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How to bleed your radiators

Although they’re often overlooked, your radiators are just as important as your boiler in keeping you toasty and warm. If you’ve noticed that your radiators are cold or have cold spots; or are making funny noises; this might indicate that air is trapped inside them and needs to be released. The good news is that releasing the trapped air, or ‘bleeding’ your radiators is a relatively straightforward task that you can do yourself. In this blog, we provide a step-by-step guide to bleeding your radiators. This will help to keep you warm and comfortable, whilst ensuring that you’re not wasting energy (and therefore money) trying to warm your home with an inefficient system.

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Wondering how to bleed your radiators?

When the cold weather hits, you’ll want to be sure that your radiators are performing to their full potential.

Although they’re often overlooked, your radiators are just as important as your boiler in keeping you toasty and warm.

If you’ve noticed that your radiators are cold, or have cold spots; or are making funny noises; this might indicate that air is trapped inside them, and needs to be released.

Otherwise your radiators won’t heat up properly, and your boiler will be working much harder to warm up your home.

The good news is that releasing the trapped air, or ‘bleeding’ your radiators is a relatively straightforward task that you can do yourself.

Not only will this keep you warm and comfortable, but it will ensure that you’re not wasting energy (and therefore money) trying to warm your home with an inefficient system.

Why do radiators need bleeding?

Air bubbles are a natural by-product of your central heating system heating and cooling water.

Unfortunately, there is nowhere for this trapped air to escape from within your heating system, so the air bubbles rise together and can create air pockets inside your radiators.

These air pockets prevent hot water from filling the entire radiator, explaining why they often develop cold spots.

When your radiators are blocked with air, your boiler will be working harder than it should to heat your home, and you’ll find that you’re needing to turn your thermostat up to get to your normal temperature. As a result, you’ll be burning more gas, which is far from cheap at the moment!

If you don’t release the air by bleeding your radiators, the problem will only get worse, until your central heating won’t get to the correct temperature at all.

Not only that, but you might find that the movement of air through your system starts to cause unwanted noises such as gurgling sounds.

Bleeding your radiators will solve these problems and ensures that you can heat your property efficiently and minimise your energy bills.

How long does it take to bleed a radiator?

It’s pretty quick to bleed a radiator, because you simply need to open a valve to let the air out. This will take up to one minute, depending on the size of the radiator and the amount of air that needs to be released.

How often should you bleed your radiators?

Since the production of air is an unavoidable consequence of using central heating, you will need to bleed your radiators regularly.

As a guide, bleeding them all at least once a year should keep them working well. If you notice any cold patches on your radiators in the interim, it’s time to get that radiator key out.

When should you bleed your radiators?

You can bleed your radiators at any time of year, but to find any problem radiators, you’ll need to have the heating on, so checking them at the start of winter is probably best.

Should you bleed radiators if you have a combi boiler?

It might be best to contact a heating engineer for help if you have a combi boiler, because sealed central heating systems need to be re-pressurised after bleeding radiators. It is possible to do this yourself, using the instructions from your boiler manual.

How to tell if you need to bleed a radiator

It’s usually easy to determine whether your radiators need bleeding. You just need to use your hand to check the temperature of your radiators, from the top to the bottom of each.

Since air rises, it is quite common for the top of a radiator to be cold, and the bottom to be hot, if it needs to be bled.

If it’s been ages since your radiators were last bled, you might not notice cold patches, but rather, the radiator feels cooler than usual.

You can always compare the temperature of different radiators in your home.

What do I need to bleed my radiators?

You don’t need much equipment to bleed your radiators. You just need:

  • 1 x radiator key – your radiators will have come with a small key that you will need to use to bleed them. Don’t worry if you can’t find it – you can also buy replacements in DIY stores.
  • 1 x old towel
  • 1 x container for collecting water

 

 

What are the steps to bleeding radiators?

To bleed your radiators, just follow these easy steps:

1.    Turn on heating system

Firstly, you need to turn your heating on and allow your radiators to warm up. This will help you to check which radiators need bleeding, and you need them to reach full heat before bleeding to build up the pressure inside them.

2.    Check radiators

Once your central heating is on, and your radiators should have reached full heat, check the temperature of each radiator in your home.

Carefully check the temperature from the top to the bottom of the radiator using your hand. You’re looking for any cold patches, or for a radiator that is much cooler than the others.

If your radiators are taking a very long time to heat up at all, this can be another sign that they need bleeding.

3.    Turn heating off

Once you’ve identified which radiators need bleeding, it’s important that you switch your heating off and allow the radiators to cool. This will protect you from being burned by any very hot water that comes out of your radiators during the bleeding process.

4.    Prepare area

Prepare the area under your radiator by putting a towel on the floor. This will protect your carpet from any dirty water. You then need to place your container underneath the bleed valve on your radiator. This will catch any drips of water released from the radiator.

5.    Fit bleed key to the valve

You now need to fit your radiator key to the bleed valve. The bleed valve is a small metal square which is found inside a round nut, usually at the top of your radiator. Some bleed valves have red markings on them, but you’ll know it’s the right valve because your key will fit.

6.    Release air from the bleed valve

Once you have fitted your radiator key to the bleed valve, slowly turn it anti-clockwise to release air. You should hear a hissing sound as the air escapes. Keep releasing air from the valve until you can no longer hear air escaping and some water begins to trickle out.

7.    Close the bleed valve

Once you have released the trapped air from your radiator, you need to close the valve quickly.

8.    Repeat for all radiators

You should repeat the above steps for all of your radiators that need bleeding. It’s a good idea to start with the radiators that are lowest in your home and then move upstairs.

9.    Check boiler pressure and switch the heating on

A mother and child by a radiator.Once you’ve finished bleeding your radiators, you should check the water pressure gauge or indicator, which is usually on the front of your boiler.

For most boilers, this should be set around the 1 bar, but check the requirements for your boiler. If the pressure needs topping up, you can do this by following your boiler’s instruction manual.

You then need to turn your heating back on to make sure everything’s working.

Are your radiators back to normal?

If bleeding your radiators has done the trick, that’s great.

But if you’re still noticing that your radiators are not working as they should be, it could be indicative of a bigger problem with your heating system, such as needing a power flush.