How do I bleed a radiator?

Before answering the question “how do I bleed a radiator?” we should probably explain why your radiators may need bleeding, the signs to look out for, and then give you the detail on what you will need and, of course, how to do it.

Afterall, we would hate you to take precious time from your day if your heating issue is actually something completely different!

Maintaining your radiators is part and parcel of an effective central heating system. However, like many other household tasks, it often slips down the list of importance, going unnoticed, until something goes wrong.

We pay attention to our boilers and soon notice when they’re not working. Yet we forget about the radiators themselves – ironically, the things we see and possibly even touch every day. Many don’t even consider asking ‘how do I bleed a radiator?’ before calling a professional in to fix their heating problems. Or else they leave them only partially working which could be costing more than necessary, in terms of bills and discomfort, especially at this time of year.

Why does my radiator need bleeding?

Without going into too much of the science behind it, we’ll simply say that air can naturally become trapped inside your radiators when new water enters the heating system, with movement caused by the central heating pump, or even when repairs and maintenance are being carried out.

What does this mean? If the air is not released, the heating system has to work harder than normal to produce the same level of heat. As air bubbles expand, the heating becomes even less efficient, and we eventually notice that the temperature is cooler within our homes.

Bleeding the radiator allows the trapped air to escape and the hot water to flow efficiently through the heating system once again.

How will I know if my radiator needs bleeding?

There are a number of signs  which will tell you air is trapped in your radiators:

• If your radiators are colder at the top than the bottom
• If they take longer to heat than normal
• Your radiators are making strange noises – rattling, banging, gurgling. Bleeding your radiators will be the first check, but these noises could be a sign of other issues, so do not ignore them.
• Worst case is that they don’t heat up at all when your central heating is switched on. This is when things get urgent, and panic mode sets in! It is advisable to call a plumbing and heating expert at this stage if you are not sure about what to do next, which is where Supreme Plumbing & Heating can step in and help
• Damp or mould patches - bleeding your radiator might not be the final resolution in this case, but it could be an indication that your radiators need inspecting and potentially further maintenance. Again, this is something you do not want to leave to build up, as it can cause health issues as well as additional and unnecessary structural damage.

What do I need to bleed a radiator?

When people ask, “how do I bleed a radiator?” they imagine it’s going to get messy and will take longer than it actually does.

Much as we love seeing our existing and, of course, new customers, we wanted to share this post with you, to encourage you to keep an eye on your radiators yourself. To help you avoid any unnecessary and unexpected costs of calling out a plumber or heating engineer.

You only need a few things to bleed your radiator:

• Radiator key (or flathead screwdriver)
• Cloth or towel to cover the radiator valve when you’ve released the pressure
• You might want to put a bowl or mug on the floor to catch any pesky drips (we’ll explain why below)
• Some advise safety gloves, but as long as you make sure your heating is switched off and the radiators are cold, you should not burn your hands on the radiator or any hot water which may escape during the process

So, now you know the reasons a radiator may need bleeding, what signs to look out for, and what you will need, we’re ready to answer, “how do I bleed a radiator?”

How do I bleed a radiator? – Follow these 7 steps

1. If you don’t know which radiator needs bleeding, turn your heating on and wait for them to get warm. You will then be able to feel, or even hear, which ones have air trapped. Remember, the more radiators you have, the longer this step will take.
2. Turn your heating off and wait for the radiators to cool down. This is essential, as the radiators could burn, and the water inside could scold.
3. Make sure you have a cloth to hand, and your bowl or mug on the floor directly underneath the radiator bleed valve.
4. The bleed valve is usually at the top corner of the radiator (look for a round hole with a square or straight line within). Turn the valve anti-clockwise to release the air. You should hear a hissing sound.
5. Wait until the hissing stops and water starts to leak out (this has cleared the trapped air), then turn the valve in a clockwise direction to close it. (This is where you could need that bowl on the floor if you’re not quick enough to close the valve before a little water comes out!)
6. Repeat this for each radiator that needs bleeding, although a pre-winter check might be a good idea for all your rads even if you think everything’s working fine.
7. Finally, check the water pressure on your boiler. If the pressure gauge is below one bar, you will need to repressurise the system. If the reading is normal (1 – 2 bars) turn your water and heating back on, put your feet up with a cuppa, and get yourselves cosy once again!

Supreme Plumbing & Heating Final Recommendations

We recommend bleeding your radiators at least once a year, but certainly before the colder weather settles in. You don’t want to get caught out just as winter starts.

If you are left with any queries after this “how do I bleed a radiator?” post, or would like any further information on any of our plumbing and heating services, please do not hesitate to contact us here at Supreme Plumbing & Heating. We are your local Gas Safe Registered experts and close at hand in an emergency, or just for some friendly advice.