How to Bleed Your Radiator

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What does ‘bleeding a radiator’ mean?

Step-by-Step Guide to Bleeding a Radiator

1. Turn your heating on: Switch your heating system on, making sure your radiators are all turned up fully. Make sure that you have waited long enough for your radiators to heat up before moving on to the next step.
2. Identify the radiators that need bleeding: Go through your home checking all of your radiators by feeling for cold spots. Make sure you are careful when doing this, so you don’t burn yourself! Good indicators of a radiator that needs bleeding include radiators with top sections that are colder than the bottom section, radiators making gurgling or spluttering noises and radiators that take a long time to heat up. Once you know which radiators need bleeding you can move onto the next step.
3. Turn your heating off: This is a very important step! Before attempting to bleed any radiators make sure your heating is turned off and your radiators have all cooled down. If you attempt to bleed your radiators while they are still warm you risk getting boiling water spurting out which could burn you. Bleeding your radiators will also be more effective if the contents have settled. Make sure you start with the ground floor radiators if you live in a multi-storey home, and always start with the radiator furthest away from your boiler.
4. Prepare the area and grab your supplies: It may be a good idea to put towels down around the radiator you are bleeding as sometimes it can be a messy job. You’ll also need a radiator key, a cloth and a container to catch drips. Bleed valve keys are usually supplied with the radiators but if you can’t find any in your home then you can buy them at most hardware stores.
5. Open the bleed valve: The bleed valve will be at the top of your radiator on one end, and most of the time it will look like a round hole with a square inside it. Insert your radiator key into the bleed valve and turn anti-clockwise slowly. Make sure you are holding a cloth in your free hand as this will help you grip, as well as catching any drips. As the air begins to escape you will begin to hear a hissing sound.
6. Bleed the radiator: Once you have completed a quarter turn or half turn of the key, the valve should be sufficiently open to let the air out. If you turn the key too far then water will pour out once all the air is gone. Keep holding the key in the same position while you hear air hissing out. Once a steady stream of water begins to drip from the valve then you know you have completed the bleeding process. Close the valve by turning the key back clockwise to seal the radiator. This process could take anywhere from 10 seconds to a whole minute depending on the size of the radiator.
7. Repeat on all radiators: Repeat the bleeding process on all radiators that you think need bleeding. 
8. Turn on your heating and check the pressure: Once you have bled all the radiators you need to, you can then turn your heating system back on. Make sure you have properly closed all bleed valves before you do this. If you have lost a lot of water whilst bleeding your radiators, then your boiler may have lost water pressure. Depending on your heating system, you can check the needle gauge or display to make sure your water pressure is correct. It’s usually between 1.0 and 1.5 bar in a typical home. If your water pressure is not within these parameters, you may need to let some more water into the system. Be sure to be careful when using your boiler and if you are unsure of what is wrong you should call a plumber for help.

Tips and Troubleshooting for Bleeding Your Radiator

• We would advise that you bleed your radiator system before the weather starts to get cold and you need your heating system more.
• It’s possible to have automatic radiator valves. These automate the bleeding process and attach to your valves, letting out air gradually and increasing the effectiveness of your radiator.
• If you have bled your radiators but your pipes and radiators are still noisy, then it may be caused by lime-scale build up. You can call a heating engineer to clean your heating system, and they can also fit a hard water filter to stop it happening again.
• If you are struggling to find a radiator key and are unable to shop for one, you may be able to use a flathead screwdriver or pliers to bleed your radiators. However, it’s not as safe and may damage the valve, so we advise you always use a radiator key if possible.

How to Improve Energy Efficiency in Your Home

• Radiator insulation foil – this sits behind your radiators and reflects heat back into the room. They are widely available in hardware stores and you can install them easily yourself.
• Radiator boosters – a fan unit which sits on your radiator and pushes the warm air into the room.
• Insulation measures – keeping your home well insulated is the best way to make sure you aren’t wasting the heat you are paying for. There are many ways you can stop draughts around doors and windows, and you may even want to look at refreshing your wall and attic insulation. It may seem expensive, but it could save you money in the long run.
• Energy providers – by comparing energy deals you could make big savings on your energy bills. Use our energy comparison tool to compare energy providers and find the best deal for you.