Riser heating system - device by example

Classification of one-pipe heating systems

In this type of heating, there is no separation into return and supply pipelines, since the coolant after leaving the boiler goes through one ring, after which it returns to the boiler again. Radiators in this case have a sequential arrangement. In each of these radiators, the coolant enters in turn, first into the first, then into the second, and so on. However, the temperature of the coolant will decrease, and the last heater in the system will have a temperature lower than the first.

The classification of one-pipe heating systems looks like this, each of the types has its own schemes:

• closed heating systems that do not communicate with air. They differ in excess pressure, the air can only be released manually by means of special valves or automatic air valves. Such heating systems can work with circular pumps. Such heating can also have a bottom wiring and a corresponding circuit;
• open heating systems that communicate with the atmosphere using an expansion tank to dump excess air. In this case, the ring with the coolant should be placed above the level of the heating devices, otherwise air will collect in them and the water circulation will be disrupted;
• horizontal - in such systems, the coolant pipes are placed horizontally. This is great for private one-story houses or apartments where there is an autonomous heating system. A single-pipe type of heating with lower wiring and the corresponding scheme is the best option;
• vertical - coolant pipes in this case are placed in a vertical plane. This heating system is best suited for private residential buildings with two to four floors.

Bottom and horizontal system wiring and its diagrams

The circulation of the coolant in the horizontal pipe laying scheme is provided by a pump. And the supply pipes are located above or below the floor. The horizontal line with the lower wiring should be laid with a slight slope from the boiler, while the radiators should be placed all at the same level.

In houses with two floors, such a wiring diagram has two risers - supply and return, while the vertical scheme allows a greater number of them. During forced circulation of the heating agent using a pump, the room temperature rises much faster. Therefore, in order to install such a heating system, it is necessary to use pipes with a smaller diameter than in cases of natural movement of the coolant.

should be 60 degrees

On the pipes that enter the floors, you need to install valves that will regulate the supply of hot water to each floor.

Consider some wiring diagrams for a one-pipe heating system:

• vertical feeding scheme - can have natural or forced circulation. In the absence of a pump, the coolant circulates by changing the density during cooling during heat exchange. From the boiler, the water rises into the mainline of the upper floors, then it is distributed along the risers to the radiators and cools down in them, after which it returns to the boiler again;
• diagram of a single-pipe vertical system with bottom wiring. In a scheme with a lower wiring, the return and supply lines go below the heating devices, and the pipeline is laid in the basement. The coolant is fed through the drain, passes through the radiator and returns down to the basement through the downpipe.With this wiring method, the heat loss will be significantly less than when the pipes are in the attic. And it will be very simple to maintain the heating system with this wiring diagram;
• diagram of a one-pipe system with top wiring. The supply pipeline in this wiring diagram is located above the radiators. The supply line runs under the ceiling or through the attic. Through this highway, the risers go down and radiators are attached to them one by one. The return highway goes either along the floor, or under it, or through the basement. Such a wiring diagram is suitable in the case of natural circulation of the coolant.

Remember that if you do not want to raise the threshold of the doors in order to lay the supply pipe, you can smoothly lower it under the door on a small piece of earth while maintaining the general slope.

Bottling

Depending on their location, there are two heating wiring schemes.

Lower

Bottom filling or heating system with bottom piping is used in most modern buildings. Both the feeder and the return pour are located in the basement. The uprights are connected in pairs by jumpers located in the apartment on the upper floor or in the attic; at the top point of each jumper there is an air vent (Mayevsky valve).

Any riser is a bridge between dispenses. The inevitable imbalance between the risers closest to the elevator unit and the risers farthest from it is compensated by the difference in the cross-country ability and the size of the pipes. Here are the usual values ​​of the remote control for the heating circuit serving the entrance in a modern ten-story building.

Plot	DN pipes
Filling near the elevator unit	50
Filling at the end risers	40
Uprights	20-25

What are the specific advantages of the lower heating pipe routing?

• All valves on paired risers are concentrated in one place. To disconnect, you do not need to go up to the attic.

• Dumping the coolant into the technical basement during repairs does not imagine any trouble.

But: often basements are used for storage or utility rooms of stores. In this case, there is no need to say about some advantage, you yourself realize: you will have to dump the risers through a hose into the sewer.

The main drawback that the lower wiring of heating systems owns is the laboriousness of starting them at the end of the reset. In order for circulation to begin through all the risers, it is necessary to bleed off the air space. At the same time, not all residents of the upper apartments can do this; one should not forget about empty premises.

Upper

Top filling, or heating with top flow distribution is fully predictably distinguished by the fact that the filling thread is taken out to the attic. The return flow remains in the basement. Any riser is a separate element, free from other risers.

In the attic, in addition to pouring the filing, in this case there are:

1. Shut-off risers from the valve supply.
2. Plugs for their discharge (more correctly, for the suction of air necessary in order to completely drain the group of heating devices).
3. Expansion tank. Regardless of the name, it does not compensate for the increase in the volume of the coolant during heating (the system is not autonomous, but connected to the heating main). The tank, located at the top of the supply fill, laid with a minimum slope, helps to collect the air that is removed from there through the relief valve.

