The efficiency of water heating systems is reduced by air congestion. To combat them, a Mayevsky crane is used. This device was invented in 1933, named after the author’s name and has survived to this day with minor changes. In documents, it is often called differently: an air bleed valve, a radiator needle air valve.

General view of a manual air release valve

Design and principle of operation

The occurrence of air jams experts call the term «airing». Because of it, heat transfer by radiators is reduced, corrosion processes are triggered, and mineral deposits appear in pipes. The movement of the coolant in the air-to-air system is accompanied by vibrations that destroy the elements of heating systems.

Thermal image of a radiator. Temperature distribution in a radiator with an air lock

Important! The reasons for the appearance of Mayevsky’s design have a socio-economic background. Initially, the air from the radiators was released through conventional shut-off valves. The population began to consider them as a source of hot water. This approach harmed people’s health and disabled heating systems.


Engineer Mayevsky improved the technical solutions available at that time and introduced a simple design. Its basis is a needle valve. When the valve is opened, the gas in the heating radiator is vented. Then the valve closes. In addition to the manual valve, an automatic version of the Mayevsky crane was created. It provides the elimination of air congestion without human intervention.

Manual air vent design

Sectional view of Mayevsky’s manual air vent. Basic structural elements

The design of the manual faucet for air release includes 4 parts:

  • frame;
  • locking screw with grooves for the passage of air;
  • housing cover with air outlet;
  • sealing ring.

When bleeding air, the user turns the screw — the working body of the valve. The conical tip of the screw opens the air outlet channel. The head of the screw is multifaceted with a slot. This makes it possible to use a screwdriver or a special key when manually opening (or closing) the Mayevsky tap. Sometimes the product is equipped with a lamb that allows you to rotate the screw without a tool. This solution is convenient, but unsafe, especially if there are children in the house.

The diameter of the channel through which the air exits is usually 2 mm. A hole of this size does not clog. The loss of water upon completion of the air outlet through the 2 mm hole is negligible. Flooding does not occur, the consequences are eliminated with an ordinary rag. In addition, the small diameter makes it easier to securely lock the air outlet duct even in the event of water hammer.

The housing cover is most often made of plastic. Other parts are made of brass or structural steel. Externally, the air valve resembles a water plug with an external thread. Valves are available with ½», ¾», and 1″ threads. The water temperature at which the air vent retains its performance can reach 120-150 ° C, pressure — from 1 to 1.6 MPa.

Automatic air vent design

The automatic air vent detects the accumulation of gas in the heating circuit and eliminates it. The main components of this device:

  • frame;
  • float;
  • lever system;
  • top cover;
  • spring return needle valve;
Automatic air vent. General view and sectional diagram explaining the principle of operation


The principle of operation of the automatic air valve is based on the ability of the float to track the liquid level. The air present in the heating system fills the float chamber. The float descends, through the lever system acts on the shut-off element of the valve. The needle valve opens and air escapes from the float chamber. It is filled with coolant, the float rises, the air valve closes.

Advantages of manual and automatic air vents

During the existence of water heating systems, several methods have been developed to combat air pollution: bleeding air through the thread, using stopcocks as air vents, and so on. Mayevsky’s design stands out among others for a number of advantages:

  • the air lock can be eliminated promptly by turning a screwdriver or a special wrench attached to the air valve;
  • the air valve installed on the radiator is cheap, simple in design, reliable;
  • the service life of the valve is equal to the service life of the heating system as a whole.
Bleeding air with a Mayevsky manual valve. Performed with a special key or screwdriver


Automatic air vents are installed at the highest points of the heating system. People living in the house may not know about their existence. This is their main advantage — the airing of the heating network is eliminated without human intervention.

Installation of Mayevsky cranes

In the heating system, both versions of Mayevsky valves are usually present — manual and automatic. They are installed in different places. A manual tap is mounted on radiators and towel dryers, an automatic tap is installed at the upper points of the heating circuit and as part of a security group.

Installation of a manual air vent

According to the location of the supply pipes, the heating circuits are divided into vertical and horizontal. When arranging a vertical circuit, air vents are installed on radiators that heat the upper floors of buildings. The horizontal scheme assumes their presence on each heating device.

Mayevsky cranes are suitable for installation on radiators of all types, including cast iron ones. In the upper part of the radiator, on the right and left, there are places for connecting pipes. One of them is often closed with a cork. Instead, a futorka is screwed in, the internal thread of which is suitable for installing an air vent.

