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How to Bleed a Radiator

Omkar Phatak
If you are looking for guidelines on bleeding a radiator system, this post will help you out. All the instructions you need to accomplish the job are provided here.
Although it may sound like it but there is no violence in bleeding a radiator! The unfortunate usage of the 'bleeding' word, makes this job sound like a job, for the mob! However, you can rest assured that it isn't.
It is just a mundane and simple job of radiator maintenance at home, that can be easily accomplished in about five minutes, without bloodshed! Okay, enough of kidding.

Why Should One Bleed a Radiator?

The immediate question that pops up when we need to do something is, why should we do it? It is a rightful thought arising out of your inherent curiosity and inquisitiveness.
Radiator bleeding is one of those jobs that are a mandatory part of maintenance, if you want your radiator to function efficiently. To know why bleeding a radiator is important, one must understand how a house radiator works.
So, let us get a basic overview of a traditional radiator system used to keep rooms warm. It all begins with the boiler, which creates steam. The heat energy required for creation of steam can be supplied by natural gas, oil, wood or electricity.
There is a network of pipes connected with this boiler (usually placed in the basement), that transport this steam to radiators inside houses. The radiator has a winding network of tubes that transports this steam. The passage of steam heats up the metal tubes and consequently they radiate heat into the room.
The steam cools and becomes water again, which is transported back to the boiler for reheating. The reason you need to know bleeding radiators is the air bubbles that get into the coils bring down its efficiency. When air bubbles get inside the coils, they displace water and reduce heating efficiency, as air is an inferior conductor of heat, than steam.
That is why, home maintenance experts highly recommend bleeding of radiator regularly, as it removes the trapped air and significantly improves heating efficiency.

How to Bleed a Radiator System?

Periodic bleeding of a radiator is recommended. There are some signs which can tell you that the radiator needs bleeding. The sure sign is a difference in temperature at the bottom and top of radiator. If the radiator top is cold while the bottom is warm, there is definite trapping of air.
If you observe that the whole radiator is cold, then a large quantity of air is trapped inside. The presence of air creates this distortion in the temperature gradient of the radiator, which can be normalized only after air release, through bleeding.

Step 1: Get a Radiator Key

One 'key' element that you need to accomplish the job of radiator bleeding is the radiator key! It is available in most of the hardware stores. By inserting this key, the radiator bleeding can be achieved. So get hold of that key.

Step 2: Switch Off Central Heating

Next turn off the central heating before you start bleeding the radiator. This will prevent any more air from entering the radiator system. Proceed only after the shut down radiator has cooled. This step is very important.

Step 3: Open Valves

Once you are sure that they've cooled, open both the valves of the radiator at the bottom. Be prepared with a small tub and place it under the screw. Also keep a towel with you.
Then insert the key into the bleed screw slot and turn it anticlockwise (about half a turn). Water will squirt out, with a hiss and drip out of the screw. Dab it with the towel.

Step 4: Close Valve and Switch on Central Heating

Once the water has squirted and pressure has been released, rotate the key clockwise (half a turn again). Job has been accomplished.
Switch on the central heating system and enjoy the considerably warmer interiors of your home. It doesn't take an Einstein to figure out the job, as you will agree with me. All that is needed is an ability to understand logic and capacity to follow simple instructions.