Such a layout of the heating system was massively used until about the 80s of the last century.

How does it look against the background of the bottom filling?

• The main trouble here is the laboriousness of resetting the launch of a separate riser. To completely drain it, you need:

• Close the valve in the attic.
• Close the valve in the basement and unscrew the plug.
• Unscrew the cap in the attic.

It is curious: the whole house has a heating system with an upper supply wiring dumped and started up much more easily, especially if the discharge from the heating expansion tank is brought out to the elevator unit. Alas: dumping a house is associated with the loss of a huge amount of coolant, which is undesirable from the standpoint of saving thermal energy.

• The main advantage of the top filling is that the launch is extremely simple and does not depend on the residents of the house. It is enough only slowly (so that there is no water hammer) to open the house valves on the supply and return, after which it remains only to throw off the air space from the expansion tank.

Single pipe heating system pros and cons

Benefits

A single-pipe heating system has both advantages and disadvantages. Benefits include the following:

• the ability to cover the entire area of ​​the building with a closed ring, which does not depend on the layout of the building;
• the ability to connect certain additional devices to the heating system, for example, warm floors, heated towel rails or equipping a built-in circulation pump;
• it is possible to direct the coolant in one direction or another. For example, in the course of circulation, you can be the first to direct colder rooms that are often ventilated. In the same two-pipe systems, this function is reduced to the location of the boiler;
• ease of installation work. There are not so many materials, and the cost of their purchase and the work itself will be much lower than when installing a two-pipe system;
• with thoughtful placement of heating devices and correct piping, the difference in temperatures in different rooms can be minimized, but it will not be possible to completely cope with this phenomenon.

disadvantages

The disadvantages of a one-pipe system are:

• the presence of special requirements for the diameter of the key pipeline;
• in the first radiator, the temperature will be the highest, and in the subsequent ones it will be lower due to the constant admixture to the coolant flow from the radiators that have already been passed;
• the last radiators should have a larger area than the first, so as not to be too cold;
• it is better not to put more than 10 radiators on one branch, since uniform heating in this way will not work.

The equalization of the temperature regime occurs due to the change in the number of radiator sections and the installation of special jumpers, thermostatic valves, valves, regulators or ball valves. It is advisable to have a circulation pump available, and in order for hot water to pass better through pipes and radiators, you need to install a special acceleration collector. In two-story houses, it is not needed.

If the wiring is of the upper type, then the supply pipe is capable of creating natural pressure, however, with such a scheme, pipes with a large diameter must be installed, and this will negatively affect the appearance of your interior. Therefore, if it is possible to put the wiring unit under the flooring, it will be much better.

We also advise when installing radiators in a two-story building in order to regulate the heating, to make a parallel connection of the batteries with the installation of taps at the entrances. Also, so that the temperature on the second floor is evenly distributed, instead of radiators, you can purchase a system of underfloor heating.

As you can see, a single-pipe system in terms of operation can have a number of difficulties. For example, it requires high pressure indicators, and in order for it to work normally, it is advisable to use a powerful pump, and this is not only unnecessary trouble, but also high costs. In addition, in a one-story building, a vertical spout and an expansion attic tank will be required.

However, despite this, the advantages of this solution are still greater.

What is heating

Bearing in mind the heating of an apartment building, one cannot boast of a large selection. All houses are heated in approximately the same way.In each room there is a cast-iron heating radiator (its dimensions depend on the size of the room and its purpose), which is supplied with hot water of a certain temperature (heat carrier) coming from the thermal station.

example of a cast iron radiator

However, the entire water supply scheme may differ depending on what kind of heating distribution is provided in a particular building - one-pipe or two-pipe. Each of these options has certain advantages and disadvantages. To better understand this issue, you need to know exactly everything about the former and the latter. So let's briefly describe them.

1. One-pipe heating system. Its design is simple, and therefore reliable and cheap. But still it is not too much in demand. The fact is that, getting into the heating system of a house, the coolant (hot water) must pass through all the heating radiators before it enters the return channel (it is also called the "return"). Of course, by heating all the radiators one by one, the coolant loses its temperature. As a result, when reaching the last user, the water has a relatively low temperature, due to which in the last room it can differ significantly from the temperature in the one to which it first comes. This often causes dissatisfaction among residents. Therefore, the described heating system of a multi-storey building is used relatively rarely.
2. Two-pipe heating system. Devoid of those disadvantages that are inherent in the heating system described above. The design of this system is significantly different. Hot water, passing through the heating radiator, does not enter the pipe leading to the next radiator, but immediately into the return channel. From there, it immediately goes back to the heating station, where it will be heated to the desired temperature. Of course, this option requires significantly higher costs both for installation of the system and for maintenance. But this scheme of the heating system device allows you to ensure the same temperature in all heated buildings. Example of a two-pipe heating system

It also makes it possible to install a heating meter. By installing it on a heating radiator, the owner can independently regulate the level of its heating and, accordingly, reduce the cost of paying heating bills. This option is not possible in a one-pipe heating system. By reducing the amount of hot water passing through your radiators, you can thus bring a lot of trouble to the neighbors to whom the coolant gets through your apartment. That is, the heating rules in this case will be frankly violated.

Of course, it is impossible to change the type of heating system in an apartment; it requires titanic efforts and enormous work that will affect the entire house. But still, it will be useful for every apartment owner to know about the pros and cons of different types of heating systems.

This video provides a broad overview of various heating systems.

Dignity

What, in fact, is good for a 2-pipe heating system?

Its main advantage is that it allows you to provide a more or less constant temperature of heating devices throughout the building.

With a single-pipe heating system, the battery connections at the beginning of the single filling ring will have a flow temperature (typically 70-75 C). at the end - the return temperature (50 C). Here, each radiator will receive a coolant with a temperature that does not differ much from that provided by the boiler at the supply or by the elevator unit after the mixing unit (elevator).

In addition, in the case of a large house with a substantial number of batteries, a 2-pipe heating system is simply uncontested: no single-pipe ring configuration will cover all the premises of an 80-apartment building.

A section of the heating system of a nine-story building.A single-pipe scheme simply cannot have the required configuration.

Anticipating objections: yes, a collector circuit can more than replace a two-pipe one. However, the price of its implementation will be ten times higher due to the colossal consumption of pipes; in addition, a large overall length of the liners will mean huge inappropriate heat loss.

Features of gravity systems

Due to the fact that turbulent flows are formed, accurate calculations of the systems cannot be carried out, therefore, when designing them, averaged values ​​are taken, for this:
• maximally raise the acceleration point;

• use wide delivery pipes;

Further, from the beginning of the first divergence to each subsequent one, a pipe of a smaller diameter is connected by a step equal to it, which uses inertial flows.

There are also other features of the installation of gravity systems. So, pipes should be laid at an angle of 1-5%, which is affected by the length of the pipeline. If the system has a sufficient difference in heights and temperatures, you can use horizontal wiring.

It is important to ensure that there are no areas with a negative angle, since they cannot be reached by the movement of the coolant, due to the formation of air jams in them.

So, the principle of operation can be based on the open type or be of the membrane (closed) type. If you make the installation in a horizontal orientation, it is recommended to install Mayevsky taps on each radiator. because with their help it is easier to eliminate air congestion in the system.

Watch the video in which the specialist talks about the conditions for the possibility of using a gravity, pumpless, gravitational heating system:

The principle of operation of a gravity heating system

The principle of operation of heating looks simple: water moves through the pipeline, driven by the hydrostatic head, which appeared due to the different mass of heated and cooled water. Such a structure is also called gravity or gravity. Circulation is the movement of the cooled liquid in the batteries and the heavy liquid under the pressure of its own mass down to the heating element, and the displacement of the light heated water into the supply pipe. The system functions when the natural circulation boiler is located below the radiators.

In open circuits, it communicates directly with the external environment, and excess air escapes into the atmosphere. The volume of water that increased from heating is eliminated, the constant pressure is normalized.

Natural circulation is also possible in a closed heating system if it is equipped with an expansion vessel with a membrane. Sometimes open-type structures are converted into closed ones. Closed circuits are more stable in operation, the coolant does not evaporate in them, but they are also independent of electricity. What affects the circulating head

The water circulation in the boiler depends on the difference in density between the hot and cold liquid and on the height difference between the boiler and the lowest radiator. These parameters are calculated even before the installation of the heating circuit is started. Natural circulation occurs because the return temperature in the heating system is low. The coolant has time to cool down, moving through the radiators, it becomes heavier and, with its mass, pushes the heated liquid out of the boiler, forcing it to move through the pipes.

Boiler water circulation diagram

The height of the battery level above the boiler increases the pressure, helping the water to more easily overcome the resistance of the pipes. The higher the radiators are in relation to the boiler, the greater the height of the cooled return column and with the greater the pressure it pushes the heated water upward when it reaches the boiler.

Density also regulates the pressure: the more the water heats up, the less its density becomes in comparison with the return. As a result, it is pushed out with more force and the head increases.For this reason, gravity heating structures are considered self-regulating, because if you change the temperature of heating the water, the pressure on the coolant will also change, which means that its consumption will change.

During installation, the boiler should be placed at the very bottom, below all other elements, in order to ensure a sufficient head of the coolant.

What it is

Let's start by describing the general principles of the heating system.

Heating of the heating devices is provided by the circulation of the heat carrier through them (industrial water, antifreeze, ethylene glycol, etc.). Circulation requires a differential created between the inlet and outlet of the device.

This drop can be provided in several ways:

• Connection through an elevator unit to a heating main, where a pressure difference of 2 - 3 kgf / cm2 is maintained between the supply and return lines.

