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How to bleed a radiator: maintenance tips for your home

November has a reputation for being the least loveable month of the year. The clocks have gone back, the days are damp and dark, and the nights are long and cold. Summer is by now a very distant memory – and the fun of the festive season is still a fair way off in the future. But November is the ideal time to crack on with those important pre-winter jobs that are necessary, although not necessarily exciting.

Making sure your heating system is in tip-top shape should be top of your to-do list. If you haven’t done so already, do book a boiler service. Regular servicing is the best way to ensure your boiler is running safely and efficiently. Now is also a good time for some seasonal radiator maintenance. Read on to discover our director Stewart Double’s advice on how to bleed a radiator, and why it’s an essential part of keeping your home warm and welcoming throughout the winter months.

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What does bleeding a radiator really mean?

Bleeding a radiator is rather a misleading term. It’s all about getting rid of the air pockets that stop hot water circulating efficiently. When this happens, it doesn’t just mean your home isn’t as warm as it could be. It also puts more strain on your boiler – and costs you more money. It’s important to understand that bleeding your radiators isn’t the same as draining or power flushing your central heating system. These processes should only be carried out by qualified central heating engineers. It’s definitely not a DIY job! But if you’ve never done it before, and don’t know how to bleed a radiator, don’t panic. It’s really not that difficult or complex, and it doesn’t take long to do.

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Why should you do this?

I’ve already established that bleeding a radiator is about getting rid of unwanted air pockets. But how does that happen in the first place? Air can make its way into your central heating system in different ways. For example, it could be manufactured by the movement of the pump as it turns. It could happen as a result of new water entering your system from the tank, or when routine maintenance is carried out. This air then tends to bubble to the top of your radiators, displacing the water. Those furthest away from the boiler – or fed by downpipes – tend to be the worst affected.

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How will I know that my radiators need bleeding?

Before I explore exactly how to bleed a radiator, it’s useful to explain how to know it needs doing in the first place! Fortunately, this is usually pretty obvious. First, when your heating is on, feel all your radiators. If they are cold at the top, that’s usually a clear sign they need bleeding. The other dead giveaway tends to be noise. If your radiators make a funny noise when they heat up, the chances are there’s air inside them. This irregular air pressure often causes vibrations, which in turn produce distinctive creaky, clicking or bubbling sounds.

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Bleeding a radiator

Once you’ve established that the job needs doing, the next step is to learn how to bleed a radiator – and indeed how to bleed a towel rail too. As with most things in life, preparation is key. Before you do anything else, make sure that your heating is off, and your radiators are cold. Safety first: the last thing you want to do is spray yourself with boiling water.

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The order in which you bleed your radiators shouldn’t be random, either. Start with the one that’s furthest away from your boiler. And if you live in a two- (or more) storey house, bleed the radiators downstairs first, and then work your way up.

Next, gather your equipment. Don’t worry, you won’t need much. It’s a good idea to protect your floor with an old towel. A jug to catch any escaping water is also useful, as is an old cloth or thick glove to grip and turn your radiator valve. The most essential piece of kit when you’re learning how to bleed a radiator is a specialist radiator bleed key. If you don’t already have one, they can easily be bought online, or from any hardware/DIY store, for around £2 to £3.

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Now look for your radiator’s bleed valve. It’s usually at the top of your radiator, but it can be at either end. It’s round in shape, with a square, notched section in the middle. Insert your bleed key here, and twist anti-clockwise to open the valve. Turn the key and valve until air starts to hiss from the valve. As soon as any water starts to appear, all the air has been ‘bled’. You should then turn the key clockwise to close the bleed valve. But take care not to overtighten, as this can damage the valve. Wipe up any water drips, and repeat the process with your other radiators.

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How to bleed a towel rail

Bleeding a radiator and bleeding a towel rail is a very similar process. You should still turn off your central heating and allow any water inside to completely cool down. The main difference is that most (although not all) heated towel rails have two lock shields. Open these fully by carefully popping off their caps, using a spanner or an Allen key. Next, locate the towel rail’s bleed valve. This is usually at the top, but is sometimes at the back. Use your bleed key, as before, to open this valve so that any air inside can escape. Once the hissing stops, tighten the valve and replace the caps.

Once you’ve finished bleeding your radiators and towel rails, turn your central heating back on. Check that your boiler pressure is normal, your radiators are warm with no cold spots, and there are no signs of leaking. Congratulations! You now know how to bleed a radiator, and get your home ready to face the rigours of the coldest winter months.

Loving classic styling in your home right now? Then read our blog on Victorian-style radiators and towel rails here.

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