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Bleeding a radiator is a very simple task that can mean your radiators get hotter and make your central heating system work more efficiently. Excess air stops the radiators from working correctly and can mean that a radiator suffers from cold spots. It is not good to have air in a central heating system as this causes corrosion of the steel in the radiators alongside reducing the amount of heat they will omit. Here at Column Rads we have put together as step by step guide to help you bleed you radiators along with an instructional video, so you can’t go wrong.

Step 1 – Turn the heating on low

Ensure your central heating system is running, but make sure it is not too hot as the water inside will be very hot when you come to vent the air. This can be done by turning down the thermostat onto a low setting. Adjust the radiator valves so that they produce less heat.

Step 2 – Find the most suitable radiator to bleed

Find the most suitable radiator to bleed in your house. Air tends to accumulate in certain radiators that form part of your system such as heated towel rails, the last radiator in the system or highest point in the system. Bathroom radiator towel rails are very susceptible to air accumulating and this is probably the easiest place to vent it and also the easiest place to add inhibitor like Fernox F1 Express as it is accessible. This inhibitor will help to protect your system against corrosion and lime scale helping keep it more efficient for longer.

Step 3 – Find the radiator key and air vent

Most air vents today have a flat head slot and a square head like the image below. The air vent is the part of the radiator that can be turned with a radiator key to let the air out of the system. Old fashioned panel radiators have the bleed valve built into the radiator and these are generally just a square head. Heated towel radiator are similar in configuration. If you are unable to find your radiator key, they are readily available to buy from Column Rads, but any new radiator purchased in the Revive range of radiators comes complete with a bleed key. You will need the radiator key, an old rag to catch any excess water from the system and an old towel on the floor if it goes really wrong.

Step 4 – Bleeding the radiators

Use the radiator key or a flat headed screw driver to turn the bleed screw on the bleed nipple anti-clockwise and gradually listen for escaping air. This sounds like a hissing noise. Make sure you do this gradually and do not allow the air to escape too quickly. This will give you more control to shut off the vent once the air has been removed from the system. The air will be released first. Don't shut the vent until the hissing sound has stopped. Once hot water starts to come out shut off the bleed valve with the slotted screwdriver. Be careful that the water is not too hot. It is as simple as that and as long as you are slow and carefully you will not have a problem. Straight away you will feel the radiator get hotter and the system will be working more efficiently. Air can accumulate in any radiator so it is really worthwhile checking them all and if persistent air pockets are found then you may need to investigate further. Column Rads can diagnose most common problems because we have so much experience in heating, so please give us a call.

What to do if your radiator still feels cold

If you feel that the radiator is not hot all over then you could have sludge build up in the radiator, which generally accumulates at the bottom in the middle as it is heavier than water. If after bleeding your radiators you find they are still cold you will need to treat it with a cleanser or cleaner.  

How to bleed a radiator video

The following video has been created by CORGI and provides a simple step by step guide by a qualified CORGI engineer showing the correct procedure for bleeding your radiators. Bleeding radiators yourself is quite a simple process once you know how.