Nuance: after the elevator, the difference between the mixture and the return is much less - 0.2 - 0.3 kgf / cm2. Exceeding this value would make the circulation excessively fast. Consequences - noise in pipes and high temperature of the return pipe.

• Circulation pump.

The circulation pump ensures the movement of the coolant.

• The difference in the density of the hot and cold coolant in the so-called gravitational (gravity) systems.

Obviously, in all cases, it is necessary to ensure that each heater is connected to the common system with two connections. This can be done in several fundamentally different ways.

Scheme	Short description
Single pipe	The heaters are connected to a common ring circuit
Two-pipe	Heaters are connected between the supply and return pipelines that run along the entire perimeter of the heated rooms
Collector	Each heater is equipped with its own pair of connections connected to a common manifold

It is curious: mixed schemes for connecting radiators prevail in apartment buildings. The presence of a dedicated supply and return heating filling makes the system a two-pipe system; at the same time, batteries are often combined in series within the riser.

And here we see a combination of collector and two-pipe schemes.

Power calculation

The effective heat output of the boiler is calculated in the same way as in all other cases.

By area

The simplest way is the calculation of the area of ​​the room recommended by SNiP. 1 kW of thermal power should fall on 10 m2 of the area of ​​the room. For the southern regions, a coefficient of 0.7 - 0.9 is taken, for the middle zone of the country - 1.2 - 1.3, for the regions of the Far North - 1.5-2.0.

As with any rough calculation, this method neglects many factors:

• The height of the ceilings. It is far from being the standard 2.5 meters everywhere.
• Heat leaks through the openings.
• The location of the room inside the house or against external walls.

All calculation methods give large errors, therefore, thermal power is usually included in the project with a certain margin.

By volume, taking into account additional factors

A more accurate picture will be given by another calculation method.

• The basis is a thermal power of 40 watts per cubic meter of air volume in the room.
• Regional coefficients apply in this case as well.
• Each standard size window adds 100 watts to our estimate. Each door is 200.
• The location of the room against the outer wall will give, depending on its thickness and material, a coefficient of 1.1 - 1.3.
• A private house with a street below and above is not warm neighboring apartments, is calculated with a coefficient of 1.5.

However: this calculation will be VERY approximate. Suffice it to say that in private houses built using energy-saving technologies, the project includes a heating power of 50-60 watts per SQUARE meter. Too much is determined by heat leaks through walls and ceilings.

Heating system project development

The heating device, starting from the introductory system and ending with heating radiators, is created immediately after the framework of an apartment building is built. Of course, by this time, a heating project for an apartment building must be developed, tested and approved.

And it is at the first stage that a number of difficulties often arise, as in the performance of any other, very complex and important work. In general, the heating system of an apartment building is complex.

The power of a heating system can depend on the strength of the wind in your area, the material of which the building is built, the thickness of the walls, the size of the premises and many other factors. Even two identical apartments, one of which is located on the corner of a building and the other in its center, require a different approach.

After all, a strong wind in the winter season cools the outer walls rather quickly, which means that the heat loss of a corner apartment will be much higher.

Therefore, they must be compensated for by installing larger heating radiators. Only experienced specialists who know exactly how all the equipment works and how they work can take into account all the nuances, choose the best solutions.

A beginner who decides to calculate the heating system in an apartment building will be doomed to failure from the very beginning. And this will not only lead to a significant waste of resources, but also put the lives of the inhabitants of the house in danger.

Central heating system structure

The main structural elements of a central heating system are:

A source of thermal energy, which can be large boiler houses or heat and power plants (CHP); they heat the coolant through the use of some type of energy source. At the same time, water is used in boiler houses to transfer heat energy to consumers, while in CHP plants it is first heated to the state of steam, which has higher energy performance and is sent to steam turbines to generate electricity. And the already spent steam is used to heat the water that enters the heating system of an apartment building.

One combined heat and power plant is capable of replacing several boiler houses, as a result of which not only construction costs are reduced and significant areas are freed up, but the overall environmental situation is significantly improved.

It should be noted that large centralized heat supply schemes have, as a rule, several heat sources connected by backup lines and ensuring the reliability and maneuverability of their operation.

Figure 1 - General scheme of central heating

Centralized heating system

No one will argue that the centralized system for supplying heat to apartment buildings, in the form in which it now exists, to put it mildly, is morally outdated.

It is no secret that losses during transportation can reach up to 30% and we have to pay for all this. Avoiding central heating in an apartment building is a tricky and troublesome process, but first, let's figure out how it works.

Heating a multi-storey building is a complex engineering structure. There is a whole set of drains, distributors, flanges that are tied to a central unit, the so-called elevator unit, through which the heating in an apartment building is regulated.

Two-pipe heating scheme.

Now it makes no sense to talk in detail about the intricacies of the operation of this system, since professionals are engaged in this and the ordinary person simply does not need this, because nothing depends on him here. For clarity, it is better to consider the scheme for supplying heat to an apartment.

Bottom filling

As the name implies, the bottom-filling distribution scheme provides for the supply of the coolant from the bottom up.The classic heating of a 5-storey building is assembled according to this principle.

