It is not uncommon for radiators to suddenly stop heating up during the heating season. One of the reasons for the failure of the system is an airlock, and then the residents face the problem of how to bleed air from the heating battery in order to restore circulation. There are several effective ways to normalize heating and how to bleed air from the system. In this case, the procedure should be determined depending on the type of heating system and the specific place of air accumulation.
The appearance of an airlock
It is quite easy to detect that an air lock has formed in the heating system. Signs of airing the system:
- gurgling sounds are sometimes heard in pipes and radiators;
- the batteries either do not heat at all, or they only heat up to half;
- in some rooms it is hot, while in others the heat does not pass.
This means that the accumulated air is to blame, and how to release it from the heating system must be decided in accordance with where it accumulated. Air bubbles always accumulate in the upper part of the heating system; therefore, radiators in rooms on the top floor usually cool down. To find the location of the air lock, you need to sequentially feel the supply pipeline and all the batteries, checking the degree of their heating. It is also advised to tap the pipes with a hammer and determine by the sound where the void has arisen, but this must be done carefully so as not to damage the paint layer on the pipes.
As a result, having found a problem area, you can already choose a method of how to bleed air from a heating radiator or, if necessary, from a pipeline.
An air lock not only impedes the circulation of the coolant, but also provokes corrosion of metal pipes. The presence of air in the system also negatively affects the operation of the circulation pump.
Where does the air in the system come from?
The reasons for the formation of an air lock can be both natural and associated with improper system design and poor-quality installation.
Naturally occurring reasons:
- when the coolant is heated, air dissolved in the liquid is released, it rises up and forms a plug;
- gas bubbles appear in the process of interaction of a hot coolant with some types of metals (in particular, aluminum);
- due to evaporation, the liquid level in the open expansion tank decreases below the critical value;
- the air does not have time to completely leave the pipes and batteries when the system, which is complex in configuration, is too quickly filled with water.
It is important to know how to drain water from the heating system, if necessary, and then refill it so that no air remains in the pipes and radiators.
In addition to natural causes, air congestion also leads to:
- incorrect routing of horizontal pipes and installation of radiators;
- pressure drops in the supply water supply;
- poorly sealed connections;
- deterioration of old pipelines;
- expansion tank malfunction.
When, during the operation of the heating system, it turns out that it was originally designed incorrectly, it will have to be redone.But in order to urgently restore the heat supply, it is necessary to decide how to bleed the air from the heating system.
Eliminating the airlock
If the heating is designed correctly, then how to bleed air from it will not be difficult. It can be arranged so that the accumulated air will be released automatically, as it accumulates. For this, special devices are used - air vents installed at critical points. In other cases, it is necessary to acquire skills on how to manually bleed air from the heating system.
In this case, it matters:
- open or closed type of system;
- natural or forced circulation of the coolant;
- upper or lower pipe routing option;
- whether the horizontal slopes of the pipes are observed.
Drain valve on the radiator
In apartment buildings, residents do not have a question of how to bleed the air from the heating; specialists of the management company should be concerned about this. Although in the old five-story buildings the heating is arranged in such a way that it is possible to bleed the air out of it only through the radiator in the apartment of the upper floor, and the residents themselves have to do this from time to time. The problem of airing looks more acute for owners of private houses with autonomous heating - it is periodically necessary to release the air. To bleed the air from the hot water radiator, a needle air valve is used, the so-called. Mayevsky crane. Such a device is installed in the upper end of the radiator battery, instead of a plug. Sometimes it is also used to release air from a heated towel rail pipe. Different models of Mayevsky's taps are slightly different, therefore, before bleeding air in heating radiators, you need to read the instructions. The tap valve is opened either with an open-end wrench, or with an ordinary screwdriver, or simply by hand.
Consider how to release the airlock from the heating battery using the Mayevsky crane installed on it:
- prepare tools (wrench or screwdriver) and a container for collecting water;
- open the thermostat completely, then unscrew the Mayevsky tap by half a turn;
- air will begin to escape through the valve with a slight hiss
- substitute the container and keep the valve open, since it is necessary to bleed air from the heating radiator until water flows;
- when a dense stream of water appears, you can turn on the tap.
If, after you bleed the air from the radiator, it still does not heat up well, drain another 200 grams of coolant through the same tap to finally remove the air lock.
Bleeding air through the expansion tank
In private houses, the device of heating systems is different, it depends on the features of the layout of the buildings. For different types of systems, appropriate expansion tanks are used - open or closed. Therefore, individual homeowners often have to think about how it is more expedient - to bleed air from a heating radiator or through an expansion tank.
In an open system, air bubbles can freely exit through an expansion tank installed in the attic. If the heating works normally, there is no need to bleed air from the system, since it comes out on its own. But the liquid gradually evaporates, and the water level in the open expansion tank can drop so low that an air lock will appear at the top of the supply line. In this case, the circulation of the coolant will slow down or completely stop, and in this situation it should already be a question of how to release air from the heating system.
To expel the airlock, you can add water to the expansion tank from the top, but it is better to replenish the volume of liquid in the system through the lower tap connected to the water supply. Water entering from below will fill the void in the pipe and force the air out through the opening of the expansion tank.
During the heating season, it is necessary to ensure that the expansion tank is constantly filled with water to about 2/3 of its volume, and when the level drops, top up with water.
In closed systems, diaphragm expansion vessels are used. Sometimes a membrane ruptures in them, and then air enters the system. If it is possible to establish that the cause of airing is a faulty expansion tank, it will have to be replaced. But before starting the repair, before draining the water from the heating system, you need to prepare everything you need so as not to leave the house without heat for a long time.
What should be the correct structure of the system
When designing, it should be considered that air can accumulate in horizontal pipes, and how to release it from the heating system will be a difficult task. Therefore, it is important that the upper supply pipe has a slight slope, starting from the riser and further along the direction of movement of the coolant. At the highest point, a device is installed that allows you to bleed air from the heating. It can be a regular tap or a Mayevsky tap, but it is better to use an automatic air vent. In a more complex heating system, air vents are installed in all places where a problem of air ventilation may arise. Then there will be no question of how to release the air in one or more heating radiators, since the accumulating bubbles will gradually bleed out from each group of elements that make up the system.
The return pipe must be laid with a slope towards the boiler. This is done to combat air congestion, and also so that you do not have to guess how to drain the water from the heating system if repairs are needed.
If the heating system is equipped with a circulation pump, then there is no need to observe the slope of the pipes with great accuracy. Nevertheless, it is desirable to lay pipelines with the correct slope for the effectiveness of the system.
Finally, we recommend that you always contact a specialist about heating problems. They know how to design a workable system and advise on how to release air trapped in radiators. But the homeowners themselves must, on the eve of the heating season, carry out a routine inspection and check of their heating system.
The video provides a visual explanation of how to bleed air from a radiator:
