How to Bleed a Radiator

Bleeding Your Radiator Ensures Efficient Heating

As we face a winter of high energy bills, it’s important to know that your heating system is working efficiently on your behalf, because this will lower your usage, and your bills. Knowing how to bleed a radiator allows you to carry out a simple maintenance over the autumn. So, when you do turn your heating on, you won’t be spending more than you need to, and you’ll be conserving precious energy.

The Simply Plumbing team has created a step-by-step guide to bleeding your radiators. Hope it helps!

Why Do Radiators Need Bleeding?

You may have noticed that your radiators sometimes develop ‘cold spots’ in the upper area, which obstinately refuse to warm up. These are the result of air that has become trapped in your heating system, and they’re very common. Once you know how to bleed a radiator, you’ll be able to clear these pockets of air, allowing all parts of your radiator to warm up. It’s always a good idea to carry out this check after the summer, before you start using your heating regularly.


How to Bleed a Radiator – a Step-by-Step Guide

Ready to give this a go? There are two things you need to have ready in order to begin: a radiator key which you can get online or at a general hardware shop, and an old towel for catching the drips.


1. Turn on Your Heating

Your radiators need to be hot when you bleed them. The heat builds pressure inside your radiators and it’s this pressure that forces the air out.


2. Check Which of Your Radiators Need Bleeding

Run your hand across the top of each of your radiators. If you find any cold spots, it’s a clear indication that the radiator has trapped air in it. More general symptoms are gurgles coming from radiators, which indicate that there are air pockets that need to be released.


Step 3. Turn Your Heating Off

The water heating your radiators is hot, so turning off the system avoids you getting scalded in the process. It’s a good idea to start with the radiator furthest from the boiler and whilst you’re waiting for it to cool down, place a towel underneath it.

Step 4. Open the Bleed Valve

Your bleed valve will normally be at the top of the radiator, at the side. It’s circular, and there’s a square in the middle which is where you insert the bleed key. 

radiator bleed valve

Start turning the key very slowly in an anti-clockwise direction. Listen carefully and you’ll hear a hissing sound which is the air being released. Turn the key no more than a quarter.

Step 5. Close the Bleed Valve

When the hissing stops and water begins to drip out, all the air has been released. Close the valve by turning the key clockwise. Complete the same process for all the radiators in your home with cold spots.


6. Check Your Boiler Pressure

If a lot of water has leaked out whilst bleeding your radiators, you may need to top the pressure up on your heating system. Start by turning your boiler back on and checking the pressure gauge on your boiler. If it’s lower than when you began the bleeding process, you should check your manufacturer’s instructions for raising the pressure to its normal level.


7. Check the Cold Spots Have Gone

Once your radiators have warmed up, check that the cold spots have gone. Bleeding a radiator normally solves this issue, so if they’re still there, the problem is elsewhere. If this is this case, we would recommend you call out a maintenance engineer to check the system rather than taking any further steps yourself.


For further simple energy saving tips check out our recent article.

About Simply Plumbing

For over 10 years now, Simply Plumbing has been providing local plumbing services in Luton and South Bedfordshire. We’re an independent business with high standards, and a friendly, professional team. Whether you’re looking for central heating maintenance, bathroom fittings, leak repairs, pipe blockages, or assistance fitting a new appliance, just call us and we’ll respond promptly.


If you have an emergency and need a plumber fast, call Simply Plumbing. We’re available 24/7 and will solve your problem promptly and efficiently.

For more guidance on how to bleed a radiator, or central heating maintenance services, call Simply Plumbing today – 01582 250030

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