How to Bleed a Radiator

Bleeding radiators is a crucial part of maintaining an efficient heating system in your home. Are your radiators not heating up properly? Are they making a lot of noise? Or you might have cold spots on the surface – then these are indicators to focus on bleeding radiators. At First Response 360, we are the central heating engineer experts and we believe you should bleed radiators around twice a year. So, your central heating can run efficiently whilst allowing your energy bills not to rise.
Our guide will help explain why you should bleed a radiator, understanding the process of how to bleed your radiators and importantly when to bleed radiators.

Why Bleed a Radiator?

Bleeding a radiator is important for ensuring that your heating system operates in an effective and efficient way, especially if your radiators need bleeding. Over time, air can become trapped in your radiators, which prevents hot water from circulating properly. If air is trapped inside your radiator, then this will prevent the radiators from heating up. If it is not dealt with for a long period then corrosion could occur within your central heating system. 

By regularly bleeding radiators, you can remove the trapped air and ensure that your radiators are fully heated, which maximises the efficiency of your heating system. This simple maintenance task can save you money and keep your home warmer during the colder months.

When to Bleed Radiators

To help understand matters, you must know when to bleed radiators is just as important as knowing how to do it. We recommend that around twice a year, you should bleed radiators. There are a few key signs that indicate it’s time to bleed your radiators:

Cold Spots
If you notice cold spots on your radiators while the heating is on, especially being cold at the top, this is an indicator that there is air trapped inside.

Noisy Radiators
Gurgling or clanking sounds coming from your radiators can indicate that air is trapped and needs to be released.

Uneven Heating
If some radiators in your home are heating up properly while others remain cold, this could be due to trapped air.

How to Bleed a Radiator

Now that you know why and when to bleed radiators, we will show you an effective process of how to bleed a radiator. Be sure to take note and follow these simple steps to improve your heating system:

Make sure you switch off your heating


Before you begin, make sure your heating system is switched off and the radiators are cool to the touch. This prevents hot water from spraying out when you bleed radiators.

Find the equipment you need to bleed your radiator

  • A radiator key (or a flathead screwdriver for some modern radiators)
  • A cloth to hold against the open valve
  • A towel to protect the floor
    A container which can help catch any water that escapes

    Locate the bleed valve on your radiator

The bleed valve is usually found at the top corner of the radiator. It’s a small valve with a square or flat slot that the radiator key or screwdriver fits into

Open the bleed valve 

Place the cloth or towel under the valve to catch any drips. Insert the radiator key or screwdriver into the valve and turn it slowly counterclockwise. You’ll hear a hissing sound as the air escapes.

Close the valve 

Once the hissing stops and water starts to dribble out, turn the valve clockwise to close it. Make sure you are careful as you do not want to overtighten the valve, as this could damage it.

Check the pressure of the boiler

After bleeding all necessary radiators, check your boiler’s pressure gauge. Bleeding radiators can cause the pressure to drop, so you may need to top it up according to the manufacturer’s instructions.

Turn the heating on

Finally, turn your heating system back on and check that your radiators are heating evenly. If necessary, repeat the bleeding process for any radiators that still have cold spots.

Following these steps, we hope this has solved your problem around bleeding radiators. However, if you require more support or have any questions then feel free to contact us. Check our blog for more insights and guides around heating and plumbing as we help solve your issues. 

Call us on 07968 039 148 if you would like to have a chat with our team who can offer their guidance and tips.