heating a solid fuel boiler.
In various mixing units.

In apartment buildings where heated towel rails are connected to a common hot water supply riser, a bypass line is also used, which operates in a similar way to a radiator line (item 1 of the list). We will explain further why it is needed there.

The pipes of heated towel rails have a large diameter and capacity; a jumper is only needed for convenient removal of the coil

The first two options are well known to owners of private houses and apartments. Unfortunately, some owners, who consider themselves major specialists, “improve” bypasses or install jumpers where they interfere with the normal operation of the heating system. We will also consider random and intentional errors.

Single-pipe radiator jumpers

In most multi-storey buildings of Soviet construction, heating is organized using single-pipe vertical risers passing through all apartments. The principle of operation of the scheme is to distribute the coolant among the batteries on the 5th-16th floors due to the high flow rate and increased pressure.

For reference. Old cast-iron batteries and steel finned convectors were distinguished by large diameters of internal channels, whose connection to the riser was designed without any bypasses. We are talking about new generation devices with high heat transfer and lower throughput.

Options for single-pipe heating schemes for multi-storey residential buildings

Please note that the radiators are connected to a single line by both connections, between which a bypass is inserted. The pipe jumper is specially shifted away from the axis of the riser, otherwise the water will not flow into the battery, but will move along a straight path down or up, depending on the direction of flow. Ideally, the circuit works like this:

Having reached the fork in the first heating device, the flow of hot coolant is divided approximately in half - one part flows into the radiator, the second rushes into the bypass.
Having cooled by 1-2 °C, the first flow is mixed with the bypass and returned to the main line. The temperature of the resulting mixture becomes 0.5-1 °C lower than the initial one.
The process is repeated in a similar way on the following heating devices. To ensure that there is enough heat for all consumers, centralized heating pumps pump a large amount of coolant through the mains, reducing the temperature difference between the first and last battery.

In a private two-story cottage, a straight section is placed on the upper radiators

Note. Similar schemes are found in two-story private houses. And although the vertical riser supplies only a couple of radiators, it is advisable to install a bypass on the upper heater, since the performance of a household circulation pump is much lower than that of its industrial “brother”.

If you remove the direct bypass line, the entire volume of water will flow through the heating device and cool by 1-3 °C. Due to the large temperature difference, each subsequent apartment will receive significantly less heat. The room with the last radiator will become as cold as a doghouse.

That is why, with a vertical single-pipe design, a simple piece of pipe on the battery plays an important role. In two-pipe distributions, the hot and cooled coolant flows through different lines, so a bypass is not required.

Here the role of the bypass line is played by the distribution pipeline itself

In country houses, the low performance of the circulation pump is compensated by increasing the diameter and throughput of the pipelines. This is done in the horizontal single-pipe system shown in the photo. The bypass is the main line, where approximately 2/3 of the coolant flows, and the third part enters the batteries.

Circulation pump bypass line

In most modern water heating systems, the pump unit cuts directly into the supply or return pipeline, which is described in detail. There is no need to install a bypass in this case:

if the power goes out and the pump stops, the coolant will still not be able to circulate on its own due to the small diameters of the pipes;
to remove the pumping unit for the purpose of repair or replacement, it is enough to turn off 2 taps and unscrew two American valves, provided that the unit is assembled correctly;
since water is unable to move along the lines without being forced, the bypass jumper will not help maintain the operation of the system while the pump is being serviced.

This scheme can operate in forced and gravity mode

The only case when you need to make a bypass branch for the circulation pump is a gravity heating system. Firstly, a unit with connection pipes DN 25-32 cannot be inserted into a Ø50 mm pipe used in the gravity heating network of private homes. Such a narrowing of the diameter will stop any gravity flow.

Secondly, the heat supply must operate according to a universal scheme. The main mode is forced from the pump; in the event of a power outage, a transition to the natural gravity flow of the coolant due to convection. To organize such heating operation, the pumping unit must be installed on bypass.

There are 2 methods of installing this unit:

A ball valve is inserted into the direct line, and the heating pump is brought to the bypass line along with a strainer - a dirt trap and shut-off valves.
A ready-made bypass unit with a pumping unit and a check valve is placed in the main gap.

Installation of a pump unit with a shut-off valve on a direct line

In the first option, the transition to gravity mode is done manually. When the power supply stops, one of the household members must go to the boiler room and open a large tap in a straight section. Otherwise, without water circulation, the boiler will stop heating, the building will cool down and you will freeze.

In the second case, after a power outage, an automatic check valve will open, which is in the closed position while the pump is running. But not everything is as rosy as it seems at first glance:

Hence the conclusion: do not install ready-made automatic bypasses with a valve and pump. It’s better to assemble a unit with a shut-off valve with your own hands. The house will begin to noticeably cool down 30-40 minutes after the shutdown, which is quite enough to open the main highway.

