The formation of an air plug in the heating system is characterized by a partial cooling of radiators or sections of a water-heated floor. Sometimes a murmur is heard in the pipes and batteries indicating the location of the accumulated air. I am interested in 2 questions: how to remove it from there and prevent similar troubles in the future. We suggest that you consider the causes of airing of heating appliances in private homes, and then we will tell you how to remove air bubbles from the heating network.
Where does the air come from in the system
Practice shows that it is impossible to isolate a water heating network perfectly from the external environment. Air enters the coolant in various ways and gradually accumulates in certain places - the upper corners of the batteries, turns of highways and high points. Incidentally, the latter should be equipped with automatic drain valves shown in the photo (air vents).
Air enters the heating system in the following ways:
- Together with water. It's no secret that most homeowners replenish the lack of coolant directly from the water supply. And from there comes water saturated with dissolved oxygen.
- As a result of chemical reactions. Again, not properly desalted water reacts with metal and aluminum alloy radiators, causing oxygen to be released.
- The piping network of a private house was originally designed or mounted with errors - there are no slopes and loops are made, facing up and not equipped with automatic valves. It is difficult to drive out air congestion from such places even at the stage of refueling with a coolant.
- A small fraction of oxygen penetrates through the walls of plastic pipes, despite the special layer (oxygen barrier).
- As a result of repair with dismantling of pipe fittings and partial or full drainage of water.
- When microcracks appear in the rubber membrane of the expansion tank.
Note. Water taken from wells and shallow wells is prone to chemical reactions, as it is saturated with active salts of magnesium and calcium.
Also, a situation often arises when, after prolonged downtime in the off-season, the pressure in a closed heating system decreases due to air ingress. It is quite simple to lower it: you need to add a couple of liters of water. A similar effect occurs in open systems, if you stop the boiler and the circulation pump, wait a couple of days and start heating again. During cooling, the liquid is compressed, giving air the opportunity to penetrate into the mains.
As for the centralized heat supply systems of apartment buildings, air enters them exclusively with the coolant or at the time of filling the network at the beginning of the season. How to deal with this - read below.
Case study. From the open heating system it was necessary to drive out air jams daily due to a completely clogged mud sump. A working pump created a vacuum in front of itself and thus sucked oxygen into the pipelines through the slightest leaks.
We remove the air plug without draining the water
You probably know how to remove air from the heating system in standard ways. Having found an unheated radiator, you need to open the Mayevsky tap in it with a screwdriver and release the air bubble. If old batteries are installed where there is no such valve, you can try removal in other ways:
- The so-called pumping of the pipeline network is used in apartments of multi-storey buildings, provided that a tap for discharging water is plugged into the radiator.Connect a hose directed to the sewer to it, open the valve to the maximum and drain until the flow moving at high speed entrains the air lock.
- In a private house, Soviet steel batteries can be re-infused with a self-tapping screw. Wrap it at the base with an FUM tape and screw it into the wall of the heater (closer to the top) with a screwdriver. Then, turn the self-tapping screw a couple of turns with a screwdriver, bleed air and tighten all the way. In the summer, cut a Mayevsky crane in this place.
- The air can be removed from the cast-iron batteries of the country house, not equipped with air vents, in two ways: by completely refueling the system or by increasing the pressure (up to 2 Bar) with simultaneous heating. Unscrewing the side plugs on the go is not recommended, then it will be difficult to pack them.
- Weak circulation and heat transfer may be due to accumulation of air in the mains pump casing. Loosen the large screw installed at the end of the unit a couple of turns. When drops of water come out from under the rubber ring, tighten it back.
Tip. In order not to collide with air traffic jams during operation, install taps for bleeding air on all radiators. If the thickness of the metal wall does not allow to cut 3-4 turns of thread, weld the boss on top with the hole of the required diameter. In cast-iron “accordions”, the valve is embedded in a side steel plug.
Recommendation. If you constantly bleed air from the heating system through batteries and find no reason for airing, temporarily put automatic valves on the heaters until you figure out what’s the matter (there may be a chemical reaction with oxygen evolution).
Fill the system correctly
It is easiest to pump water or antifreeze into pipelines connected to an open expansion tank. To do this, open all the valves (except the drain valve) and, having connected the hose to the feed fitting, fill the pipes and radiators with coolant. In this matter, it is important not to rush and to allow air to leave the system on its own through the expansion tank.
Tip. After filling, turn on the circulation pump and boiler, and then warm up all heating devices. Then release the remaining air from them through Mayevsky's taps. Do not forget to air the pump before starting, as described above.
Now about how to bleed air from batteries and pipelines of a closed heating system of a private house. The proposed methodology, constantly practiced by our expert - plumber Vitaliy Dashko, is performed in the following order:
- Open all shut-off valves of the main circuits (except for the drain).
- Turn off all radiator taps, excluding the most recent batteries at the ends of the hinges, to allow circulation through them.
- Attract an assistant to the work. Its task is to be in the boiler room and maintain the pressure in the network at the level of 1 Bar with the help of a pressure pump or through the make-up branch from the water supply.
- Having opened water supply, fill the main highways, expansion and boiler tank. Air must be vented through the safety valve and air vent at the highest point (if any).
- Go to the first radiator from the boiler and simultaneously open both taps (slowly). Bleed the air through the Majewski valve and close the valves again. The assistant at this time does not allow the pressure to fall below 1 Bar.
- Repeat the operation on all batteries, then turn on the circulation pump and start the heat generator. When the lines start to warm up, open all the radiator taps in turn and remove any remaining air from them.
An important point. Before squeezing the air plugs from the radiators, be sure to bleed the air from the circulation pump and turn it on for 5-10 minutes to pump the pipelines.
After complete heating of the heating devices, the pressure in the system should be in the range 1.3–1.6 Bar. On this procedure is considered complete. If the system contains warm floors, then they must be filled in last, using the same algorithm (for cold!). That is, having pumped up pressure in the main line, it is necessary to open and close the floor circuits one by one, letting air through the manifold valves, and then warm up and adjust the flow rate of the coolant.
Note regarding the installation of automatic air vent valves. Such a device should always be in the safety group of the boiler, and the second, third and so on - only if the lines pass above the radiators. With a lower wiring in a one-story house, air accumulates in the batteries, since they stand above the pipelines, and valves are not necessary on them.
Conclusion
It is not difficult to bleed air from radiators, but to drive it out of the entire heating system, including underfloor heating, is a laborious task. If in the process of filling the heating circuits you make a mistake and a wandering air plug appears, then it can take up to several weeks to eliminate it. So take your time and do this job thoroughly.