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How To Bleed A Radiator

Is your central heating not working as efficiently as it used to? This is likely to be a sign that your radiators need bleeding.


How to bleed a radiator

Signs Your Radiator Needs Bleeding


If the radiators in your home aren’t heating up properly, or you notice cold spots or that they’re getting warm at the bottom but staying cold at the top, it’s a sign that it’s time to bleed your radiators. While some level of noise when you turn your heating on is normal, if you notice a gurgling, bubbling, or ticking noise this is also a sign that your heating system isn’t running efficiently.


Another sign to look out for is if your energy bills are higher than expected. If your tariff has stayed the same and you haven’t turned up your thermostat or had your heating on more than usual it’s likely that your central heating is inefficient and that it’s time to bleed your radiators.


What Happens When You Bleed Your Radiators


Bleeding your radiators gets rid of any air pockets that are preventing hot water from circulating

around your central heating system efficiently. It allows any trapped air to escape and allows you to enjoy a more comfortable home without paying more for your energy bills.


Step By Step Guide To Bleeding A Radiator


Before you start bleeding your radiators, you’ll need a radiator bleed key (which can be bought for under £5 either online or from any hardware store) and an old cloth or jug to catch any water that escapes.


If you’re bleeding more than one radiator, it’s best to bleed the downstairs radiators first and then move on to the ones upstairs. For the best results, start with the radiator furthest away from your boiler on each floor. Make sure your heating is turned off and all radiators are cold before you begin to prevent hot water from spraying out.


Once your radiators are cold, you have everything you need, and you know which radiator you’ll be starting with, it’s time to begin.


  1. Hold your cloth or jug under the bleed valve and insert the bleed key

  2. Turn the key anti-clockwise until you hear a hissing sound (this allows trapped air to escape)

  3. When water starts escaping, turn the key clockwise to close the valve

Repeat this process on your other radiators as necessary, making sure to leave the valve open until you hear a hissing noise. Turn the heating back on and check that your radiators are now working correctly.


You may notice that bleeding your radiators causes your boiler pressure to drop. If it’s dropped below 1 bar you’ll need to top it up so that the gauge on your boiler shows between 1 - 1.5 bars. Check your boiler instruction manual for how to do this, you may need to attach a filling loop or one may already be in place.



Signs You Need To Call A Professional


If your heating problems persist after you’ve tried bleeding your radiators, you’ll need to have your central heating system drained and flushed by a professional. This clears a material called magnetite, which is a dissolved metal that appears as black sludge in your radiators. Magnetite naturally builds up over time and can’t be cleared by bleeding.


If you find that your radiators need bleeding more than once a year it’s worth having your heating system checked out by a professional. They can identify any underlying causes that will save you time and money in the long run.


What To Expect After Bleeding Your Radiators


After bleeding your radiators, they will heat up evenly and you should no longer hear any gurgling, bubbling, or ticking noises when you turn on your heating. Setting a reminder to repeat the process once a year will keep your heating system working at its best and prevent any inefficiencies before they occur.


Releasing air will allow your heating system to function at its best, so you can enjoy a higher level of comfort for a lower cost. If you want to save even more money on your energy bills, why not join our Heatio Energy Challenge Group? This is where we share new and innovative ways that you can reduce your bills while still enjoying a warm and comfortable home. Find out more here.


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