The rubber ball rolls freely inside the chamber and closes the passage under water pressure

Option two: mount a bypass assembly from separate parts, using a brass check valve with a loose rubber ball not pressed down by a spring. What such an element looks like, look at the photo and video:

Mixing nodes

These elements of heating systems consist of a three-way thermostatic valve and a bypass connecting the return pipeline to the supply. The bottom line is this: the bypass branch helps to collect coolant from two lines in the valve chamber, and at the outlet obtain water at the required temperature.

The principle of dismounting using a jumper and a 3-way valve is used in various sections of the heating network:

small circulation circuit of a wood-burning boiler;
piping a buffer tank or heat accumulator;
along the heating circuits of a water heated floor.

For reference. The scope of application of mixing units is quite wide. A controlled decrease in water temperature by stirring is used in air heating units (heaters) and other climate control units.

Scheme with a boiler circuit that protects the heat generator from condensation

The bypass shown in the diagram with a three-way valve, forming a small circulation circuit, protects the solid fuel boiler from the release of condensate during the heating phase. The process algorithm looks like this:

When the wood is ignited and the pump is turned on, the valve remains closed on the heating system side. Leaving the heat generator jacket, the water turns into the bypass line and returns to the boiler.
As it heats up, the temperature of the looped coolant increases. When it reaches the threshold level of 50-60 °C (depending on the setting), the valve thermocouple is activated, gradually opening the flow from the radiators.
The more the water in the boiler circuit heats up, the wider the passage for cold coolant from the system opens. Mixing occurs in the valve chamber, but the outlet flow temperature will not fall below the set threshold until the fuel is burned.

With a cast iron heat exchanger, the bypass mixing unit plays the role of a safety element. Situation: the heating is working at full capacity, the firewood is blazing, and suddenly the lights go out. If there is no safety net in the form of a UPS or electric generator, and the power supply is restored after 30 minutes, the water in the batteries has time to cool down.

A relief line with a bypass valve is not always found on factory manifolds, but it will extend pump life.

Please note that the boiler will not have time to cool down within half an hour - the firebox is full of heat and firewood. As soon as the pump turns on, cold coolant is pumped into the boiler jacket and the cast iron section bursts due to temperature shock. Therefore, in this case you cannot do without a bypass.

A similar principle of mixing by means of a jumper and a valve is used in the distribution system. When the temperature in the heating circuits has reached normal (35-45 °C), the 3-way valve closes the supply side of the boiler, and the pump drives the coolant through the bypass along the inner ring.

Note. In case the automatically adjustable circuits close together, the comb is equipped with an unloading bypass. Thanks to it, the pump “spins” water through two collectors, rather than mixing it inside itself, which reduces the resource of the unit.

The use of a connecting jumper in the buffer tank piping is identical to the previous options and is shown in the diagram.

When connecting a buffer tank to a solid fuel boiler, 2 bypasses are used

Installation errors

Some home, or rather, apartment craftsmen, when replacing old cast-iron radiators with new aluminum ones, deliberately make two stupid mistakes:

install a ball valve on a straight bypass pipe in order to direct all the coolant into its own battery;
Having listened to the advice of “smart” people, they assemble a mixing unit with a three-way valve in order to regulate the heat transfer of the heating device.

Let’s immediately make a reservation that such installation in a private house is not considered a mistake: you live there alone and control the heating yourself. In a high-rise building, such actions harm your neighbors, since you unbalance the system and take away more heat. This means that adjacent apartments receive less. How this happens, watch the video:

Instead of further listing the errors, we suggest that you familiarize yourself with the recommendations on how to properly install the bypass yourself:

The jumper on the battery of an apartment building is a pipe without any shut-off fittings or valves. The maximum that is allowed is to reduce the diameter by 1 standard size (riser DN 20 - connector DN 15);
If you want to regulate the heat transfer of radiators, please install manual or automatic thermostats. There are special full-bore models for centralized networks.
In multi-storey buildings with common risers, it is unacceptable to install fittings on the bypass pipeline
If energy-independent gravitational heating is installed in a country house, install the pump only on the bypass. Gravity flow is not provided - no jumper is needed.
When assembling mixing units yourself, make sure that the circulation pump is on the side of the open outlet of the valve. Other options don't work.
, equipped with a thermal head, operates from a remote temperature sensor. Place the latter on the pipe behind the valve, where the mixed coolant exits. Then the element can be guided by its temperature.

Point #3 requires clarification. With 3-way valves, one pipe is always open - the one from which the resulting mixture comes out. A pump is installed on the same side. If the unit is placed on any inlet pipe, then further events will follow one of two scenarios: the circulation will stop or the coolant will flow through the bypass, close in the boiler circuit and not get into the radiators.

In conclusion, briefly about DHW

Since we made all the main conclusions during the description, we will supplement the information picture by installing a bypass on the heated towel rail. This is the only case when a piece of pipe is installed only for ease of maintenance or replacement of the heater. The element has virtually no effect on heat transfer due to the flow speed and pressure in the water supply. The principle of operation is similar to the operation of a bypass on radiators, only here we distribute hot water.