Is there a radiator in your home that feels cold to the touch even when the heat is turned up high? This may indicate that there is trapped air in your radiator and it is constructing normal flow. Fortunately, this very common problem can be easily fixed with only a few basic tools.


Your radiator may require bleeding because it has air that is cool being trapped in its upper section. You will know there is an issue if after you turn on the heat, either the bottom portion feels warm while the top portion feels cold or the entire radiator feels cold. As a side note, a cold radiator can also indicate other issues. Therefore, it is important to also investigate all of the other common issues caused by non-functioning radiators. If none of the other issues seems to be a problem then your radiator may require only simple bleeding.

RadiatorAlways be cautious, radiators can become quite hot and it may be necessary to protect your hands before feeling for warmth. If you have more than one radiator in your home and they all are not functioning properly, it could mean that you have a bigger heating system issue. If you notice water accumulation below the radiator then the issue might be a leak.

Sometimes a leak can be fixed simply by turning off the heat and tightening all of the nuts on the radiator’s inlet valve. If you live in a home that has two floors and the radiators on the lower floor are functioning fine but the radiators on the upper floor are not, then it may be a boiler pressure issue.

Radiator Key

If you decide that the issue is simply a matter of bleeding the radiator, search for a radiator key to open up the bleed valve. The bleed valve will be at the top of one end of your radiator and it is a small valve. Most hardware stores carry radiator keys if you cannot find one. You need to use a radiator key that is the correct size. You can also open up the valve with a small wrench. Some of the more modern radiators come with valves that can be opened easily with a simple flat-head screwdriver. Remember, if you decide to bleed one radiator then you should also bleed every radiator in your home.

Heat – On/Off

Before you begin bleeding the radiator, it is important to turn the central heating switch off. An active central heating system will introduce more air into the system. You will want all of the radiator’s content to completely settle before you can release any trapped air within. Allow some time for the heat to dissipate. Check each radiator, top and bottom, for heat and if there is still warmth, allow it to cool down some more before proceeding to the next step.

Temperature of RadiatorRadiator Valve- Open

Turn both the exit and intake valves of your radiator to the open position. Next, put your radiator key into the bleed screw and turn it counter-clockwise so as to open the valve. You should at this time be hearing a hissing sound as any trapped air starts to escape from your radiator. As the air escapes, there will also probably be water sputter from the bleed valve. Simply place a cloth or kitchen towel underneath the bleed screw and catch any drips of water.

Once a steady stream, not sputtering, comes through the bleed valve it means that all of the air trapped inside of your radiator has been released. At this point, you can close the bleed valve by screwing it clockwise. Check to see that there are no additional leaks and then use a cloth to wipe up any excessive water.

You want to make sure that all of the excess air has been drained from your heating system by bleeding all of the radiators. This is important even if you are only having a problem with one radiator. In fact, it is important to bleed your radiators regularly for a well-maintained heating system. Normally, annual bleeding is adequate or if you have had any modifications or repairs recently done to your heating system then you should also use this as an opportunity to bleed the entire system. Your final step will be to make sure that the boiler’s pressure level is correct.