As a rule, the supply and return are installed along the perimeter of the building and run in the basement. The supply and return risers, in this case, are a jumper between the lines. It is a closed system that rises to the top floor and descends back into the basement.

Two types of filling in comparison.

Despite the fact that this scheme is considered the simplest, putting it into operation is troublesome for locksmiths. The fact is that at the top point of each riser a device for bleeding air is installed, the so-called Mayevsky crane. Before each start, you need to release air, otherwise the air lock will block the system, and the riser will not be heated.

Important: some residents of the outer floors are trying to move the air relief valve to the attic, so as not to collide with housing and communal services workers every season. This conversion can be expensive.

Attic - the room is cold and if you stop heating for an hour in winter, the pipes in the attic will freeze and burst.

A serious disadvantage here is that on one side of the five-story building, where the input passes, the batteries are hot, and on the opposite side they are cool. This is especially true on the lower floors.

Radiator connection option.

Top filling

The heating device in a nine-story building is made according to a completely different principle. The supply line, bypassing the apartments, is immediately carried out to the upper technical floor. An expansion tank, an air relief valve and a valve system are also based here, which allows you to cut off the entire riser if necessary.

In this case, the heat is more evenly distributed over all radiators of the apartment, regardless of their location. But here comes another problem, the heating of the first floor in a nine-story building leaves much to be desired. After all, after passing through all the floors, the coolant comes down already barely warm, you can fight this only by increasing the number of sections in the radiator.

Important: the problem of freezing water on the technical floor, in this case, is not so acute. After all, the cross-section of the supply line is about 50 mm, plus in the event of an accident, you can completely discharge water from the entire riser in a few seconds, you just need to open the air vent in the attic and the valve in the basement

Temperature balance

Of course, everyone knows that central heating in an apartment building has its own clearly regulated standards. So during the heating season, the temperature in the rooms should not fall below +20 ºС, in the bathroom or in the combined bathroom +25 ºС.

Modern heating of new buildings.

In view of the fact that the kitchen in old houses does not differ in a large square, plus it is naturally heated due to the periodic operation of the oven, the permissible minimum temperature in it is +18 ºС.

Important: all the above data are valid for apartments located in the central part of the building. For side apartments, where most of the walls are external, the instruction prescribes an increase in temperature above the standard by 2 - 5 ºС

Heating standards by region.

Problems

It was also not without them.

Costs

Obviously, with the same diameter, two pipes will always be more expensive than one. With a small area of ​​the heated building, the benefits obtained will not compensate for this difference: it is easier to compensate for the temperature spread by increasing the number of radiator sections at the end of the one-pipe ring.

Balancing

The two-pipe heating system of the cottage needs balancing.

What it is?

First, let's outline the essence of the problem.

Imagine that two pipes extend from a heating boiler deep into the house. Through the first, water flows to the radiators, and through the second, it returns. Moreover, each radiator is a jumper between these pipes.

What is the problem here? Yes, in that each heater will extinguish the difference between supply and return. If on the first battery it will be equal, say, 0.2 kgf / cm2, then on the second - already 1.75, on the third - 1.5, and so on.

The difference on the right convector will be less than on the left.

As a result, we get a very unsightly picture:

• We will not talk about a stable battery temperature. The smaller the difference, the slower the circulation, the lower the temperature of the coolant reaching the radiator.
• What is much worse, in extreme cold, cooling of the end batteries can lead to the formation of ice plugs with a complete stop of circulation and inevitable defrosting of heating pipes.

Instructions for balancing the heating system of a cottage with your own hands looks like this:

1. Each radiator is supplied with a choke on one of the connections (preferably on the return).
2. The flow rate of the heating agent through the first heating devices from the boiler or elevator is limited until their temperature equals with the latter.

Useful: a more convenient functional analogue of a throttle in use - a thermostatic head. It allows you to set not the flow of water through it, but the target temperature.

The thermal head will greatly simplify balancing.

A reasonable question: how does a two-pipe circuit work in an apartment building? There, throttling of batteries is not practiced, however, the temperature spread between them is relatively small.

The function of the throttle there is performed by the variable diameter of the pipes. Here are the typical values ​​for a ten-story house built in the 80-90s.

Heating system section	DN, mm
Radiator or convector lead	20
Riser	25
End filling	32 — 40
Elevator filling	40 — 50

The photo clearly shows the difference in the cross-section of the liner and the riser.

Each section transition limits the flow rate of the coolant; taking into account the deliberately overestimated filling capacity, this is enough for the operation of the circuit in the normal mode.

Top-piped two-pipe heating system

Installing a two-pipe top-wired heating system minimizes or eliminates many of the above disadvantages. In this case, the radiators are connected in parallel.

For its installation, much more materials are needed, since two parallel lines are installed. A hot coolant flows through one of them, and a cooled one flows through the other. Why is this top-drawer heating system preferred for private homes? One of the significant advantages is the relatively large area of ​​the room. The two-pipe system can effectively maintain a comfortable temperature level in houses with a total area of ​​up to 400 m².

In addition to this factor, for a heating scheme with top filling, such important performance characteristics are noted:

• Uniform distribution of hot coolant over all installed radiators;
• The ability to install control valves not only on the piping of batteries, but also on separate heating circuits;
• Installation of a water-heated floor system. The hot water distribution manifold is only possible with two-pipe heating.

For the organization of forced top filling in the heating system, it is necessary to install additional units - a circulation pump and a membrane expansion tank. The latter will replace an open expansion tank. But the place of its installation will be different. Diaphragm sealed models are mounted on the return line and always in a straight section.

The advantage of such a scheme is the optional observance of the slope of the pipelines, which is characteristic of the upper and lower distribution of heating with natural circulation. The required head will be generated by a circulation pump.

But does a two-pipe forced heating system with an overhead wiring have any drawbacks? Yes, and one of them is dependence on electricity.During a power outage, the circulation pump stops working. With a large hydrodynamic resistance, the natural circulation of the coolant will be difficult. Therefore, when designing a single-pipe heating system with an upper wiring, all the required calculations must be performed.

You should also take into account the following features of installation and operation:

• When the pump stops, the reverse movement of the coolant is possible. Therefore, in critical areas, it is necessary to install a check valve;
• Excessive heating of the coolant can cause the critical pressure to be exceeded. In addition to the expansion tank, air vents are installed as an additional measure of protection;
• To increase the efficiency of the heating system with an upper piping, it is necessary to provide for automatic replenishment of the coolant. Even a slight decrease in pressure below normal can lead to a decrease in the heating of the radiators.

The video will help you to clearly see the difference for different heating schemes:

Most of the heating systems of apartment buildings and private houses are built according to this scheme. What are its advantages and are there any disadvantages?

Can a do-it-yourself two-pipe heating system be installed?

Convector in a two-pipe heating system

Classification

Let's start with an overview of the properties that differentiate the different schemas.

Serial and ray wiring

In the first case, the radiators are mounted to a common pipeline. Consecutive wiring does not mean that each radiator breaks the main fill. On the contrary, very often a bypass is mounted between its inserts, which makes it possible to regulate the temperature regime of the heater independently of others.

Important: when installing any throttling valves, a bypass is required. Otherwise, we will begin to regulate the patency not of the radiator piping, but of the entire circuit.

Radial (collector) wiring means that combs with throttles or valves are mounted on the supply and return pipelines, from which the coolant is diluted with a pair of connections to each heating device. The disadvantage of this solution is obvious: the pipe consumption increases many times over.

• Temperature control is very convenient. From one point, the owner of a house or apartment can regulate the heat transfer of each radiator.
• Each pair of pipes leading from the collector serves only one heater. If so, you can get by with a smaller pipe diameter, which, in turn, allows you to lay the eyeliner in the screed or the space between the sub-floor logs. The pipes will not remain in sight and spoil the design of the room.

One-pipe and two-pipe schemes

The difference between the two is easier to explain with examples.

A typical one-pipe heating system is Leningradka, a simple wiring, which is a filling ring laid along the perimeter of the house. Heating devices break it or, more correctly, are connected in parallel.

What does such a realization of heating give?

• Cheapness. It is clear that one pipe will cost less than two.
• Exceptional resiliency. While the coolant circulates in the circuit, stopping its movement in a separate heating device and defrosting it is impossible in principle.

The price of these qualities is a wide range of temperatures on radiators, as close as possible to the heat source and far from it. However, heat transfer is easy to equalize with chokes or by varying the number of battery sections. In addition, the contour must be continuous: a door or panoramic window will have to be encircled by pouring from below or from above.

In the case of two-pipe heating, we lay two independent filling lines - supply and return. Each radiator is a jumper between them.

Important: balancing of two-pipe heating with throttles is mandatory.Otherwise, the entire volume of the coolant will go through nearby heating devices; distant ones can be thawed. There were precedents.

Dead-end and passing schemes

In a dead-end wiring, the supply filling reaches the far point of the contour, after which the coolant returns to the starting point along the return, moving in the opposite direction to the original direction.

However, in the event that the heating circuit surrounds the entire house or apartment around the perimeter, the coolant can return to its starting point and continue moving in the same direction. In this case, the scheme is called passing.

Of course, subdivision on this basis is possible only for two-pipe schemes.

Top and bottom filling

A typical scheme for five-story Soviet-built buildings is when, in a two-pipe heating system, both dispenses are located below, in the basement. Each pair of risers connected on the upper floor serves as a jumper between them. This is the so-called bottom filling.

Nuance: by professionals, bottling means both the direction of movement of the coolant, and the pipe along which it moves to the risers.

In houses with an overhead filling, the supply pipe is taken out to the attic. EACH riser serves as a jumper between the supply and return pipelines.

Which circuit is better? It is hard to say unequivocally.

• For bottom filling, all valves and fittings are located in the basement. Leaks won't flood apartments.
• On the other hand, starting circulation in the heating system becomes more complicated. After all, the jumpers between the paired risers are airborne; and they are in apartments, access to which is often problematic.

