How to bleed a radiator - Quick guide

Does your radiator feel cold at the top and warm at the bottom? If so, it's likely that the problem is being caused by air that has been trapped in your radiator. Let PlumbNation show you how to bleed a radiator.

How to bleed a radiator ? Why ?

The key reason for bleeding your radiators is that air has entered your central heating system. Trapped air leads to a reduction in efficiency in the central heating system. There are a few ways to check whether you need to bleed your radiators. The quickest way to check is:

  • With your central heating turned on, touch your radiator. If the radiator is warm at the bottom and cold this is generally a sign that there is air in it.

Another way to improve efficiency is by learning how to balance a radiator. This involves adjusting the radiator valves, making sure that all radiators evenly heat up around your home

How to Bleed Radiators: Guide

Bleeding your radiators can be dirty work, get some old towels or some kitchen roll to make sure none of that dirty water spoils your flooring.

Bleed the radiators

Switch off your central heating.

Get your radiator key ready with some cloth/kitchen roll. (Radiator keys are available from all hardware stores if you can’t find yours) or you can use a slotted screwdriver.

Find the valve at the top of the radiator. You can attach the radiator key to the square bit in the centre or put the end of the screwdriver into the groove.

Keeping it nice and tidy, hold the key or screwdriver with a cloth. Extra cloth can be used to catch any excess dripping.

Slowly turn your radiator key or screwdriver in an anti-clockwise motion. If you hear a hissing sound, don’t be alarmed this is just the gas escaping.

Get Ready. Once all of the gas has escaped, liquid will come out of the radiator and the valve has to be closed quickly to ensure a clean job.

Be Careful, with the more modern screwdriver operated escape valve, liquid will likely come out as a jet rather than a gentle dribble.

Check the pressure

Now that you have confidently bled the radiators, you will have to check the old pressure of your central heating system. Take a quick look at the gauge on your boiler.

If you find that the pressure is now too low in the system, you'll need to top up You can do this using the lever or tap on your boiler, known as the filling loop.

Afterwards, you may want to run another hot test to check that your efforts have been successful. Simply turn your heating on, wait for all the radiators to heat up and check for any cool spots.

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