How Do I Bleed A Radiator?

How Do I Bleed A Radiator?

Posted on June 27, 2021

Yes, we know, it’s June and we’re still talking about heating. But we wouldn’t blame you if you’d sneaked your thermostat up a bit today and nudged the heating to come on!

Summer (even a British summer!) is actually a great time of year to take a look at your heating system and get any niggles you had over the Winter sorted out ready for the next cold season.

During the Summer months we don’t rely as much on our heating as generally it’s warmer, so we don’t need to be heating our home. So not only will calling out a heating engineer now have less impact on your home life, they are also less likely to be in demand over the Summer months so you won’t have to wait as long for a call out as you might do in Winter.

Cold Spots

Last week we touched on cold spots on radiators and how they could be a sign of an airlock. If you noticed that some of your radiators had cold spots on them towards the end of the Winter (or now, if you’ve still got your heating on – No judgement here!) then it’s definitely worth bleeding your radiators and getting rid of any trapped air.

Also, whilst it’s not too hot but not too cold, it’s a good chance to check everything is in working order. If bleeding your radiators doesn’t get rid of the cold spots then it may indicate that there is another issue – In which case, now would be a good time to get it sorted out. 

Why would I need to bleed a radiator?

If you have cold spots on your radiator, particularly at the top, bleeding them is the first thing to try. Luckily, bleeding your radiators is an easy fix and something you can do at home yourself without needing to call a heating engineer.

Cold spots on your radiator are commonly caused by trapped air. This pocket of trapped air stops the hot water from being able to circulate around your radiator(s) properly, thus causing a cold spot.

This also means that your radiators won’t be able to heat up your rooms or home as effectively or efficiently as usual, which may prompt you to turn the heating up or fire up the boiler more often. Over a period of time, this will negatively impact your energy bills, causing them to go up.

So not only will bleeding your radiators enable you to heat your home better, it may also even save you money.

You might also have noticed a gurgling, clanking or banging noise coming from your radiators. If you’ve got noisy radiators like this, bleeding them is a good idea.  

It’s good to get in the habit of bleeding your radiators once a year, even if you think they are working properly. Releasing even a small amount of trapped air will stop it causing problems later on.

How do I bleed a radiator?

Bleeding a radiator is really straightforward and you should be able to do it yourself without calling a professional. However, if you don’t feel confident carrying out the steps below or are at all unsure, always call a heating engineer to carry it out for you.


You’ll only need a couple of things to be able to bleed your radiators.

          A radiator key – You can pick these up from any good DIY stores

          A small container or cloth to catch any water


You can bleed your radiators in just a few easy steps.

1.     – Make sure your heating is turned off, and the radiators have cooled right down. You should not attempt to bleed a radiator when the heating is on or it feels hot to touch as you could injure yourself on the radiator or any hot water that leaks out.

2.     – Using your radiator key, slowly turn the valve at the top of the radiator in an anticlockwise direction. The radiator key should fit easily into the square groove in the centre of the valve. Once the valve has opened, you will likely here a hissing sound when any of the trapped air escapes. When the hissing stops, some water may come out. Use your container or cloth to catch any water that leaks out.

3.       – Once only liquid is coming out of the valve and the hissing has stopped, quickly retighten the valve to stop too much water from escaping the system.

4.      – Switch your central heating back on.

5.      – Looking at the pressure gauge on your boiler, check the boiler pressure. Sometimes, bleeding your radiator can cause the pressure to drop. If the pressure is too low, then you will need to top it up via the filling loop which is a lever or tap on the boiler. Always check your boiler manufacturer instructions to see what your specific boiler pressure should read.

6.     – Go and check that your radiators have heated up properly, and that any cold spots have gone. If they are working effectively with no more cold spots, then you’ve fixed the problem!

If you find that after bleeding your radiators, you still have cold spots then it is likely being caused by something else. Call a professional heating engineer to come and diagnose the problem and get it resolved before Summer is over.

Here at Aura Heating we only use our own heating engineers, not subcontractors, so you can be confident that any call out will be from a friendly, local heating engineer that is professional and Gas Safe registered.

If you have any concerns about your heating system that you would like resolved over the summer months, please don’t hesitate to get in contact with us today.

As always, if you’re at all unsure about any of the steps in the method above, then leave it to the professionals and call out a Gas Safe registered heating engineer to take a look at it for you.