Heating does not start cause. Why is the radiator hot above and cold below. Wrong choice of heating system

The heating system must ensure uniform heating of all rooms. If the temperature in radiators or risers drops, then often the reason for this is a violation of circulation. For the efficient operation of the heating network and comfortable climatic conditions in the housing, there must be free circulation of the coolant along the highway. You should worry about this even at the design stage. Why there is no circulation of the coolant in the riser and the main and what needs to be done, you should know thoroughly in order to quickly eliminate this problem in the future.

The circulation of water in the system is disrupted due to complete or partial clogging in the riser or in the piping to the heating device, airing the mains, freezing the network, errors in pipe laying. Also, this is caused by the misalignment of the central heating system and the appearance of coolant leaks.

Poor pump performance

The purpose of the pump is to maintain the required water pressure in the heating circuit. A well-functioning pump must meet the following requirements:

A necessary indicator of work productivity;
Pressure;
Appliance pressure;
Compliance with the type of fluid;
Compliance with the pipe diameter;
The dimensions of the device are in accordance with the line length.

What to consider when choosing a pump

The pump must be able to handle its load. But it is imperative to consider whether it will work constantly or will only turn on to feed the heating system and adjust the pressure. This should be taken into account when choosing the pump power. For a pump that runs continuously, it is important to consider the energy consumption figure.

If you choose the wrong pump, it will not "push" the coolant well, and as a result, the battery heats up unevenly, and the pump itself may burn out from overheating. Poor water circulation will also be noted if the diameter of the accessories for connection to the system is incorrectly selected.

When the pump is selected correctly, the heating system functions reliably and fully, and the movement of water is unimpeded.

If you have difficulties with choosing a pump, then it is better to contact a specialist, they will help you choose the right device for a specific heating system.

Incorrectly selected pipe diameter

This is also one of the common reasons for poor water circulation in the heating main. It is necessary to choose the diameter of the pipes at the design stage.

First of all, it is necessary to take into account that different heating systems have their own rules according to which pipes are selected.

If the heating network is supplied to the central heating main, then the diameter of the pipes is chosen in the same way as for the apartment heating system. For autonomous heating, such diameters may differ. It all depends on whether there is a circulation pump in the system or whether the work will be carried out due to the natural circulation of water.

Also, the choice is influenced by:

Pipe production material;
Type of coolant used;
Specific features of the heating mains wiring;
Planned pressure in the system;
The speed of movement of water along the highway.

Important! When calculating the diameter, the type of pipes must be taken into account, because the measurement system differs based on the material of manufacture. Steel and cast iron products are marked taking into account the inner diameter, and copper materials along the outer section. This must be taken into account when planning a pipeline, where several different materials are combined in the pipeline.

Clogged system

As already noted, if there is no water circulation in the riser and the heating system, then the problem may be in the debris accumulated in the system. A coarse filter will help get rid of it.

Dirt that has entered the pipes is easier to remove by trapping it in the filter. First of all, the pump is protected with such a filter. It is also recommended to install a filter at the boiler inlet. Such a water filter should be installed in front of every plumbing fixture. When installing the device, pay attention to the filter housing. There is an arrow on it that indicates which side to install the filter, depending on the direction of movement of the coolant.

The filter should be cleaned regularly. To do this, turn off the water, unscrew the plug, take out the mesh, rinse it, put it back in place and screw the plug back, after which you can open the taps.

Advice! To prevent clogging of the pipeline, during installation, it is necessary to control so that there is no debris in the pipes; for this, the ends are covered in the pipes. It is also necessary to check the radiators, as new products may contain factory shavings or other debris.

Airiness of the heating system

If the installation of the line is carried out in violation of the rules, then air locks are formed. They block the movement of water. To quickly solve such a problem, air vents or a Mayevsky crane are installed. For the central system, where a lot of air accumulates, automatic Mayevsky taps are used. The air is quickly removed and the movement of the coolant through the network is restored.

These devices not only improve the circulation of the coolant through the central heating main, but also reduce heating costs.

Check valves

Often, for normal circulation in the network, some pumps become few, then check valves are installed. In this case, each circuit can work independently of the others. Even in a radiator branched system with several circuits, where there are several pumps, it is better to install check valves. It is not worth saving on their installation.

