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Is your radiator cold at the top? Top tips on how to bleed a radiator!

December 16, 2019

Keeping your radiators running efficiently is essential to keep your home warm and cosy, even more so during the winter months. When your home is cold, you need to be able to know that your radiators will warm up quickly and also keep warm. With us, all relying on our radiators more and more during the winter months, issues such as radiators being cold at the top don’t always come to light until we need them the most. It can be handy for yourself to have some basic skills and knowledge about how to bleed a radiator. Within this how-to guide, we will show you how to fix radiators which are cold at the top in a few simple steps. All of which can help to improve the efficiency of central heating, cut down your energy bills and also make your home warmer.

What issues will bleeding a radiator help to solve?

Are you finding yourself asking ‘why is my radiator cold at the top’? If you start to notice that your radiator is cold at the top, then you may benefit from bleeding your radiator.

Be aware that cold at the bottom of the radiator could indicate something more serious, for example, silt may have become trapped in the system. If bleeding the radiator doesn’t fix the issue of it being cold, you should immediately call a professional in to fully inspect your heating system.

Bleeding your radiator is the process of letting out any air that has become trapped within the heating system. The trapped air prevents the water from heating the whole radiator, which can often lead to cold spots. If your radiator is hot at the bottom and cold at the top, then you may have trapped air causing the cold spot. In which case, in this scenario, you would benefit from bleeding your radiators and removing the trapped air.

Luckily, bleeding a radiator is a quick and easy fix, which can be done with just a towel and a radiator bleed key which is used to open up the radiator vent valve.

fixing radiator cold at bottom

How to successfully bleed a radiator?

Step one – turn on your heating system
It is essential to make sure that you turn on your heating system to make sure that your radiators are warmed up. You need to make sure that all of the radiators have warmed up properly to build up the pressure within the radiators as this will help to push the trapped air out.

Step two – work out which radiators require bleeding
You will need to go round your house and check each radiator individually looking for any cold spots. If your radiator is cold at the top, then this could be an indication of trapped air and would require bleeding. You may also notice gurgling sounds or rattles, and this is another indication that your system needs bleeding. If you find you are asking yourself, why are all my radiators cold at the top? Then you will need to bleed them all, and if this doesn’t solve the issue, then you will benefit from an expert professional, who will be able to find a solution as to how to fix your radiators from being cold at the top if bleeding has not worked.

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Step three – turn the heating system off
This step is important to ensure that you don’t burn yourself on the now scorching radiators. If you leave your heating on during the process of bleeding your radiator, then you could end up burning yourself with the hot water.

Step four – get prepared
It’s time for you to prep the area and lay down old towels. Sometimes when bleeding a radiator, you will find that the water may be dirty and therefore wherever possible you will want to avoid the water getting on your flooring.

Step five – open the valves
Using your radiator bleed key which you will find at many DIY shops open the bleed valve on the radiator. The bleed valves are often located at the top of the radiator or to the side, and the valve is a round hole with a square within. Turn the valve key anti-clockwise, when you begin doing this, you may notice the air escaping, be careful not to burn yourself with the hot air. When this happens, it can sometimes make a hissing sound, don’t be alarmed this is normal.

Step six – begin to bleed the radiator
Turn the valves to about a quarter to half a turn, avoid opening the valves completely because water will rush out. Keep the valves open this amount until all of the air has been removed from the system. You will know when the trapped air has been removed because water will begin to drip from the radiator. When this has happened close the valve by turning clockwise.

Step seven – repeat on the other identified radiators
During step two, we identified all of the radiators which were cold at the top, you need to repeat the process from step four to step six with the other radiators.

Step eight – now check your systems pressure
Now that you have bled all of your radiators and removed any trapped air that was causing your radiators being cold at the top, you are ready to re-pressurise your heating. Due to the process of bleeding your radiators, it is common for the heating system to lose some water. You will know if the pressure in your heating system is right because the needle on the boiler gauge will be pointing towards the green. If the needle is pointing yellow, you need to re-pressurise the system. You will need to find what is known as the central filling loop, which is on the boiler. It will look similar to tap and is connected to the water supply. Make sure you turn the tap slowly to make sure that the pressure is adjusted slowly. If you turn the central filling loop too much, it will make the needle on the gauge point red. You will then have to use the bleed tap to bring the pressure back into the green.

We advise you to bleed your radiators at the beginning of the heating season for maximum efficiency and to ensure that your heating is ready for when you need it. However, if you don’t feel comfortable bleeding your radiators or if you have and your radiator is still warm at the top and cold at the top then why not get a central heating engineer in to have a look for you.

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