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Clearing an Airlock in Your Pipes – How to Do It?

If you are having problems with your water or you have noticed that your radiator has a cold spot, then you could have an airlock in your hot water or heating system pipes.

Airlock – What is It?

This is when air is trapped in your system. This creates a blockage that prevents hot water from moving around your system.

An airlock in your hot water system will prevent water from exiting the affected tap. If you have an airlock in your heating system then some or all of your radiators will have cold spots.

Signs You Have an Airlock?

If you have an airlock in your system, then you might have the following problems:

  • No hot water from your taps or shower
  • Water sputters out of taps
  • Cold spots on your radiators
  • Clearing an Airlock From Your Hot Water System

Fortunately, this is an issue that you can solve yourself. However, if you are unsure then it helps to call out an engineer.

Technique 1

For this technique you will require:

  • Duct Tape
  • Garden hose pipe – 1m in length

The Method

  • Select one of the sinks in your home and attach the hose to the hot tap using the duct tape, ensuring it is secure
  • Turn on the hot tap
  • Now turn on the cold tap for around five seconds and then turn it back off
  • Find another sink in the house and turn on the hot tap, leaving it to run
  • Continue this process for up to 8 times.
  • Then test the original tap and see if the hot water is flowing correctly. If so, then you have cleared the airlock.

Technique 2

If the hosepipe method doesn’t find success for you then you do have another option. You can try this method and you don’t even need any equipment!


  • Begin by turning off your water supply at the mains
  • Begin on the top floor in your house and then work your way down, turning on all of the taps
  • Now wait until all of the water has stopped flowing from the taps
  • Now go to each bathroom and flush all toilets until there is no water remaining
  • Go back to every tap and turn them so that they are almost closed but just open enough to let water flow through
  • Now turn your water supply back on at the mains
  • Then turn all of your taps so that they are halfway open
  • Now turn them so that they are fully open

Finally, check to see if you now have hot water from any of the hot water taps and then turn all of them back off again. If you do have hot water flowing then you have done the job and forced the trapped air out of your system and got everything back up and running again.

Should the two techniques above not work and the airlock still exists and you still do not have access to hot water from your taps or shower, then it is time to call on some expert assistance. You’ll need a heating engineer who can help to solve the problem for you.

Clearing an Airlock From Your Central Heating System

As explained above, if you are finding that you have cold spots on a single radiator or all of them, especially if the cold spot is at the top, then there is a high chance that you might have an airlock in your pipes.

The airblock in your pipes causes a blockage and that prevents hot water from moving around your heating system correctly and that means that it doesn reach your radiators either.

Instead of turning up the heating, which can add an additional strain to your system, you should see if you can clear a potential airlock from your system to see if this solves the problem.

Just like your hot water system, this is an issue that you can do yourself if you feel confident enough to do so. However, if you are unsure then it can help to call a heating engineer. So, all you will need to do is bleed your radiators.

Bleeding Your Radiators to Clear an Airlock – How to Do It

The good thing about this is that it is something you can do yourself safely at home.

The equipment you will need is:

  • A radiator key which can be purchased from a DIY store and is relatively inexpensive.
  • A towel
  • Small buck to catch water.


  • If your central heating is on or is likely to come on then you should turn it off
  • All of the radiators should be cool
  • Now find the bleed valve on the radiator
  • Place the bucket or even a pot underneath the valve to catch any water that could come out
  • Use the radiator key to turn the bleed valve in an anti-clockwise direction
  • You will notice a hissing sound and this is the air escaping.
  • After the hissing has stopped, water will begin to trickly out of the valve. Once you notice this water, you should then turn the valve clockwise until it’s closed but avoid overtightening
  • You should now repeat the steps above for every radiator in your home
  • After you have completed the process for each radiator, you should then look at the pressure gauge in your boiler – it should read around 1.5 bar, although you should make sure that you read the manufacturer instructions to make sure.
  • Next you should check to see if there are any leaks around the boiler and all of the radiators.
  • If there are no signs of a leak, then you can turn your heating system back on to see if the cold spot or spots have gone. If they have, then you have taken care of the problem. If it still exists then it could be caused by a build-up of sludge and that will need to be handled by a professional.

Don’t Hesitate to Call The Experts

All of the tips we have provided above should be enough to help you deal with the problem of an airlock in your hot water or heating system. If the problem still persists, then you should call in the experts and let a qualified engineer solve the problem. The issue might not be caused by an airlock and in this case, your engineer will be able to diagnose the problem and find a suitable solution.

At Prime Time Boilers, we are the experts in heating systems. So, if you need your boiler serviced, need a new boiler or want us to take a look at your system, then all you need to do is give us a call!

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