Bleed screw: operating principles, types, proper installation

A very common problem in heating system is incomplete warming battery. But not everyone has the necessary information to solve the problem yourself. Many experts call every time there is a failure of such a plan, others cope by using an adjustable wrench and a basin of water. And the rest, after reading this article to set yourself bleed screw. The principle of this device is described hereinafter.

What is a bleed screw, operation principle

In 1931, an unknown plumber-fitter SA Swarms of Minsk has developed a special device that allows you to lower the air out radiators of the heating system through overlapping of two parts with a gasket between them. In 1932, this crane experienced users and is recognized as an operating device. But in 1933 revealed to the world the inventor b & w Majewski, who improved device via improved sealing valve design "cone into cone" and secure key to bring it into act. Since Majewski crane is used to this day, although the official name of the device, which is indicated on a visit and SNIP - radiator air valve needle.

The device is based on the principle of unauthorized release of air from the battery. The crane is constructed such that when opening the gate raised needle, which in turn opens a special hole diameter of 2 mm. Through this hole goes all the excess air, which met in the battery. Tetrahedral screw head moves working nozzle valve.

Important! In the operation of the valve must be shut down circulation electric pump for more efficient venting of air. In that case, if your boiler is equipped with a built-in pump for circulating the liquid, it must be disconnected from the network.

Photos bleed screw and a description of his species

Each project heating system different arrangement of working bodies (batteries and towel warmer), so the design is not always possible to place the crane Majewski in an accessible location for service. What led developers to create several types of valve.

Manual crane model

The most common modification, since it has enough reliable mechanism, as long as access to it was free, since the valve opens with a flat screwdriver or a special key for the crane tetrahedral Majewski. Needle mechanism works in two varieties, a horizontally opening valve for the passage of air, and with the hole in the nut body.

bleed screw

How to operate the automatic air vent

The principle of operation of the automatic air vent for heating is the presence of the float. Float backs needle valve through a spring system tuned to a certain air pressure in the radiator, once air will be greater than the permissible value, the valve will open and bleed off any excess air through a hole in the head center crane. When the pressure in the norm pass away, the valve will close. Installing this version of the device only applies to remote nodes heating. In the industrial-scale use other tools to remove zavozdushennosti batteries.

Majewski automatic crane

Crane with a safety valve

This is an advanced manual bleed screw, complete, high sensor pressure. The essence of his work is to prevent damage to the heating system and its working bodies in the case, if the pressure coolant will exceed 15 atmospheres. The valve will open and excess water will descend from the stack. excessive pressure It may be created due to water hammer.

Why in the air accumulates system?

Airlock - a malicious enemy of the heating system. The more air in the batteries, the worse they are warm because the air does not allow the coolant to completely fill the heater, and it is not heated at full power. The causes of air entering:

• depressurization pipe during repair work or riser panels.

• Has been entirely drained coolant from the system. In such a case, the presence of air pockets in the pipes inevitably.

• If damage has occurred in the joints of individual parts of the structure.

• Poor heating assembly, expressed in defective fixing of one or more nodes.

There are a number of other causes oxygen getting into the pipe, but they are very rare.

Important! During regular zavozdushennosti, metal heating elements are subject to corrosion since oxygen adversely affects the structure of the material, destroying it. This system will serve far less than heating with a rare hit the air in the radiators.

Installing a crane in

First of all it is necessary to carry out preparatory work. The list varies according to the type radiator. With regard to general recommendations, before any work is necessary to drain the coolant from the system.

Installation of devices in a cast-iron battery

Initially, the old modification cast iron radiators It does not imply special holes for additional devices that improve the heating performance. Therefore, we need a little sweat to Majewski crane was adapted for cast iron radiators.

1. Completely disconnect the conclusions drawn by the tube from the battery. Remove it from wall hooks and the residue completely drain the water through the bottom opening.
2. Determine the direction that is opposite from the side that includes the hot water.
3. Now, in the center of the top plug to be drilled hole, whose diameter coincides with the purchased you tap (it is better to buy a minimum diameter of the thread to make it easier to make a hole under it). Having made the entrance, it is necessary to cut the thread with a pitch of 1.5 mm.