It is not always possible to unscrew the plug, especially for old radiators. In this case, you have to drill a hole, cut a thread in it, install a through nut on it, then an air bleed valve. Threaded connections are sealed with FUM tape or sanitary tow.

Manual air release valve on the heated towel rail. Option when the valve is hidden under a decorative cap


When implementing single-pipe heating circuits, Mayevsky air vents must be present on heated towel rails. Many models of these devices are manufactured with air outlet valves already installed. If their factory installation is not provided, they proceed simply: a tee is installed in the section between the supply pipe and the dryer. An air valve is screwed into the free threaded outlet of the tee.

Air vents installed on the heated towel rail through a tee

Installing an automatic air vent

An automatic air valve is installed at the top of the heating system. If during operation places are identified where air cushions are constantly formed, then in these parts of the system an automatic device is installed to bleed accumulated gases.

For ease of installation, two versions of the valve are produced: with a vertical and horizontal arrangement of the connecting thread. The automatic valve is mounted in the same way as a manual valve. Upon completion of the installation, it is necessary to slightly open the cap on the valve, a tightly wrapped cap will not allow bleed air to escape.

Closed heating systems are supplied with so-called safety groups. This is a design consisting of three devices: a monometer, a safety valve and an automatic air vent. The security group is purchased and assembled assembled.

Automatic air vent as part of the security group

Important! The most effective multi-stage air control systems. These include manual valves installed on radiators and towel warmers. Automatic taps remove the air collected from the entire heating circuit.

Tools and materials required for installation


Installation of manual and automatic faucets for bleeding air is carried out using conventional plumbing tools and materials:

  • gas or universal keys of large size;
  • rust removal aerosol — will help when unscrewing the plug from the radiator;
  • FUM tape or linen tow — for sealing threaded connections;
  • a medium-sized slotted screwdriver or a special key for opening (closing) the air valve.

When making a new threaded connection between the air vent and the thermal device, you will need serious locksmith tools:

  • powerful drill;
  • a set of drills with victorious tips;
  • ½ inch tap;
  • emulsion for cooling the drill, it is often replaced with kerosene or water;
  • rags, rags for cleaning.
Place of installation of the air vent on the heating radiator

Operation features

The crucial moment in the life of the heating system is its initial filling. At the same time, such volumes of air are displaced that Mayevsky’s cranes cannot cope with them. Drainage valves come to the rescue.

Starting heating after a long downtime is an equally important stage of operation. After start-up, uneven heating of radiators is often detected. In this case, the user is armed with a screwdriver, a wide-mouth jar and a rag. Next, the bleeding begins. A jar is substituted for the drain hole, the locking screw is turned counterclockwise half a turn.

Bleeding air from the heating radiator. Final phase

After the release of air, the hissing stops, the coolant begins to flow out. Next, the screw is tightened, thereby closing the air valve. A rag is used to eliminate traces of the fight against airing.

Automatic air vents have a weakness — they do not perceive polluted water well. The presence of blockage can be diagnosed if the heat-carrying pipes directly under the valve do not warm up, that is, a plug has formed, the valve does not work.

Automatic air vent and shut-off valve

Repair begins with dismantling. An air bleed valve is usually connected to the system via a shut-off valve. Its task is to allow the air vent to be removed without draining the coolant from the system. The removed crane is disassembled and cleaned, the operation is performed with locksmith skills and operating instructions.

Expert advice

Aluminum and bimetallic radiators are more prone to air locks than others. This is due to the fact that aluminum, when in contact with water, initiates a chemical reaction with the release of hydrogen. Therefore, thermal appliances made using aluminum are the first candidates for the installation of air valves.

The presence of air in the heating circuit is indicated not only by the uneven heating of the radiators. Pipes and heaters sometimes begin to sound. The reasons may be different. Common — the appearance of air congestion.

With periodic airing, the Mayevsky crane has to be used repeatedly. This may indicate an underestimated pressure in the heating circuit, a slow movement of the coolant. In this case, there is not enough air bleeding. It is necessary to involve specialists, diagnose and repair the entire heating system.

Filter for heating system

Installers of thermal systems recommend installing a filter in front of the automatic valve. An inexpensive device will eliminate the need to periodically remove and clean the automatic air valve.


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