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How often should you bleed your radiators?

How to guides

If you’ve noticed that your radiators aren’t working properly, but you still have hot water, it might be a sign that you need to bleed your radiators. Our helpful guide will walk you through everything you need to know about bleeding your radiators, from how often you should do it, to what tools you’ll need and how to bleed a radiator.

How often should you bleed your radiators

Radiators should be bled at least once a year, but the main signs that you need to take action are:

If when the heating is on, the top half of your radiator is noticeably colder than the bottom half, it’s time to bleed your radiators as there may be trapped air inside, affecting the performance of your central heating system.

Other signs that your radiators need bleeding are gurgling sounds when the heating is on, and if your heating takes longer than usual to heat up. Bleeding will remove the trapped air and your central heating system should return to normal performance.

Why should you bleed your radiators

If you’ve noticed that your radiators aren’t heating up properly, there might be trapped air inside. In this situation, you’ll need to bleed your radiators as the trapped air stops hot water from circulating properly.

Alternatively, if your boiler has high pressure (above 3 on the pressure gauge), you might find that bleeding your radiators will remove the excess water from the system, lowering the boiler pressure back into the normal range.

How to bleed a radiator

If you’ve never bled a radiator before, our simple steps below will walk you through the process, giving you everything you need to know to successfully bleed your radiators. But first, there’s a couple of other things to consider:

What do you need to bleed a radiator?

To bleed your radiators, the only things you’ll need is a radiator bleed key (available at most DIY shops), and an old cloth in case of drips.

Is there a specific order to bleed radiators in?

If your home has more than one floor, begin with the downstairs radiators first, furthest away from the boiler, and work your way through the first floor towards the boiler. Begin the process again on the second floor, starting with the radiators further away from the boiler. Repeat the process if you have additional floors in your home.

If you live in a bungalow or apartment, follow the same process as for the first floor, starting with the radiator the furthest away from your boiler and work towards it.

If heating problems persist after bleeding your radiators you’ll need to call out a qualified engineer to assess the problem. Check out our central heating services for more information.

Let’s get started:

  1. Begin by turning off your heating and allowing your radiators to cool if necessary

  2. Use the radiator bleed key to carefully turn the valve at the top of the radiator anti-clockwise. You should hear a hissing sound. Use the cloth to mop up any drips

  3. One the hissing stops, quickly retighten the valve

  4. Turn your heating back on and check the pressure gauge on your boiler. Repressurise if the pressure is now too low (this is normal, bleeding radiators often causes low boiler pressure)

  5. Check that you radiators now heat up as they should

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