How to Drain a Radiator

By Megan

3rd Jun 2024

7 mins read

DIY & Technical

Draining a radiator is important to ensure that your radiator is well maintained and is working efficiently. However if you haven’t done this before you may not know where to start. By following our step by step guide you will be able to safely and correctly drain your radiator.

How to Drain a Radiator

Draining your radiators is one of the best ways to maintain them and ensure that they are working as efficiently as they should. It is recommended that you drain your radiator once a year to remove any sludge or debris that may be in the water. Doing this in the summer months when you do not need to switch the heating on is the best way to ensure that you have efficient working radiators by the time winter rolls back around.

However, you should also drain your radiator if you are planning to move it for painting or replace your radiator entirely. That is why it’s important that you know how to drain your radiator safely and correctly to avoid any big messes or potentially damaging your radiator. 


How to Drain your radiator in 7 simple steps


What You Need

What you need
  • Buckets
  • Old towels
  • Pliers or grips
  • Spanner
  • Radiator bleed key


Step 1 - Prep


The first and one of the most important steps is to make sure that your heating is switched off and the radiator is cool. Otherwise you might scald yourself with very hot water. 

With the heating off and the radiator cool, you can start to prepare the surrounding space to avoid any water spillages or damage. 

You will see two pipes on each side of the radiator, this is where the water passes through the radiator and allows it to heat up. Place your old towels under each pipe then place buckets or containers under both pipes to catch any water that might spill out.


Step 2 - Shut Thermostatic Radiator Valve

Shut off valve

The thermostatic radiator valve is the self regulating valve that controls the temperature of the room. You can adjust this by turning the valve to make the radiator warmer or cooler. 

You want to make sure that this is closed by turning the valve until it reaches zero. This will completely shut off the thermostatic radiator valve.


Step 3 - Shut Lockshield Valve

Shut lockshield valve

On the other side of the radiator you will see the lockshield valve. This valve is usually covered with a plastic cap and is responsible for balancing the radiators within your heating system to ensure they all heat up at the same rate.

To turn the valve off, remove the plastic cap and use your pliers or grips to turn the valve clockwise until it is fully shut. Make sure to take note of how many times you turn the radiator to ensure that you can turn it back to the same setting to help balance out your system.


Step 4 - Remove Thermostatic Radiator Valve Nut

Remove valve nut

With both valves fully switched off, you can make a start of the disconnecting process. Be aware that some pliers or grips might damage the finish on the pipes and ruin the look of them, you can avoid this by placing some tape around the pipes.

Next you can remove the thermostatic radiator valve nut. Use your pliers or grips to hold the thermostatic radiator valve in place so that it is not able to move. Then, using your spanner, you can start to loosen the nut that connects the valve to the radiator.

This is when water will start to run from the radiator so make sure that your bucket is in place to catch the water.


Step 5 - Open the Bleed Valve

Open bleed valve

Now you want to take your radiator bleed key to open the bleed valve. The bleed valve is located at the top of your radiator at either the top left or top right side. Use the bleed key to turn the valve anti-clockwise to allow air into the radiator. This will help to flush out the water and any sludge that might be inside.


Step 6 - Remove the Lockshield Valve Nut

Remove Lockshield Valve Nut

Turning your attention back to the lockshield valve on the other side of the radiator, you can remove the lockshield valve nut. Similarly to the thermostatic radiator valve nut, you will need to use your pliers or grips to hold the valve steady. Then you can use your spanner to remove the nut from the radiator. 

Again, you will need to be prepared for water to rush from the radiator so make sure you have your bucket ready and your towels in place, just in case!


Step 7 - Drain any Remaining Water

Drain remaining water

Last but not least, you will need to drain any remaining water that is left in the radiator. With both of the valves disconnected, you will be able to tilt your radiator up from one side and allow the water to run out into the bucket. If your radiator is heavy make sure to ask for assistance to avoid a nasty injury.

And there you have it, you have drained your radiator!


How to Drain a Radiator With a Drain Valve

Some radiators will have a handy drain valve which will make the drain process easier. These are the 4 simple steps to drain your radiator with a 


Step 1 - Turn off the Heating

The first thing to do is make sure that you have switched off the heating and let all radiators cool down. Then, you will need to switch off the water supply. 


Step 2 - Locate the Bleed Valve

With the heating switched off, you will be able to start the draining process. At least one of the radiators in your home will have a bleed valve at either the bottom left or bottom right side. Once you have found the bleed valve, connect a hose pipe using clips and lead the other end of the hosepipe outside or to a bucket.


Step 3 - Open Radiator Valves

Next, you want to make sure that both the thermostatic radiator valve and lockshield valve are open on all of the radiators in your home. You can also open the bleed valves on any of the other radiators to help speed up the process.


Step 4 - Open the Drain Off Valve

Now you can open the drain off valve with the connected hose pipe to allow the water to run from the system. Then you just need to wait for the water to drain out of the system completely and you will have successfully drained your radiator. 

Once fully drained, you can close the bleed valves and the drain off valve and start refilling the system. 

White radiator on green wall

Reconnect Radiator

Now that you have successfully drained your radiator, you can reconnect your radiator and refill it, most conventional radiators will do this automatically. Don’t forget to carry out this process every 12 months to ensure that our radiator is well maintained. 

Or perhaps it's time to rip out those dated and dingy radiators and replace them with some efficient modern radiators. After you have drained your radiator you will be able to remove it completely, making way for your new one.



Megan is an expert bathroom blogger, she enjoys writing helpful DIY articles and bathroom inspo blogs. As well as specialist bathroom advice, Megan also shares expert how-to blogs with step by step guides.

Related Stories