Flushing of gas heating systems: procedure and rules for carrying out work

Has the heating in your home started to work noticeably worse? Do you have to turn on the boiler more and more often and gas bills are steadily increasing? Do not rush to repair and change the heat exchanger of the boiler or battery - flushing gas heating systems in most cases eliminates such problems.

This relatively inexpensive procedure will extend the service life and improve the efficiency of each link in the system, avoiding or significantly delaying expensive repairs. In this article, you will learn about the different ways to flush the heating system, their advantages and disadvantages. We will also tell you how to understand when flushing is necessary, how to do it yourself and what to do to make the system clog up much less.

When is it necessary to flush the heating system?

The procedure for flushing heating systems is mandatory in the maintenance of heating networks, the procedure for its implementation is clearly regulated by SNiP and PPRF. The regulations recommend annual cleaning, however, this only applies to district heating systems.

These systems are large-scale and multicomponent, consist mainly of old steel pipelines, and the coolant is often replenished and not always sufficiently cleaned. The combination of these factors makes annual flushing justified and necessary.

However, private heating systems serving a single-family house or apartment function in different conditions, and therefore they need to be flushed out as needed, and not annually.

You can determine that the system needs flushing by the following signs:

1. The radiator warms up unevenly: individual sections or the lower part are much colder.
2. Steel supply pipes are much hotter than batteries.
3. The whole system heats up more slowly than before.
4. The gas consumption has increased, the mechanically controlled boiler needs to be set to high power more often.
5. Extraneous sounds have appeared in the boiler or in any part of the system.
6. The filter installed in the return line is regularly clogged.

Even if you have all the symptoms described, flushing is not always necessary - airing the system has the same symptoms, and it is much easier to fix it - through Mayevsky crane or a special valve. Therefore, first of all, the possibility of an airlock in the cold part of the radiator is eliminated, and only then the cleaning method is chosen.

By neglecting timely flushing of the heating system, you risk not only overpaying for gas. Accumulating in the boiler heat exchanger, solid particles overheat the metal and provoke its burning out. In addition, the raid is capable of incapacitating circulation pump, expansion tank, boiler, cause leaks.

On the other hand, cleaning too often, especially with chemicals, can do more harm than good. First, the inner surface of the pipeline and all connections wear out faster. Secondly, the fresh coolant carries a new portion of salts and air, which provokes a new wave of corrosion.

The least common cleaning is for systems with plastic pipes and aluminum radiators, because they do not form rust. However, they do not exclude limescale, and therefore you should not completely forget about rinsing.

Mechanical cleaning methods

Mechanical action on deposits is safer for pipes than chemical action, but it is not always possible to flush the system to a pure metal using these methods. Nevertheless, mechanical cleaning is popular due to its availability and efficiency for not too dense plaque; in private networks, it is quite enough.

When cleaning yourself, the main thing is not to harm. Do not disassemble the system if you are not sure that you can assemble it without leaks, and when choosing a flushing agent, strictly observe the appropriate materials and the recommended exposure times.

The choice of flushing method depends on many factors:

1. Radiator and pipe material. Solid rust forms on steel, on cast iron - a dark oily coating, in plastic there can be only limescale or mucus at low pressure and temperature, for example, underfloor heating.
2. Forced or gravitational circulation of the coolant. The higher the pressure in the system, the less deposits on the walls, and the denser they are.
3. The type and thickness of deposits - it is easy to determine after opening the system.
4. System age and last flush time. Up to 3-5 years, even rust is quite loose and can be easily removed.
5. The presence and condition of filters.
6. The location of the boiler and the structural features of the system: availability indirect heating boiler, pipelines of complex shapes, the total length of the pipeline, etc.

Employees of specialized services can take into account all these parameters of your system, conduct diagnostics with a thermal imager and choose the most rational cleaning methods.

Flushing from the tap

The easiest way to flush is to open the heating circuit and run tap water through it. To do this, shut off the water supply and outlet taps from the boiler, shut off expansion tank.

Then the coolant is drained through a special valve in the return line, preferably into a prepared container. If you plan to reuse it, the coolant will need to be carefully filtered.

One hose connects the water tap and the beginning of the heating circuit, at the boiler outlet. The second hose is led from the discharge valve to the sewer.

Open the water supply valve to the maximum pressure and observe what flows into the sewer. When the water is clean at the outlet, its supply is shut off.

For greater efficiency, it is recommended to swap the hoses and flush the system in the opposite direction, and then repeat the procedure again, but only in the opposite direction.

