Clearing an Airlock in Pipes: How can you do it yourself?

Frosty mornings, freezing days, bitterly cold nights. Not the time of year you want your radiators running cold or your hot water taps not running at all. But that’s exactly what can happen if you get an airlock in your pipes.

What happens when you get an airlock in a pipe?

If air gets trapped in your central heating or hot water system, this can stop hot water from circulating, causing radiators to stop heating up and hot water taps to stop running. Getting the hot water flowing again requires releasing the air out of the system.

How to clear airlocks from your pipes

We’re assuming that you don’t want to go to the hassle and expense of calling out a heating engineer to sort out the problem. But let’s state right here that, if you’re not sure your problem is caused by a pipe airlock, or you’re not 100% confident you can deal with the problem yourself, it’s always best to call out a professional.

Still reading? That must mean you’ve decided not to look for the contact details of your nearest, highest-rated heating engineer. Though please note if you have one of our home boiler covers, then just call us, and we will get the job done for you. 

OK. So let’s look at two ways you can release the trapped air from your hot water system yourself.

Clearing trapped air from your hot water system: Option A


  • A hose pipe that’s at least 1metre long
  • Gaffer/duct tape


STEP 1: Make sure your hot water supply is turned on.

STEP 2: Choose one of your sinks and connect the hot tap outlet with the cold water tap using the hose pipe and tape.

STEP 3: Ensure the open ends of the hose are where the water comes out and secure them using more tape.

STEP 4: Now turn on the hot water tap.

STEP 5: With the hot tap still running, turn on the cold tap and let it run for about 5 seconds before turning it off.

STEP 6: Head off to another sink in the house and run the hot water tap there.

STEP 7: Repeat this process at least 5 times.

You’ll be able to tell if this method has worked because your hot water should be back working. If not, don’t give up, as we've got another method you could try.

Clearing trapped air from your hot water system: Option B

Here’s an alternative way to get your hot water system working again:

STEP 1: Turn off your water supply at the mains.

STEP 2: Turn on every tap in the house, starting at the top and working your way downstairs.

STEP 3: Wait for the water to stop flowing out of the taps.

STEP 4: Now flush all the toilets until no water is left there either.

STEP 5: Turn your taps almost off until only a small amount of water can trickle out.

STEP 6: It’s time to turn your water supply back on.

STEP 7: Now turn on all taps halfway.

STEP 8: Then fully open up all the taps.

This is a process that should force out any air that’s trapped in your hot water system, allowing the hot water to flow out of your taps again. 

If neither of the above methods has done the trick, you’ll need to contact a heating engineer to resolve the problem.

Clearing an airlock from your central heating system

If some or all of your radiators aren’t heating up, or are only doing so from the bottom, it’s a sure sign that air is stopping the circulation of hot water. What you need to do in this case is to bleed your radiators. Here’s how:

STEP 1: Turn on your heating so all the radiators warm up.

STEP 2: Find out which radiators aren’t working. Those with cold areas or ones that are making gurgling noises are likely to have trapped air.

STEP 3: Now turn off your central heating.

STEP 4: Prepare for the bleeding process by putting towels down by the radiators to stop water staining your flooring.

STEP 5: Open the radiator bleed valve – this is usually found at the top of the radiator to one side and looks like a round hole with a square inside. Insert your radiator bleed key into the square slot and turn it anti-clockwise up to halfway round (no further). You should hear a hissing sound which is a sign that trapped air is escaping.

STEP 6: Hold the radiator bleed key in place until the hissing stops and until only a little water drips out.

STEP 7: Turn the radiator key back clockwise to seal the radiator.

STEP 8: Repeat the above steps for each of the radiators that you’ve identified as not working properly.

STEP 9: Finally, check the pressure of your heating system.

If bleeding your radiators yourself doesn’t fix the problem, you should call in a heating engineering expert. If you have the home emergency boiler cover with us, then you will be totally covered.

Here’s hoping you clear the air from your pipes and enjoy a snug and happy winter!