The absence of these mechanisms leads to the fact that the movement of water in the system slows down. This happens in those situations when a network with several circuits is laid. In order for warm water to flow along such a circuit where the pump operates, and its movement occurs in the desired direction, check valves are used. These elements are not always put, but only in those situations when there are no other technical solutions. Everything is explained by the fact that these elements create high hydraulic resistance, depending on the design. Therefore, there are limitations for installing these valves in natural circulation systems, and the reason for the limitations is the low water pressure in the line.

The actuator in the product is a spring that closes the shutter when the normal operating conditions of the heating network change. For systems with different operating parameters, products are selected with the appropriate elasticity and massiveness of the spring. Valves are a very important element, they ensure trouble-free operation of the central heating system, increase the efficiency of all equipment and improve circulation.

System leaks

If the system does not have good water circulation, there may be a leak in some areas. As a result of a leak, the network does not work correctly, the water movement is poor and the boiler malfunctions.

The first thing to do is to find the “weak points”. Leaks occur in places where the connections are loosened due to corrosion damage, or poor installation of the system becomes the cause. If the network is openly mounted, then checking is not difficult. All such damage is quickly and easily identified. And to inspect a closed highway, you will have to call a specialist.

If a problem area is found, then it is necessary:

Tighten loose connections and wind up with sealing tape or tow;
Replace worn-out nodes;
Cut and replace damaged pipe sections.

The construction of an autonomous gravity-type heating network is chosen if it is impractical, and sometimes impossible, to install a circulation pump or connect to a centralized power supply.

Such a system is cheaper to set up and completely independent of electricity. However, its performance largely depends on the design accuracy.

For a natural circulation heating system to function smoothly, it is necessary to calculate its parameters, correctly install the components and reasonably select a water circuit diagram. We will help in solving these issues.

We described the main principles of the gravitational system, gave advice on choosing a pipeline, outlined the rules for assembling the circuit and placing working units. We paid special attention to the design and operation features of one- and two-pipe heating schemes.

The process of movement of water in the heating circuit without the use of a circulation pump occurs due to natural physical laws.

Understanding the nature of these processes will make it possible to competently for typical and non-standard cases.

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With water heating with natural circulation, the speed depends on the following factors:

pressure differences between fragments of the contour at its lowest point;
hydrodynamic resistance heating system.

Methods for ensuring the maximum pressure difference have been discussed above. The hydrodynamic resistance of a real system cannot be accurately calculated due to a complex mathematical model and a large number of input data, the accuracy of which is difficult to guarantee.

However, there are general rules, the observance of which will reduce the resistance of the heating circuit.

The main reasons for a decrease in the speed of water movement are the resistance of the pipe walls and the presence of restrictions due to the presence of fittings or valves. At low flow rates, there is practically no wall resistance.

The exception is the long and thin pipes typical for heating with help. As a rule, separate circuits with forced circulation are allocated for it.

When choosing the types of pipes for a circuit with natural circulation, you will have to take into account the presence of technical restrictions when installing the system. Therefore, it is undesirable to use it with natural circulation of water due to their connection with fittings with a much smaller inner diameter.

Rules for the selection and installation of pipes

The slope of the return line is made, as a rule, in the direction of the chilled water movement. Then the lower point of the circuit will coincide with the inlet of the return pipe to the heat generator.

The most common combination of flow and return slope directions for removing air pockets from a natural circulation water circuit

Uniform heating of each room in the building is ensured by the correct circulation of hot water in the pipes and radiators of the heating system. This can be achieved with competent design, high-quality installation of the pipeline and smooth operation of the pumps. Water circulation can be impaired for various reasons. Signs of such a failure are a decrease in the temperature of the radiators, interruptions in the water supply, and characteristic sounds from the pipeline.

Some reasons for incorrect circulation can be avoided even at the stage of creating a project and installing a heating system.

Malfunction of the pumping system

The pumping system must provide the required water pressure in the heating circuits. To do this, it must meet the following requirements:

Have the required power based on the size of the system circuit and the volume of water supplied.
Have the required degree of pressure of the device, which will provide the required degree of pressure.
The pumps must correspond to the diameter of the pipes, and it is better to immediately install the time-tested double pumps presented in the store https://nasos-ovk.com.ua/.