In the case of top filling, all air locks are forced into the expansion tank located at the upper point of the supply pipeline, from where the air is vented through a valve or an automatic air vent.

Natural and forced circulation

Let's imagine a certain closed volume filled with water. Now let's place a heating element of any type in it. What will happen to the liquid?

Having heated up, the water in full accordance with the laws of physics will expand, reduce its density. Then it will be forced out by the colder and denser masses surrounding it into the upper part of the vessel.

It is this effect that underlies the operation of a gravitational heating system. How does it work?

• After the boiler, the filling rises vertically upward, forming a booster manifold. An air vent is mounted at its upper point (in the case of an open system without overpressure, an open-type expansion tank).
• The rest of the contour runs with a slight constant slope along the contour of the house. The cooling water makes its way through the filling by gravity, giving off heat to the heating devices. Having reached the boiler, it heats up again - and then in a circle.

Types of gravity circulation heating systems

Despite the simple design of a water heating system with self-circulation of the coolant, there are at least four popular installation schemes. The choice of the type of wiring depends on the characteristics of the building itself and the expected performance.

To determine which scheme will work, in each individual case it is required to perform a hydraulic calculation of the system, take into account the characteristics of the heating unit, calculate the pipe diameter, etc. Professional help may be required when performing calculations.

Closed system with gravity circulation

In the EU countries, closed systems are the most popular among other solutions. In the Russian Federation, the scheme has not yet received widespread use. The principles of operation of a closed-type water heating system with a pumpless circulation are as follows:

• When heated, the coolant expands, water is displaced from the heating circuit.
• Under pressure, the liquid enters the closed diaphragm expansion tank.The design of the container is a cavity divided into two parts by a membrane. One half of the reservoir is filled with gas (most models use nitrogen). The second part remains empty for filling with a coolant.
• When the liquid is heated, enough pressure is created to push the membrane and compress the nitrogen. After cooling down, the reverse process takes place, and the gas squeezes the water out of the tank.

Otherwise, closed-type systems work like other natural circulation heating schemes. The disadvantages are the dependence on the volume of the expansion tank. For rooms with a large heated area, you will need to install a spacious container, which is not always advisable.

Open system with gravity circulation

The open-type heating system differs from the previous type only in the design of the expansion tank. This scheme was most often used in older buildings. The advantages of an open system are the ability to independently manufacture containers from scrap materials. The tank usually has a modest size and is installed on the roof or under the ceiling of the living room.

The main disadvantage of open structures is the ingress of air into pipes and heating radiators, which leads to increased corrosion and rapid failure of heating elements. Airing the system is also a frequent "guest" in open-type circuits. Therefore, radiators are installed at an angle; Mayevsky taps are required to bleed air.

One-pipe system with self-circulation

A single-pipe horizontal system with natural circulation has a low thermal efficiency, therefore it is used extremely rarely. The essence of the scheme is that the supply pipe is connected in series to the radiators. The heated coolant enters the upper branch pipe of the battery and is discharged through the lower branch. After that, the heat goes to the next heating unit and so on until the last point. Return flow is returned from the extreme battery to the boiler.
This solution has several advantages:

1. There is no paired piping under the ceiling and above the floor level.
2. Funds are saved on the installation of the system.

The disadvantages of this solution are obvious. The heat transfer of heating radiators and the intensity of their heating decreases with distance from the boiler. As practice shows, a one-pipe heating system of a two-story house with natural circulation, even if all slopes are observed and the correct pipe diameter is selected, is often altered (by installing pumping equipment).

Self-circulation two-pipe system

The two-pipe heating system in a private house with natural circulation has the following design features:

1. The supply and return pass through different pipes.
2. The supply line is connected to each radiator through an inlet branch.
3. The second line connects the battery to the return line.

As a result, the two-pipe radiator-type system offers the following advantages:

1. Even distribution of heat.
2. No need to add radiator sections for better heating.
3. It is easier to adjust the system.
4. The diameter of the water circuit is at least one size smaller than in one-pipe circuits.
5. Lack of strict rules for installing a two-pipe system. Small deviations with respect to slopes are allowed.

The main advantage of a two-pipe heating system with lower and upper wiring is simplicity and, at the same time, efficiency of the design, which makes it possible to neutralize errors made in calculations or during installation work.

general information

Highlights

The absence of a circulation pump and generally moving elements and a closed circuit, in which the amount of suspended matter and mineral salts, of course, makes the service life of a heating system of this type very long.When using galvanized or polymer pipes and bimetallic radiators - at least half a century. The natural circulation of heating means a fairly small pressure drop. Pipes and heating devices inevitably provide a certain resistance to the movement of the coolant. That is why the recommended radius of the heating system of interest to us is estimated at about 30 meters. Obviously, this does not mean that with a radius of 32 meters, the water will freeze - the border is rather arbitrary. The inertia of the system will be quite large. It may take several hours between the kindling or starting of the boiler and the stabilization of the temperature in all heated rooms. The reasons are clear: the boiler has to warm up the heat exchanger, and only then the water will begin to circulate, and rather slowly. All horizontal sections of pipelines are made with a mandatory slope along the direction of water movement. It will provide free movement of cooling water by gravity with minimal resistance.

