How Do I Clear an Airlock in my Pipes?

How Do I Clear an Airlock in my Pipes?

Posted on June 16, 2021

Is your hot water on the blink? A cold spot on your radiator? You might have an airlock in the pipes of your hot water or heating system.

What is an airlock?

An airlock is when air becomes trapped in the system. The air in the pipe creates a blockage which gets in the way of the hot water trying to make its way around the central heating system or to your taps.

Airlocks in your hot water system will stop water from coming out of the affected tap. An airlock in your central heating system will results in some or all your radiators having cold spots or failing to heat up properly.

What are the signs of an airlock?

If you have an airlock in your system you might find yourself with the following issues:

  • Getting no hot water from your taps or the shower
  • Hot water taps spluttering out water when turned on
  • Radiator(s) with cold spots

How do I clear an airlock from my hot water system?

You’ll be pleased to know that this is an issue you can probably solve yourself, without having to call out a heating engineer. However, if you are in any hesitation whatsoever about any of the methods below, please do not attempt to do it yourself and instead, call a professional heating engineer.

You’ll be spurred into action if you turn your hot water tap on and find that nothing is coming out. Here are two ways to try and clear the air from your hot water system.

How to Clear an Airlock – Technique 1:

If you suspect an airlock in your hot water system, this is the first thing to try.

Equipment needed:

  • 1m garden hose pipe
  • Duct tape


  • Using one of the sinks in your home, attach the hose pipe to the hot tap where the water comes out with the duct tape. Make sure it’s secure.
  • Turn on the hot tap.
  • Turn on the cold tap for up to 5 seconds and then turn it back off.
  • At a sink in another room, turn the hot tap on and let it run.
  • Repeat this process between 5 and 8 times.
  • Test the original hot tap and see if the hot water is working. If it is the congratulations – You have successfully cleared the airlock in your hot water system! If there’s still no hot water coming out, then read on for something else to try.

How to Clear an Airlock – Technique 2

The hose pipe trick doesn’t always work – But don’t worry! Give this method a go instead. No equipment needed!


  • Turn off your water supply at the mains.
  • Starting from the top floor in your home and working your way down, turn on all the taps.
  • Wait until the water stops flowing from all the taps.
  • Go to each of your bathrooms and flush the toilet(s) until there is no water left.
  • Go around all your taps and turn them so they are almost completely off, making sure that only a tiny amount of water can get through.
  • Turn you water supply back on at the mains.
  • Turn all your taps to halfway open.
  • Turn all your taps open all the way.
  • Check to see if you have hot water from any of your hot water taps and then turn them all back off again. If you’ve got hot water flowing, then you’ve managed to force the trapped air out of your hot water system and got everything back in working order.

If the above two techniques don’t clear the airlock in your system and you’re still not getting any hot water out of your taps or shower, then now it’s time to call in the professionals. Get in touch with a heating engineer and let them sort the problem for you.

How do I clear an airlock from my central heating system?

As we explained above, if you are experiencing cold spots on one or more of your radiators, particularly if it’s at the top, then it’s a strong possibility that you have an airlock in your pipes.

The air in the pipes causes a blockage which stops the hot water from being able to circulate around your heating system properly and effectively heating your radiators.

Rather than putting additional strain on your boiler by turning your heating up, see if clearing a potential airlock from your heating system solve the problem.

Clearing an airlock from your heating system is something you can do yourself rather than calling a professional heating engineer. You’ll need to just bleed your radiators.

How to Bleed Your Radiators to Clear an Airlock From Your Heating System

Fortunately, this is also something you can safely do at home yourself.


  • Radiator key – You can get these from all good DIY shops, usually for less than £3.
  • A towel
  • A small bucket or pot to catch water


  • If your central is on or is likely to come on, turn it off.
  • Make sure all the radiators have cooled down.
  • Find the bleed valve on the radiator.
  • Place the bucket or pot underneath the valve to catch any water that might come out.
  • Using your radiator key, turn the bleed value anti-clockwise.
  • You’ll likely hear a hissing sound at this point – That is the air escaping.
  • Once this sound stops, you’ll find water will start to trickle out of the valve. When you notice the water, turn the valve clockwise until it’s closed (but not too tight).
  • Turn off the central heating and wait for it to cool all the way down.
  • Repeat all of the above steps for every radiator in your home.
  • After you’ve bled each radiator, have a look at the pressure gauge in your boiler – It should read approximately 1.5 bar (check the manufacturer instructions for your boiler if you’re not sure).
  • Make sure there are no signs of leaking anywhere around your boiler or any of the radiators.
  • Turn your heating system back on and check to see if the cold spots on the radiator(s) has gone. If it has you have successfully bled your radiators and got rid of the airlock. If the cold spot is still there, it may be due to sludge which will need to be resolved by a professional heating engineer.

Call the experts

Hopefully the above tips will have helped you to clear any airlock in your hot water or heating system. If not, then don’t hesitate to call in the experts and let a professional heating engineer help you to solve the issue. Perhaps the problem isn’t actually an airlock – In which case the heating engineer will be able to diagnose the fault and advise how it can be repaired.

Here at Aura Heating our friendly, local heating engineers are experts with hot water systems, heating and boilers – Don’t hesitate to give us a call if you need any assistance.

Disclaimer: Please do not attempt anything you don’t feel confident with, and instead seek professional assistance if unsure.