Bleeding a radiator

If you encounter noise problems on your radiators or notice that they do not heat at the same temperature everywhere, it is likely that they need to be purged. Bleeding a radiator allows air to be evacuated inside. It is recommended to do this at least once a year to optimize the performance of the installation. We will see more precisely when and how to purge a radiator.

Bleed radiators before heating

It is recommended to carry out this operation once a year, generally before restarting its heating. After winter, air may have entered the circuit and take the place of water. Consequently, we can end up with radiators that hiss or heat less well (for example, which are colder at the top than at the bottom). In general, a purge can solve these problems and optimize the performance of its installation. Radiators that are well maintained will save you money and extend the life of your boiler, which will be less stressed.

How to purge a radiator?

Now that we have seen the time to perform the purge, we will see how to proceed. This operation can be done very easily yourself. It must be done cold, and your boiler must be stopped.

1) You will need only 2 tools:
– A clamp or a screwdriver
– A small container

2) The majority of radiators are now equipped with a trap, this is a small screw surrounded by a white contour that is at the top of the radiator, opposite the pipes. To bleed, simply turn this screw with your screwdriver until the air comes out of the radiator. On older transmitters, you will need a clamp. A little water will flow at the same time (hence the need to have a small container next to it), it is necessary to let the equivalent of a small glass to pour well.

Method for purging a radiator

Location of the trap on a radiator
If the water coming out of your radiator is dark, your installation may be tapped. Sludge is accumulated over time in your network and prevents the proper circulation of water in the circuit. In this case, we advise you to carry out an unblocking.

3) Once the operation is finished, you just need to screw back and you’re done! It is advisable to start with the radiator located closest to your boiler and to finish with the furthest. Once you have restarted your boiler, make sure you have tightened the screws of all your radiators.

Check the pressure in the heating circuit

After purging your radiators, also consider controlling the pressure level of your boiler. It must be between 1.5 and 2 bars. If you see that the pressure is too low, simply open the faucet on your boiler (accessible below the appliance) to raise the level.


Purging radiators is therefore a rather simple operation. If you think of doing this every year before restarting your heating, your radiators will transmit heat better and you will avoid overconsumption.

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