In the last flushing, the water supply is not shut off, but only reduced, and the expansion tank is opened. Then remove the discharge hose, close the valve and feed the system to the desired level. Only after that the water supply is turned off and the boiler is connected to the circuit.

The effectiveness of this flushing method depends on the type of contamination and the pressure in the water supply system. If your water flows softly and smoothly from the maximum open tap, such cleaning is practically useless. Among its indisputable advantages are the possibility of self-flushing, without special equipment, as well as dumping waste directly into the sewer.

Hydrodynamic flushing method

This method requires special equipment, but it is one of the most effective and safe.

The essence of the method is the use of a special head on a flexible hose, which forms thin high-pressure jets inside a pipe or radiator. Water is supplied to this head through a pump, and the tip itself is inserted into the gap in the heating circuit. In general, the principle is similar to a car wash.

In this way, you can safely flush the most problematic and hard-to-reach areas - for example, the bottom and middle sections of a large radiator. It is suitable for any material and type of contamination, and the flushing waste is absolutely safe. A point effect allows you to wash any surfaces to the metal without using chemicals, and also to stop more carefully in places of greatest contamination.

Among the disadvantages of the method are the need to open the heating circuit, organize the drainage of water into the sewer, as well as the need for special equipment and a limited range of the head.

Cleaning with a pneumatic tool

Compressed air from a compressor is often used to clean something, including a heating system. This option is safe and effective, and therefore popular.

It is possible to purge the entire system at once, in the forward and reverse directions, or its individual sections, having previously dismantled them. The second option is more time consuming, but more efficient, especially in systems of considerable length.

Cleaning is carried out not with a constant pressure of air, but with short pulses with maximum pressure, if possible - with a change in the angle of feed into the pipe. Before filling the system with a constant coolant, it must be rinsed with clean water to remove all particles knocked down from the walls.

In addition to turbulent flows of compressed air in empty pipes, hydropneumatic flushing is also used. Its key difference is that air is supplied to pipes filled with a coolant. As a result, bubbles form, water boils in the system, washing away all deposits from the walls. Such flushing is effective even in large multi-apartment systems, and has become very popular due to the low cost of consumables.

Hydropneumatic impulse flushing involves the supply of a mixture of compressed air and water in a series of short shocks, using a pneumatic pistol. After 60 m of the pipeline, or with a diameter of more than 4 inches, the tremors lose their speed, and therefore their destructive force for the raid.

However, in private heating systems, it is hydropneumatic pulse cleaning that allows you to achieve the best results, evenly cleaning the entire system in a short time. In addition, after it there is no toxic waste left, and the pipes are not damaged.

Flushing of each unit with dismantling

If you decide to flush the heating system as efficiently and safely as possible without the help of professionals and special equipment, it is better to completely disassemble it. In a private house, it is convenient to wash everything outside, so choose a warm, clear day.

In the fall, shortly before starting, dismantle the radiators, pump, expansion tank, if any, turn off the indirect heating boiler and other equipment. Remember where was which gasket, or better, buy new ones in their places. Arm yourself with hoses with adapters, sewer cable, a long brush with metal bristles, possibly a metal brush for a grinder, if available, a pump.

First of all, try to clean as much deposits as possible with a wire rope and brushes. Unscrew all plugs from the radiators, clean all holes and joints, each thread. Thread the cable and twist it well to wipe all the walls. It is convenient to clean pipes with a brush, the handle can be extended with a stiff wire.

After cleaning each element, rinse it with clean water by connecting a hose from the water supply and plugging unnecessary holes in the radiators. Pass the water pressure in both the forward and reverse direction. Repeat cable and brush cleaning and rinse again. Repeat the procedures until clean water flows out immediately after cleaning.

Do not forget to flush the boiler coil, just do not use brushes on it. If there was a lot of hard deposits on other elements of the system, clean the coil with a cable, and then flush it by connecting two hoses.

After reassembling and filling the system with coolant, check all connections for leaks.

Chemical cleaning methods

The most impressive results are obtained with the use of chemical compositions, besides, such cleaning is the least time consuming. However, most of the products for flushing a heating system with a gas boiler are based on acids, which can destroy not only plaque, but also metal.

Therefore, this cleaning method is used where others cannot cope, and as rarely as possible.

When choosing a chemical flushing agent, pay attention to the following points:

• Compatible materials. Owners of aluminum radiators should be especially careful - most compositions are unacceptable for them, but specialized solutions exist.
• Proportions and time of use. Putting too concentrated a solution into the system, or for too long a period, will certainly damage it.
• Sediment type. Remember, the more types of deposits a product can remove, the more likely it is to damage pipes, radiators, and gaskets on the joints.
• The need for disposal. Many compounds are prohibited from being discharged into the sewer, and the collection, removal and processing of such a volume of liquid can become a problem.

How to use the composition for chemical cleaning of the heating system is described in detail in its instructions. In most cases, it is necessary to drain the coolant, prepare a solution from the same volume of water and reagent, mix well, pour into the system and start up.

As a rule, the composition should circulate along the circuit from 2 to 24 hours, after which it must be drained, and the entire system must be rinsed with clean running water and filled with a new coolant.

Please note that the coolant with the reagent must always circulate through the system forcibly, under pressure - that is, through the pump.

It is also possible to clean a part of the heating circuit with a reagent, including boiler heat exchanger. In this case, it is desirable to carry out flushing in the direction opposite to the normal flow of the heat carrier.

Among the types of chemical cleaning, it is worth highlighting microbiological and dispersed. They differ only in the formulations used: in the first case, they are of biological origin and do not require special disposal.

Disperse washing is a new, advanced technology, in which the bonds of sediment particles are destroyed, and the metal does not enter into a reaction.

After dispersed flushing, a film forms on the inside of the pipes and radiators, which prevents the metal from contacting with water and its oxidation, and also reduces the frictional resistance. This film is preserved, according to the assurances of the manufacturers, for 3 seasons, which means that during this period your heating system will not clog.

Electrohydro-impulse cleaning of heating systems

This is another method of professional cleaning of the heating system, in which impulse cleaning devices are placed in a pipe filled with water. In this way, even the most neglected pipes can be cleaned, regardless of the complexity of their shape and bends, at a speed of 1–8 m per minute.

This method cleans the pipes completely, down to metal or plastic, without damaging them. It is safe for equipment made of any material, consumables are inexpensive, and waste is absolutely safe. This method perfectly removes scale, salt and lime deposits, however, it is powerless against rust.

How to fill the system after flushing?

After you have flushed the heating system and saw how many different deposits there are, the issue of choosing a new coolant becomes especially acute. It should contain a minimum of salt and calcium impurities, microorganisms, as well as air, because all this provokes corrosion and forms plaque on the walls of pipes and radiators.

Filling the heating circuit directly from the water supply is perhaps the worst choice. It is often too hard, that is, with an abundance of salts of various metals. In addition, it carries in itself all the dirt from the pipes of the central water supply system, and is so enriched with oxygen that it sometimes turns out to be white - with a strong pressure.

In order to use such water for the heating circuit, at a minimum, it must be allowed to settle well so that all gases, including chlorine, disappear, and solid particles settle to the bottom. In addition, it would be good to pass it through a filter.

Alternatively, you can use rainwater as it is soft and affordable. However, sedimentation or filtration is still required. In addition, microorganisms often multiply in rainwater, which can affect radiators in a bad way.

Distilled water is a good choice as it contains absolutely no precipitates. In addition, such a choice is not cheap, because the volume of the heating system is not 5-10 liters, but ten times more.

Oddly enough, one of the best options is the old coolant, drained from the system before flushing. All the impurities in it that could react with the pipes and settle on their walls have already done this, and the air came out during operation.

It is enough to filter it thoroughly to remove particles washed away from the walls of the pipes, and distilled water can be added to the required level - in this case, very little of it will be needed.

Sometimes it is advised to fill the heating circuit with antifreeze with special anti-rust additives. Indeed, such a coolant does not form a plaque, but it is expensive, and its heat capacity and heat transfer are worse than that of water. As a result, the bay is such an expensive coolant, you will pay more and more for gas, because the system will not work as efficiently.

Taking this into account, it is possible to recommend antifreeze only if the heating is not used constantly in winter, and there is no possibility or desire to drain the coolant every time. More information about the different types of coolant for heating systems can be found in this material.

Conclusions and useful video on the topic

You can see how to flush a heating system that consists entirely of underfloor heating in this video. The chemical flushing method was not chosen by chance, because other options are almost impossible to implement with such a number of pipes, joints and bends:

Cleaning a single radiator hydropneumatically is shown and described here:

When choosing a flush method for your heating system, try to find a balance of convenience, price and safety for both piping and the environment. Remember that only you can live with this system and repair it in the coming years.

How often do you flush your heating system? Do you use the services of professionals or do you manage it yourself? Which flushing method do you prefer? Join the discussion of the topic in the block under the article.