Occasionally there are problems with a central heating system that you can solve yourself.

Whenever the top of your radiator is cold and the underside is hot it in all likelihood implies that the radiatorradiator bleeding image requires bleeding. If you would like to check this take care to not burn your hand on the radiator.

If the radiator is virtually full of air, no divergence in temperature between the top and underside of the radiator will be experienced, but in these extreme situations, the whole radiator will be cool. This will be a direct contrast with the rest of your central heating system where the other radiators will be hot to feel.

You ought only bleed your radiator when there’s a problem such as that outlined above. If there’s no problem leave well alone.

How do I bleed a problem radiator?

The process for radiator bleeding is comparatively simple and safe. All radiators are supplied with a small-scale tool known as a bleed key. There will also be a extrusion near the top of the radiator, to one side, called the bleed valve. You need to open this valve a small degree to enable the air to leak from the top of the radiator while not enabling the water to flow out.

Whenever you plan to bleed a radiator in a sealed central heating system you should cut down the general pressure of the system (refer to your manual), this should not be a problem if you top up the system later on from the primary cold water feed.

TAKE CARE whilst twisting the valve. Have an old cloth available to protect your hand and a small bowl to catch any small beads of water which outflow. You do not need water dripping on to the carpet.

bleed radiator imageFirst switch off the heating or you could import more air into the heating system and radiators. Fit the bleed key into the bleed valve and cautiously twist it anticlockwise only a small turn, normally just a 1/4 or 1/2 turn. The air will start escaping with a hissing noise similar to a bicycle tire. When water starts to drip out, all the air is purged, and you can gently return the bleed valve to its originalposition. You should then remember to switch the heating back on and ensure that there are no leakages from the radiator valve – did you tighten it once more?

As said earlier if the central heating system was a sealed system, check the pressure and top up wherever necessary by referring to your system manual.

The video below will give you a visual guide of how to bleed your radiator.

If radiator bleeding doesn’t seem to improve the operation of your heating, particularly if numerous radiators in your household are malfunctioning, there may be a different problem.

7 Responses to “Radiator Bleeding”

  • georgeJ:

    Wish I had read the tip about having the old rag and small bowl ready before.

    I did my own radiator 3 months ago and a lot of the water landed on the carpet creating a large stain.

  • questioning:

    Is this included in boiler care contracts?

  • Boiler Care Guide:

    No, this is one of the tasks which can easily be done by the householder or one of their family who is comfortable with d.i.y.

    Boiler care contracts deal with the more complex problems and gives you peace of mind with frequent safety and maintenance inspections.

  • Garry:

    I have model 35cdi on a few occasions I have had to press reset button and bleed radiators. BUT recently heating has been in OFF position and one morning i awoke to find reset flashing ,water pressure had dropped and digital reading was 23, I turned kitchen tap on and noticed pressure down then I pressed reset button everything appeared ok and later on in afternoon pressure gauge had risen back to previous day.. What I would like to know is the supply water pressure to the boiler an importaint factor OR is something faulty
    Hope you can answer
    Thanks GARRY

  • Boiler Care Guide:

    The water supply pressure to a combi boiler is important, they all have water pressure minimum requirements as advised by the manufacturer. With lower water pressures the hot water flow rate is reduced. If the supply ceases there is no hot water.

    If you investigate and discover that there has been no change in the water supply pressure you should call in an expert to review the operation of the boiler.

    If you have previously taken out a boiler care agreement with appropriate cover you should call in an engineer.

  • julie payne:

    when bleeding radiators do you need to turn the pump off aswell as the heating or is it ok to leave the pump on?

  • Boiler Care Guide:

    When the article states turn off the heating we mean the boiler and the pump.