August 17, 2022


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

Radiators are responsible for efficiently heating your home in the winter months. When you notice that the radiators are not providing adequate heat, they may need bleeding. Bleeding a radiator allows the hot water to circulate through the system properly. Read below for a step-by-step guide on how to bleed radiators so that they heat your home more effectively.

How do you know when a radiator needs bleeding?

Below are signs that the boiler is not working and the radiator needs bleeding.

  • Complete lack of heating signals poor circulation, especially if the thermostatic valve is already working
  • Hearing strange noises from the radiator, such as a rattling or whistling
  • The top of the radiator feels cold, but the bottom is hot.

Things Required for bleeding a radiator

things required to bleed the radiator

For bleeding a radiator, you’ll need the following items.

  • A radiator bleed key or a flathead screwdriver
  • A small bucket or a cloth to help collect the water escaping.

Step by Step Guide: How to Bleed a Radiator

Below are the simple steps for bleeding a radiator to return it to its efficient operating condition

Turn on heating

After turning on the heating, wait for all the radiators to warm up to their maximum heat. This step will help you to identify which radiator(s) need bleeding.

Identify which radiators need bleeding

identify which radiators need bleeding

Now check each radiator carefully, if you find any radiators that are cold at the top or hear any gurgling noises, that is a sign that the radiator needs bleeding.

Turn off your heating and wait for the radiators to cool

Now you will turn off the radiators and allow them to cool down completely. It is a necessary safety measure so that the hot does not burn you when you start bleeding a radiator.

Place a cloth below the radiator bleed valve

place a cloth below radiator valve

Place an old cloth, or a towel, under the bleed valve, and insert the bleed key. It is to catch water and protect your flooring from discoloured water.

Open the bleed valve and release the air

open bleed valve

Close the end of the inlet and outlet valve. Then remove the screw from the centre of the valve. Now, insert the radiator key into the bleed valve and turn it anti-clockwise. The air will be able to escape, which will cause a hissing sound. Hold the cloth next to the valve to catch any drips.

Close the bleed valve on the radiator

When the hissing has stopped and water has started to leak, close the bleed valve on the radiator by turning the key clockwise.

Bleed your other radiators

Do the above-explained steps for each radiator that need bleeding.

Check the boiler pressure

check pressure

Once all radiators have been bled, you must check the boiler pressure now. If the pressure in the boiler is low, repressurize the system. You can turn on the heating if the pressure is between 1 and 2 bars.

Turn on your boiler for a final check

Once you repressurize the boiler to normal, you can switch your heating system on. If you find there are still some cold areas at the top of the radiator, repeat the process.

Are your radiators still cold after bleeding?

In case the problem remains, consider seeking professional help immediately. A highly trained and experienced engineer can find the source of the problem and repair (or replace) your radiator in little time.

How to Bleed a Radiator – FAQs

Why do radiators need bleeding?

Radiators need to bleed when they have air trapped inside of them. This trapped air prevents warm water from circulating on your radiator. When this happens, the radiator can become cold at the top but remain warm at the bottom. It will decrease efficiency in your central heating system and can cause your room to take longer to warm up.

What does a bleeding radiator mean?

When your radiator makes strange noises like gurgling or banging, it may be time to bleed it. Bleeding a radiator releases air that has become trapped in your heating system. This will help you heat your home more effectively.

How to Bleed a Radiator

By inserting the radiator key into the valve and turning the valve anti-clockwise, you will release the trapped air within it. It allows the heat to circulate more efficiently once you turn heat on.

Do You Bleed Your Radiators With The Heating On Or Off?

Before bleeding a radiator, make sure your boiler is switched off and the radiators are cold.

How Often Should You Bleed Your Radiators?

Bleed radiators at least once a year before the winter months arrive. This way you will be well prepared before the temperature begins to drop.

How Long Should It Take To Bleed A Radiator?

Depending on the size of the radiator and the amount of trapped air, this process should take 20 to 30 minutes.

Can I use automatic radiator valves to bleed my radiators?

You can bleed some radiators automatically, but not all models offer this feature. However, if your radiators have an automatic valve, this will keep them running efficiently.

What happens if you bleed the radiator with the boiler on?

If the radiator is too hot to touch or the valve is dripping hot water, there is risk of getting burned.

If you properly bleed a radiator, there is a good chance that your boiler will heat up without any problems. After following these directions your boiler still isn’t heating up properly, it may need to be replaced by a certified boiler specialist. You can contact us if you need a professional for a new boiler installation.

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