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Vent the heating
Vent the heating

Video: Vent the heating

Отличия серверных жестких дисков от десктопных
Video: DARK SCREEN | White Noise | Furnace Heating Vent [TEN HOURS] Sleep Relax 2023, January

Gurgling, knocking, bubbling, rustling: if you are woken up by such noises at night, your heating system knocks in the truest sense of the word. Then it is probably high time to vent your heating. Another very clear indication is when the radiators no longer get really warm. These are the clearest signs of too much air in the heating pipes.

Vent heating - cause and solution

The heating season usually begins in early October and lasts until the end of April. It is important to vent the heating a few weeks before the heating season. Because if something goes wrong or something else turns out to be, there is still enough time to order a craftsman before the cold season begins. It often happens that air accumulates in the heating pipes and radiators over time. As a result, the hot water, which is responsible for heating the heating, has less space and can no longer circulate properly. The result is that not enough water gets into the circulation pump, the radiator is no longer really warm, and the energy consumption increases enormously. So if you bleed your heating, you will also save a lot of money in the heating season. Noises in the radiators can have the following causes:

  • Too much air in the heaters
  • Water pressure too low (this also occurs when there is too much air in circulation)
  • The speed of the circulation pump is set incorrectly or too high

In most cases, the air circulation in the heating pipes actually creates annoying noises. If you have checked the pressure gauge, i.e. the pressure gauge on the circulation pump and the water pressure is correct, you can adjust yourself to venting the radiators. As a tenant, you can and should normally vent the heating independently. Unless otherwise agreed. Then you should consult the owners. A normal venting of the heating takes about ten minutes, is harmless and usually runs without complications. If you want to bleed a circulation pump in the house, you should definitely hire a heating technician, as there is a risk of injury if hot steam escapes.

Bei der Entlüftung der Heizung sollte man immer einen Auffangbehälter parat haben
Bei der Entlüftung der Heizung sollte man immer einen Auffangbehälter parat haben

When venting the heater, you should always have a container ready, as some of the water could flow out.

Photo: M.Dörr & M.Frommherz /

Vent heating: You need it

Be sure to have a bowl or bucket ready as a collection container, as the heater almost always loses water when it is vented. A cloth or kitchen paper to wipe up the water quickly if necessary. If you have very sensitive floors, you can just lay out a few towels as a precaution. Then you need a so-called square key, also called a ventilation key. You can get this from the hardware store or from sanitary supplies. There are valves that can be opened with a flat-blade screwdriver or pliers, but this is rarely the case.

Turning on: Before you can start venting, you must open all the radiators fully. Set all heads to the highest level.

Switching off the circulation pump: To achieve the best result, you should switch off the circulation pump before venting. Otherwise the air could continue to circulate in the heating pipes. If you are a tenant, you may not have access to the circulation pump. In this case, it is sufficient to switch off the heating circuit in your home.

If the circulation pump or its heating circuit is switched off, the air first collects in the heating. The whole thing takes about an hour. During this time, you should not do anything to the radiators.

When the hour is over, you can start venting. If you vent a house, it is worth starting on the upper floor, as experience has shown that most of the air collects here.

The drain valve is usually located on the side of the top of the radiator. In the middle there is a square pin on which you can attach the square key. For towel radiators, you will usually find the valve in the top area at the rear. Once you have found the valve, you must now proceed very slowly and carefully in order to stop any strong water escaping from the heating pipes. Just keep the container at hand. Now you can slowly make a quarter to a half turn to the left, i.e. counterclockwise, with the bleed key.

Ideally, you can now hear it “hiss”. As soon as you can hear that the air is escaping from the heating, do not open the valve any more, but leave it at this level. Otherwise there is a risk, among other things, that the square pin falls out of the heater and the water flows out unhindered. As the air escapes, water usually flows out moderately, which you collect in the bucket. Don't worry if the water is dirty, that's normal. If the air and water are outside, the heating system has been vented successfully! Now you can close the valve clockwise, i.e. to the right.

Now it goes on to the other radiators. Vent throughout the house, working your way from top to bottom. It may be that you are finished faster on the lower floors, since experience has shown that much less air accumulates there than on the upper floors.


A manometer measures the exact water pressure. From its display you can quickly see whether there is too much air in the radiators.

Photo: iStock / alder7

Check water pressure

Now it makes sense to check the water pressure on the manometer. If the display here is too low, it is best to add water immediately. You can usually use a garden hose.

You can recognize the ideal water pressure by the color marking. There are usually two pointers: one in red and one in black. The red pointer is usually static and does not change. It indicates the upper limit of the water pressure and can act as a warning signal if the actual pressure exceeds the limit. The black pointer shows the current water pressure. Ideally, the black pointer is always in front of or below the red pointer. So when you turn on the heater, the black pointer moves to the red one because the radiators are filled with warm water. It is important that it stops in front of the red pointer. If the heating is switched off, the pressure drops and the black pointer moves towards zero. If too little water is filled in, it is probably because there is too much air circulating in the radiators. You can usually see this very clearly on the manometer. As soon as the black pointer does not rise properly, you can assume that you must vent the heaters. If it happens that too much water is filled and the limit is exceeded, you should always contact a heating installer.

Violetta Hoffmann editors

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