How to Bleed a Radiator

The Ultimate guide on How to Bleed a Radiator

If the bottom of your central heating radiator is warm but the top is cold it means that the radiatorradiator bleeding image is malfunctioning and needs bleeding. Remember to take care and not burn your hand on the radiator when you are checking this. Bleeding is not a medical process but it is a way of getting care and of the radiator so that the hot water can properly flow through the radiator keep it warm and able to your property.

So, lets see how to bleed a radiator:

If the whole radiator is cool radiator despite the fact that the central heating system is on then it could be that the radiator is almost full of air. The air prevents the hot water circulating and no real difference in temperature between the top and bottom of the radiator will be experienced.

This problem will contrast with the remainder of the other radiators in your central heating system which will be hot to the touch if they are operating normally.

How do I bleed a radiator at home?

The process for bleeding a home radiator is relatively simple and safe if you follow a few procedures. All radiators are supplied with a small bleed key. If you don’t have one they can be obtained cheaply from a local diy shop.

Look carefully near the top of the radiator and on one side you should see a small protrusion called the bleed valve. To bleed the radiator you need to open this bleed valve a small amount.

When you do this listed carefully and you will hear the air escape from the top of the radiator.

Ensure that you do not allow the water to flow out as it could scald you or mark the carpets. Pay attention because at some point the air will have been fully expelled and will be followed by hot water.

At this moment you need to be able to switch the valve off without delay.

If you decide you want to bleed a radiator in a sealed system you will first need to reduce the air pressure in the whole system (consult your manual for how to do this). Do remember that when you have finished you will need to top up the system afterward from the main cold water feed.

BE CAREFUL when turning the bleed valve. Have a small plastic bowl to catch any drops of water which escape and an old rag to shield your hand if required.

bleed radiator imageFirst switch off the heating boiler, failure to do this could allow more air to get into your system. Use the radiator bleed key to carefully turn the bleed valve counter-clockwise a small amount, 1/2 turn would be ample here.

The air trapped in the radiator will start escaping with the hissing sound we mentioned – it is similar to a that in a bicycle tire. when you start to pump it up.

When finally water begins to drip out of the valve you will know that all the air has been purged, and you can now carefully gently twist the bleed valve the other way to close it.

Check for any leaks and then switch the heating back on and thoroughly check that there are no ongoing leaks from the radiator valve you have just bled. If there are check that you tightened it properly.

As we covered earlier check the system pressure and top up the water f the central heating system was a sealed system, if you have any problems consult your central heating system manual.

If you have followed the radiator bleeding process as outlined and it not seem to improve the operating performance of your heating, especially if several central heating radiators are malfunctioning, there may be another problem and you will need to call out a plumber.

How much do replacement radiators cost?

If you are searching for replacement radiators they can be purchased direct from suppliers for installation by a trained CORGI engineer. Some examples are illustrated below.