Flushing gas heating systems: flushing methods and work procedure
Has the heating in your home started to work noticeably worse? Do you have to turn the boiler on to maximum more and more often and your gas bills are steadily rising? Do not rush to repair or 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 increase the efficiency of each part of the system, allowing you to avoid or significantly delay expensive repairs. From this article you will learn about various methods of flushing a heating system, their advantages and disadvantages. We’ll also tell you how to understand when flushing is necessary, how to do it yourself, and what to do to make the system clog significantly less.
The content of the article:
When is it necessary to flush your 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 SNiPs and PPRF. Regulations recommend annual cleaning, however, this only applies to central heating systems.
These systems are large-scale and multi-component, consisting mainly of steel pipelines of considerable age, and the coolant is often replenished and is not always sufficiently purified. The combination of these factors makes annual flushing justified and necessary.
However, private heating systems serving a single-family home or apartment operate under different conditions, and therefore need to be flushed as needed, and not annually.
You can determine that the system needs flushing by the following signs:
- The radiator heats up unevenly: individual sections or the lower part are much colder.
- Steel supply pipes are much hotter than batteries.
- The entire system heats up more slowly than before.
- Gas consumption has increased; a mechanically controlled boiler more often needs to be set to high power.
- Extraneous sounds have appeared in the boiler or in any part of the system.
- The filter installed in the return line gets clogged regularly.
Even if you have all the described symptoms, flushing is not always necessary - airing of the system has the same symptoms, but is corrected much easier - through Mayevsky crane or a special valve. Therefore, first of all, eliminate the possibility of an air lock in the cold part of the radiator, and only then choose a cleaning method.
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 cause it to burn out. In addition, the raid can disable circulation pump, expansion tank, boiler, cause leaks.
On the other hand, too frequent cleaning, especially with chemicals, can do more harm than good. Firstly, the inner surface of the pipeline and all connections wear out faster. Secondly, fresh coolant carries a new portion of salts and air, which provokes a new wave of corrosion.
Cleaning is least necessary for systems with plastic pipes and aluminum radiators, because rust does not form in them. However, they do not exclude limescale deposits, and therefore you should not completely forget about washing.
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 clean metal using these methods. However, mechanical cleaning is popular due to its accessibility and effectiveness for not too dense plaque; in private networks it is quite sufficient.
When cleaning yourself, the main thing is not to do any harm. Do not disassemble the system if you are not sure that you can assemble it without leaks, and when choosing cleaning agents, strictly observe the compliance of the materials and the recommended exposure periods.
The choice of washing method depends on many factors:
- Material of radiators and pipes. Hard rust forms on steel, a dark oily coating forms on cast iron, and in plastic there can only be limescale or mucus at low pressure and temperature, for example, a heated floor.
- Forced or gravitational circulation of coolant.The higher the pressure in the system, the fewer deposits on the walls, and the denser they are.
- The type and thickness of deposits is easy to determine after opening the system.
- Age of the system and time of last flush. Up to 3-5 years, even rust is quite loose and can be easily removed.
- Availability and condition of filters.
- Boiler location and system structural features: availability indirect heating boiler, pipelines of complex shapes, total pipeline length, etc.
Specialized service workers 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, turn off the water supply and outlet valves from the boiler, turn 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 into the sewer.
Open the water supply tap to maximum pressure and observe what flows into the sewer. When the water at the outlet is clean, 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.
During the last flush, the water supply is not cut off, but only reduced and the expansion tank is opened. Then remove the discharge hose, close the valve and recharge the system to the required level. Only after this is the water supply turned off and the boiler connected to the circuit.
The effectiveness of this flushing method depends on the type of contaminants and pressure in the water supply. If water flows softly and smoothly from your tap as open as possible, such cleaning is practically useless. Among its indisputable advantages is the possibility of self-flushing, without special equipment, as well as discharging waste directly into the sewer.
Hydrodynamic flushing method
This method requires special equipment, but is one of the most effective and safe.
The essence of the method is to use 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 a gap in the heating circuit. In general, the principle is similar to a car wash.
In this way, you can safely wash 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 washing waste is absolutely safe. A targeted effect allows you to wash any surfaces down to metal without using chemicals, and also stop more carefully in the places of greatest contamination.
Among the disadvantages of the method is the need to open the heating circuit, organize the drainage of water into the sewer system, as well as the need for special equipment and the limited radius of action of the head.
Cleaning with air tools
Compressed air from a compressor is often used to clean anything, including a heating system. This option is safe and effective, and therefore popular.
You can blow through the entire system at once, in the forward and reverse directions, as well as its individual sections, having previously dismantled them. The second option is more labor-intensive, but more effective, especially in systems of considerable length.
Cleaning is carried out not with constant air pressure, but with short pulses with maximum pressure, if possible with a change in the angle of supply into the pipe. Before filling the system with permanent coolant, it must be washed with clean water to remove all particles knocked off 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 into pipes filled with coolant. As a result, bubbles form and water bubbles in the system, washing away all deposits from the walls. Such flushing is effective even in large systems of apartment buildings, and due to the low cost of consumables, it has become very popular.
Hydropneumatic pulse flushing involves supplying a mixture of compressed air and water in a series of short bursts using a pneumatic gun.After 60 m of the pipeline, or with a diameter of more than 4 inches, the shocks lose their speed, and therefore their destructive force for the attack.
