Airlock in Pipes? Here’s How to Clear It

An airlock in central heating system pipes is no joke! Winter is the worst time for you to realise that your heating system is not working. You’re cold and the water in the taps is torture on those freezing nights and frosty mornings. But if that happens, there is a good chance it is because there is an airlock in your pipes.

Not to worry, there are things you can do on your own and fix it even if you are not a very handy person when it comes to these things. We will walk you through some solutions. But before that, let’s understand the problem.

What Is an Airlock in Your Pipes?

As the name suggests, an airlock happens when your heating system traps some air in the pipes. This stops the material in your hot water systems and boilers from circulating. The heating process stops and you won’t get the expected result.

You need to release the trapped air from the system if you want your heating systems working as they are meant to. There are a few ways to do this yourself if you think you can handle it yourself instead of calling an engineer.

Ideally, you should take matters into your own hands only if you are completely sure that this is an airlock situation. Otherwise, it is best to contact a professional.

Once you are sure, here’s what you need to do.

Clear an Airlock from Hot Water System

There are a couple of ways to get the airlock out of a hot water system. Let’s take a look at both depending on what kind of taps you have to work with.

Method 1: For Separate Hot/Cold Taps in the Kitchen

If you don’t have a mixer tap, it means your hot and cold water taps in the kitchen are separate. For this method to work, you must turn on the hot water tap. If you don’t see water coming out, that means there is an airlock and this is what you must do.

If you don’t have a mixer tap, it means your hot and cold water taps in the kitchen are separate. For this method to work, you must turn on the hot water tap. If you don’t see water coming out, that means there is an airlock and here is what you must do.

Step 1: Both the taps must be turned off.

A simple place to star but easy to forget if you have been testing the hot water tap for an airlock.

Step 2: Connect them both to a hose.

A garden hose will suffice using the usual air-tight tap connector. Make sure it’s affixed tightly

Step 3: Turn on the hot water tap followed by the cold water tap.

This will make sure that the water coming out of the cold water tap will put pressure on the hot water system too. The airlock will be forced back into the water tank.

Step 4: Keep the cold water tap running for a couple of minutes and then turn it off.

This simple step will help to ensure any smaller air pockets are forced out of the system.

Step 5: Keep the hot water tap running for a couple more minutes to make sure the airlock has been taken care of and then turn it off.

Step 6: Remove the hose. You’re good to go. 

You may need to some small clean up of any water that’s leaked as a result of the process, but that’s it.

Sometimes this procedure takes more than one attempt to fix the airlock. Feel free to repeat the steps. If it doesn’t work after repeating it about three times, it is time to call a professional.

Method 2: For a Mixed Tap

Unlike the first method, if you have a mixed tap in your kitchen, here’s what you need to do.

  • Step 1: Cover your hands with a cloth and turn on the hot tap. The cloth is meant to control any water that’s going to come spilling out.
  • Step 2: Turn on the cold water tap slowly while blocking it. Because of the blockade, the cold water will come gushing through the hot water tap and in the process, it will push the air trapped inside the hot water tap back into the tank.
  • Step 3: Run the cold water tap for a couple of minutes and then turn it off.
  • Step 4: Run the hot water tap for a couple of minutes to make sure the airlock is cleared and then turn it off.

Once again, you might have to do this more than once. And if you’re not sure that this is an airlock problem, as you can see in the steps, you might injure yourself with boiling hot water.

How to Clear an Airlock from Central Heating System

This requires a little knowledge of how a plumbing system works. If you have that knowledge, well, we have something to work with. Otherwise, it is really best to call a professional rather than mess with the piping.

Method 1

This is the go-to method for anyone who is sure that there is an airlock problem in their central heating system.

  • Step 1: Turn the system off.
  • Step 2: If there are any motorised valves, open them with their respective latches.
  • Step 3: Switch off the part of the radiator that has a problem. You can do this at the end of the lock shield.
  • Step 4: You will need the bleed key to remove the existing pressure from the radiator.
  • Step 5: Remove the entire radiator bleed point with a towel covering your hands because there will be some amount of drip.
  • Step 6: At the point of the air bleed, attach a hose.
  • Step 7: Take the hose outside and run it.
  • Step 8: Locate the thermostatic radiator valves or the TRV end. It basically adjusts hot and cold water for your radiator to adjust the room temperature.
  • Step 9: Open this end and let it flush for 10 seconds. Meanwhile, listen for some air pressure sounds.
  • Step 10: Do the same at the lock-shield end and close both the valves.
  • Step 11: Remove the hose and install the bleed point back.
  • Step 12: Switch on the lock shield and the TRV.
  • Step 13: Unlatch the motorised valves and turn on the heating system to check if it worked.

Unlike the process for your kitchen hot water system, this should work in one go.

Know When It’s Time to Call a Pro

When you are handling your kitchen water system, there will be cases when it is the cold water tap that is airlocked. You can follow the same procedure but it might take some more time. You might want to check with a professional before you try the same.

And with the central heating system, well, you read the procedure. If any part of it is not making sense, it is best to call a professional instead of tinkering with the system.

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Last Updated on May 29, 2021

Frequently Asked Questions

What causes air locks in water pipes?

When air enters a central heating or home water system, it can build up in high points and stop the natural flow of water and when there is insufficient pressure to push the bubble through the pipe, you have an air lock. 

Can air in water pipes cause damage?

Air in water pipes will not usually cause any damage to a central heating or water system. It can be the source of annoying noise though. 


Author: Indra Gupta

Indra is an in-house writer with a love of Newcastle United and all things sustainable.

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