1. Everything is possible to screw tap into the prepared hole.

Note! The central heating system frequent hydroblows occur, so buy tap with safety valve. In such systems, the installation of automatic air vent is not practical due to its operating principle and coolant contamination. Drainage hole is often clogged. Clean it quite simple: you have to take a needle and clean the hole until free of dirt.

crane installation Majewski in modern systems

Default new generation radiators are designed for the installation of all kinds instruments and cranes. Therefore, the installation of valve It made significantly easier.

1. Merging all water.
2. Remove the cover, which is sealed to you right hole. If the connector has an unusual size, then you need to completely unscrew the core, and buying the right, to make the assembly of all the elements.
3. The very need to tighten the tap so that the drain plug from the wall and looked at 45 degrees from the horizontal down. It is an ideal position for the location of the tank required when draining the fluid.

Nuances during operation

For the process to bleed the accumulated air in the system occurred without adverse effects, here is the detailed instruction of all manipulations.

• If the motion is due to a heat exchanger circulation pumpTherefore, it must be disconnected. This is done 15 minutes before the start of work. This is necessary to stop the air to mix with water and has accumulated at the top battery.

• Stock up on a dry cloth and an empty bucket, because as opening the valve, it is necessary to wait until the air cease to hiss, followed by water will pour. Close the valve only when Vodicka will not leak even intermittent jet.
• What if the air does not cease to bleed? Search breakdown or weak twist served in the battery area. This can be done by using a piece of paper. Leave the valve open and move a paper from a distance of 1 cm on all possible sites on the radiator and suitable for him pipe. Having found the location of air leaks, replace the damaged element.
• When the vent system is not used for several years, the valve thread can sour. We'll have to use a lubricant such as WD-40, and then with a light tap on the faucet trying to unscrew it.

wd-40

How to choose the right device

Today, there are a large range of modifications and Design crane Majewski. There are certain nuances that should look for when buying. The main indicator of longevity - a brass base. In addition to the metal, it is necessary to pay attention to the quality of the thread, ease of operation of the mechanism for opening the valve, the presence of the sealing rubber bands on the nozzle. The size of the incoming pipe extends to 1, 1/2, 1/4.

Modern devices have finished plastic valve that relieves the owner from using improvised means. But these models are not very practical in rooms where children are often found.

For an illustrative example in the table shows the models from different manufacturers with price

Picture	Manufacturer	type of modification	price, rub.
	JSC "BAZ"	Manual, 1/2 inch	35
	Santeh-world	Automatic, 1 inch	449
	House-Thermo	Manual, 1/2 inch	310
	RBM	Manual, 3/4	352
	carlo Poletti	Manual, 3/4	318
	"Delta"	Automatic fuse	335

bleed screw

Alternatives replacement

• Water-folding cranes. Often they are put at the end point of the heating system. It serves as a valve for filling pipes with water and for draining it. If a stand-alone heating, put a valve at the beginning of the system to be able to conduct an audit to determine the presence of air pockets. To the initial water supply tap is connected, and with its end fused certain amount of time to drive out all air. Such a system is radically different from the bleed screw and its principle of operation.

• If the owner for some reason does not want to install the bleed screw, can be made the following procedure. Loosening the thread on the tube coming out of the top radiator. So, will the air and at the same time and splattered all around.
• In the case where the system does not imply the use of a pump means and the water flow rate is small. In this case it is possible to organize a natural removal of oxygen. Thus, the upper portion of the battery in the tube area cuts with vertical outlet expansion tank empty at the end.
• When using ion boiler with a closed water circulation system, Majewski crane long period. The fact is that the coolant is added to the saline solution for a greater acceleration of ions in the boiler. When bleed air, the valve will be retained within the salts that will lead to quick breakage. For ionic boilers are provided special devices, resistant to salts.

Important! Any tinkering with the design of the heating system, which is not fixed in CCITT standards or Snip, it is necessary for heating align with the specialists of public services instruments. Otherwise you endanger not only themselves, but all the people around you.

Summarizing

Of course, every owner of the heaters based on the heat-transfer fluid has the right to decide how best to modify your system and whether to do it at all. But I want to note that the use of a crane Majewski, firstly, raise the efficiency of the entire installation, and secondly, facilitate maintenance batteries, thirdly, does not take away from you a lot of money, because as you notice given on paper table shows the cheapness products. Now you know what a bleed screw, operation principle and nuances of operation.