However, in private heating systems, it is hydropneumatic pulse cleaning that allows you to achieve the best results, uniformly cleaning the entire system in a short time. In addition, it leaves no toxic waste behind and the pipes are not damaged.
Washing 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 home, it is convenient to wash everything outside, so choose a warm, clear day.
In the fall, shortly before startup, dismantle the radiators, pump, expansion tank, and if available, turn off the indirect heating boiler and other equipment. Remember where each gasket was, or better yet, buy new ones in their place. Arm yourself with hoses with adapters, cable for drain cleaning, a long brush with metal bristles, possibly a metal brush for an angle grinder, and, if available, a pump.
First of all, try to clean off as much deposits as possible with a cable and brushes. Unscrew all the plugs from the radiators, clean all the holes and connections, every thread. Thread the cable and twist it well to wipe all the walls. It is convenient to clean the pipes with a brush; the handle can be extended with a stiff wire.
After cleaning each element, rinse it with clean water, connecting the hose from the water supply and plugging the extra holes in the radiators. Let the water flow in both forward and reverse directions. Repeat cleaning with cable and brushes, and rinse again. Repeat the procedures until clean water comes out immediately after cleaning.
Don't forget to clean the boiler coil, just don't 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 rinse 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 by using chemical compounds; moreover, such cleaning is the least labor-intensive. However, most 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 wash, pay attention to the following points:
- Compatible materials. Owners of aluminum radiators should be especially careful - most compounds are unacceptable for them, but specialized solutions exist.
- Proportions and time of use.Running a too concentrated solution into the system, or for too long a period, will most likely damage it.
- Type of deposits. Remember, the more types of deposits a product can remove, the greater the likelihood of damage to pipes, radiators, and gaskets at connections.
- The need for recycling. Many compounds are prohibited from being poured down the drain, and collecting, removing and processing 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 put it into operation.
As a rule, the composition should circulate through the circuit for 2 to 24 hours, after which it must be drained, and the entire system should be rinsed with clean running water and filled with new coolant.
Please note that the coolant with the reagent must always circulate through the system forcibly, under pressure - that is, through a pump.
It is also possible to clean part of the heating circuit with the reagent, including boiler heat exchanger. In this case, it is advisable to carry out flushing in the direction opposite to the normal flow of the coolant.
Among the types of chemical cleaning, it is worth highlighting microbiological and dispersed. They differ only in the compositions used: in the first case, they are of biological origin and do not require special disposal.
Dispersive washing is a new, advanced technology in which the bonds of sediment particles are destroyed, and the metal does not react.
After dispersed washing, a film is formed inside the pipes and radiators, preventing contact of the metal with water and its oxidation, and also reducing friction resistance. According to the manufacturers, this film is preserved for 3 seasons, which means that during this period your heating system will not become clogged.
Electrohydropulse cleaning of heating systems
This is another method of professional cleaning of the heating system, in which pulse cleaning devices are placed in a pipe filled with water. In this way, you can clean even the most neglected pipes, 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 materials, consumables are inexpensive, and the waste is absolutely safe. This method perfectly removes scale, salt and lime deposits, however, it is powerless against rust.
What should I fill the system with after flushing?
After you have flushed the heating system and seen how many different deposits there are in it, the issue of choosing a new coolant becomes especially acute. It must contain a minimum of impurities of salts and calcium, 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 all the dirt from the pipes of the central water supply, and is so enriched with oxygen that sometimes it turns white - under strong pressure.
To use such water for a heating circuit, at a minimum, it must be allowed to settle thoroughly so that all gases, including chlorine, evaporate, and solid particles settle to the bottom. In addition, it would be good to pass it through a filter.
Alternatively, you can use rainwater, because it is soft and accessible. However, settling or filtration is still required. In addition, microorganisms often multiply in rainwater, which can have a negative effect on radiators.
A good choice is distilled water, because it contains absolutely no precipitated impurities. In addition, such a choice is not cheap, because the volume of the heating system is not 5-10 liters, but tens of times more.
Oddly enough, one of the best options is the old coolant drained from the system before flushing. All the impurities that could have reacted with the pipes and settled on their walls have already done so, and the air escaped during operation.
It is enough to filter it thoroughly to remove particles washed off from the walls of the pipes, and you can add distilled water to the desired level - in this case you will need very little of it.
Sometimes it is advised to fill the heating circuit with antifreeze with special anti-rust additives. Indeed, such a coolant does not form a deposit, but it is expensive, and its heat capacity and heat transfer are worse than those of water. As a result, if you fill up with such an expensive coolant, you will also pay more for gas, because the system will not work as efficiently.
Taking this into account, antifreeze can be recommended only if heating is not used constantly in winter, and there is no possibility or desire to drain the coolant every time. You can read more about the different types of coolant for heating systems in this material.
Conclusions and useful video on the topic
You can see how to flush a heating system that consists entirely of heated floors in this video. The chemical washing method was not chosen by chance, because other options are almost impossible to implement with so many tubes, connections and bends:
Cleaning a separate radiator using the hydropneumatic method is shown and described here:
When choosing a flushing method for your heating system, try to find a balance of convenience, cost and safety for both the pipes and the environment. Remember that it is up to you to 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 it yourself? Which washing method do you prefer? Join the discussion on the topic in the block below the article.
But if you add antifreeze to the heating system (double-circuit boiler). how to use hot water then?