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How Do I Bleed a Radiator?

Radiators maintain the heat in a home or a building. However, like any appliance or mechanical device, their performance can deteriorate over time. It is necessary to “bleed” the radiator—and this is a simple task that can be done with no training and very simple tools (a radiator key and a small bowl).

Radiators need “bleeding” when the heat circulation deteriorates or the machine shows uneven heating: the upper part of the machine is cold, while the lower part is warm. Sometimes the whole machine is cold.This is a sign that the air has become trapped, which lessens its ability to generate heat.

It is important to turn off the radiator and the home’s central heating system before “bleeding” it. Then, get the bleed key and find the bleed valve. In most models the bleed valve can be found at the upper part. Insert the key and then push counterclockwise by a half-turn.

Once the key is turned, you will hear a “hiss.” This is the sign that the radiator valve has become open, and that air has escaped. So don’t be alarmed—this is normal! Then, close the valve once you notice that water has begun to escape. That’s why you need a small bowl and perhaps a few rags—to wipe up any water that may drip in the “bleeding” process. To close the valve, just push the key clockwise, also by half a turn.

It is better to “bleed” all the radiators in the house or building before switching the central heating system back on.

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