How To Drain A Radiator In 8 Steps


Did you come across this article because you were searching for "how to drain a central heating system myself" Well if you did, you have come to the right place.

Regular maintenance of your central heating system is crucial as it will ensure your house is properly and efficiently heated during the cold winter months. Maintenance will also ensure there are no surprises or problems that arise.

Fortunately, should a problem occur, more often than not, simply bleeding your radiator could be a quick fix. For larger problems, such as the build-up of sludge or leaks in your central heating system, you may have to drain your central heating system completely.

Whether you want to replace your radiator, upgrade your bathrooms, or carry out regular radiator maintenance, we have created this guide so you can safely drain your radiators by yourself.

Tools Required

Here is a complete list of tools and plumbing supplies required when you drain your central heating system (or just a single radiator). Apart from these items, you may need an assistant to help you bleed valves safely.

Two containers small enough to fit beneath the radiator pipes but large enough to catch the water.

  • Two or more old towels that could get dirty, as well as additional cloths to wipe up dirty water.

  • A notepad and pen to record how many times you turn the lockshield valve.

  • A container to contain the radiator valves, nuts and other parts.

  • A pair of pliers or grips and an adjustable spanner to loosen the nuts.

  • Radiator bleed key to open the radiator bleed valve.

  • Gloves with grip.

  • Plastic bucket and a bin bag for any rubbish.

  • Adhesive tape.

    8 Steps To Drain Your Radiator

    Steps to drain your radiator

    Here are the eight steps involved in successfully draining your radiator.

    • Turn off the central heating system

    Before you get started, you have to turn off your central heating system and also give the system time to cool down for an hour or more.

    This is to prevent burning yourself with scalding water when you bleed the radiator.

    • Prepare to drain the radiator

    When the radiator is cool, start preparing for the work you have to do.

    Look for the two pipes on both sides of your radiator. The one pipe with the temperature control receives the hot water from your boiler, and the other with the lockshield valve returns water to the boiler.

    Fold your two old towels and place one under each pipe. Set your containers to catch water on top of the towels. This prevents you from causing a mess and any puddles once you loosen the pipes.

    • Shut the thermostatic radiator valve

    Once the system is cool, and your containers and towels are in place, you are ready to start.

    Close the thermostatic radiator valve (TRV) by turning it clockwise until you reach zero.

    • Shut the lockshield valve

    Move to the other side of the radiator and close the lockshield valve.

    To do this, remove the plastic protective cap. Using your pliers or spanner, turn the valve clockwise. Note how often the valve is turned to close, and note this on your notepad.

    This will ensure that all your radiators are balanced when you reattach the one you are working on or install a new radiator.

    • Remove the thermostatic radiator valve nut

    Now that both radiator valves are off, it is time to start disconnecting the radiator. You can use adhesive tape to protect the pipes during these steps.

    Start on the side with the TRV. Using your pliers, hold the valve steady, and use your flat spanner to wiggle loose the TRV nut, which connects the valve and the radiator.

    Water will begin to flow from the radiator at this time, so be ready with your container and towel.

    • Open the bleed valve

    Take your special bleed key and open the radiator bleed valve by twisting it in an anti-clockwise direction to allow air to flow into the system. This will help more water flow from the radiator and speed up the process.

    • Loosen and remove the lockshield valve nut

    Move to the other side of the radiator where the lockshield valve is located. Like the TRV nut, lift the plastic cap, use the pliers to hold the valve in place, and loosen the nut using the adjustable spanner. Again, water will begin to flow out from the loosened nut.

    • Lift the radiator to drain it completely

    Now that both the radiator valves and the bleed valve are open and disconnected, you can lift your radiator and tilt it up on one side (ask your assistant to help), allowing all the water to drain.

    Catch this water in your bucket (and go empty it in your flower bed!).

    Well done, you have now safely drained your radiator.

    How Do I Drain My Radiator If I Have A Drain Valve?

    In the case of a radiator with a drain valve, the draining process is fairly similar but slightly easier.

    Start with turning off your central heating system. Next, cut the water supply to your system. You can do this at the boiler, or if you have a combi-boiler, you will have to switch off the main water supply to the house.

    One radiator in your house will have a drain-off valve on the bottom left or right corner. Once you have located the valve, attach a hosepipe to the valve using clips. The other end of the attached hosepipe should be in a bucket or outside.

    Ensure all the radiator valves are open on your other radiators, and then open the drain-off valve. Water will begin flowing into the hosepipe, and you can open the bleed valves on the other radiators to help speed up the process.

    Once all the water is out of the whole system, close the bleed valves and the drain-off valve and begin refilling the system.

    Why Should I Drain My Radiators?

    Why should I drain my radiator

    There can be multiple reasons why you have to drain your radiators.

    Perhaps you want to paint, repair or completely remove your radiator and install a new one. You may also notice your central heating system isn't working efficiently due to the build-up of radiator sludge, in which case draining the radiator is a great solution.

    Your radiator may also be leaking, and to fix it, you will first have to turn it off and drain it to locate the problem.

    No matter the reason, you will probably have to drain your radiator a couple of times throughout your life.

    It is important to remember that working with a hot water system can be dangerous, and if you are unsure of what you are doing, it is always best to phone the experts.


    How long will it take to drain my central heating completely?

    Depending on your system type, it can take between 20 minutes and an hour to drain your central heating system - or even a single radiator.

    Should I bleed all the radiators in my home?

    Regular maintenance of your central heating system is key. If you notice a problem with one radiator that is not heating efficiently, then bleeding all the radiators in your home will be worth it. It will save you from having to bleed or drain each radiator separately if problems arise.

    Can I drain my radiator with the central heating system on?

    You should never drain your radiator while the heating system is on. This will increase your risk of burning yourself or having scalding hot water sprayed onto you. It is best to switch off the heating and wait an hour for it to cool down before doing any work on your radiators.

    How often should radiators be bled?

    Air naturally builds up in the heating system. This means you will have to bleed your radiators fairly regularly. We recommend bleeding your radiators at least twice yearly to keep them efficient. Maintaining your central heating system needn't be hard as long as you completely drain your radiator regularly - no more interruptions for your hot water supply are guaranteed.