When selecting pumps, you should decide whether they will work constantly or only during the heating season. Based on this, pumps should be selected with technical parameters that will withstand the expected load.

Wrong pipe diameters and types

Pipes should be selected when developing a project, taking into account the type of heating: autonomous or connected to the central heating network. To do this, pay attention to the following parameters:

compliance with the diameter of the central pipeline in the case of connection to such a system;
pipe materials;
expected loads, pressure, water pressure in the system;
wiring features.

Important! When calculating the diameters, the pipe materials should be taken into account. For example, a steel or cast iron pipe is marked with an inner diameter and a copper pipe with an outer section. This is especially important in a combined system of different types of pipelines.

Clogged piping

Cleaning the pipes from accumulated debris and sediment will greatly facilitate the installation of coarse filters. It is recommended to install these devices at the sections where the pipeline is connected to the pump, at the inlet of the heating boiler in an autonomous system, at the section where it connects to the central highway, in front of each piece of plumbing equipment.

All debris will accumulate on a removable mesh inside the filter, which should be cleaned regularly, after shutting off the water. The device must be installed in the direction of water flow in the direction of the arrow indicated on its body.

Periodically, it is necessary to carry out preventive cleaning of the batteries during the period when there is no need for heating.

Airlock formation

An air lock can form due to improper piping installation. This problem can be solved by installing air outlets or Mayevsky taps. In central heating systems, automatic Mayevsky taps are used. With their help, excess air is vented from the pipes, which normalizes the circulation of water.

Lack of check valves

The design of the check valves allows you to maintain the desired speed, pressure and direction of hot water in the pipeline. Their installation is especially relevant in systems with several circuits and pumps. The absence of such valves can slow down the movement of water and disrupt its circulation, so you should not save on their installation. The choice of valves of the appropriate size and degree of elasticity depends on the load and the type of heating system.

Leakage

The reasons for water leaks in the system can be poor-quality pipe installation, damage to the connection areas as a result of corrosion or mechanical breakdowns. With an open type piping system, leaks can be easily detected by visual inspection. To identify damage and check the hidden system, it is necessary to involve a specialist.

The leak can be eliminated by tightening and wrapping a loose connection with tow, replacing leaking parts, or cutting and replacing damaged pipe sections.

A breakdown in the heating system, imperfections, flaws, everything leads to cold radiators. If there is no circulation of the coolant, then the cause must be determined. Most often, the answer to why the heating does not work is on the surface, it is obvious.

Let us analyze in order the main causes of heating malfunctions, why water does not circulate through the pipes, and what needs to be done first.

Let's start with the simplest and most obvious reasons.

Clogged, clogged.

Each heating system must have a coarse filter. A completely small device with a fine mesh and a sump (installed downward! At least to the side) saves equipment, pumps, a boiler from contamination of the coolant that will be present in any system. Shavings, thread scraps, rust, water sludge…. everything is trapped by the mesh in the filter.

The sump must be periodically untwisted, the mesh must be cleaned.

If the circulation in the heating system of a private house is disturbed, then the first step is to check the filter, which should be installed on the return line in front of the boiler.

Air in the system, airing

Bleeding can occur in any closed-circuit piping arrangement where no air removal measures have been taken. Air is always present in the coolant, including in a dissolved state, is released during pressure drops, and accumulates at the highest points. Including in the boiler.

Automatic air vents are installed at characteristic, highest points of the system, as well as on collectors and on special separators - the normal circuit is equipped with a special air trapping device in which air bubbles are released from the coolant.

In addition, Mayevsky taps (manual air vents) should be on each radiator, as well as possibly in other elevated places.

Check the air supply, bleed air, install air vents - the usual procedure if the circulation stops and the batteries are cold.

The circulation pump does not work

In private houses, the reason for the termination of the heating system is the breakdown of electrical equipment that controlled the movement of the coolant through the pipes.

If the heating suddenly stops working, then you need to check the performance of the circulation pump near the solid fuel boiler or the pump in the automated boiler. In addition, the same unit can be installed in each circuit, which must work properly.