What is equally important - in this case, all air locks will be forced out to the upper point of the heating system, where the expansion tank is mounted - sealed, with an air vent, or open.

All the air will collect at the top.

Self-regulation

Heating of a house with natural circulation is a self-regulating system. The colder it is in the house, the faster the coolant circulates. How it works?

The fact is that the circulating head depends on:

Differences in height between the boiler and the bottom heater. The lower the boiler is relative to the lower radiator, the faster the water will flow into it by gravity. The principle of communicating vessels, remember? This parameter is stable and unchanged during the operation of the heating system.

The diagram demonstrates the principle of heating clearly.

Curious: that is why it is recommended to install the heating boiler in the basement or just as low as possible inside the room. However, the author has seen a perfectly functioning heating system, in which the heat exchanger in the furnace firebox was noticeably higher than the radiators. The system was fully operational.

Differences in density of water leaving the boiler and in the return pipe. Which, of course, is determined by the temperature of the water. And it is precisely thanks to this feature that natural heating becomes self-regulating: as soon as the temperature in the room drops, the heating devices cool down.

With a drop in the temperature of the coolant, its density increases, and it begins to quickly displace the heated water from the lower part of the circuit.

Circulation rate

In addition to the pressure, the rate of circulation of the coolant will be determined by a number of other factors.

• The diameter of the distribution pipes. The smaller the internal section of the pipe, the more resistance it will exert to the movement of the liquid in it. That is why pipes with a deliberately overestimated diameter - DU32 - DU40 are taken for wiring in the case of natural circulation.
• Pipe material. Steel (especially damaged by corrosion and covered with deposits) has several times more resistance to flow than, for example, a polypropylene pipe with the same cross section.
• The number and radius of turns. Therefore, the main wiring is best done as straight as possible.
• Availability, quantity and type of valves. a variety of retaining washers and pipe diameter transitions.

Every valve, every bend causes a drop in head.

It is because of the abundance of variables that an accurate calculation of a heating system with natural circulation is extremely rare and gives very approximate results. In practice, it is enough to use the recommendations already given.

Horizontal inter-apartment wiring

In many new buildings, it is possible to find a relatively exotic scheme: bends from risers enter the apartment, allowing heating devices to be diluted under an arbitrary layout.Along with this, the diameter of the risers and bends is selected so that the horizontal contour in your apartment does not set the heating parameters in the apartments higher or lower.

In addition to an arbitrary layout, a horizontal circuit with an outlet and one inlet allows you to establish heat metering. As the price of heating per square meter increases, the installation of meters becomes more and more relevant.

How to correctly make the heating wiring in the horizontal circuit of a separately taken apartment?

According to the author's humble point of view, it would be most reasonable to adapt a Leningrad or barrack wiring scheme to this situation.

• An unbreakable ring of DN25 size is laid along the perimeter of the apartment. Under doorways, it is heated in a screed or laid under a flooring floor.
• Heating devices cut parallel to the ring without breaking it. The size of the connections is DU20. Connection diagram for a separate radiator - bottom or diagonal.
• Any radiator is equipped with an air vent in one of the upper plugs. Optionally, chokes or thermal heads and shut-off valves on the connections can be installed.

House heating scheme

As mentioned above, most modern houses in cities are heated with a centralized heating system. That is, there is a heating station where (in most cases with the help of coal) heating boilers heat water to a very high temperature. Most often it is more than 100 degrees Celsius!

Water is supplied to all buildings connected to the heating main. When a house is connected to a heating plant, inlet valves are installed to control the process of supplying hot water to it. A heating unit is also connected to them, as well as a number of specialized equipment.

heating unit operation scheme

Water can be supplied both from top to bottom and from bottom to top (when using a one-pipe system, which will be discussed below), depending on how the heating pipes are located, or simultaneously to all apartments (with a two-pipe system).

Hot water, getting into the heating radiators, heats them up to the required temperature, providing it with the required level in each room. The dimensions of the radiators depend both on the size of the room and on its purpose. Of course, the larger the radiators are, the warmer it will be where they are installed.

Useful little things

• When balancing with throttles, the time interval between the change in the throttling mode and the stabilization of the temperature of the heating devices reaches 6 - 8 hours.
• For a cottage with an area of ​​up to 100 m2 with forced circulation of the heat carrier in a two-pipe system, a reasonable minimum of the filling section is DN2, up to 200 m2 - DN25.
• In a gravity system, filling cannot be made thinner than DU32 when using polymer pipes and DU40 - steel... In addition, gravity systems are used on an area of ​​no more than 100 m2: in a large room, the hydraulic resistance of a long circuit simply will not provide the minimum required circulation rate.

Gravitational two-pipe scheme.