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Kummler+Matter EVT

Heating efficiently and quietly thanks to venting!

24.03.2021Bouygues Energies & Services

Discover how to remove the air in just a few steps and thus reduce your energy usage from heating by up to 15% per cent in our step-by-step instruction.


How air causes problems in heating systems


Your radiators are linked to the boiler via a system of pipes. This system of pipes transports the heat from your boiler to the radiators and from there to the rooms. Alongside water, air can also enter the heating system. The problem is that, unlike water, air is not good at transporting heat. This results in not all radiators being evenly warm, leading to lower room temperatures. Air also causes annoying noises such as gurgling and bubbling in the radiators. If you hear these kinds of noises, or notice that only parts of your radiator become warm, it's best to vent your heating. But, regardless, you should vent your heating every three years, ideally in the autumn before switching your heating on.

How does this work?


If you live in a rented apartment, it's possible that you won't be able to carry out steps 2 and 4. But you can still vent your system. Choose a time to vent when the heating has been switched off for a long period of time. Then go directly from step 1 to step 3. If your heating is not working properly after venting, contact your landlord so that they can carry out the fourth step of checking the water pressure.

  1. Turning the heating on full
    First, set the heating to the highest level in all rooms. Then wait approximately 30 to 60 minutes until all radiators are warm.

  2. Switch off the circulating pump
    As a next step, switch off the circulating pump. You can find this near the heating system, and you can usually close it using a screwdriver. You now have to wait for approximately another hour so that the air can rise to the top of the radiators. Then you can switch the circulating pump on again.

  3. Venting the heating
    For this step, you will need a small container, gloves, a cloth and a square socket key or a screwdriver – depending on the type of vent valve. You can find this at the top of the radiator opposite the turn knob. It is possible that you will need to open the valve with pliers in older radiators.

    As the water and the air can be very hot, you should protect your hands with gloves or a towel. You can also place a towel on the floor to prevent water stains. If you live in a multi-storey house, you need to bleed the air out of your radiators starting downstairs going up.

    Place your container directly under the vent valve and open it slowly anti-clockwise until you hear a slight whistling sound.

    Close the valve as soon as only water and no more air comes out. Don't close the valve too tightly.

  4. Checking the water level
    Finally, check the water level of your heating system. If the pressure indicator in your heating is below the green area, it needs topping up with water. This should be done by your heating engineer, as there are special requirements for topping up water.