Bad polypropylene pipes

Often the consumer (customer) believes that polypropylene pipes are absolutely reliable and cannot cause problems with heating, cool batteries.

But polypropylene is much more insidious than old steel or metal-plastic pipelines. Each place of soldering (welding) is a potential increased resistance in the system or the reason for the cessation of circulation (weakened movement of water through the batteries), due to fusion of the material inside.

It is impossible to control the quality of the connections from the outside, all that remains is to cut out pieces, re-solder, redo the polypropylene pipes again.

A malfunctioning polypropylene system is a real problem for the home installer. Good professionals don't take this material at all.

Bad project

It is not uncommon for bad circulation where there is bad design. Typically, the batteries are not turned on correctly, according to some sequential scheme, where the last battery in the circuit receives much less coolant.

Another bad project is one-pipe circuits, where it is also difficult to establish the necessary circulation of the coolant through each battery.

If the radiators do not heat up evenly, there is poor circulation of the coolant on individual heating devices, first of all it is necessary to consider how the connection corresponds to the classic schemes - shoulder, passing, radial. It is necessary to bring home heating to the usual design standards, and then expect good circulation and the same heating of radiators from it.

Small diameter, overgrown pipes

Old steel pipes from the inside are overgrown with rust, deposits, their throughput capacity significantly decreases over time, and there is only one solution - you need to change to modern ones.

But even during installation, for the sake of economy, mistakes can be made with the choice of the diameter of the pipeline - on the highways, on groups of heating devices, diameters of 16 or 20 mm can be installed. As a result - noise in pipes, excessive consumption of electricity, lack of flow rate of the coolant.

A complex system

A type of bad design is a complex heating system improperly made, consisting of many heating circuits and several boilers. Here, whole contours will already work incorrectly if the work of one will affect the neighboring one.

As a rule, one boiler (the reserve one does not count) and three circuits - a boiler, radiators, a warm floor with their pumps are coordinated normally, and no questions arise. But if you connect another working boiler plus a circuit (for example, heating a garage and greenhouse), then the system will become complex. It is difficult to say how the coolant will circulate in it without equalizing the pressure at the connection points.

In complex systems, a competent design is important, the installation of a hydraulic arrow or a ring of equal pressure, you can learn more about the hydraulic separator

No balancing

Many home heating schemes involve balancing; balancing, control valves are installed in them. For example, between floors, between the shoulders, and for each radiator. The cranes cover the direction with less hydraulic resistance, respectively, more will go to other points of the coolant.

Children can play around with cranes. Or the system is not initially balanced. Setting up, as a rule, is no problem, you just need to find this crane….

Neighbors don't give warmth

But the complex schemes of heating projects are of little concern to residents of high-rise buildings, which have a separate riser for each radiator in the apartment. And if any radiator stops heating normally, then there is no circulation in the riser, therefore ...

You need to contact the heating network, the housing office (service organization) to adjust the power through the risers, and if this does not help, then with the requirement to check the neighbors.

Often, unauthorized connection, replacement of radiators, pipes in central heating systems leads to a redistribution of pressure, circulation through individual batteries decreases, disappears.

No circulation in a gravity system

In gravity systems, the pressure difference is low, they are especially sensitive to air locks, to pipe diameters, gaps in radiators.

In old schemes, gradual deposits occur in radiators and pipes, circulation may decrease over time, and the treatment for this is only replacing everything with a more modern one.

You also need to pay attention to the correctness of the circuit itself - the middle heating line is below the cooling line (the boiler heat exchanger is below the radiators), and also - the hot feed rises up to the highest point, and from there goes down to the radiators ... More about gravity circuits

Various breakdowns in heating systems

Closed, valves, valves - check if everything is open to ensure circulation.
There is a leak in the system - there is little coolant, check the pressure, eliminate the leak.
Installation with flexible pipes - pipe is pinched.
Breakdown of automatic equipment - thermal heads on mixing units, radiators, mixing units themselves - silting, failure, it is necessary to check the correctness of work. Also - electronics breakdown.
Incorrect balancing on the distribution manifold, - in beam circuits, complex systems, collectors with balancing and tuning equipment can be the reason for the lack of circulation anywhere, due to breakdowns and incorrect settings.
Low pressure, no air in the expansion tank - check the pressure in the pipes and pumping the tank, automated units will not work at all without the required pressure.
Violation of the circuit, extra bypass - check the conformity of the installation to the project, the consistency of the circuit, whether there are any short-circuits of the jet, parallel branches to radiators and circuits.

