How does an automatic heating system air vent work?

When air circulates in the heating lines, bubbles form at the time of filling the system. They interfere with the normal movement of the coolant. Heating air vents remove them automatically. For the correct choice of a device for a home or apartment system, it is worth knowing its principle of operation, design and installation rules.

Why does the airing of the system occur?

Air masses in pipes negatively affect the operation of heating equipment. Iron that comes into contact with oxygen rusts faster. In the presence of plugs, the coolant cannot fully move along the contour, which makes heating minimal. Air bubbles also cause damage to the circulation pumps.

Air jams can occur for several reasons:

• The heat carrier is ordinary water with undissolved oxygen. The substance at the time of heating comes into a gaseous state and accumulates at the bends or at the top of the pipes.
• The system fills up quickly with water.
• The heating medium is supplied from the top and no bubbles are displaced.
• The connection points have lost their tightness during operation.
• The heating system is incorrectly designed.
• Connecting the radiator at the wrong angle.
• Air access to the pipeline during repair work.

Airing on a permanent section leads to a decrease in pressure inside the communications. To eliminate this phenomenon, air vents are installed on the pipelines.

Design features of air vents

The vent for air from the heating system is made as a cylindrical or conical brass body. It contains a hollow polypropylene or Teflon float. The element is connected to the release valve with a special lever.

The drain valve is made with a plastic plug (cap) to prevent water leakage in the event of a malfunction. At the time of operation, the cap is open, but the user unscrews it.

On the side of the drain there is a nozzle connected to the body by an O-ring. A holder with a spool is used to close the flow channel of the jet.

When connected, an adapter from a check-off valve is used in the form of a spring-loaded locking mechanism and a flag associated with it. At the moment of screwing in, the device presses on the flag, which goes down, and water enters the air vent body.

Operating principle

The automatic air vent for the heating system has a very simple operating principle:

1. The chamber is filled with water in working order. The float is on top, the valve is closed with a spring.
2. When air accumulates at the top of the chamber, the amount of coolant decreases. The float is gradually lowered.
3. At the moment the coolant falls to the critical point, the float overcomes the rigidity of the spring mechanism. After this action, the air is vented outside.
4. Due to the excess pressure, water removes air from the container, enters its place and pushes the float.
5. The valve becomes closed.

Some of the air bubbles remain under the cover, but the heating system will operate normally.

Descent characteristics

Manufacturers produce fixtures that equip a multi-apartment type of building or a private house. When choosing a relief valve, you should pay attention to the following characteristics:

• Thread Diameter - Available in ½, ¾, and 3/8 in. Domestic marking of the first Du-15, the second - Du-20.
• Mounting method - straight and side devices with a top or side outlet valve are used.
• Thread type - external and internal.
• Working pressure - air vents for the home can operate at a maximum value of up to 10-12 bar. It is better to choose a 6 bar option for an apartment.
• The temperature limit of the coolant - for centralized systems, models up to +90 degrees are suitable, it is better to put the product in private households up to +150 degrees.

Air vents made of sanitary brass are more durable and more reliable than silumin ones.

Varieties of automatic air valves

Depending on the design, the air deflectors for heating are radiator, angle and straight. Despite the differences in appearance, the devices have the same air removal mechanism.

Direct options

At the upper end of the vertical riser, the underfloor heating collector, the circulation pump, it is better to install a direct air vent designed for the heating system. It cuts into the top of the vertical pipe with a tee and automatically releases air from the highest point.

Corner modifications

If the pipe is horizontal, an angle model is required. It features a 90 degree nozzle. The trigger is also used in problem areas - on the threaded end of a dead-end branch.

All direct air vents of the system can be replaced with angled ones.

Radiator air vents

To effectively and quickly remove air congestion in the batteries, a radiator auto-air vent is used - it is best suited for the heating system of an apartment. The device has an angular design, but due to a special thread, it is installed without an adapter. The bleed screw is twisted with a rotary handle, a square wrench, a flat screwdriver (slotted elements).

Radiator models are compatible with aluminum and bimetal, equipped with valves in the form of a threaded adapter with springs. The element must be screwed onto the thread in front of the ejector.

The valve adapter is easy to clean and maintainable.

Places for installing air vents

Air bubbles most often form in the upper part of the line, which is farthest from the connection point. For this reason, the air vent must be placed vertically on the heating system piping in the following areas:

• The top point of the system. Installation of pipes is carried out with an outlet upward. If the communications bend around the obstacle and are retracted downward, the descender is attached at the top. It prevents airborne emissions when light vapors are lifted up.
• Batteries. The heating type of devices is distinguished by a complex shape and a large number of sections. Air accumulates in their cavities. Threaded automatic air vent should be used for heating radiators located above, below, diagonally.
• Heated towel rails in the form of a ladder. If the kit does not include a straight nipple, the drain is placed on top. This will eliminate the inconvenience of tightening the hand screw and will preserve the aesthetic appearance of the product.
• U-shaped line taps and bypasses. A pipe twisted into a loop will accumulate air, therefore an automatic shut-off valve is placed at the highest point.
• Boiler piping. The valve prevents damage to the heating equipment when airing the system.
• Hydrostrel.Radiator collectors and circulation pumps are equipped with the mechanism. If they are placed vertically, an air vent is screwed in at the top.
• Comb collectors of warm floors. Elements for the loop pipeline are removed above the floor level, therefore air dumpers are installed at the points of supply and return of the coolant.

If the pipe is located above the door, the air vent should be installed at the top of the opening.

Features of installation of an air trap in a private house

The air vent, intended for the heating communications of a private house, must be installed strictly in a vertical position. For installation work, you will need a threaded tee, an FUM tape, an open-end wrench.

The installation process is carried out in stages:

1. Fastening the tee. You will need a piece of pipe on which the tee is fixed by soldering, glue or simple shrinkage.
2. Preliminary check of the location of the vent at the highest point of the equipment. The connection of the device must have an upward direction.
3. Installation of the shut-off valve on the hexagon of the device with an open-end wrench.
4. Connect the automatic air vent so that the protective cap with the nipple points upwards.
5. Tightly tighten the cap to prevent debris from accumulating.
6. Checking the tilt of the device (for radiator models). The battery drain section rises slightly upward.

After installation, the fixtures do not need to be adjusted - they will release air automatically.

It is better to install the air carrier with a cut-off valve - this way it is easier to remove it for repair or replacement.

Features of the multistage scheme

The multi-stage de-airing scheme provides for the installation of automatic devices along the entire line. Such connection of the dumpers allows local and simultaneous removal of air locks. The automatic device is placed in the turning zone, loop formation. To extend its service life of the valve, a filter is additionally mounted. Once assembled, the system works when the heatsink is hot at the bottom but cold at the top.

In two-story houses, the installation of drainage devices is necessarily carried out on the top floor.

Angled, straight or radiator air vents are suitable for heating mains in an apartment building or private house. The automatic device is simple, reliable and maintainable. After installing it, the owner does not have to spend time monitoring the system and manually bleeding the air.