If there is no circulation of the coolant in the heating system, then there is nothing to say about any comfortable living in the house in winter. Because no matter how hot the boiler is, the radiators will still be cold. However, you need to think about this not when the system “worked, worked and suddenly stopped,” but even at the design stage, that is, now. In this article, we will deal with the problems leading to poor circulation of the coolant.

Reasons for poor circulation of the coolant

There may be no circulation of the coolant in the heating system for the following reasons:

insufficient power of the circulation pump (or pumps, if there are more than one). For this reason, the coolant simply does not reach the radiators farthest from the boiler, so they are cold (or slightly warm, which is why it is still not easier). There are several articles and videos in the section on heating calculations on how to choose the power of the circulation pump;
check valves not installed. Usually their absence is "painful" for complex systems with several circuits. Check valves are used to ensure that the coolant moves along the desired contour and in the right direction (read on for more details);
system pollution. It happens that the pipes are clogged along their entire diameter - what kind of circulation is there! It is treated in only one way: by replacing the pipes. This is exactly the case when prevention is the best treatment. And "prevention" should be carried out even at the stage of installation of the pipeline and radiators. First, make sure that no debris gets inside the pipes. To do this, first making sure that there is nothing inside, we close the ends of the pipes with something before installation. For example, it is convenient to use simple plastic bags. Secondly, there may be debris in the radiators. Even new ones! So we check and get rid of;
the pipe diameter is too small. A small diameter of pipes - a large hydraulic resistance - the pump is not able to "push" the coolant along the entire pipeline - there is no circulation in the heating system (well, or it is so bad that it doesn't matter if it doesn't exist). Again, at the design stage, the hydraulic resistance must be calculated;
accumulation of air in the system (airing). Air, of course, is not debris, but air locks will also prevent the coolant from circulating freely. Air jams may appear due to violations of the rules for installing the heating system. Getting rid of the air is simple - install an automatic air vent at the highest point of the system and Mayevsky taps on the radiators.

Heating medium circulation in a combined (branched) heating system

Let's start analyzing the circulation of the coolant from a complex system - then you will figure it out with simple schemes without problems.

Here is a diagram of such a heating system:

It has three contours:

1) boiler - radiators - boiler;

2) boiler - collector - water heated floor - boiler;

3) boiler - indirect heating boiler - boiler.

Firstly, it is imperative to have circulation pumps (H) for each circuit. But this is not enough.

For the system to work as we want it: the boiler is separate, the radiators are separate, check valves (K) are needed:

Without check valves, for example, we turned on the boiler, but the radiators “for no reason, no reason” began to warm up (and it’s summer outside, we just needed hot water in the mains). Cause? The coolant went not only to the boiler circuit, which we need now, but also to the radiator circuits. And all because we saved on check valves, which would not let the coolant go where it is not needed, but would allow each circuit to work independently of the others.

Even if we have a system without boilers and not a combined one (radiators + water heated floor), but “only” branched with several pumps, then we put check valves on each branch, the price of which is definitely less than the alteration of the system.

Coarse filter

As mentioned above, one of the reasons that there is no circulation of the coolant may be the accumulation of debris in the pipeline. To completely avoid this, again, we do not save on pennies, but put a coarse filter in front of each device:

With the help of a filter, it is easier to catch dirt than to correct the consequences of a clogged pipeline or boiler heat exchangers.

Conclusion! We put coarse filters in front of each device of the heating system (pump, boiler, etc.) and in front of each plumbing device. We do NOT save a penny to "buy" problems. Arrows are embossed on the filter housing, indicating the direction of movement of the coolant or water in the water supply ...

The filter should be cleaned regularly. And it is very simple to do this: close the valves before and after the filter - unscrew the plug (1) on the filter - take out and rinse the mesh under the tap - insert it into place and tighten the plug. Everything. Not that changing pipes :)

These are the simple "gestures" you need to do so that you never complain that there is no circulation in the heating system. Good luck.

no circulation in the heating system